HAP.h

// Copyright (c) 2015-2019 The HomeKit ADK Contributors
//
// Licensed under the Apache License, Version 2.0 (the “License”);
// you may not use this file except in compliance with the License.
// See [CONTRIBUTORS.md] for the list of HomeKit ADK project authors.

#ifndef HAP_H
#define HAP_H

#ifdef __cplusplus
extern "C" {
#endif

// Core features.
#ifndef HAP_IP
#define HAP_IP 1
#endif
#ifndef HAP_BLE
#define HAP_BLE 1
#endif
#if !HAP_IP && !HAP_BLE
#error "At least one of IP or BLE must be enabled at compilation time"
#endif

#include "HAPPlatform.h"

#if __has_feature(nullability)
#pragma clang assume_nonnull begin
#endif

/**
 * Compatibility version of the HAP interface.
 *
 * - If this version differs from the one returned by HAPGetCompatibilityVersion,
 *   the library is incompatible and must not be used.
 */
#define HAP_COMPATIBILITY_VERSION (7)

/**
 * Gets the compatibility version of the HAP library.
 *
 * - If the compatibility version differs from HAP_COMPATIBILITY_VERSION,
 *   the library is incompatible and may not be used.
 *
 * @return Compatibility version of the HAP library.
 */
HAP_RESULT_USE_CHECK
uint32_t HAPGetCompatibilityVersion(void);

/**
 * Gets the identification of the HAP library.
 *
 * @return HAP library identification string.
 */
HAP_RESULT_USE_CHECK
const char* HAPGetIdentification(void);

/**
 * Gets the version string of the HAP library.
 *
 * @return Version string of the HAP library.
 */
HAP_RESULT_USE_CHECK
const char* HAPGetVersion(void);

/**
 * Gets the build version string of the HAP library.
 *
 * @return Build version string of the HAP library.
 */
HAP_RESULT_USE_CHECK
const char* HAPGetBuild(void);

/**
 * 128-bit UUID.
 *
 * - The encoding of UUIDs uses reversed byte order compared to RFC 4122, i.e. network byte order backwards.
 *
 * Sample:
 *   UUID: 00112233-4455-6677-8899-AABBCCDDEEFF
 *   bytes: 0xFF, 0xEE, 0xDD, 0xCC, 0xBB, 0xAA, 0x99, 0x88, 0x77, 0x66, 0x55, 0x44, 0x33, 0x22, 0x11, 0x00
 */
typedef struct {
    uint8_t bytes[16]; /**< UUID bytes in reversed network byte order. */
} HAPUUID;
HAP_STATIC_ASSERT(sizeof(HAPUUID) == 16, HAPUUID);
HAP_NONNULL_SUPPORT(HAPUUID)

/**
 * Returns whether or not two UUIDs are equal.
 *
 * @param      uuid                 UUID to compare.
 * @param      otherUUID            UUID to compare with.
 *
 * @return true                     If both UUIDs are equal.
 * @return false                    Otherwise.
 */
HAP_RESULT_USE_CHECK
bool HAPUUIDAreEqual(const HAPUUID* uuid, const HAPUUID* otherUUID);

/**
 * TLV type.
 *
 * - The type semantics depend on the context.
 */
typedef uint8_t HAPTLVType;

/**
 * TLV.
 */
typedef struct {
    /** Type. */
    HAPTLVType type;

    /** Value. */
    struct {
        const void* _Nullable bytes; /**< Buffer containing value. */
        size_t numBytes;             /**< Length of buffer. */
    } value;
} HAPTLV;

/**
 * TLV Reader.
 */
typedef HAP_OPAQUE(32) HAPTLVReaderRef;

/**
 * Creates a new TLV reader.
 *
 * @param      reader               An uninitialized TLV reader.
 * @param      bytes                Buffer containing raw TLV data. Will be modified by the reader. Must remain valid.
 * @param      numBytes             Length of buffer.
 */
void HAPTLVReaderCreate(HAPTLVReaderRef* reader, void* _Nullable bytes, size_t numBytes);

/**
 * Fetches the next TLV item from a TLV reader's buffer. TLV item content is NULL-terminated for convenience.
 *
 * @param      reader               Reader to fetch TLV item from.
 * @param[out] found                True if a TLV item has been fetched. False otherwise.
 * @param[out] tlv                  Next TLV item. Valid when @p found is true. Fragments are merged automatically.
 *
 * @return kHAPError_None           If successful.
 * @return kHAPError_InvalidData    If parsing failed (Incomplete item, or violation of TLV rules).
 */
HAP_RESULT_USE_CHECK
HAPError HAPTLVReaderGetNext(HAPTLVReaderRef* reader, bool* found, HAPTLV* tlv);

/**
 * Fetches TLV items by type into @p tlvs.
 *
 * On input, @p tlvs is a NULL-terminated array to TLV items.
 * For each TLV item, the type shall be specified. Types must be unique.
 *
 * On output, @p tlvs are updated to contain the actual TLV items.
 * If multiple TLV items with one of the requested types are found, an error is returned.
 * TLV item contents are NULL-terminated for convenience.
 *
 * - This API must be used on a freshly initialized TLV reader. All TLV items will be read.
 *
 * @param     reader                Reader to fetch TLV items from.
 * @param[in,out] tlvs              NULL-terminated array to TLV structures.
 *                                  On input, type filters are specified. On output, actual TLV items are filled in.
 *                                  For TLV items not found, values are set to NULL.
 *                                  Each type may only be requested once.
 *
 * @return kHAPError_None           If successful.
 * @return kHAPError_InvalidData    If parsing failed (Incomplete item, or violation of TLV rules), or if multiple TLV
 *                                  items with a requested type are found.
 */
HAP_RESULT_USE_CHECK
HAPError HAPTLVReaderGetAll(HAPTLVReaderRef* reader, HAPTLV* _Nullable const* _Nonnull tlvs);

/**
 * TLV Writer.
 */
typedef HAP_OPAQUE(32) HAPTLVWriterRef;
HAP_NONNULL_SUPPORT(HAPTLVWriterRef)

/**
 * Creates a new TLV writer.
 *
 * @param      writer               An uninitialized TLV writer.
 * @param      bytes                Buffer to serialize TLV data into. Must remain valid.
 * @param      maxBytes             Capacity of the buffer.
 */
void HAPTLVWriterCreate(HAPTLVWriterRef* writer, void* bytes, size_t maxBytes);

/**
 * Serializes a TLV item and appends it to the writer's buffer.
 *
 * - Multiple items of same type must be separated by an item with different type.
 *
 * @param      writer               Writer to append serialized TLV to.
 * @param      tlv                  TLV to write.
 *
 * @return kHAPError_None           If successful.
 * @return kHAPError_OutOfResources If the writer's buffer is not large enough to hold the serialized TLV item.
 */
HAP_RESULT_USE_CHECK
HAPError HAPTLVWriterAppend(HAPTLVWriterRef* writer, const HAPTLV* tlv);

/**
 * Retrieves the buffer containing the serialized TLV data.
 *
 * @param      writer               Writer to retrieve buffer from.
 * @param[out] bytes                Buffer containing serialized TLV data written so far.
 * @param[out] numBytes             Length of buffer.
 */
void HAPTLVWriterGetBuffer(const HAPTLVWriterRef* writer, void* _Nonnull* _Nonnull bytes, size_t* numBytes);

/**
 * Retrieves a temporary buffer of unused memory, e.g. to prepare the next TLV payload to be written.
 *
 * - /!\ The buffer becomes invalid after writing to the TLV writer again.
 *
 * @param      writer               Writer to retrieve buffer from.
 * @param[out] scratchBytes         Temporary buffer of free memory.
 * @param[out] numScratchBytes      Capacity of scratch buffer.
 */
void HAPTLVWriterGetScratchBytes(
        const HAPTLVWriterRef* writer,
        void* _Nonnull* _Nonnull scratchBytes,
        size_t* numScratchBytes);

/**
 * HomeKit Accessory server.
 */
#ifndef HAP_ACCESSORY_SERVER_SIZE
#define HAP_ACCESSORY_SERVER_SIZE 1912
#endif
typedef HAP_OPAQUE(HAP_ACCESSORY_SERVER_SIZE) HAPAccessoryServerRef;
HAP_NONNULL_SUPPORT(HAPAccessoryServerRef)

/**
 * HomeKit Session.
 */
#ifndef HAP_SESSION_SIZE
#define HAP_SESSION_SIZE 488
#endif
typedef HAP_OPAQUE(HAP_SESSION_SIZE) HAPSessionRef;
HAP_NONNULL_SUPPORT(HAPSessionRef)

/**
 * Formats that HomeKit characteristics can have.
 *
 * - IMPORTANT: The format must always match the type of the characteristic structure!
 *   For example, kHAPCharacteristicFormat_UInt8 may only be used on HAPUInt8Characteristic.
 *
 * - For Apple-defined characteristics, the format must be used exactly as defined in the specification.
 *   For example, in the specification the Brightness characteristic is defined to have type "int".
 *   Therefore, a HAPIntCharacteristic must be used for it (with format kHAPCharacteristicFormat_Int).
 *
 * - For vendor-specific characteristics, any format may be chosen.
 */
HAP_ENUM_BEGIN(uint8_t, HAPCharacteristicFormat) { /**
                                                    * Opaque data blob. Raw bytes.
                                                    *
                                                    * - Default format in case no other format has been specified.
                                                    */
                                                   kHAPCharacteristicFormat_Data,

                                                   /**
                                                    * Boolean. True or false.
                                                    */
                                                   kHAPCharacteristicFormat_Bool,

                                                   /**
                                                    * Unsigned 8-bit integer.
                                                    */
                                                   kHAPCharacteristicFormat_UInt8,

                                                   /**
                                                    * Unsigned 16-bit integer.
                                                    */
                                                   kHAPCharacteristicFormat_UInt16,

                                                   /**
                                                    * Unsigned 32-bit integer.
                                                    */
                                                   kHAPCharacteristicFormat_UInt32,

                                                   /**
                                                    * Unsigned 64-bit integer.
                                                    */
                                                   kHAPCharacteristicFormat_UInt64,

                                                   /**
                                                    * Signed 32-bit integer.
                                                    */
                                                   kHAPCharacteristicFormat_Int,

                                                   /**
                                                    * 32-bit floating point.
                                                    */
                                                   kHAPCharacteristicFormat_Float,

                                                   /**
                                                    * UTF-8 string.
                                                    */
                                                   kHAPCharacteristicFormat_String,

                                                   /**
                                                    * One or more TLV8s.
                                                    */
                                                   kHAPCharacteristicFormat_TLV8
} HAP_ENUM_END(uint8_t, HAPCharacteristicFormat);

/**
 * Properties that HomeKit characteristics can have.
 *
 * For Apple-defined characteristics, the default values for the following properties are defined by the specification:
 * - readable (Paired Read)
 * - writable (Paired Write)
 * - supportsEventNotification (Notify)
 *
 * The remaining properties have to be evaluated on a case by case basis.
 */
typedef struct {
    /**
     * The characteristic is readable.
     *
     * - A read handler must be plugged into the characteristic structure's corresponding callback field.
     *   Only controllers with a secured connection can perform reads.
     */
    bool readable : 1;

    /**
     * The characteristic is writable.
     *
     * - A write handler must be plugged into the characteristic structure's corresponding callback field.
     *   Only controllers with a secured connection can perform writes.
     */
    bool writable : 1;

    /**
     * The characteristic supports notifications using the event connection established by the controller.
     * The event connection provides unidirectional communication from the accessory to the controller.
     *
     * - A read handler must be plugged into the characteristic structure's corresponding callback field.
     *   Only controllers with a secured connection can subscribe to events.
     *
     * - When the characteristic state changes, the HAPAccessoryServerRaiseEvent or
     *   HAPAccessoryServerRaiseEventOnSession function must be called.
     */
    bool supportsEventNotification : 1;

    /**
     * The characteristic should be hidden from the user.
     *
     * - This is useful for characteristics to configure the accessory or to update firmware on the accessory.
     *   Generic HomeKit applications on the controller won't show these characteristics.
     *
     * - When all characteristics in a service are marked hidden then the service must also be marked as hidden.
     */
    bool hidden : 1;

    /**
     * The characteristic will only be accessible by admin controllers.
     *
     * - Reads and writes to the characteristic will only execute if the controller has admin permissions.
     *
     * - Event notification values for the characteristic will only be delivered to controllers with admin permissions.
     */
    HAP_DEPRECATED_MSG("Use properties readRequiresAdminPermissions and writeRequiresAdminPermissions instead.")
    bool requiresAdminPermissions : 1;

    /**
     * The characteristic will only be accessible for read operations by admin controllers.
     *
     * - Reads to the characteristic will only execute if the controller has admin permissions.
     *
     * - Event notification values for the characteristic will only be delivered to controllers with admin permissions.
     *
     * - The subscription state of event notifications for the characteristic will only be modified by controllers with
     *   admin permissions.
     */
    bool readRequiresAdminPermissions : 1;

    /**
     * The characteristic will only be accessible for write operations by admin controllers.
     *
     * - Writes to the characteristic will only execute if the controller has admin permissions.
     */
    bool writeRequiresAdminPermissions : 1;

    /**
     * The characteristic requires time sensitive actions.
     *
     * - Writes to the characteristic will only execute if the accessory can be reached within a short time frame.
     *   This is useful for example for security class characteristics like Lock Target State or Target Door State.
     *
     * - A write handler must be plugged into the characteristic structure's corresponding callback field.
     *   The characteristic must also be marked as writable.
     */
    bool requiresTimedWrite : 1;

    /**
     * The characteristic requires additional authorization data.
     *
     * - Additional authorization data is controller-provided data that the accessory may use to validate that the
     *   controller is authorized to perform a requested operation. The contents of the authorization data are
     *   manufacturer specific. The additional authorization data is provided by the accessory app (an iOS app
     *   provided by the accessory manufacturer to control or configure the accessory) to iOS and stored by iOS
     *   on the controller. The additional authorization data must not be unique per write request as the controller
     *   will not construct or receive unique authorization data for each request. Additional authorization data
     *   may change periodically, e.g. once per month, or when user permissions change.
     *
     * - A write handler must be plugged into the characteristic structure's corresponding callback field.
     *   The characteristic must also be marked as writable.
     *
     * - It is left up to the write handler to validate additional authorization data.
     *   If authorization is insufficient, kHAPError_NotAuthorized must be returned from the handler.
     *
     * @see iOS documentation for [HMCharacteristic updateAuthorizationData(_:completionHandler:)]
     *
     * @see HomeKit Accessory Protocol Specification R14
     *      Section 2.3.3.2 Additional Authorization Data
     */
    bool supportsAuthorizationData : 1;

    /**
     * These properties only affect connections over IP (Ethernet / Wi-Fi).
     *
     * - If the accessory only supports Bluetooth, these properties can be ignored.
     */
    struct {
        /**
         * This flag prevents the characteristic from being read during discovery.
         *
         * - Normally, all characteristic values are being read during discovery over an IP transport.
         *   If a characteristic maintains state across multiple reads / writes, depending on the timing
         *   such discovery operations may interfere with correct operation.
         *
         * - Setting this flag prevents the characteristic from being read during discovery.
         *   Instead, a NULL value will be sent to the controller during discovery. Only explicit reads are processed.
         *
         * - This property may be useful for characteristics that handle firmware updates of the accessory.
         */
        bool controlPoint : 1;

        /**
         * Write operations on the characteristic require a read response value.
         *
         * - This property is typically applicable to write control point operations.
         *
         * - Write and read handlers must be plugged into the characteristic structure's corresponding callback fields.
         *   The characteristic must also be marked as writable.
         *
         * - After a successful write, a read operation is always requested immediately (i.e. without any other requests
         *   in-between).
         */
        bool supportsWriteResponse : 1;
    } ip;

