properties.rs

// properties.rs
//
// The set of properties in an MQTT v5 packet.
//
// This file is part of the Eclipse Paho MQTT Rust Client library.
//

/*******************************************************************************
 * Copyright (c) 2019-2020 Frank Pagliughi <fpagliughi@mindspring.com>
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * and Eclipse Distribution License v1.0 which accompany this distribution.
 *
 * The Eclipse Public License is available at
 *    http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at
 *   http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * Contributors:
 *    Frank Pagliughi - initial implementation and documentation
 *******************************************************************************/

//! MQTT v5 properties.

use std::{
    any::{Any, TypeId},
    ffi::CString,
    mem,
    os::raw::{c_char, c_int},
    ptr,
};

use crate::{errors::Result, ffi};

/// Error code for property mismatches
const INVALID_PROPERTY_ID: i32 = ffi::MQTT_INVALID_PROPERTY_ID;

/// The type for properties that take binary data.
pub type Binary = Vec<u8>;

/// The Property `value` union type.
pub type Value = ffi::MQTTProperty__bindgen_ty_1;

/// The struct to encapsulate property string values.
type LenString = ffi::MQTTLenString;

#[repr(u32)]
#[derive(Clone, Copy, PartialEq, Debug)]
pub enum PropertyType {
    Byte = 0,
    TwoByteInteger = 1,
    FourByteInteger = 2,
    VariableByteInteger = 3,
    BinaryData = 4,
    Utf8EncodedString = 5,
    Utf8StringPair = 6,
}

// Local alias for the C property type
type Type = ffi::MQTTPropertyTypes;

impl PropertyType {
    /// Tries to create a property type from a C integer value
    pub fn new(typ: ffi::MQTTPropertyTypes) -> Option<Self> {
        match typ {
            0 => Some(Self::Byte),
            1 => Some(Self::TwoByteInteger),
            2 => Some(Self::FourByteInteger),
            3 => Some(Self::VariableByteInteger),
            4 => Some(Self::BinaryData),
            5 => Some(Self::Utf8EncodedString),
            6 => Some(Self::Utf8StringPair),
            _ => None,
        }
    }

    /// Gets the any::TypeId that corresponds to the property type.
    pub fn type_of(&self) -> TypeId {
        match *self {
            Self::Byte => TypeId::of::<u8>(),
            Self::TwoByteInteger => TypeId::of::<u16>(),
            Self::FourByteInteger => TypeId::of::<u32>(),
            Self::VariableByteInteger => TypeId::of::<i32>(),
            Self::BinaryData => TypeId::of::<Binary>(),
            Self::Utf8EncodedString => TypeId::of::<String>(),
            Self::Utf8StringPair => TypeId::of::<(String, String)>(),
        }
    }
}

/// The enumerated codes for the MQTT v5 properties.
///
/// The property code defines both the meaning of the value in the property
/// (Correlation Data, Server Keep Alive) and the data type held by the
/// property.
#[repr(u32)]
#[derive(Clone, Copy, PartialEq, Debug)]
pub enum PropertyCode {
    PayloadFormatIndicator = 1,
    MessageExpiryInterval = 2,
    ContentType = 3,
    ResponseTopic = 8,
    CorrelationData = 9,
    SubscriptionIdentifier = 11,
    SessionExpiryInterval = 17,
    AssignedClientIdentifer = 18,
    ServerKeepAlive = 19,
    AuthenticationMethod = 21,
    AuthenticationData = 22,
    RequestProblemInformation = 23,
    WillDelayInterval = 24,
    RequestResponseInformation = 25,
    ResponseInformation = 26,
    ServerReference = 28,
    ReasonString = 31,
    ReceiveMaximum = 33,
    TopicAliasMaximum = 34,
    TopicAlias = 35,
    MaximumQos = 36,
    RetainAvailable = 37,
    UserProperty = 38,
    MaximumPacketSize = 39,
    WildcardSubscriptionAvailable = 40,
    SubscriptionIdentifiersAvailable = 41,
    SharedSubscriptionAvailable = 42,
}

// Local alias for the C property code integer type
type Code = ffi::MQTTPropertyCodes;