    /**
     * These properties only affect connections over Bluetooth LE.
     *
     * - If the accessory only supports IP (Ethernet, Wi-Fi), these properties can be ignored.
     */
    struct {
        /**
         * The characteristic supports broadcast notifications. Such broadcasts happen when the characteristic state
         * changes while no controller is connected. This allows paired controllers to quickly react to the notification
         * without having to re-establish a secured connection.
         *
         * - When this property is not set, controllers may only receive state updates while connected.
         *
         * - A read handler must be plugged into the characteristic structure's corresponding callback field.
         *   Only paired controllers can decode and process the broadcasts.
         *
         * - When the characteristic state changes, the HAPAccessoryServerRaiseEvent or
         *   HAPAccessoryServerRaiseEventOnSession function must be called.
         */
        bool supportsBroadcastNotification : 1;

        /**
         * The characteristic supports disconnected notifications. When the characteristic state changes while no
         * controller is connected, paired controllers will re-establish a secured connection to the accessory and
         * fetch the updated characteristic state.
         *
         * - When this property is set, the following properties must also be set:
         *   - readable
         *   - supportsEventNotification
         *   - ble.supportsBroadcastNotification
         *
         * - This property must be set on at least one characteristic of an accessory to work around an issue
         *   in certain versions of the Home app that would otherwise claim that Additional Setup is required.
         *
         * - Disconnected events should only be used to reflect important state changes in the accessory.
         *   For example, contact sensor state changes or current door state changes should use this property.
         *   On the other hand, a temperature sensor must not use this property for changes in temperature readings.
         *
         * - A read handler must be plugged into the characteristic structure's corresponding callback field.
         *
         * - When the characteristic state changes, the HAPAccessoryServerRaiseEvent or
         *   HAPAccessoryServerRaiseEventOnSession function must be called.
         */
        bool supportsDisconnectedNotification : 1;

        /**
         * The characteristic is always readable, even before a secured session is established.
         *
         * - This is mainly an internal property that is used on characteristics that handle the pairing process.
         *
         * - A read handler must be plugged into the characteristic structure's corresponding callback field.
         */
        bool readableWithoutSecurity : 1;

        /**
         * The characteristic is always writable, even before a secured session is established.
         *
         * - This is mainly an internal property that is used on characteristics that handle the pairing process.
         *
         * - A write handler must be plugged into the characteristic structure's corresponding callback field.
         */
        bool writableWithoutSecurity : 1;
    } ble;
} HAPCharacteristicProperties;
HAP_STATIC_ASSERT(sizeof(HAPCharacteristicProperties) == 4, HAPCharacteristicProperties);

/**
 * Units that numeric HomeKit characteristics can have.
 *
 * For Apple-defined characteristics, the corresponding units are defined by the specification.
 */
HAP_ENUM_BEGIN(uint8_t, HAPCharacteristicUnits) { /**
                                                   * Unitless. Used for example on enumerations.
                                                   */
                                                  kHAPCharacteristicUnits_None,

                                                  /**
                                                   * The unit of the characteristic is degrees celsius.
                                                   */
                                                  kHAPCharacteristicUnits_Celsius,

                                                  /**
                                                   * The unit of the characteristic is the degrees of an arc.
                                                   */
                                                  kHAPCharacteristicUnits_ArcDegrees,

                                                  /**
                                                   * The unit of the characteristic is a percentage %.
                                                   */
                                                  kHAPCharacteristicUnits_Percentage,

                                                  /**
                                                   * The unit of the characteristic is lux (that is, illuminance).
                                                   */
                                                  kHAPCharacteristicUnits_Lux,

                                                  /**
                                                   * The unit of the characteristic is seconds.
                                                   */
                                                  kHAPCharacteristicUnits_Seconds
} HAP_ENUM_END(uint8_t, HAPCharacteristicUnits);

/**
 * Transport type over which a request has been received or over which a response will be sent.
 */
HAP_ENUM_BEGIN(uint8_t, HAPTransportType) { /**
                                             * HAP over IP (Ethernet / Wi-Fi).
                                             */
                                            kHAPTransportType_IP = 1,

                                            /**
                                             * HAP over Bluetooth LE.
                                             */
                                            kHAPTransportType_BLE
} HAP_ENUM_END(uint8_t, HAPTransportType);

typedef void HAPCharacteristic;
typedef struct HAPService HAPService;
typedef struct HAPAccessory HAPAccessory;

// <editor-fold desc="HAPDataCharacteristic">

typedef struct HAPDataCharacteristic HAPDataCharacteristic;

/**
 * Data characteristic read request.
 */
typedef struct {
    /**
     * Transport type over which the response will be sent.
     */
    HAPTransportType transportType;

    /**
     * The session over which the response will be sent.
     *
     * - A controller may be logged in on multiple sessions concurrently.
     * - May be NULL if a request is generated internally (e.g. for BLE broadcasts while disconnected).
     *
     * - For remote requests (e.g. via Apple TV), the associated controller may not be
     *   the one who originated the request, but instead the admin controller who set up the Apple TV.
     */
    HAPSessionRef* _Nullable session;

    /**
     * The characteristic whose value is to be read.
     */
    const HAPDataCharacteristic* characteristic;

    /**
     * The service that contains the characteristic.
     */
    const HAPService* service;

    /**
     * The accessory that provides the service.
     */
    const HAPAccessory* accessory;
} HAPDataCharacteristicReadRequest;

/**
 * Data characteristic write request.
 */
typedef struct {
    /**
     * Transport type over which the request has been received.
     */
    HAPTransportType transportType;

    /**
     * The session over which the request has been received.
     *
     * - A controller may be logged in on multiple sessions concurrently.
     *
     * - For remote requests (e.g. via Apple TV), the associated controller may not be
     *   the one who originated the request, but instead the admin controller who set up the Apple TV.
     */
    HAPSessionRef* session;

    /**
     * The characteristic whose value is to be written.
     */
    const HAPDataCharacteristic* characteristic;

    /**
     * The service that contains the characteristic.
     */
    const HAPService* service;

    /**
     * The accessory that provides the service.
     */
    const HAPAccessory* accessory;

    /**
     * Whether the request appears to have originated from a remote controller, e.g. via Apple TV.
     */
    bool remote;

    /**
     * Additional authorization data.
     */
    struct {
        const void* _Nullable bytes; /**< Raw AAD data, if applicable. */
        size_t numBytes;             /**< Length of additional authorization data. */
    } authorizationData;
} HAPDataCharacteristicWriteRequest;

/**
 * Data characteristic subscription request.
 */
typedef struct {
    /**
     * Transport type over which the request has been received.
     */
    HAPTransportType transportType;

    /**
     * The session over which the request has been received.
     *
     * - A controller may be logged in on multiple sessions concurrently.
     */
    HAPSessionRef* session;

    /**
     * The characteristic whose value is to be subscribed or unsubscribed.
     */
    const HAPDataCharacteristic* characteristic;

    /**
     * The service that contains the characteristic.
     */
    const HAPService* service;

    /**
     * The accessory that provides the service.
     */
    const HAPAccessory* accessory;
} HAPDataCharacteristicSubscriptionRequest;

/**
 * HomeKit Data characteristic.
 */
struct HAPDataCharacteristic {
    /**
     * Format. Must be kHAPCharacteristicFormat_Data.
     */
    HAPCharacteristicFormat format;

    /**
     * Instance ID.
     *
     * - Must be unique across all service or characteristic instance IDs of the accessory.
     * - Must not change while the accessory is paired, including over firmware updates.
     * - Must not be 0.
     * - For accessories that support Bluetooth LE, must not exceed UINT16_MAX.
     */
    uint64_t iid;

    /**
     * The type of the characteristic.
     */
    const HAPUUID* characteristicType;

    /**
     * Description for debugging (based on "Type" field of HAP specification).
     */
    const char* debugDescription;

    /**
     * Description of the characteristic provided by the manufacturer of the accessory.
     */
    const char* _Nullable manufacturerDescription;

    /**
     * Characteristic properties.
     */
    HAPCharacteristicProperties properties;

    /**
     * Value constraints.
     */
    struct {
        uint32_t maxLength; /**< Maximum length. */
    } constraints;

    /**
     * Callbacks.
     */
    struct {
        /**
         * The callback used to handle read requests.
         * On success, the value stored in the value buffer is sent back to the controller.
         *
         * - Required if the characteristic is marked readable in the characteristic properties.
         * - The callback must not block. Consider prefetching values if it would take too long.
         * - The returned value must satisfy the constraints of the characteristic.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param[out] valueBytes           Value buffer.
         * @param      maxValueBytes        Capacity of value buffer.
         * @param[out] numValueBytes        Length of value buffer.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         *
         * @return kHAPError_None           If successful.
         * @return kHAPError_Unknown        If unable to perform operation with requested service or characteristic.
         * @return kHAPError_InvalidState   If the request cannot be processed in the current state.
         * @return kHAPError_OutOfResources If out of resources to process request.
         * @return kHAPError_Busy           If the request failed temporarily.
         */
        HAP_RESULT_USE_CHECK
        HAPError (*_Nullable handleRead)(
                HAPAccessoryServerRef* server,
                const HAPDataCharacteristicReadRequest* request,
                void* valueBytes,
                size_t maxValueBytes,
                size_t* numValueBytes,
                void* _Nullable context);

        /**
         * The callback used to handle write requests.
         *
         * - Required if the characteristic is marked writeable in the characteristic properties.
         * - The callback must not block. Consider queueing values if it would take too long.
         * - The value is already checked against the constraints of the characteristic.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param      valueBytes           Value buffer.
         * @param      numValueBytes        Length of value buffer.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         *
         * @return kHAPError_None           If successful.
         * @return kHAPError_Unknown        If unable to perform operation with requested service or characteristic.
         * @return kHAPError_InvalidState   If the request cannot be processed in the current state.
         * @return kHAPError_InvalidData    If the controller sent a malformed request.
         * @return kHAPError_OutOfResources If out of resources to process request.
         * @return kHAPError_NotAuthorized  If additional authorization data is insufficient.
         * @return kHAPError_Busy           If the request failed temporarily.
         */
        HAP_RESULT_USE_CHECK
        HAPError (*_Nullable handleWrite)(
                HAPAccessoryServerRef* server,
                const HAPDataCharacteristicWriteRequest* request,
                const void* valueBytes,
                size_t numValueBytes,
                void* _Nullable context);

        /**
         * The callback used to handle subscribe requests.
         *
         * - The callback must not block. Consider queueing values if it would take too long.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         */
        void (*_Nullable handleSubscribe)(
                HAPAccessoryServerRef* server,
                const HAPDataCharacteristicSubscriptionRequest* request,
                void* _Nullable context);

        /**
         * The callback used to handle unsubscribe requests.
         *
         * - The callback must not block. Consider queueing values if it would take too long.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         */
        void (*_Nullable handleUnsubscribe)(
                HAPAccessoryServerRef* server,
                const HAPDataCharacteristicSubscriptionRequest* request,
                void* _Nullable context);
    } callbacks;
};

// </editor-fold>
// <editor-fold desc="HAPBoolCharacteristic">

typedef struct HAPBoolCharacteristic HAPBoolCharacteristic;

/**
 * Bool characteristic read request.
 */
typedef struct {
    /**
     * Transport type over which the response will be sent.
     */
    HAPTransportType transportType;

    /**
     * The session over which the response will be sent.
     *
     * - A controller may be logged in on multiple sessions concurrently.
     * - May be NULL if a request is generated internally (e.g. for BLE broadcasts while disconnected).
     *
     * - For remote requests (e.g. via Apple TV), the associated controller may not be
     *   the one who originated the request, but instead the admin controller who set up the Apple TV.
     */
    HAPSessionRef* _Nullable session;

    /**
     * The characteristic whose value is to be read.
     */
    const HAPBoolCharacteristic* characteristic;

    /**
     * The service that contains the characteristic.
     */
    const HAPService* service;

    /**
     * The accessory that provides the service.
     */
    const HAPAccessory* accessory;
} HAPBoolCharacteristicReadRequest;

/**
 * Bool characteristic write request.
 */
typedef struct {
    /**
     * Transport type over which the request has been received.
     */
    HAPTransportType transportType;

    /**
     * The session over which the request has been received.
     *
     * - A controller may be logged in on multiple sessions concurrently.
     *
     * - For remote requests (e.g. via Apple TV), the associated controller may not be
     *   the one who originated the request, but instead the admin controller who set up the Apple TV.
     */
    HAPSessionRef* session;

    /**
     * The characteristic whose value is to be written.
     */
    const HAPBoolCharacteristic* characteristic;

    /**
     * The service that contains the characteristic.
     */
    const HAPService* service;

    /**
     * The accessory that provides the service.
     */
    const HAPAccessory* accessory;

    /**
     * Whether the request appears to have originated from a remote controller, e.g. via Apple TV.
     */
    bool remote;

    /**
     * Additional authorization data.
     */
    struct {
        const void* _Nullable bytes; /**< Raw AAD data, if applicable. */
        size_t numBytes;             /**< Length of additional authorization data. */
    } authorizationData;
} HAPBoolCharacteristicWriteRequest;

/**
 * Bool characteristic subscription request.
 */
typedef struct {
    /**
     * Transport type over which the request has been received.
     */
    HAPTransportType transportType;

    /**
     * The session over which the request has been received.
     *
     * - A controller may be logged in on multiple sessions concurrently.
     */
    HAPSessionRef* session;

    /**
     * The characteristic whose value is to be subscribed or unsubscribed.
     */
    const HAPBoolCharacteristic* characteristic;

    /**
     * The service that contains the characteristic.
     */
    const HAPService* service;

    /**
     * The accessory that provides the service.
     */
    const HAPAccessory* accessory;
} HAPBoolCharacteristicSubscriptionRequest;

/**
 * HomeKit Bool characteristic.
 */
struct HAPBoolCharacteristic {
    /**
     * Format. Must be kHAPCharacteristicFormat_Bool.
     */
    HAPCharacteristicFormat format;

    /**
     * Instance ID.
     *
     * - Must be unique across all service or characteristic instance IDs of the accessory.
     * - Must not change while the accessory is paired, including over firmware updates.
     * - Must not be 0.
     * - For accessories that support Bluetooth LE, must not exceed UINT16_MAX.
     */
    uint64_t iid;

    /**
     * The type of the characteristic.
     */
    const HAPUUID* characteristicType;

    /**
     * Description for debugging (based on "Type" field of HAP specification).
     */
    const char* debugDescription;

    /**
     * Description of the characteristic provided by the manufacturer of the accessory.
     */
    const char* _Nullable manufacturerDescription;

    /**
     * Characteristic properties.
     */
    HAPCharacteristicProperties properties;

    /**
     * Callbacks.
     */
    struct {
        /**
         * The callback used to handle read requests.
         * On success, the value stored in @p value is sent back to the controller.
         *
         * - Required if the characteristic is marked readable in the characteristic properties.
         * - The callback must not block. Consider prefetching values if it would take too long.
         * - The returned value must satisfy the constraints of the characteristic.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param[out] value                Value.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         *
         * @return kHAPError_None           If successful.
         * @return kHAPError_Unknown        If unable to perform operation with requested service or characteristic.
         * @return kHAPError_InvalidState   If the request cannot be processed in the current state.
         * @return kHAPError_OutOfResources If out of resources to process request.
         * @return kHAPError_Busy           If the request failed temporarily.
         */
        HAP_RESULT_USE_CHECK
        HAPError (*_Nullable handleRead)(
                HAPAccessoryServerRef* server,
                const HAPBoolCharacteristicReadRequest* request,
                bool* value,
                void* _Nullable context);

        /**
         * The callback used to handle write requests.
         *
         * - Required if the characteristic is marked writeable in the characteristic properties.
         * - The callback must not block. Consider queueing values if it would take too long.
         * - The value is already checked against the constraints of the characteristic.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param      val                  Value.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         *
         * @return kHAPError_None           If successful.
         * @return kHAPError_Unknown        If unable to perform operation with requested service or characteristic.
         * @return kHAPError_InvalidState   If the request cannot be processed in the current state.
         * @return kHAPError_InvalidData    If the controller sent a malformed request.
         * @return kHAPError_OutOfResources If out of resources to process request.
         * @return kHAPError_NotAuthorized  If additional authorization data is insufficient.
         * @return kHAPError_Busy           If the request failed temporarily.
         */
        HAP_RESULT_USE_CHECK
        HAPError (*_Nullable handleWrite)(
                HAPAccessoryServerRef* server,
                const HAPBoolCharacteristicWriteRequest* request,
                bool value,
                void* _Nullable context);

        /**
         * The callback used to handle subscribe requests.
         *
         * - The callback must not block. Consider queueing values if it would take too long.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         */
        void (*_Nullable handleSubscribe)(
                HAPAccessoryServerRef* server,
                const HAPBoolCharacteristicSubscriptionRequest* request,
                void* _Nullable context);

        /**
         * The callback used to handle unsubscribe requests.
         *
         * - The callback must not block. Consider queueing values if it would take too long.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         */
        void (*_Nullable handleUnsubscribe)(
                HAPAccessoryServerRef* server,
                const HAPBoolCharacteristicSubscriptionRequest* request,
                void* _Nullable context);
    } callbacks;
};

// </editor-fold>
// <editor-fold desc="HAPUInt8Characteristic">

typedef struct HAPUInt8Characteristic HAPUInt8Characteristic;

/**
 * UInt8 characteristic read request.
 */
typedef struct {
    /**
     * Transport type over which the response will be sent.
     */
    HAPTransportType transportType;

    /**
     * The session over which the response will be sent.
     *
     * - A controller may be logged in on multiple sessions concurrently.
     * - May be NULL if a request is generated internally (e.g. for BLE broadcasts while disconnected).
     *
     * - For remote requests (e.g. via Apple TV), the associated controller may not be
     *   the one who originated the request, but instead the admin controller who set up the Apple TV.
     */
    HAPSessionRef* _Nullable session;

    /**
     * The characteristic whose value is to be read.
     */
    const HAPUInt8Characteristic* characteristic;

    /**
     * The service that contains the characteristic.
     */
    const HAPService* service;

    /**
     * The accessory that provides the service.
     */
    const HAPAccessory* accessory;
} HAPUInt8CharacteristicReadRequest;

/**
 * UInt8 characteristic write request.
 */
typedef struct {
    /**
     * Transport type over which the request has been received.
     */
    HAPTransportType transportType;

    /**
     * The session over which the request has been received.
     *
     * - A controller may be logged in on multiple sessions concurrently.
     *
     * - For remote requests (e.g. via Apple TV), the associated controller may not be
     *   the one who originated the request, but instead the admin controller who set up the Apple TV.
     */
    HAPSessionRef* session;

    /**
     * The characteristic whose value is to be written.
     */
    const HAPUInt8Characteristic* characteristic;

    /**
     * The service that contains the characteristic.
     */
    const HAPService* service;

    /**
     * The accessory that provides the service.
     */
    const HAPAccessory* accessory;

    /**
     * Whether the request appears to have originated from a remote controller, e.g. via Apple TV.
     */
    bool remote;

    /**
     * Additional authorization data.
     */
    struct {
        const void* _Nullable bytes; /**< Raw AAD data, if applicable. */
        size_t numBytes;             /**< Length of additional authorization data. */
    } authorizationData;
} HAPUInt8CharacteristicWriteRequest;

/**
 * UInt8 characteristic subscription request.
 */
typedef struct {
    /**
     * Transport type over which the request has been received.
     */
    HAPTransportType transportType;

    /**
     * The session over which the request has been received.
     *
     * - A controller may be logged in on multiple sessions concurrently.
     */
    HAPSessionRef* session;

    /**
     * The characteristic whose value is to be subscribed or unsubscribed.
     */
    const HAPUInt8Characteristic* characteristic;

    /**
     * The service that contains the characteristic.
     */
    const HAPService* service;

    /**
     * The accessory that provides the service.
     */
    const HAPAccessory* accessory;
} HAPUInt8CharacteristicSubscriptionRequest;

/**
 * Valid Values range for a UInt8 characteristic.
 *
 * @see HomeKit Accessory Protocol Specification R14
 *      Section 7.4.5.4 Valid Values Range Descriptor
 */
typedef struct {
    uint8_t start; /**< Starting value. */
    uint8_t end;   /**< Ending value. */
} HAPUInt8CharacteristicValidValuesRange;

/**
 * HomeKit UInt8 characteristic.
 */
struct HAPUInt8Characteristic {
    /**
     * Format. Must be kHAPCharacteristicFormat_UInt8.
     */
    HAPCharacteristicFormat format;

    /**
     * Instance ID.
     *
     * - Must be unique across all service or characteristic instance IDs of the accessory.
     * - Must not change while the accessory is paired, including over firmware updates.
     * - Must not be 0.
     * - For accessories that support Bluetooth LE, must not exceed UINT16_MAX.
     */
    uint64_t iid;

    /**
     * The type of the characteristic.
     */
    const HAPUUID* characteristicType;

    /**
     * Description for debugging (based on "Type" field of HAP specification).
     */
    const char* debugDescription;

    /**
     * Description of the characteristic provided by the manufacturer of the accessory.
     */
    const char* _Nullable manufacturerDescription;

    /**
     * Characteristic properties.
     */
    HAPCharacteristicProperties properties;

    /**
     * The units of the values for the characteristic.
     */
    HAPCharacteristicUnits units;

    /**
     * Value constraints.
     */
    struct {
        uint8_t minimumValue; /**< Minimum value. */
        uint8_t maximumValue; /**< Maximum value. */
        uint8_t stepValue;    /**< Step value. */

        /**
         * List of valid values in ascending order. NULL-terminated. Optional.
         *
         * - Only supported for Apple defined characteristics.
         *
         * @see HomeKit Accessory Protocol Specification R14
         *      Section 7.4.5.3 Valid Values Descriptor
         */
        const uint8_t* _Nullable const* _Nullable validValues;

        /**
         * List of valid values ranges in ascending order. NULL-terminated. Optional.
         *
         * - Only supported for Apple defined characteristics.
         *
         * @see HomeKit Accessory Protocol Specification R14
         *      Section 7.4.5.4 Valid Values Range Descriptor
         */
        const HAPUInt8CharacteristicValidValuesRange* _Nullable const* _Nullable validValuesRanges;
    } constraints;

    /**
     * Callbacks.
     */
    struct {
        /**
         * The callback used to handle read requests.
         * On success, the value stored in @p value is sent back to the controller.
         *
         * - Required if the characteristic is marked readable in the characteristic properties.
         * - The callback must not block. Consider prefetching values if it would take too long.
         * - The returned value must satisfy the constraints of the characteristic.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param[out] value                Value.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         *
         * @return kHAPError_None           If successful.
         * @return kHAPError_Unknown        If unable to perform operation with requested service or characteristic.
         * @return kHAPError_InvalidState   If the request cannot be processed in the current state.
         * @return kHAPError_OutOfResources If out of resources to process request.
         * @return kHAPError_Busy           If the request failed temporarily.
         */
        HAP_RESULT_USE_CHECK
        HAPError (*_Nullable handleRead)(
                HAPAccessoryServerRef* server,
                const HAPUInt8CharacteristicReadRequest* request,
                uint8_t* value,
                void* _Nullable context);

        /**
         * The callback used to handle write requests.
         *
         * - Required if the characteristic is marked writeable in the characteristic properties.
         * - The callback must not block. Consider queueing values if it would take too long.
         * - The value is already checked against the constraints of the characteristic.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param      val                  Value.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         *
         * @return kHAPError_None           If successful.
         * @return kHAPError_Unknown        If unable to perform operation with requested service or characteristic.
         * @return kHAPError_InvalidState   If the request cannot be processed in the current state.
         * @return kHAPError_InvalidData    If the controller sent a malformed request.
         * @return kHAPError_OutOfResources If out of resources to process request.
         * @return kHAPError_NotAuthorized  If additional authorization data is insufficient.
         * @return kHAPError_Busy           If the request failed temporarily.
         */
        HAP_RESULT_USE_CHECK
        HAPError (*_Nullable handleWrite)(
                HAPAccessoryServerRef* server,
                const HAPUInt8CharacteristicWriteRequest* request,
                uint8_t value,
                void* _Nullable context);

        /**
         * The callback used to handle subscribe requests.
         *
         * - The callback must not block. Consider queueing values if it would take too long.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         */
        void (*_Nullable handleSubscribe)(
                HAPAccessoryServerRef* server,
                const HAPUInt8CharacteristicSubscriptionRequest* request,
                void* _Nullable context);

        /**
         * The callback used to handle unsubscribe requests.
         *
         * - The callback must not block. Consider queueing values if it would take too long.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         */
        void (*_Nullable handleUnsubscribe)(
                HAPAccessoryServerRef* server,
                const HAPUInt8CharacteristicSubscriptionRequest* request,
                void* _Nullable context);
    } callbacks;
};

// </editor-fold>
// <editor-fold desc="HAPUInt16Characteristic">

typedef struct HAPUInt16Characteristic HAPUInt16Characteristic;

/**
 * UInt16 characteristic read request.
 */
typedef struct {
    /**
     * Transport type over which the response will be sent.
     */
    HAPTransportType transportType;

    /**
     * The session over which the response will be sent.
     *
     * - A controller may be logged in on multiple sessions concurrently.
     * - May be NULL if a request is generated internally (e.g. for BLE broadcasts while disconnected).
     *
     * - For remote requests (e.g. via Apple TV), the associated controller may not be
     *   the one who originated the request, but instead the admin controller who set up the Apple TV.
     */
    HAPSessionRef* _Nullable session;

    /**
     * The characteristic whose value is to be read.
     */
    const HAPUInt16Characteristic* characteristic;

    /**
     * The service that contains the characteristic.
     */
    const HAPService* service;

    /**
     * The accessory that provides the service.
     */
    const HAPAccessory* accessory;
} HAPUInt16CharacteristicReadRequest;

/**
 * UInt16 characteristic write request.
 */
typedef struct {
    /**
     * Transport type over which the request has been received.
     */
    HAPTransportType transportType;

    /**
     * The session over which the request has been received.
     *
     * - A controller may be logged in on multiple sessions concurrently.
     *
     * - For remote requests (e.g. via Apple TV), the associated controller may not be
     *   the one who originated the request, but instead the admin controller who set up the Apple TV.
     */
    HAPSessionRef* session;

    /**
     * The characteristic whose value is to be written.
     */
    const HAPUInt16Characteristic* characteristic;

    /**
     * The service that contains the characteristic.
     */
    const HAPService* service;

    /**
     * The accessory that provides the service.
     */
    const HAPAccessory* accessory;

    /**
     * Whether the request appears to have originated from a remote controller, e.g. via Apple TV.
     */
    bool remote;

    /**
     * Additional authorization data.
     */
    struct {
        const void* _Nullable bytes; /**< Raw AAD data, if applicable. */
        size_t numBytes;             /**< Length of additional authorization data. */
    } authorizationData;
} HAPUInt16CharacteristicWriteRequest;

/**
 * UInt16 characteristic subscription request.
 */
typedef struct {
    /**
     * Transport type over which the request has been received.
     */
    HAPTransportType transportType;

    /**
     * The session over which the request has been received.
     *
     * - A controller may be logged in on multiple sessions concurrently.
     */
    HAPSessionRef* session;

    /**
     * The characteristic whose value is to be subscribed or unsubscribed.
     */
    const HAPUInt16Characteristic* characteristic;

    /**
     * The service that contains the characteristic.
     */
    const HAPService* service;

    /**
     * The accessory that provides the service.
     */
    const HAPAccessory* accessory;
} HAPUInt16CharacteristicSubscriptionRequest;

/**
 * HomeKit UInt16 characteristic.
 */
struct HAPUInt16Characteristic {
    /**
     * Format. Must be kHAPCharacteristicFormat_UInt16.
     */
    HAPCharacteristicFormat format;

    /**
     * Instance ID.
     *
     * - Must be unique across all service or characteristic instance IDs of the accessory.
     * - Must not change while the accessory is paired, including over firmware updates.
     * - Must not be 0.
     * - For accessories that support Bluetooth LE, must not exceed UINT16_MAX.
     */
    uint64_t iid;

    /**
     * The type of the characteristic.
     */
    const HAPUUID* characteristicType;

    /**
     * Description for debugging (based on "Type" field of HAP specification).
     */
    const char* debugDescription;

    /**
     * Description of the characteristic provided by the manufacturer of the accessory.
     */
    const char* _Nullable manufacturerDescription;

    /**
     * Characteristic properties.
     */
    HAPCharacteristicProperties properties;

    /**
     * The units of the values for the characteristic.
     */
    HAPCharacteristicUnits units;

    /**
     * Value constraints.
     */
    struct {
        uint16_t minimumValue; /**< Minimum value. */
        uint16_t maximumValue; /**< Maximum value. */
        uint16_t stepValue;    /**< Step value. */
    } constraints;

    /**
     * Callbacks.
     */
    struct {
        /**
         * The callback used to handle read requests.
         * On success, the value stored in @p value is sent back to the controller.
         *
         * - Required if the characteristic is marked readable in the characteristic properties.
         * - The callback must not block. Consider prefetching values if it would take too long.
         * - The returned value must satisfy the constraints of the characteristic.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param[out] value                Value.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         *
         * @return kHAPError_None           If successful.
         * @return kHAPError_Unknown        If unable to perform operation with requested service or characteristic.
         * @return kHAPError_InvalidState   If the request cannot be processed in the current state.
         * @return kHAPError_OutOfResources If out of resources to process request.
         * @return kHAPError_Busy           If the request failed temporarily.
         */
        HAP_RESULT_USE_CHECK
        HAPError (*_Nullable handleRead)(
                HAPAccessoryServerRef* server,
                const HAPUInt16CharacteristicReadRequest* request,
                uint16_t* value,
                void* _Nullable context);

        /**
         * The callback used to handle write requests.
         *
         * - Required if the characteristic is marked writeable in the characteristic properties.
         * - The callback must not block. Consider queueing values if it would take too long.
         * - The value is already checked against the constraints of the characteristic.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param      val                  Value.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         *
         * @return kHAPError_None           If successful.
         * @return kHAPError_Unknown        If unable to perform operation with requested service or characteristic.
         * @return kHAPError_InvalidState   If the request cannot be processed in the current state.
         * @return kHAPError_InvalidData    If the controller sent a malformed request.
         * @return kHAPError_OutOfResources If out of resources to process request.
         * @return kHAPError_NotAuthorized  If additional authorization data is insufficient.
         * @return kHAPError_Busy           If the request failed temporarily.
         */
        HAP_RESULT_USE_CHECK
        HAPError (*_Nullable handleWrite)(
                HAPAccessoryServerRef* server,
                const HAPUInt16CharacteristicWriteRequest* request,
                uint16_t value,
                void* _Nullable context);

        /**
         * The callback used to handle subscribe requests.
         *
         * - The callback must not block. Consider queueing values if it would take too long.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         */
        void (*_Nullable handleSubscribe)(
                HAPAccessoryServerRef* server,
                const HAPUInt16CharacteristicSubscriptionRequest* request,
                void* _Nullable context);

        /**
         * The callback used to handle unsubscribe requests.
         *
         * - The callback must not block. Consider queueing values if it would take too long.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         */
        void (*_Nullable handleUnsubscribe)(
                HAPAccessoryServerRef* server,
                const HAPUInt16CharacteristicSubscriptionRequest* request,
                void* _Nullable context);
    } callbacks;
};

// </editor-fold>
// <editor-fold desc="HAPUInt32Characteristic">

typedef struct HAPUInt32Characteristic HAPUInt32Characteristic;

/**
 * UInt32 characteristic read request.
 */
typedef struct {
    /**
     * Transport type over which the response will be sent.
     */
    HAPTransportType transportType;