impl PropertyCode {
    pub fn new(code: ffi::MQTTPropertyCodes) -> Option<Self> {
        match code {
            1 => Some(Self::PayloadFormatIndicator),
            2 => Some(Self::MessageExpiryInterval),
            3 => Some(Self::ContentType),
            8 => Some(Self::ResponseTopic),
            9 => Some(Self::CorrelationData),
            11 => Some(Self::SubscriptionIdentifier),
            17 => Some(Self::SessionExpiryInterval),
            18 => Some(Self::AssignedClientIdentifer),
            19 => Some(Self::ServerKeepAlive),
            21 => Some(Self::AuthenticationMethod),
            22 => Some(Self::AuthenticationData),
            23 => Some(Self::RequestProblemInformation),
            24 => Some(Self::WillDelayInterval),
            25 => Some(Self::RequestResponseInformation),
            26 => Some(Self::ResponseInformation),
            28 => Some(Self::ServerReference),
            31 => Some(Self::ReasonString),
            33 => Some(Self::ReceiveMaximum),
            34 => Some(Self::TopicAliasMaximum),
            35 => Some(Self::TopicAlias),
            36 => Some(Self::MaximumQos),
            37 => Some(Self::RetainAvailable),
            38 => Some(Self::UserProperty),
            39 => Some(Self::MaximumPacketSize),
            40 => Some(Self::WildcardSubscriptionAvailable),
            41 => Some(Self::SubscriptionIdentifiersAvailable),
            42 => Some(Self::SharedSubscriptionAvailable),
            _ => None,
        }
    }

    /// Get the property type from the code identifier.
    pub fn property_type(&self) -> PropertyType {
        let typ = unsafe { ffi::MQTTProperty_getType(*self as Code) as Type };
        PropertyType::new(typ).unwrap()
    }

    /// Gets the any::TypeId that corresponds to the property type.
    pub fn type_of(&self) -> TypeId {
        self.property_type().type_of()
    }
}

/////////////////////////////////////////////////////////////////////////////

/// A single MQTT v5 property.
///
/// An MQTT v5 property consists of both a property "code"  and a value. The
/// code indicates what the property contains (Response Topic, Will Delay
/// Interval, etc), and also the data type for the value. Each copde
/// corresponds to a single, specific data type as described in the v5
/// spec, here:
/// https://docs.oasis-open.org/mqtt/mqtt/v5.0/os/mqtt-v5.0-os.html#_Toc3901027
///
/// There are only a limited number of data types that are possible for
/// properties:
///   "Byte"  - u8
///   "Two Byte Integer"  - u16
///   "Four Byte Integer"  - u32
///   "Binary Data"  - Vec<u8>
///   "UTF-8 Encoded String"  - String
///   "UTF-8 String Pair"  - (String,String)
///
#[derive(Debug)]
pub struct Property {
    pub(crate) cprop: ffi::MQTTProperty,
}

impl Property {
    /// Creates a new property for a given code and value.
    ///
    /// The type for the value must match the type expected for the given
    /// property code exactly, otherwise it will be rejected and return None.
    pub fn new<T>(code: PropertyCode, val: T) -> Result<Property>
    where
        T: Any + 'static,
    {
        let rval: &(dyn Any + 'static) = &val;

        // Try some manual mappings first

        if code.type_of() == TypeId::of::<Binary>() {
            // A binary type can accept strings
            if let Some(v) = rval.downcast_ref::<&str>() {
                return Self::new_binary(code, v.as_bytes());
            }
            else if let Some(v) = rval.downcast_ref::<String>() {
                return Self::new_binary(code, v.as_bytes());
            }
        }

        // Note that we could potentially insist that the types must
        // match exactly, but this seems too restrictive:
        //
        // if code.type_of() != TypeId::of::<T>() {
        //     return Err(INVALID_PROPERTY_ID.into());
        // }