    /**
     * The session over which the response will be sent.
     *
     * - A controller may be logged in on multiple sessions concurrently.
     * - May be NULL if a request is generated internally (e.g. for BLE broadcasts while disconnected).
     *
     * - For remote requests (e.g. via Apple TV), the associated controller may not be
     *   the one who originated the request, but instead the admin controller who set up the Apple TV.
     */
    HAPSessionRef* _Nullable session;

    /**
     * The characteristic whose value is to be read.
     */
    const HAPUInt32Characteristic* characteristic;

    /**
     * The service that contains the characteristic.
     */
    const HAPService* service;

    /**
     * The accessory that provides the service.
     */
    const HAPAccessory* accessory;
} HAPUInt32CharacteristicReadRequest;

/**
 * UInt32 characteristic write request.
 */
typedef struct {
    /**
     * Transport type over which the request has been received.
     */
    HAPTransportType transportType;

    /**
     * The session over which the request has been received.
     *
     * - A controller may be logged in on multiple sessions concurrently.
     *
     * - For remote requests (e.g. via Apple TV), the associated controller may not be
     *   the one who originated the request, but instead the admin controller who set up the Apple TV.
     */
    HAPSessionRef* session;

    /**
     * The characteristic whose value is to be written.
     */
    const HAPUInt32Characteristic* characteristic;

    /**
     * The service that contains the characteristic.
     */
    const HAPService* service;

    /**
     * The accessory that provides the service.
     */
    const HAPAccessory* accessory;

    /**
     * Whether the request appears to have originated from a remote controller, e.g. via Apple TV.
     */
    bool remote;

    /**
     * Additional authorization data.
     */
    struct {
        const void* _Nullable bytes; /**< Raw AAD data, if applicable. */
        size_t numBytes;             /**< Length of additional authorization data. */
    } authorizationData;
} HAPUInt32CharacteristicWriteRequest;

/**
 * UInt32 characteristic subscription request.
 */
typedef struct {
    /**
     * Transport type over which the request has been received.
     */
    HAPTransportType transportType;

    /**
     * The session over which the request has been received.
     *
     * - A controller may be logged in on multiple sessions concurrently.
     */
    HAPSessionRef* session;

    /**
     * The characteristic whose value is to be subscribed or unsubscribed.
     */
    const HAPUInt32Characteristic* characteristic;

    /**
     * The service that contains the characteristic.
     */
    const HAPService* service;

    /**
     * The accessory that provides the service.
     */
    const HAPAccessory* accessory;
} HAPUInt32CharacteristicSubscriptionRequest;

/**
 * HomeKit UInt32 characteristic.
 */
struct HAPUInt32Characteristic {
    /**
     * Format. Must be kHAPCharacteristicFormat_UInt32.
     */
    HAPCharacteristicFormat format;

    /**
     * Instance ID.
     *
     * - Must be unique across all service or characteristic instance IDs of the accessory.
     * - Must not change while the accessory is paired, including over firmware updates.
     * - Must not be 0.
     * - For accessories that support Bluetooth LE, must not exceed UINT16_MAX.
     */
    uint64_t iid;

    /**
     * The type of the characteristic.
     */
    const HAPUUID* characteristicType;

    /**
     * Description for debugging (based on "Type" field of HAP specification).
     */
    const char* debugDescription;

    /**
     * Description of the characteristic provided by the manufacturer of the accessory.
     */
    const char* _Nullable manufacturerDescription;

    /**
     * Characteristic properties.
     */
    HAPCharacteristicProperties properties;

    /**
     * The units of the values for the characteristic.
     */
    HAPCharacteristicUnits units;

    /**
     * Value constraints.
     */
    struct {
        uint32_t minimumValue; /**< Minimum value. */
        uint32_t maximumValue; /**< Maximum value. */
        uint32_t stepValue;    /**< Step value. */
    } constraints;

    /**
     * Callbacks.
     */
    struct {
        /**
         * The callback used to handle read requests.
         * On success, the value stored in @p value is sent back to the controller.
         *
         * - Required if the characteristic is marked readable in the characteristic properties.
         * - The callback must not block. Consider prefetching values if it would take too long.
         * - The returned value must satisfy the constraints of the characteristic.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param[out] value                Value.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         *
         * @return kHAPError_None           If successful.
         * @return kHAPError_Unknown        If unable to perform operation with requested service or characteristic.
         * @return kHAPError_InvalidState   If the request cannot be processed in the current state.
         * @return kHAPError_OutOfResources If out of resources to process request.
         * @return kHAPError_Busy           If the request failed temporarily.
         */
        HAP_RESULT_USE_CHECK
        HAPError (*_Nullable handleRead)(
                HAPAccessoryServerRef* server,
                const HAPUInt32CharacteristicReadRequest* request,
                uint32_t* value,
                void* _Nullable context);

        /**
         * The callback used to handle write requests.
         *
         * - Required if the characteristic is marked writeable in the characteristic properties.
         * - The callback must not block. Consider queueing values if it would take too long.
         * - The value is already checked against the constraints of the characteristic.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param      val                  Value.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         *
         * @return kHAPError_None           If successful.
         * @return kHAPError_Unknown        If unable to perform operation with requested service or characteristic.
         * @return kHAPError_InvalidState   If the request cannot be processed in the current state.
         * @return kHAPError_InvalidData    If the controller sent a malformed request.
         * @return kHAPError_OutOfResources If out of resources to process request.
         * @return kHAPError_NotAuthorized  If additional authorization data is insufficient.
         * @return kHAPError_Busy           If the request failed temporarily.
         */
        HAP_RESULT_USE_CHECK
        HAPError (*_Nullable handleWrite)(
                HAPAccessoryServerRef* server,
                const HAPUInt32CharacteristicWriteRequest* request,
                uint32_t value,
                void* _Nullable context);

        /**
         * The callback used to handle subscribe requests.
         *
         * - The callback must not block. Consider queueing values if it would take too long.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         */
        void (*_Nullable handleSubscribe)(
                HAPAccessoryServerRef* server,
                const HAPUInt32CharacteristicSubscriptionRequest* request,
                void* _Nullable context);

        /**
         * The callback used to handle unsubscribe requests.
         *
         * - The callback must not block. Consider queueing values if it would take too long.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         */
        void (*_Nullable handleUnsubscribe)(
                HAPAccessoryServerRef* server,
                const HAPUInt32CharacteristicSubscriptionRequest* request,
                void* _Nullable context);
    } callbacks;
};

// </editor-fold>
// <editor-fold desc="HAPUInt64Characteristic">

typedef struct HAPUInt64Characteristic HAPUInt64Characteristic;

/**
 * UInt64 characteristic read request.
 */
typedef struct {
    /**
     * Transport type over which the response will be sent.
     */
    HAPTransportType transportType;

    /**
     * The session over which the response will be sent.
     *
     * - A controller may be logged in on multiple sessions concurrently.
     * - May be NULL if a request is generated internally (e.g. for BLE broadcasts while disconnected).
     *
     * - For remote requests (e.g. via Apple TV), the associated controller may not be
     *   the one who originated the request, but instead the admin controller who set up the Apple TV.
     */
    HAPSessionRef* _Nullable session;

    /**
     * The characteristic whose value is to be read.
     */
    const HAPUInt64Characteristic* characteristic;

    /**
     * The service that contains the characteristic.
     */
    const HAPService* service;

    /**
     * The accessory that provides the service.
     */
    const HAPAccessory* accessory;
} HAPUInt64CharacteristicReadRequest;

/**
 * UInt64 characteristic write request.
 */
typedef struct {
    /**
     * Transport type over which the request has been received.
     */
    HAPTransportType transportType;

    /**
     * The session over which the request has been received.
     *
     * - A controller may be logged in on multiple sessions concurrently.
     *
     * - For remote requests (e.g. via Apple TV), the associated controller may not be
     *   the one who originated the request, but instead the admin controller who set up the Apple TV.
     */
    HAPSessionRef* session;

    /**
     * The characteristic whose value is to be written.
     */
    const HAPUInt64Characteristic* characteristic;

    /**
     * The service that contains the characteristic.
     */
    const HAPService* service;

    /**
     * The accessory that provides the service.
     */
    const HAPAccessory* accessory;

    /**
     * Whether the request appears to have originated from a remote controller, e.g. via Apple TV.
     */
    bool remote;

    /**
     * Additional authorization data.
     */
    struct {
        const void* _Nullable bytes; /**< Raw AAD data, if applicable. */
        size_t numBytes;             /**< Length of additional authorization data. */
    } authorizationData;
} HAPUInt64CharacteristicWriteRequest;

/**
 * UInt64 characteristic subscription request.
 */
typedef struct {
    /**
     * Transport type over which the request has been received.
     */
    HAPTransportType transportType;

    /**
     * The session over which the request has been received.
     *
     * - A controller may be logged in on multiple sessions concurrently.
     */
    HAPSessionRef* session;

    /**
     * The characteristic whose value is to be subscribed or unsubscribed.
     */
    const HAPUInt64Characteristic* characteristic;

    /**
     * The service that contains the characteristic.
     */
    const HAPService* service;

    /**
     * The accessory that provides the service.
     */
    const HAPAccessory* accessory;
} HAPUInt64CharacteristicSubscriptionRequest;

/**
 * HomeKit UInt64 characteristic.
 */
struct HAPUInt64Characteristic {
    /**
     * Format. Must be kHAPCharacteristicFormat_UInt64.
     */
    HAPCharacteristicFormat format;

    /**
     * Instance ID.
     *
     * - Must be unique across all service or characteristic instance IDs of the accessory.
     * - Must not change while the accessory is paired, including over firmware updates.
     * - Must not be 0.
     * - For accessories that support Bluetooth LE, must not exceed UINT16_MAX.
     */
    uint64_t iid;

    /**
     * The type of the characteristic.
     */
    const HAPUUID* characteristicType;

    /**
     * Description for debugging (based on "Type" field of HAP specification).
     */
    const char* debugDescription;

    /**
     * Description of the characteristic provided by the manufacturer of the accessory.
     */
    const char* _Nullable manufacturerDescription;

    /**
     * Characteristic properties.
     */
    HAPCharacteristicProperties properties;

    /**
     * The units of the values for the characteristic.
     */
    HAPCharacteristicUnits units;

    /**
     * Value constraints.
     */
    struct {
        uint64_t minimumValue; /**< Minimum value. */
        uint64_t maximumValue; /**< Maximum value. */
        uint64_t stepValue;    /**< Step value. */
    } constraints;

    /**
     * Callbacks.
     */
    struct {
        /**
         * The callback used to handle read requests.
         * On success, the value stored in @p value is sent back to the controller.
         *
         * - Required if the characteristic is marked readable in the characteristic properties.
         * - The callback must not block. Consider prefetching values if it would take too long.
         * - The returned value must satisfy the constraints of the characteristic.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param[out] value                Value.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         *
         * @return kHAPError_None           If successful.
         * @return kHAPError_Unknown        If unable to perform operation with requested service or characteristic.
         * @return kHAPError_InvalidState   If the request cannot be processed in the current state.
         * @return kHAPError_OutOfResources If out of resources to process request.
         * @return kHAPError_Busy           If the request failed temporarily.
         */
        HAP_RESULT_USE_CHECK
        HAPError (*_Nullable handleRead)(
                HAPAccessoryServerRef* server,
                const HAPUInt64CharacteristicReadRequest* request,
                uint64_t* value,
                void* _Nullable context);

        /**
         * The callback used to handle write requests.
         *
         * - Required if the characteristic is marked writeable in the characteristic properties.
         * - The callback must not block. Consider queueing values if it would take too long.
         * - The value is already checked against the constraints of the characteristic.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param      val                  Value.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         *
         * @return kHAPError_None           If successful.
         * @return kHAPError_Unknown        If unable to perform operation with requested service or characteristic.
         * @return kHAPError_InvalidState   If the request cannot be processed in the current state.
         * @return kHAPError_InvalidData    If the controller sent a malformed request.
         * @return kHAPError_OutOfResources If out of resources to process request.
         * @return kHAPError_NotAuthorized  If additional authorization data is insufficient.
         * @return kHAPError_Busy           If the request failed temporarily.
         */
        HAP_RESULT_USE_CHECK
        HAPError (*_Nullable handleWrite)(
                HAPAccessoryServerRef* server,
                const HAPUInt64CharacteristicWriteRequest* request,
                uint64_t value,
                void* _Nullable context);

        /**
         * The callback used to handle subscribe requests.
         *
         * - The callback must not block. Consider queueing values if it would take too long.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         */
        void (*_Nullable handleSubscribe)(
                HAPAccessoryServerRef* server,
                const HAPUInt64CharacteristicSubscriptionRequest* request,
                void* _Nullable context);

        /**
         * The callback used to handle unsubscribe requests.
         *
         * - The callback must not block. Consider queueing values if it would take too long.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         */
        void (*_Nullable handleUnsubscribe)(
                HAPAccessoryServerRef* server,
                const HAPUInt64CharacteristicSubscriptionRequest* request,
                void* _Nullable context);
    } callbacks;
};

// </editor-fold>
// <editor-fold desc="HAPIntCharacteristic">

typedef struct HAPIntCharacteristic HAPIntCharacteristic;

/**
 * Int characteristic read request.
 */
typedef struct {
    /**
     * Transport type over which the response will be sent.
     */
    HAPTransportType transportType;

    /**
     * The session over which the response will be sent.
     *
     * - A controller may be logged in on multiple sessions concurrently.
     * - May be NULL if a request is generated internally (e.g. for BLE broadcasts while disconnected).
     *
     * - For remote requests (e.g. via Apple TV), the associated controller may not be
     *   the one who originated the request, but instead the admin controller who set up the Apple TV.
     */
    HAPSessionRef* _Nullable session;

    /**
     * The characteristic whose value is to be read.
     */
    const HAPIntCharacteristic* characteristic;

    /**
     * The service that contains the characteristic.
     */
    const HAPService* service;

    /**
     * The accessory that provides the service.
     */
    const HAPAccessory* accessory;
} HAPIntCharacteristicReadRequest;

/**
 * Int characteristic write request.
 */
typedef struct {
    /**
     * Transport type over which the request has been received.
     */
    HAPTransportType transportType;

    /**
     * The session over which the request has been received.
     *
     * - A controller may be logged in on multiple sessions concurrently.
     *
     * - For remote requests (e.g. via Apple TV), the associated controller may not be
     *   the one who originated the request, but instead the admin controller who set up the Apple TV.
     */
    HAPSessionRef* session;

    /**
     * The characteristic whose value is to be written.
     */
    const HAPIntCharacteristic* characteristic;

    /**
     * The service that contains the characteristic.
     */
    const HAPService* service;

    /**
     * The accessory that provides the service.
     */
    const HAPAccessory* accessory;

    /**
     * Whether the request appears to have originated from a remote controller, e.g. via Apple TV.
     */
    bool remote;

    /**
     * Additional authorization data.
     */
    struct {
        const void* _Nullable bytes; /**< Raw AAD data, if applicable. */
        size_t numBytes;             /**< Length of additional authorization data. */
    } authorizationData;
} HAPIntCharacteristicWriteRequest;

/**
 * Int characteristic subscription request.
 */
typedef struct {
    /**
     * Transport type over which the request has been received.
     */
    HAPTransportType transportType;

    /**
     * The session over which the request has been received.
     *
     * - A controller may be logged in on multiple sessions concurrently.
     */
    HAPSessionRef* session;

    /**
     * The characteristic whose value is to be subscribed or unsubscribed.
     */
    const HAPIntCharacteristic* characteristic;

    /**
     * The service that contains the characteristic.
     */
    const HAPService* service;

    /**
     * The accessory that provides the service.
     */
    const HAPAccessory* accessory;
} HAPIntCharacteristicSubscriptionRequest;

/**
 * HomeKit Int characteristic.
 */
struct HAPIntCharacteristic {
    /**
     * Format. Must be kHAPCharacteristicFormat_Int.
     */
    HAPCharacteristicFormat format;

    /**
     * Instance ID.
     *
     * - Must be unique across all service or characteristic instance IDs of the accessory.
     * - Must not change while the accessory is paired, including over firmware updates.
     * - Must not be 0.
     * - For accessories that support Bluetooth LE, must not exceed UINT16_MAX.
     */
    uint64_t iid;

    /**
     * The type of the characteristic.
     */
    const HAPUUID* characteristicType;

    /**
     * Description for debugging (based on "Type" field of HAP specification).
     */
    const char* debugDescription;

    /**
     * Description of the characteristic provided by the manufacturer of the accessory.
     */
    const char* _Nullable manufacturerDescription;

    /**
     * Characteristic properties.
     */
    HAPCharacteristicProperties properties;

    /**
     * The units of the values for the characteristic.
     */
    HAPCharacteristicUnits units;

    /**
     * Value constraints.
     */
    struct {
        int32_t minimumValue; /**< Minimum value. */
        int32_t maximumValue; /**< Maximum value. */
        int32_t stepValue;    /**< Step value. */
    } constraints;

    /**
     * Callbacks.
     */
    struct {
        /**
         * The callback used to handle read requests.
         * On success, the value stored in @p value is sent back to the controller.
         *
         * - Required if the characteristic is marked readable in the characteristic properties.
         * - The callback must not block. Consider prefetching values if it would take too long.
         * - The returned value must satisfy the constraints of the characteristic.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param[out] value                Value.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         *
         * @return kHAPError_None           If successful.
         * @return kHAPError_Unknown        If unable to perform operation with requested service or characteristic.
         * @return kHAPError_InvalidState   If the request cannot be processed in the current state.
         * @return kHAPError_OutOfResources If out of resources to process request.
         * @return kHAPError_Busy           If the request failed temporarily.
         */
        HAP_RESULT_USE_CHECK
        HAPError (*_Nullable handleRead)(
                HAPAccessoryServerRef* server,
                const HAPIntCharacteristicReadRequest* request,
                int32_t* value,
                void* _Nullable context);

        /**
         * The callback used to handle write requests.
         *
         * - Required if the characteristic is marked writeable in the characteristic properties.
         * - The callback must not block. Consider queueing values if it would take too long.
         * - The value is already checked against the constraints of the characteristic.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param      val                  Value.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         *
         * @return kHAPError_None           If successful.
         * @return kHAPError_Unknown        If unable to perform operation with requested service or characteristic.
         * @return kHAPError_InvalidState   If the request cannot be processed in the current state.
         * @return kHAPError_InvalidData    If the controller sent a malformed request.
         * @return kHAPError_OutOfResources If out of resources to process request.
         * @return kHAPError_NotAuthorized  If additional authorization data is insufficient.
         * @return kHAPError_Busy           If the request failed temporarily.
         */
        HAP_RESULT_USE_CHECK
        HAPError (*_Nullable handleWrite)(
                HAPAccessoryServerRef* server,
                const HAPIntCharacteristicWriteRequest* request,
                int32_t value,
                void* _Nullable context);

        /**
         * The callback used to handle subscribe requests.
         *
         * - The callback must not block. Consider queueing values if it would take too long.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         */
        void (*_Nullable handleSubscribe)(
                HAPAccessoryServerRef* server,
                const HAPIntCharacteristicSubscriptionRequest* request,
                void* _Nullable context);

        /**
         * The callback used to handle unsubscribe requests.
         *
         * - The callback must not block. Consider queueing values if it would take too long.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         */
        void (*_Nullable handleUnsubscribe)(
                HAPAccessoryServerRef* server,
                const HAPIntCharacteristicSubscriptionRequest* request,
                void* _Nullable context);
    } callbacks;
};

// </editor-fold>
// <editor-fold desc="HAPFloatCharacteristic">

typedef struct HAPFloatCharacteristic HAPFloatCharacteristic;

/**
 * Float characteristic read request.
 */
typedef struct {
    /**
     * Transport type over which the response will be sent.
     */
    HAPTransportType transportType;

    /**
     * The session over which the response will be sent.
     *
     * - A controller may be logged in on multiple sessions concurrently.
     * - May be NULL if a request is generated internally (e.g. for BLE broadcasts while disconnected).
     *
     * - For remote requests (e.g. via Apple TV), the associated controller may not be
     *   the one who originated the request, but instead the admin controller who set up the Apple TV.
     */
    HAPSessionRef* _Nullable session;

    /**
     * The characteristic whose value is to be read.
     */
    const HAPFloatCharacteristic* characteristic;

    /**
     * The service that contains the characteristic.
     */
    const HAPService* service;

    /**
     * The accessory that provides the service.
     */
    const HAPAccessory* accessory;
} HAPFloatCharacteristicReadRequest;

/**
 * Float characteristic write request.
 */
typedef struct {
    /**
     * Transport type over which the request has been received.
     */
    HAPTransportType transportType;

    /**
     * The session over which the request has been received.
     *
     * - A controller may be logged in on multiple sessions concurrently.
     *
     * - For remote requests (e.g. via Apple TV), the associated controller may not be
     *   the one who originated the request, but instead the admin controller who set up the Apple TV.
     */
    HAPSessionRef* session;

    /**
     * The characteristic whose value is to be written.
     */
    const HAPFloatCharacteristic* characteristic;

    /**
     * The service that contains the characteristic.
     */
    const HAPService* service;

    /**
     * The accessory that provides the service.
     */
    const HAPAccessory* accessory;

    /**
     * Whether the request appears to have originated from a remote controller, e.g. via Apple TV.
     */
    bool remote;

    /**
     * Additional authorization data.
     */
    struct {
        const void* _Nullable bytes; /**< Raw AAD data, if applicable. */
        size_t numBytes;             /**< Length of additional authorization data. */
    } authorizationData;
} HAPFloatCharacteristicWriteRequest;

/**
 * Float characteristic subscription request.
 */
typedef struct {
    /**
     * Transport type over which the request has been received.
     */
    HAPTransportType transportType;

    /**
     * The session over which the request has been received.
     *
     * - A controller may be logged in on multiple sessions concurrently.
     */
    HAPSessionRef* session;

    /**
     * The characteristic whose value is to be subscribed or unsubscribed.
     */
    const HAPFloatCharacteristic* characteristic;

    /**
     * The service that contains the characteristic.
     */
    const HAPService* service;

    /**
     * The accessory that provides the service.
     */
    const HAPAccessory* accessory;
} HAPFloatCharacteristicSubscriptionRequest;

/**
 * HomeKit Float characteristic.
 */
struct HAPFloatCharacteristic {
    /**
     * Format. Must be kHAPCharacteristicFormat_Float.
     */
    HAPCharacteristicFormat format;

    /**
     * Instance ID.
     *
     * - Must be unique across all service or characteristic instance IDs of the accessory.
     * - Must not change while the accessory is paired, including over firmware updates.
     * - Must not be 0.
     * - For accessories that support Bluetooth LE, must not exceed UINT16_MAX.
     */
    uint64_t iid;

    /**
     * The type of the characteristic.
     */
    const HAPUUID* characteristicType;

    /**
     * Description for debugging (based on "Type" field of HAP specification).
     */
    const char* debugDescription;

    /**
     * Description of the characteristic provided by the manufacturer of the accessory.
     */
    const char* _Nullable manufacturerDescription;

    /**
     * Characteristic properties.
     */
    HAPCharacteristicProperties properties;

    /**
     * The units of the values for the characteristic.
     */
    HAPCharacteristicUnits units;

    /**
     * Value constraints.
     */
    struct {
        float minimumValue; /**< Minimum value. */
        float maximumValue; /**< Maximum value. */
        float stepValue;    /**< Step value. */
    } constraints;

    /**
     * Callbacks.
     */
    struct {
        /**
         * The callback used to handle read requests.
         * On success, the value stored in @p value is sent back to the controller.
         *
         * - Required if the characteristic is marked readable in the characteristic properties.
         * - The callback must not block. Consider prefetching values if it would take too long.
         * - The returned value must satisfy the constraints of the characteristic.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param[out] value                Value.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         *
         * @return kHAPError_None           If successful.
         * @return kHAPError_Unknown        If unable to perform operation with requested service or characteristic.
         * @return kHAPError_InvalidState   If the request cannot be processed in the current state.
         * @return kHAPError_OutOfResources If out of resources to process request.
         * @return kHAPError_Busy           If the request failed temporarily.
         */
        HAP_RESULT_USE_CHECK
        HAPError (*_Nullable handleRead)(
                HAPAccessoryServerRef* server,
                const HAPFloatCharacteristicReadRequest* request,
                float* value,
                void* _Nullable context);

        /**
         * The callback used to handle write requests.
         *
         * - Required if the characteristic is marked writeable in the characteristic properties.
         * - The callback must not block. Consider queueing values if it would take too long.
         * - The value is already checked against the constraints of the characteristic.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param      val                  Value.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         *
         * @return kHAPError_None           If successful.
         * @return kHAPError_Unknown        If unable to perform operation with requested service or characteristic.
         * @return kHAPError_InvalidState   If the request cannot be processed in the current state.
         * @return kHAPError_InvalidData    If the controller sent a malformed request.
         * @return kHAPError_OutOfResources If out of resources to process request.
         * @return kHAPError_NotAuthorized  If additional authorization data is insufficient.
         * @return kHAPError_Busy           If the request failed temporarily.
         */
        HAP_RESULT_USE_CHECK
        HAPError (*_Nullable handleWrite)(
                HAPAccessoryServerRef* server,
                const HAPFloatCharacteristicWriteRequest* request,
                float value,
                void* _Nullable context);

        /**
         * The callback used to handle subscribe requests.
         *
         * - The callback must not block. Consider queueing values if it would take too long.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         */
        void (*_Nullable handleSubscribe)(
                HAPAccessoryServerRef* server,
                const HAPFloatCharacteristicSubscriptionRequest* request,
                void* _Nullable context);

        /**
         * The callback used to handle unsubscribe requests.
         *
         * - The callback must not block. Consider queueing values if it would take too long.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         */
        void (*_Nullable handleUnsubscribe)(
                HAPAccessoryServerRef* server,
                const HAPFloatCharacteristicSubscriptionRequest* request,
                void* _Nullable context);
    } callbacks;
};

// </editor-fold>
// <editor-fold desc="HAPStringCharacteristic">

typedef struct HAPStringCharacteristic HAPStringCharacteristic;

/**
 * String characteristic read request.
 */
typedef struct {
    /**
     * Transport type over which the response will be sent.
     */
    HAPTransportType transportType;

    /**
     * The session over which the response will be sent.
     *
     * - A controller may be logged in on multiple sessions concurrently.
     * - May be NULL if a request is generated internally (e.g. for BLE broadcasts while disconnected).
     *
     * - For remote requests (e.g. via Apple TV), the associated controller may not be
     *   the one who originated the request, but instead the admin controller who set up the Apple TV.
     */
    HAPSessionRef* _Nullable session;

    /**
     * The characteristic whose value is to be read.
     */
    const HAPStringCharacteristic* characteristic;

    /**
     * The service that contains the characteristic.
     */
    const HAPService* service;

    /**
     * The accessory that provides the service.
     */
    const HAPAccessory* accessory;
} HAPStringCharacteristicReadRequest;

/**
 * String characteristic write request.
 */
typedef struct {
    /**
     * Transport type over which the request has been received.
     */
    HAPTransportType transportType;

    /**
     * The session over which the request has been received.
     *
     * - A controller may be logged in on multiple sessions concurrently.
     *
     * - For remote requests (e.g. via Apple TV), the associated controller may not be
     *   the one who originated the request, but instead the admin controller who set up the Apple TV.
     */
    HAPSessionRef* session;

    /**
     * The characteristic whose value is to be written.
     */
    const HAPStringCharacteristic* characteristic;

    /**
     * The service that contains the characteristic.
     */
    const HAPService* service;

    /**
     * The accessory that provides the service.
     */
    const HAPAccessory* accessory;

    /**
     * Whether the request appears to have originated from a remote controller, e.g. via Apple TV.
     */
    bool remote;

    /**
     * Additional authorization data.
     */
    struct {
        const void* _Nullable bytes; /**< Raw AAD data, if applicable. */
        size_t numBytes;             /**< Length of additional authorization data. */
    } authorizationData;
} HAPStringCharacteristicWriteRequest;

/**
 * String characteristic subscription request.
 */
typedef struct {
    /**
     * Transport type over which the request has been received.
     */
    HAPTransportType transportType;

    /**
     * The session over which the request has been received.
     *
     * - A controller may be logged in on multiple sessions concurrently.
     */
    HAPSessionRef* session;

    /**
     * The characteristic whose value is to be subscribed or unsubscribed.
     */
    const HAPStringCharacteristic* characteristic;

    /**
     * The service that contains the characteristic.
     */
    const HAPService* service;

    /**
     * The accessory that provides the service.
     */
    const HAPAccessory* accessory;
} HAPStringCharacteristicSubscriptionRequest;

/**
 * HomeKit String characteristic.
 */
struct HAPStringCharacteristic {
    /**
     * Format. Must be kHAPCharacteristicFormat_String.
     */
    HAPCharacteristicFormat format;

    /**
     * Instance ID.
     *
     * - Must be unique across all service or characteristic instance IDs of the accessory.
     * - Must not change while the accessory is paired, including over firmware updates.
     * - Must not be 0.
     * - For accessories that support Bluetooth LE, must not exceed UINT16_MAX.
     */
    uint64_t iid;

    /**
     * The type of the characteristic.
     */
    const HAPUUID* characteristicType;

    /**
     * Description for debugging (based on "Type" field of HAP specification).
     */
    const char* debugDescription;

    /**
     * Description of the characteristic provided by the manufacturer of the accessory.
     */
    const char* _Nullable manufacturerDescription;

    /**
     * Characteristic properties.
     */
    HAPCharacteristicProperties properties;

    /**
     * Value constraints.
     */
    struct {
        uint16_t maxLength; /**< Maximum length. */
    } constraints;

    /**
     * Callbacks.
     */
    struct {
        /**
         * The callback used to handle read requests.
         * On success, the value stored in @p value is sent back to the controller.
         *
         * - Required if the characteristic is marked readable in the characteristic properties.
         * - The callback must not block. Consider prefetching values if it would take too long.
         * - The returned value must satisfy the constraints of the characteristic.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param[out] value                Value. NULL-terminated.
         * @param      maxValueBytes        Capacity of value. NULL-terminator must fit within capacity.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         *
         * @return kHAPError_None           If successful.
         * @return kHAPError_Unknown        If unable to perform operation with requested service or characteristic.
         * @return kHAPError_InvalidState   If the request cannot be processed in the current state.
         * @return kHAPError_OutOfResources If out of resources to process request.
         * @return kHAPError_Busy           If the request failed temporarily.
         */
        HAP_RESULT_USE_CHECK
        HAPError (*_Nullable handleRead)(
                HAPAccessoryServerRef* server,
                const HAPStringCharacteristicReadRequest* request,
                char* value,
                size_t maxValueBytes,
                void* _Nullable context);

        /**
         * The callback used to handle write requests.
         *
         * - Required if the characteristic is marked writeable in the characteristic properties.
         * - The callback must not block. Consider queueing values if it would take too long.
         * - The value is already checked against the constraints of the characteristic.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param      value                Value. NULL-terminated.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         *
         * @return kHAPError_None           If successful.
         * @return kHAPError_Unknown        If unable to perform operation with requested service or characteristic.
         * @return kHAPError_InvalidState   If the request cannot be processed in the current state.
         * @return kHAPError_InvalidData    If the controller sent a malformed request.
         * @return kHAPError_OutOfResources If out of resources to process request.
         * @return kHAPError_NotAuthorized  If additional authorization data is insufficient.
         * @return kHAPError_Busy           If the request failed temporarily.
         */
        HAP_RESULT_USE_CHECK
        HAPError (*_Nullable handleWrite)(
                HAPAccessoryServerRef* server,
                const HAPStringCharacteristicWriteRequest* request,
                const char* value,
                void* _Nullable context);

        /**
         * The callback used to handle subscribe requests.
         *
         * - The callback must not block. Consider queueing values if it would take too long.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         */
        void (*_Nullable handleSubscribe)(
                HAPAccessoryServerRef* server,
                const HAPStringCharacteristicSubscriptionRequest* request,
                void* _Nullable context);

        /**
         * The callback used to handle unsubscribe requests.
         *
         * - The callback must not block. Consider queueing values if it would take too long.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         */
        void (*_Nullable handleUnsubscribe)(
                HAPAccessoryServerRef* server,
                const HAPStringCharacteristicSubscriptionRequest* request,
                void* _Nullable context);
    } callbacks;
};

// </editor-fold>
// <editor-fold desc="HAPTLV8Characteristic">

typedef struct HAPTLV8Characteristic HAPTLV8Characteristic;

/**
 * TLV8 characteristic read request.
 */
typedef struct {
    /**
     * Transport type over which the response will be sent.
     */
    HAPTransportType transportType;

    /**
     * The session over which the response will be sent.
     *
     * - A controller may be logged in on multiple sessions concurrently.
     * - May be NULL if a request is generated internally (e.g. for BLE broadcasts while disconnected).
     *
     * - For remote requests (e.g. via Apple TV), the associated controller may not be
     *   the one who originated the request, but instead the admin controller who set up the Apple TV.
     */
    HAPSessionRef* _Nullable session;

    /**
     * The characteristic whose value is to be read.
     */
    const HAPTLV8Characteristic* characteristic;

    /**
     * The service that contains the characteristic.
     */
    const HAPService* service;

    /**
     * The accessory that provides the service.
     */
    const HAPAccessory* accessory;
} HAPTLV8CharacteristicReadRequest;

/**
 * TLV8 characteristic write request.
 */
typedef struct {
    /**
     * Transport type over which the request has been received.
     */
    HAPTransportType transportType;

    /**
     * The session over which the request has been received.
     *
     * - A controller may be logged in on multiple sessions concurrently.
     *
     * - For remote requests (e.g. via Apple TV), the associated controller may not be
     *   the one who originated the request, but instead the admin controller who set up the Apple TV.
     */
    HAPSessionRef* session;

    /**
     * The characteristic whose value is to be written.
     */
    const HAPTLV8Characteristic* characteristic;

    /**
     * The service that contains the characteristic.
     */
    const HAPService* service;

    /**
     * The accessory that provides the service.
     */
    const HAPAccessory* accessory;

    /**
     * Whether the request appears to have originated from a remote controller, e.g. via Apple TV.
     */
    bool remote;

    /**
     * Additional authorization data.
     */
    struct {
        const void* _Nullable bytes; /**< Raw AAD data, if applicable. */
        size_t numBytes;             /**< Length of additional authorization data. */
    } authorizationData;
} HAPTLV8CharacteristicWriteRequest;

/**
 * TLV8 characteristic subscription request.
 */
typedef struct {
    /**
     * Transport type over which the request has been received.
     */
    HAPTransportType transportType;

    /**
     * The session over which the request has been received.
     *
     * - A controller may be logged in on multiple sessions concurrently.
     */
    HAPSessionRef* session;

    /**
     * The characteristic whose value is to be subscribed or unsubscribed.
     */
    const HAPTLV8Characteristic* characteristic;

    /**
     * The service that contains the characteristic.
     */
    const HAPService* service;

    /**
     * The accessory that provides the service.
     */
    const HAPAccessory* accessory;
} HAPTLV8CharacteristicSubscriptionRequest;

/**
 * HomeKit TLV8 characteristic.
 */
struct HAPTLV8Characteristic {
    /**
     * Format. Must be kHAPCharacteristicFormat_TLV8.
     */
    HAPCharacteristicFormat format;

    /**
     * Instance ID.
     *
     * - Must be unique across all service or characteristic instance IDs of the accessory.
     * - Must not change while the accessory is paired, including over firmware updates.
     * - Must not be 0.
     * - For accessories that support Bluetooth LE, must not exceed UINT16_MAX.
     */
    uint64_t iid;

    /**
     * The type of the characteristic.
     */
    const HAPUUID* characteristicType;

    /**
     * Description for debugging (based on "Type" field of HAP specification).
     */
    const char* debugDescription;

    /**
     * Description of the characteristic provided by the manufacturer of the accessory.
     */
    const char* _Nullable manufacturerDescription;

    /**
     * Characteristic properties.
     */
    HAPCharacteristicProperties properties;

    /**
     * Callbacks.
     */
    struct {
        /**
         * The callback used to handle read requests.
         * On success, the value stored in @p value is sent back to the controller.
         *
         * - Required if the characteristic is marked readable in the characteristic properties.
         * - The callback must not block. Consider prefetching values if it would take too long.
         * - The returned value must satisfy the constraints of the characteristic.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param      responseWriter       TLV writer for serializing the response.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         *
         * @return kHAPError_None           If successful.
         * @return kHAPError_Unknown        If unable to perform operation with requested service or characteristic.
         * @return kHAPError_InvalidState   If the request cannot be processed in the current state.
         * @return kHAPError_OutOfResources If out of resources to process request.
         * @return kHAPError_Busy           If the request failed temporarily.
         */
        HAP_RESULT_USE_CHECK
        HAPError (*_Nullable handleRead)(
                HAPAccessoryServerRef* server,
                const HAPTLV8CharacteristicReadRequest* request,
                HAPTLVWriterRef* responseWriter,
                void* _Nullable context);

        /**
         * The callback used to handle write requests.
         *
         * - Required if the characteristic is marked writeable in the characteristic properties.
         * - The callback must not block. Consider queueing values if it would take too long.
         * - The value is already checked against the constraints of the characteristic.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param      requestReader        TLV reader for parsing the value.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         *
         * @return kHAPError_None           If successful.
         * @return kHAPError_Unknown        If unable to perform operation with requested service or characteristic.
         * @return kHAPError_InvalidState   If the request cannot be processed in the current state.
         * @return kHAPError_InvalidData    If the controller sent a malformed request.
         * @return kHAPError_OutOfResources If out of resources to process request.
         * @return kHAPError_NotAuthorized  If additional authorization data is insufficient.
         * @return kHAPError_Busy           If the request failed temporarily.
         */
        HAP_RESULT_USE_CHECK
        HAPError (*_Nullable handleWrite)(
                HAPAccessoryServerRef* server,
                const HAPTLV8CharacteristicWriteRequest* request,
                HAPTLVReaderRef* requestReader,
                void* _Nullable context);

        /**
         * The callback used to handle subscribe requests.
         *
         * - The callback must not block. Consider queueing values if it would take too long.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         */
        void (*_Nullable handleSubscribe)(
                HAPAccessoryServerRef* server,
                const HAPTLV8CharacteristicSubscriptionRequest* request,
                void* _Nullable context);

        /**
         * The callback used to handle unsubscribe requests.
         *
         * - The callback must not block. Consider queueing values if it would take too long.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         */
        void (*_Nullable handleUnsubscribe)(
                HAPAccessoryServerRef* server,
                const HAPTLV8CharacteristicSubscriptionRequest* request,
                void* _Nullable context);
    } callbacks;
};

// </editor-fold>

/**
 * Properties that HomeKit services can have.
 *
 * - If service properties are enabled, a Service Signature characteristic must be attached to the service.
 *   This is only necessary if the accessory supports Bluetooth LE, but also okay for IP accessories.
 */
typedef struct {
    /**
     * The service is the primary service on the accessory.
     *
     * - Only one service may be marked as primary.
     */
    bool primaryService : 1;

    /**
     * The service should be hidden from the user.
     *
     * - This is useful for services to configure the accessory or to update firmware on the accessory.
     *   Generic HomeKit applications on the controller won't show these services.
     *
     * - When all characteristics in a service are marked hidden then the service must also be marked as hidden.
     */
    bool hidden : 1;

    /**
     * These properties only affect connections over Bluetooth LE.
     *
     * - If the accessory only supports IP (Ethernet / Wi-Fi), these properties can be ignored.
     */
    struct {
        /**
         * The service supports configuration.
         *
         * - This must be set on the HAP Protocol Information service.
         * - This must not be set on other services.
         */
        bool supportsConfiguration : 1;
    } ble;
} HAPServiceProperties;
HAP_STATIC_ASSERT(sizeof(HAPServiceProperties) == 2, HAPServiceProperties);

/**
 * Service request.
 */
typedef struct {
    /**
     * Transport type over which the request has been received.
     */
    HAPTransportType transportType;

    /**
     * The session over which the request has been received.
     *
     * - A controller may be logged in on multiple sessions concurrently.
     *
     * - For remote requests (e.g. via Apple TV), the associated controller may not be
     *   the one who originated the request, but instead the admin controller who set up the Apple TV.
     */
    HAPSessionRef* session;

    /**
     * The service that is being accessed.
     */
    const HAPService* service;

    /**
     * The accessory that provides the service.
     */
    const HAPAccessory* accessory;
} HAPServiceRequest;

/**
 * HomeKit service.
 */
struct HAPService {
    /**
     * Instance ID.
     *
     * - Must be unique across all service or characteristic instance IDs of the accessory.
     * - Must not change while the accessory is paired, including over firmware updates.
     * - Must be 1 for the Accessory Information Service.
     * - Must not be 0.
     * - For accessories that support Bluetooth LE, must not exceed UINT16_MAX.
     */
    uint64_t iid;

    /**
     * The type of the service.
     */
    const HAPUUID* serviceType;

    /**
     * Description for debugging (based on "Type" field of HAP specification).
     */
    const char* debugDescription;

    /**
     * The name of the service.
     *
     * - Must be set if the service provides user visible state or interaction.
     * - Must not be set for user invisible services like a Firmware Update service.
     * - The user may adjust the name on the controller. Such changes are local only and won't sync to the accessory.
     *
     * - If a name is set, a Name characteristic must be attached to the service.
     */
    const char* _Nullable name;

    /**
     * HAP Service properties.
     *
     * - Only one service may be marked as primary.
     * - If all characteristics in a service are marked as hidden, the service must also be marked as hidden.
     *
     * - If service properties are enabled, a Service Signature characteristic must be attached to the service.
     *   This is only necessary if the accessory supports Bluetooth LE, but also okay for IP accessories.
     */
    HAPServiceProperties properties;

    /**
     * Array containing instance IDs of linked services. 0-terminated.
     *
     * - Links are not transitive. If A links to B and B links to C, it is not implied that A links to C as well.
     * - Services may not link to themselves.
     *
     * - If linked services are used, a Service Signature characteristic must be attached to the service.
     *   This is only necessary if the accessory supports Bluetooth LE, but also okay for IP accessories.
     */
    const uint16_t* _Nullable linkedServices;

    /**
     * Array of contained characteristics. NULL-terminated.
     *
     * - All HAPCharacteristic structures can be used in this array.
     *   Please ensure that the "format" field of each structure is correct!
     */
    const HAPCharacteristic* _Nullable const* _Nullable characteristics;
};
HAP_NONNULL_SUPPORT(HAPService)

/**
 * Accessory category.
 *
 * - An accessory with support for multiple categories should advertise the primary category. An accessory for which a
 *   primary category cannot be determined or the primary category isn't among the well defined categories falls in the
 *   `Other` category.
 *
 * @see HomeKit Accessory Protocol Specification R14
 *      Section 13 Accessory Categories
 */
HAP_ENUM_BEGIN(uint8_t, HAPAccessoryCategory) {
    /** Accessory that is accessed through a bridge. */
    kHAPAccessoryCategory_BridgedAccessory = 0,

    /** Other. */
    kHAPAccessoryCategory_Other = 1,

    /** Bridges. */
    kHAPAccessoryCategory_Bridges = 2,

    /** Fans. */
    kHAPAccessoryCategory_Fans = 3,

    /**
     * Garage Door Openers.
     *
     * - This accessory category must use programmable tags if NFC is supported.
     */
    kHAPAccessoryCategory_GarageDoorOpeners = 4,

    /** Lighting. */
    kHAPAccessoryCategory_Lighting = 5,

    /**
     * Locks.
     *
     * - This accessory category must use programmable tags if NFC is supported.
     */
    kHAPAccessoryCategory_Locks = 6,

    /** Outlets. */
    kHAPAccessoryCategory_Outlets = 7,

    /** Switches. */
    kHAPAccessoryCategory_Switches = 8,

    /** Thermostats. */
    kHAPAccessoryCategory_Thermostats = 9,

    /** Sensors. */
    kHAPAccessoryCategory_Sensors = 10,

    /**
     * Security Systems.
     *
     * - This accessory category must use programmable tags if NFC is supported.
     */
    kHAPAccessoryCategory_SecuritySystems = 11,

    /**
     * Doors.
     *
     * - This accessory category must use programmable tags if NFC is supported.
     */
    kHAPAccessoryCategory_Doors = 12,

    /**
     * Windows.
     *
     * - This accessory category must use programmable tags if NFC is supported.
     */
    kHAPAccessoryCategory_Windows = 13,

    /** Window Coverings. */
    kHAPAccessoryCategory_WindowCoverings = 14,

    /** Programmable Switches. */
    kHAPAccessoryCategory_ProgrammableSwitches = 15,

    /**
     * Range Extenders.
     *
     * @remark Obsolete since R10.
     *
     * @see HomeKit Accessory Protocol Specification R9
     *      Table 12-3 Accessory Categories
     */
    kHAPAccessoryCategory_RangeExtenders = 16,

    /** Air Purifiers. */
    kHAPAccessoryCategory_AirPurifiers = 19,

    /** Heaters. */
    kHAPAccessoryCategory_Heaters = 20,

    /** Air Conditioners. */
    kHAPAccessoryCategory_AirConditioners = 21,

    /** Humidifiers. */
    kHAPAccessoryCategory_Humidifiers = 22,

    /** Dehumidifiers. */
    kHAPAccessoryCategory_Dehumidifiers = 23,

    /** Sprinklers. */
    kHAPAccessoryCategory_Sprinklers = 28,

    /** Faucets. */
    kHAPAccessoryCategory_Faucets = 29,

    /** Shower Systems. */
    kHAPAccessoryCategory_ShowerSystems = 30,
} HAP_ENUM_END(uint8_t, HAPAccessoryCategory);

/**
 * Accessory identify request.
 */
typedef struct {
    /**
     * Transport type over which the request has been received.
     */
    HAPTransportType transportType;

    /**
     * The session over which the request has been received.
     *
     * - A controller may be logged in on multiple sessions concurrently.
     *
     * - For remote requests (e.g. via Apple TV), the associated controller may not be
     *   the one who originated the request, but instead the admin controller who set up the Apple TV.
     */
    HAPSessionRef* session;

    /**
     * The accessory that is being accessed.
     */
    const HAPAccessory* accessory;

    /**
     * Whether the request appears to have originated from a remote controller, e.g. via Apple TV.
     */
    bool remote;
} HAPAccessoryIdentifyRequest;

/**
 * HomeKit accessory.
 */
struct HAPAccessory {
    /**
     * Accessory instance ID.
     *
     * For regular accessories (Bluetooth LE / IP):
     * - Must be 1.
     *
     * For bridged accessories:
     * - Must be unique for the bridged accessory and not change across firmware updates or power cycles.
     */
    uint64_t aid;

    /**
     * Category information for the accessory.
     *
     * For regular accessories (Bluetooth LE / IP):
     * - Must match the functionality of the accessory's primary service.
     *
     * For bridged accessories:
     * - Must be kHAPAccessoryCategory_BridgedAccessory.
     */
    HAPAccessoryCategory category;

    /**
     * The display name of the accessory.
     *
     * - Maximum length 64 (excluding NULL-terminator).
     * - ':' and ';' characters should not be used for accessories that support Bluetooth LE.
     * - The user may adjust the name on the controller. Such changes are local only and won't sync to the accessory.
     */
    const char* name;

    /**
     * The manufacturer of the accessory.
     *
     * - Maximum length 64 (excluding NULL-terminator).
     */
    const char* manufacturer;

    /**
     * The model name of the accessory.
     *
     * - Minimum length 1 (excluding NULL-terminator).
     * - Maximum length 64 (excluding NULL-terminator).
     */
    const char* model;

    /**
     * The serial number of the accessory.
     *
     * - Minimum length 2 (excluding NULL-terminator).
     * - Maximum length 64 (excluding NULL-terminator).
     */
    const char* serialNumber;

    /**
     * The firmware version of the accessory.
     *
     * - x[.y[.z]] (e.g. "100.1.1")
     * - Each number must not be greater than UINT32_MAX.
     * - Maximum length 64 (excluding NULL-terminator).
     */
    const char* firmwareVersion;

    /**
     * The hardware version of the accessory.
     *
     * - x[.y[.z]] (e.g. "100.1.1")
     * - Maximum length 64 (excluding NULL-terminator).
     */
    const char* _Nullable hardwareVersion;

    /**
     * Array of provided services. NULL-terminated.
     */
    const HAPService* _Nullable const* _Nullable services;

    /**
     * Callbacks.
     */
    struct {
        /**
         * The callback used to invoke the identify routine.
         *
         * - The accessory must implement an identify routine, a means of identifying the accessory
         *   so that it can be located by the user. The identify routine should run no longer than five seconds.
         *
         * @param      server               Accessory server.
         * @param      request              Request.
         * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
         *
         * @return kHAPError_None           If successful.
         * @return kHAPError_Unknown        If unable to perform operation with requested service or characteristic.
         * @return kHAPError_InvalidState   If the request cannot be processed in the current state.
         * @return kHAPError_InvalidData    If the controller sent a malformed request.
         * @return kHAPError_OutOfResources If out of resources to process request.
         * @return kHAPError_Busy           If the request failed temporarily.
         */
        HAP_RESULT_USE_CHECK
        HAPError (*_Nullable identify)(
                HAPAccessoryServerRef* server,
                const HAPAccessoryIdentifyRequest* request,
                void* _Nullable context);
    } callbacks;
};
HAP_NONNULL_SUPPORT(HAPAccessory)

/**
 * Minimum number of supported pairings.
 *
 * - Pairings are stored in one of the domains of the platform's key-value store.
 *   The maximum number of supported pairings is restricted to the available number of keys per domain (256).
 */
#define kHAPPairingStorage_MinElements ((HAPPlatformKeyValueStoreKey) 16)

/**
 * IP read context.
 */
typedef HAP_OPAQUE(48) HAPIPReadContextRef;

/**
 * IP write context.
 */
typedef HAP_OPAQUE(64) HAPIPWriteContextRef;

/**
 * IP session descriptor.
 */
#ifndef HAP_IP_SESSION_SIZE
#define HAP_IP_SESSION_SIZE 832
#endif
typedef HAP_OPAQUE(HAP_IP_SESSION_SIZE) HAPIPSessionDescriptorRef;

/**
 * IP event notification.
 */
typedef HAP_OPAQUE(24) HAPIPEventNotificationRef;

/**
 * Default size for the inbound buffer of an IP session.
 */
#define kHAPIPSession_DefaultInboundBufferSize ((size_t) 32768)

/**
 * Default size for the outbound buffer of an IP session.
 */
#define kHAPIPSession_DefaultOutboundBufferSize ((size_t) 32768)

/**
 * Default size for the scratch buffer of an IP session.
 */
#define kHAPIPSession_DefaultScratchBufferSize ((size_t) 32768)

/**
 * IP session.
 *
 * - For accessories that support IP (Ethernet / Wi-Fi), one of these structures needs to be allocated
 *   per concurrently supported IP connection, and provided as part of a HAPIPSessionStorage structure.
 *
 * - The provided memory must remain valid while the accessory server is initialized.
 */
typedef struct {
    /**
     * IP session descriptor.
     */
    HAPIPSessionDescriptorRef descriptor;
} HAPIPSession;

/**
 * Default number of elements in a HAPIPSessionStorage.
 */
#define kHAPIPSessionStorage_DefaultNumElements ((size_t) 17)

/**
 * IP server storage.
 *
 * - For accessories that support IP (Ethernet / Wi-Fi), one of these structures needs to be allocated
 *   and provided as part of the initialization options in HAPAccessoryServerCreate.
 *
 * - The provided memory (including the HAPIPServerStorage structure) must remain valid
 *   while the accessory server is initialized.
 */
typedef struct {
    /**
     * IP sessions.
     *
     * - One session must be provided per concurrently supported IP connection.
     *   Each session contains additional memory that needs to be allocated. See HAPIPSession.
     *
     * - At least eight elements are required for IP (Ethernet / Wi-Fi) accessories.
     */
    HAPIPSession* sessions;

    /**
     * Number of sessions.
     */
    size_t numSessions;

    /**
     * Scratch buffer.
     */
    struct {
        /**
         * Scratch buffer. Memory must be allocated and must remain valid while the accessory server is initialized.
         *
         * - It is recommended to allocate at least kHAPIPSession_DefaultScratchBufferSize bytes,
         *   but the optimal size may vary depending on the accessory's attribute database.
         */
        void* bytes;

        /**
         * Size of scratch buffer.
         */
        size_t numBytes;
    } scratchBuffer;
} HAPIPAccessoryServerStorage;
HAP_NONNULL_SUPPORT(HAPIPAccessoryServerStorage)

/**
 * HAP over IP (Ethernet / Wi-Fi) accessory server transport.
 */
/**@{*/
typedef struct HAPIPAccessoryServerTransport HAPIPAccessoryServerTransport;
extern const HAPIPAccessoryServerTransport kHAPAccessoryServerTransport_IP;
HAP_NONNULL_SUPPORT(HAPIPAccessoryServerTransport)
/**@}*/

/**
 * Element of the BLE GATT table.
 *
 * - For accessories that support Bluetooth LE, at least one of these elements must be allocated per HomeKit
 *   characteristic and service, and provided as part of a HAPBLEAccessoryServerStorage structure.
 */
typedef HAP_OPAQUE(56) HAPBLEGATTTableElementRef;

/**
 * Minimum number of BLE session cache elements in a HAPBLEAccessoryServerStorage.
 */
#define kHAPBLESessionCache_MinElements ((size_t) 8)

/**
 * Element of the BLE Pair Resume session cache.
 *
 * - For accessories that support Bluetooth LE, at least kHAPBLESessionCache_MinElements
 *   of these elements must be allocated and provided as part of a HAPBLEAccessoryServerStorage structure.
 */
typedef HAP_OPAQUE(48) HAPBLESessionCacheElementRef;

/**
 * HAP-BLE procedure.
 *
 * - For accessories that support Bluetooth LE, at least one of these procedures must be allocated
 *   and provided as part of a HAPBLEAccessoryServerStorage structure.
 */
typedef HAP_OPAQUE(160) HAPBLEProcedureRef;

/**
 * BLE accessory server storage.
 *
 * - For accessories that support Bluetooth LE, one of these structures needs to be allocated
 *   and provided as part of the initialization options in HAPAccessoryServerCreate.
 *
 * - The provided memory (including the HAPBLEAccessoryServerStorage structure) must remain valid
 *   while the accessory server is initialized.
 */
typedef struct {
    /**
     * BLE GATT table elements.
     *
     * - At least one of these elements is required per HomeKit characteristic and service
     *   and must remain valid while the accessory server is initialized.
     */
    HAPBLEGATTTableElementRef* gattTableElements;

    /**
     * Number of BLE GATT table elements.
     */
    size_t numGATTTableElements;

    /**
     * BLE Pair Resume session cache. Storage must remain valid.
     *
     * - Controllers may use the cache to speed up re-connections to the accessory by allowing them
     *   to resume previously established sessions ("Pair Resume").
     *
     * - The cache size determines how many different controllers can take advantage of this feature
     *   before they have to do a re-connection with regular speed again.
     *
     * - At least kHAPBLESessionCache_MinElements elements are required
     *   and must remain valid while the accessory server is initialized.
     */
    HAPBLESessionCacheElementRef* sessionCacheElements;

    /**
     * Number of BLE session cache elements.
     */
    size_t numSessionCacheElements;

    /**
     * BLE session storage. Storage must remain valid.
     */
    HAPSessionRef* session;

    /**
     * HAP-BLE procedures. Storage must remain valid.
     */
    HAPBLEProcedureRef* procedures;

    /**
     * Number of HAP-BLE procedures.
     */
    size_t numProcedures;

    /**
     * Buffer that the HAP-BLE procedures may use.
     *
     * - This must be large enough to fit the largest characteristic value.
     */
    struct {
        /**
         * HAP-BLE procedure buffer.
         */
        void* bytes;

        /**
         * Size of HAP-BLE procedure buffer.
         */
        size_t numBytes;
    } procedureBuffer;
} HAPBLEAccessoryServerStorage;
HAP_NONNULL_SUPPORT(HAPBLEAccessoryServerStorage)

/**
 * Minimum supported advertising interval for Bluetooth LE.
 */
#define kHAPBLEAdvertisingInterval_Minimum (HAPBLEAdvertisingIntervalCreateFromMilliseconds(160))

/**
 * Maximum supported advertising interval for Bluetooth LE.
 */
#define kHAPBLEAdvertisingInterval_Maximum (HAPBLEAdvertisingIntervalCreateFromMilliseconds(2500))

/**
 * Minimum duration of broadcast notifications and disconnected notifications in ms.
 */
#define kHAPBLENotification_MinDuration (HAPBLEAdvertisingIntervalCreateFromMilliseconds(3000))

/**
 * HAP over Bluetooth LE accessory server transport.
 */
/**@{*/
typedef struct HAPBLEAccessoryServerTransport HAPBLEAccessoryServerTransport;
extern const HAPBLEAccessoryServerTransport kHAPAccessoryServerTransport_BLE;
HAP_NONNULL_SUPPORT(HAPBLEAccessoryServerTransport)
/**@}*/

/**
 * Accessory server initialization options.
 */
typedef struct {
    /**
     * Maximum number of allowed pairings.
     *
     * - Must be at least kHAPPairingStorage_MinElements.
     */
    HAPPlatformKeyValueStoreKey maxPairings;
#if HAP_IP
    /**
     * IP specific initialization options.
     */
    struct {
        /**
         * Transport.
         *
         * - If the accessory supports HAP over IP (Ethernet / Wi-Fi), must refer to kHAPAccessoryServerTransport_IP.
         *
         * - If this is set to NULL, the other IP specific initialization options are ignored.
         */
        const HAPIPAccessoryServerTransport* _Nullable transport;

        /**
         * Accessory supports HAP over IP (Ethernet / Wi-Fi).
         *
         * - If this is set to false, the other IP specific initialization options are ignored.
         */
        HAP_DEPRECATED_MSG("Set ip.transport to &kHAPAccessoryServerTransport_IP instead.")
        bool available : 1;

        /**
         * IP accessory server storage. Storage must remain valid.
         */
        HAPIPAccessoryServerStorage* _Nullable accessoryServerStorage;
    } ip;
#endif
#if HAP_BLE
    /**
     * BLE specific initialization options.
     */
    struct {
        /**
         * Transport.
         *
         * - If the accessory supports HAP over Bluetooth LE, must refer to kHAPAccessoryServerTransport_BLE.
         *
         * - If this is set to NULL, the other BLE specific initialization options are ignored.
         */
        const HAPBLEAccessoryServerTransport* _Nullable transport;

        /**
         * Accessory supports HAP over Bluetooth LE.
         *
         * - If this is set to false, the other BLE specific initialization options are ignored.
         */
        HAP_DEPRECATED_MSG("Set ble.transport to &kHAPAccessoryServerTransport_BLE instead.")
        bool available : 1;

        /**
         * BLE accessory server storage. Storage must remain valid.
         */
        HAPBLEAccessoryServerStorage* _Nullable accessoryServerStorage;

        /**
         * Preferred Regular Advertising Interval in ms.
         *
         * Accessories must choose the regular advertising intervals in the range of kHAPBLEAdvertisingInterval_Minimum
         * ms to kHAPBLEAdvertisingInterval_Maximum ms, depending on the accessory category and its power consumption
         * characteristics.
         *
         * Mains powered accessories or accessories with larger battery capacity should use a shorter interval between
         * 160 ms to 800 ms for its regular advertisements. Battery powered accessories that do not have any
         * controllable Apple defined characteristics (such as temperature sensors, door sensors etc) are allowed to
         * use a larger regular advertising interval between 1250 ms and 2500 ms for enhanced battery life.
         *
         * Preferred advertising intervals:
         * - 211.25 ms
         * - 318.75 ms
         * - 417.5 ms
         * - 546.25 ms
         * - 760 ms
         * - 852.5 ms
         * - 1022.5 ms
         * - 1285 ms
         *
         * Note: Longer advertising intervals usually result in longer discovery and connection times.
         *
         * Use HAPBLEAdvertisingIntervalCreateFromMilliseconds to convert an advertising interval in milliseconds
         * to an advertising interval for Bluetooth LE.
         *
         * @see HomeKit Accessory Protocol Specification R14
         *      Section 7.4.1.4 Advertising Interval
         *
         * @see Accessory Design Guidelines for Apple Devices R7
         *      Section 11.5 Advertising Interval
         */
        HAPBLEAdvertisingInterval preferredAdvertisingInterval;

        /**
         * Preferred duration of events in ms.
         *
         * Must be at least kHAPBLENotification_MinDuration.
         */
        HAPBLEAdvertisingInterval preferredNotificationDuration;
    } ble;
#endif
} HAPAccessoryServerOptions;

/**
 * HomeKit platform structure.
 *
 * The following platform modules must be implemented additionally:
 * - HAPPlatformAbort
 * - HAPPlatformLog
 * - HAPPlatformRandomNumber
 * - HAPPlatformClock
 * - HAPPlatformTimer
 * - HAPPlatformRunLoop
 */
typedef struct {
    /**
     * Key-Value store.
     */
    HAPPlatformKeyValueStoreRef keyValueStore;

    /**
     * Accessory setup manager.
     */
    HAPPlatformAccessorySetupRef accessorySetup;

    /**
     * Accessory setup display.
     *
     * - This platform module is only necessary if the accessory supports displaying accessory setup information.
     */
    HAPPlatformAccessorySetupDisplayRef _Nullable setupDisplay;

    /**
     * Accessory setup programmable NFC tag.
     *
     * - This platform module is only necessary if the accessory supports a programmable NFC tag for accessory setup.
     */
    HAPPlatformAccessorySetupNFCRef _Nullable setupNFC;

    /**
     * These platform modules are only necessary if the accessory supports HAP over IP (Ethernet / Wi-Fi).
     */
    struct {
        /**
         * TCP stream manager.
         */
        HAPPlatformTCPStreamManagerRef _Nullable tcpStreamManager;

        /**
         * Service discovery.
         */
        HAPPlatformServiceDiscoveryRef _Nullable serviceDiscovery;
    } ip;

    /**
     * These platform modules are only necessary if the accessory supports HAP over Bluetooth LE.
     */
    struct {
        /**
         * BLE peripheral manager.
         */
        HAPPlatformBLEPeripheralManagerRef _Nullable blePeripheralManager;
    } ble;

    /**
     * These platform modules are only necessary for production accessories
     *
     * - Only one authentication method needs to be implemented.
     */
    struct {
        /**
         * Apple Authentication Coprocessor provider.
         *
         * - This platform module is only necessary if an Apple Authentication Coprocessor is connected.
         */
        HAPPlatformMFiHWAuthRef _Nullable mfiHWAuth;

        /**
         * Software Token provider.
         *
         * - This platform module is only necessary if Software Authentication is supported.
         */
        HAPPlatformMFiTokenAuthRef _Nullable mfiTokenAuth;
    } authentication;
} HAPPlatform;

/**
 * Accessory server callbacks.
 *
 * - Callbacks must not block.
 */
typedef struct {
    /**
     * Invoked when the accessory server state changes.
     *
     * - Updated state may be retrieved through the HAPAccessoryServerGetState
     *   HAPAccessoryServerIsPaired methods.
     *
     * - The callback must not block.
     *
     * @param      server               Accessory server.
     * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
     */
    void (*handleUpdatedState)(HAPAccessoryServerRef* server, void* _Nullable context);

    /**
     * The callback used when a HomeKit Session is accepted.
     *
     * @param      server               Accessory server.
     * @param      session              The newly accepted session.
     * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
     */
    void (*handleSessionAccept)(HAPAccessoryServerRef* server, HAPSessionRef* session, void* _Nullable context);

    /**
     * The callback used when a HomeKit Session is invalidated.
     *
     * - /!\ WARNING: The HomeKit Session must no longer be used after this callback returns.
     *
     * @param      server               Accessory server.
     * @param      session              The session being invalidated.
     * @param      context              The context parameter given to the HAPAccessoryServerCreate function.
     */
    void (*handleSessionInvalidate)(HAPAccessoryServerRef* server, HAPSessionRef* session, void* _Nullable context);
} HAPAccessoryServerCallbacks;

/**
 * Creates a new HomeKit accessory server.
 *
 * - Callbacks are always invoked synchronously. They must not block.
 *   This also applies to characteristic value read / write callbacks.
 *
 * @param[out] server               An uninitialized accessory server.
 * @param      options              Initialization options for the accessory server.
 * @param      platform             Initialized HomeKit platform structure.
 * @param      callbacks            Callbacks to receive server events. Callbacks must not block.
 * @param      context              Client context pointer. Will be passed to callbacks.
 */
void HAPAccessoryServerCreate(
        HAPAccessoryServerRef* server,
        const HAPAccessoryServerOptions* options,
        const HAPPlatform* platform,
        const HAPAccessoryServerCallbacks* callbacks,
        void* _Nullable context);

/**
 * Releases resources associated with an initialized HomeKit accessory server.
 *
 * - If the accessory server is currently running, it will be ungracefully stopped by this method.
 *   Consider stopping the accessory server first and waiting for proper shutdown to occur before releasing resources.
 *
 * - IMPORTANT: Do not use this method on accessory server structures that are not initialized!
 *
 * @param      server               An initialized accessory server.
 */
void HAPAccessoryServerRelease(HAPAccessoryServerRef* server);

/**
 * Accessory server state.
 */
HAP_ENUM_BEGIN(uint8_t, HAPAccessoryServerState) { /** Server is initialized but not running. */
                                                   kHAPAccessoryServerState_Idle,

                                                   /** Server is running. */
                                                   kHAPAccessoryServerState_Running,

                                                   /** Server is shutting down. */
                                                   kHAPAccessoryServerState_Stopping
} HAP_ENUM_END(uint8_t, HAPAccessoryServerState);

/**
 * Gets the state of an initialized HomeKit accessory server.
 *
 * @param      server               An initialized accessory server.
 *
 * @return Accessory server state.
 */
HAP_RESULT_USE_CHECK
HAPAccessoryServerState HAPAccessoryServerGetState(const HAPAccessoryServerRef* server);

/**
 * Returns whether the HomeKit accessory server is paired with any controllers.
 *
 * @param      server               An initialized accessory server.
 *
 * @return Whether the accessory server is paired with any controllers.
 */
HAP_RESULT_USE_CHECK
bool HAPAccessoryServerIsPaired(const HAPAccessoryServerRef* server);

/**
 * Starts the accessory server.
 *
 * - To start a bridge, use HAPAccessoryServerStartBridge instead.
 *
 * - The server state can be observed using the handleUpdatedState callback. The server never stops on its own.
 *
 * @param      server               An initialized accessory server that is not running.
 * @param      accessory            Accessory to serve. Must remain valid while started.
 */
void HAPAccessoryServerStart(HAPAccessoryServerRef* server, const HAPAccessory* accessory);

/**
 * Maximum number of supported bridged accessories not including the bridge itself.
 *
 * @see HomeKit Accessory Protocol Specification R14
 *      Section 2.5.3.2 Bridges
 */
#define kHAPAccessoryServerMaxBridgedAccessories ((size_t) 149)

/**
 * Starts the accessory server for a bridge accessory. A bridge is a special type of HAP accessory server that
 * bridges HomeKit Accessory Protocol and different RF/transport protocols, such as ZigBee or Z-Wave.
 * A bridge must ensure that the instance ID assigned to the HAP accessory objects exposed on behalf of its
 * connected bridged endpoints do not change for the lifetime of the server/client pairing.
 *
 * - Only supported for HAP over IP (Ethernet / Wi-Fi).
 *
 * - A bridge accessory must not bridge more than kHAPAccessoryServerMaxBridgedAccessories accessories.
 *
 * - To change the bridged accessories (e.g. after firmware update or after modified bridge configuration),
 *   stop the server, then apply changes to the @p bridgedAccessories array, then start the server again.
 *
 * - The server state can be observed using the handleUpdatedState callback. The server never stops on its own.
 *
 * @param      server               An initialized accessory server that is not running.
 * @param      bridgeAccessory      Bridge accessory to serve. Must remain valid while started.
 * @param      bridgedAccessories   Array of bridged accessories. NULL-terminated. Must remain valid while started.
 * @param      configurationChanged Whether or not the bridge configuration changed since the last start.
 *                                  This includes adding / removing accessories or updating FW of a bridged accessory.
 */
void HAPAccessoryServerStartBridge(
        HAPAccessoryServerRef* server,
        const HAPAccessory* bridgeAccessory,
        const HAPAccessory* _Nullable const* _Nullable bridgedAccessories,
        bool configurationChanged);

/**
 * Stops the accessory server.
 *
 * - When the accessory server is fully stopped, the handleUpdatedState callback will be invoked.
 *   The server can only be started again after that callback has been invoked.
 *
 * @param      server               An initialized accessory server.
 */
void HAPAccessoryServerStop(HAPAccessoryServerRef* server);

/**
 * Enters the pairing mode.
 * In pairing mode, setup payload is presented on applicable displays and programmable NFC tags.
 * Pairing mode deactivates automatically after 5 minutes or when a pairing attempt is registered.
 *
 * This function only has an effect if:
 * - Dynamic setup code is supported by the platform.
 * - No pairing attempt is in progress.
 * - The accessory is not paired. To reset the pairing, perform a factory reset or remove the pairing.
 *
 * @param      server               Accessory server.
 */
HAP_DEPRECATED_MSG(
        "For displays: See HAPPlatformAccessorySetupDisplay. For NFC: Use HAPAccessoryServerEnterNFCPairingMode "
        "instead.")
void HAPAccessoryServerEnterPairingMode(HAPAccessoryServerRef* server);

/**
 * Refreshes the setup payload that is presented for pairing on applicable displays and programmable NFC tags.
 *
 * - The setup payload is automatically refreshed periodically if no pairing attempt is in progress.
 *   This function may be used to manually refresh the setup payload.
 *
 * - If a pairing attempt is in progress, the setup payload may not be refreshed and this function has no effect.
 *
 * @param      server               Accessory server.
 */
void HAPAccessoryServerRefreshSetupPayload(HAPAccessoryServerRef* server);

/**
 * Duration after which NFC pairing mode exits automatically.
 *
 * @see HomeKit Accessory Protocol Specification R14
 *      Section 4.4.2.1 Requirements
 */
#define kHAPAccessoryServer_NFCPairingModeDuration ((HAPTime)(5 * HAPMinute))

/**
 * Enters the pairing mode for programmable NFC tags.
 * NFC pairing mode exits automatically after 5 minutes or when pairing completes.
 *
 * - Note that displays are always updated with a setup payload, even when NFC pairing mode is not entered.
 *   For security reasons, entering NFC pairing mode must require user interaction.
 *
 * @param      server               Accessory server.
 */
void HAPAccessoryServerEnterNFCPairingMode(HAPAccessoryServerRef* server);

/**
 * Exits the pairing mode for programmable NFC tags.
 *
 * @param      server               Accessory server.
 */
void HAPAccessoryServerExitNFCPairingMode(HAPAccessoryServerRef* server);

/**
 * Raises an event notification for a given characteristic in a given service provided by a given accessory object.
 *
 * @param      server               Accessory server.
 * @param      characteristic       The characteristic whose value has changed.
 * @param      service              The service that contains the characteristic.
 * @param      accessory            The accessory that provides the service.
 */
void HAPAccessoryServerRaiseEvent(
        HAPAccessoryServerRef* server,
        const HAPCharacteristic* characteristic,
        const HAPService* service,
        const HAPAccessory* accessory);

/**
 * Raises an event notification for a given characteristic in a given service provided by a given accessory object
 * on a given session.
 *
 * @param      server               Accessory server.
 * @param      characteristic       The characteristic whose value has changed.
 * @param      service              The service that contains the characteristic.
 * @param      accessory            The accessory that provides the service.
 * @param      session              The session on which to raise the event.
 */
void HAPAccessoryServerRaiseEventOnSession(
        HAPAccessoryServerRef* server,
        const HAPCharacteristic* characteristic,
        const HAPService* service,
        const HAPAccessory* accessory,
        HAPSessionRef* session);

/**
 * Restores the given key-value store to factory settings.
 *
 * - The accessory server must be stopped completely before restoring factory settings!
 *
 * - Only HomeKit related data is reset. Application specific data must be restored manually.
 *
 * @param      keyValueStore        Key-value store.
 *
 * @return kHAPError_None           If successful.
 * @return kHAPError_Unknown        If persistent store access failed.
 */
HAP_RESULT_USE_CHECK
HAPError HAPRestoreFactorySettings(HAPPlatformKeyValueStoreRef keyValueStore);

/**
 * Purges all HomeKit pairings from the given key-value store.
 *
 * - The accessory server must be stopped completely before issuing a pairing reset!
 *
 * @param      keyValueStore        Key-value store.
 *
 * @return kHAPError_None           If successful.
 * @return kHAPError_Unknown        If persistent store access failed.
 */
HAP_RESULT_USE_CHECK
HAPError HAPRemoveAllPairings(HAPPlatformKeyValueStoreRef keyValueStore);

/**
 * Device ID of an accessory server.
 */
typedef struct {
    /**
     * Device ID.
     */
    uint8_t bytes[6];
} HAPAccessoryServerDeviceID;
HAP_STATIC_ASSERT(sizeof(HAPAccessoryServerDeviceID) == 6, HAPAccessoryServerDeviceID);

/**
 * Imports a Device ID into an un-provisioned key-value store.
 * This is useful to import legacy settings from a different HomeKit SDK.
 *
 * - This function must no longer be called after the initial HAPAccessoryServerCreate call.
 *
 * @param      keyValueStore        Un-provisioned key-value store.
 * @param      deviceID             Device ID of the accessory server.
 *
 * @return kHAPError_None           If successful.
 * @return kHAPError_Unknown        If an error occurred while accessing the key-value store.
 */
HAP_RESULT_USE_CHECK
HAPError HAPLegacyImportDeviceID(HAPPlatformKeyValueStoreRef keyValueStore, const HAPAccessoryServerDeviceID* deviceID);

/**
 * Imports a configuration number into an un-provisioned key-value store.
 * This is useful to import legacy settings from a different HomeKit SDK.
 *
 * - This function must no longer be called after the initial HAPAccessoryServerCreate call.
 *
 * @param      keyValueStore        Un-provisioned key-value store.
 * @param      configurationNumber  Configuration number.
 *
 * @return kHAPError_None           If successful.
 * @return kHAPError_Unknown        If an error occurred while accessing the key-value store.
 */
HAP_RESULT_USE_CHECK
HAPError HAPLegacyImportConfigurationNumber(HAPPlatformKeyValueStoreRef keyValueStore, uint32_t configurationNumber);

/**
 * Ed25519 long-term secret key of an accessory server.
 */
typedef struct {
    /**
     * Ed25519 long-term secret key.
     */
    uint8_t bytes[32];
} HAPAccessoryServerLongTermSecretKey;
HAP_STATIC_ASSERT(sizeof(HAPAccessoryServerLongTermSecretKey) == 32, HAPAccessoryServerLongTermSecretKey);

/**
 * Imports a Ed25519 long-term secret key into an un-provisioned key-value store.
 * This is useful to import legacy settings from a different HomeKit SDK.
 *
 * - This function must no longer be called after the initial HAPAccessoryServerCreate call.
 *
 * @param      keyValueStore        Un-provisioned key-value store.
 * @param      longTermSecretKey    Long-term secret key of the accessory server.
 *
 * @return kHAPError_None           If successful.
 * @return kHAPError_Unknown        If an error occurred while accessing the key-value store.
 */
HAP_RESULT_USE_CHECK
HAPError HAPLegacyImportLongTermSecretKey(
        HAPPlatformKeyValueStoreRef keyValueStore,
        const HAPAccessoryServerLongTermSecretKey* longTermSecretKey);

/**
 * Imports an unsuccessful authentication attempts counter into an un-provisioned key-value store.
 * This is useful to import legacy settings from a different HomeKit SDK.
 *
 * - This function must no longer be called after the initial HAPAccessoryServerCreate call.
 *
 * @param      keyValueStore        Un-provisioned key-value store.
 * @param      numAuthAttempts      Unsuccessful authentication attempts counter.
 *
 * @return kHAPError_None           If successful.
 * @return kHAPError_Unknown        If an error occurred while accessing the key-value store.
 */
HAP_RESULT_USE_CHECK
HAPError HAPLegacyImportUnsuccessfulAuthenticationAttemptsCounter(
        HAPPlatformKeyValueStoreRef keyValueStore,
        uint8_t numAuthAttempts);

/**
 * Pairing identifier of a paired controller.
 */
typedef struct {
    /**
     * Buffer containing pairing identifier.
     */
    uint8_t bytes[36];

    /**
     * Number of used bytes in buffer.
     */
    size_t numBytes;
} HAPControllerPairingIdentifier;

/**
 * Public key of a paired controller.
 */
typedef struct {
    /**
     * Public key.
     */
    uint8_t bytes[32];
} HAPControllerPublicKey;
HAP_STATIC_ASSERT(sizeof(HAPControllerPublicKey) == 32, HAPControllerPublicKey);

/**
 * Imports a controller pairing into an un-provisioned key-value store.
 * This is useful to import legacy settings from a different HomeKit SDK.
 *
 * - This function must no longer be called after the initial HAPAccessoryServerCreate call.
 *
 * @param      keyValueStore        Un-provisioned key-value store.
 * @param      pairingIndex         Key-value store pairing index. 0 ..< Max number of pairings that will be supported.
 * @param      pairingIdentifier    HomeKit pairing identifier.
 * @param      publicKey            Ed25519 long-term public key of the paired controller.
 * @param      isAdmin              Whether or not the added controller has admin permissions.
 *
 * @return kHAPError_None           If successful.
 * @return kHAPError_Unknown        If an error occurred while accessing the key-value store.
 */
HAP_RESULT_USE_CHECK
HAPError HAPLegacyImportControllerPairing(
        HAPPlatformKeyValueStoreRef keyValueStore,
        HAPPlatformKeyValueStoreKey pairingIndex,
        const HAPControllerPairingIdentifier* pairingIdentifier,
        const HAPControllerPublicKey* publicKey,
        bool isAdmin);

#if __has_feature(nullability)
#pragma clang assume_nonnull end
#endif

#include "HAPCharacteristicTypes.h"
#include "HAPRequestHandlers.h"
#include "HAPServiceTypes.h"

#ifdef __cplusplus
}
#endif

#endif