        if let Some(v) = rval.downcast_ref::<u8>() {
            Self::new_byte(code, *v)
        }
        else if let Some(v) = rval.downcast_ref::<u16>() {
            Self::new_u16(code, *v)
        }
        else if let Some(v) = rval.downcast_ref::<i16>() {
            Self::new_u16(code, *v as u16)
        }
        else if let Some(v) = rval.downcast_ref::<u32>() {
            Self::new_u32(code, *v)
        }
        else if let Some(v) = rval.downcast_ref::<i32>() {
            Self::new_int(code, *v)
        }
        else if let Some(v) = rval.downcast_ref::<Binary>() {
            Self::new_binary(code, v.clone())
        }
        else if let Some(v) = rval.downcast_ref::<&[u8]>() {
            Self::new_binary(code, *v)
        }
        else if let Some(v) = rval.downcast_ref::<&[u8; 1]>() {
            Self::new_binary(code, v.to_vec())
        }
        else if let Some(v) = rval.downcast_ref::<&[u8; 2]>() {
            Self::new_binary(code, v.to_vec())
        }
        else if let Some(v) = rval.downcast_ref::<&[u8; 3]>() {
            Self::new_binary(code, v.to_vec())
        }
        else if let Some(v) = rval.downcast_ref::<&[u8; 4]>() {
            Self::new_binary(code, v.to_vec())
        }
        else if let Some(v) = rval.downcast_ref::<&[u8; 5]>() {
            Self::new_binary(code, v.to_vec())
        }
        else if let Some(v) = rval.downcast_ref::<&[u8; 6]>() {
            Self::new_binary(code, v.to_vec())
        }
        else if let Some(v) = rval.downcast_ref::<&[u8; 7]>() {
            Self::new_binary(code, v.to_vec())
        }
        else if let Some(v) = rval.downcast_ref::<&[u8; 8]>() {
            Self::new_binary(code, v.to_vec())
        }
        else if let Some(v) = rval.downcast_ref::<&[u8; 9]>() {
            Self::new_binary(code, v.to_vec())
        }
        else if let Some(v) = rval.downcast_ref::<&[u8; 10]>() {
            Self::new_binary(code, v.to_vec())
        }
        else if let Some(v) = rval.downcast_ref::<&[u8; 11]>() {
            Self::new_binary(code, v.to_vec())
        }
        else if let Some(v) = rval.downcast_ref::<&[u8; 12]>() {
            Self::new_binary(code, v.to_vec())
        }
        else if let Some(v) = rval.downcast_ref::<&[u8; 13]>() {
            Self::new_binary(code, v.to_vec())
        }
        else if let Some(v) = rval.downcast_ref::<&[u8; 14]>() {
            Self::new_binary(code, v.to_vec())
        }
        else if let Some(v) = rval.downcast_ref::<&[u8; 15]>() {
            Self::new_binary(code, v.to_vec())
        }
        else if let Some(v) = rval.downcast_ref::<&[u8; 16]>() {
            Self::new_binary(code, v.to_vec())
        }
        else if let Some(v) = rval.downcast_ref::<&[u8; 17]>() {
            Self::new_binary(code, v.to_vec())
        }
        else if let Some(v) = rval.downcast_ref::<&[u8; 18]>() {
            Self::new_binary(code, v.to_vec())
        }
        else if let Some(v) = rval.downcast_ref::<&[u8; 19]>() {
            Self::new_binary(code, v.to_vec())
        }
        else if let Some(v) = rval.downcast_ref::<&[u8; 20]>() {
            Self::new_binary(code, v.to_vec())
        }
        else if let Some(v) = rval.downcast_ref::<&[u8; 21]>() {
            Self::new_binary(code, v.to_vec())
        }
        else if let Some(v) = rval.downcast_ref::<&[u8; 22]>() {
            Self::new_binary(code, v.to_vec())
        }
        else if let Some(v) = rval.downcast_ref::<&[u8; 23]>() {
            Self::new_binary(code, v.to_vec())
        }
        else if let Some(v) = rval.downcast_ref::<&[u8; 24]>() {
            Self::new_binary(code, v.to_vec())
        }
        else if let Some(v) = rval.downcast_ref::<&[u8; 25]>() {
            Self::new_binary(code, v.to_vec())
        }
        else if let Some(v) = rval.downcast_ref::<&[u8; 26]>() {
            Self::new_binary(code, v.to_vec())
        }
        else if let Some(v) = rval.downcast_ref::<&[u8; 27]>() {
            Self::new_binary(code, v.to_vec())
        }
        else if let Some(v) = rval.downcast_ref::<&[u8; 28]>() {
            Self::new_binary(code, v.to_vec())
        }
        else if let Some(v) = rval.downcast_ref::<&[u8; 29]>() {
            Self::new_binary(code, v.to_vec())
        }
        else if let Some(v) = rval.downcast_ref::<&[u8; 30]>() {
            Self::new_binary(code, v.to_vec())
        }
        else if let Some(v) = rval.downcast_ref::<&[u8; 31]>() {
            Self::new_binary(code, v.to_vec())
        }
        else if let Some(v) = rval.downcast_ref::<&[u8; 32]>() {
            Self::new_binary(code, v.to_vec())
        }
        else if let Some(v) = rval.downcast_ref::<String>() {
            Self::new_string(code, &*v)
        }
        else if let Some(v) = rval.downcast_ref::<&str>() {
            Self::new_string(code, v)
        }
        else if let Some(v) = rval.downcast_ref::<(String, String)>() {
            Self::new_string_pair(code, &v.0, &v.1)
        }
        else if let Some(v) = rval.downcast_ref::<(&str, &str)>() {
            Self::new_string_pair(code, v.0, v.1)
        }
        else if let Some(v) = rval.downcast_ref::<(&str, String)>() {
            Self::new_string_pair(code, v.0, &v.1)
        }
        else if let Some(v) = rval.downcast_ref::<(String, &str)>() {
            Self::new_string_pair(code, &v.0, v.1)
        }
        else {
            Err(INVALID_PROPERTY_ID.into())
        }
    }

    /// Creates a single-byte property
    pub fn new_byte(code: PropertyCode, val: u8) -> Result<Property> {
        match code.property_type() {
            PropertyType::Byte => Self::new_int(code, val as i32),
            _ => Err(INVALID_PROPERTY_ID.into()),
        }
    }

    /// Creates a 2-byte integer property
    pub fn new_u16(code: PropertyCode, val: u16) -> Result<Property> {
        match code.property_type() {
            PropertyType::TwoByteInteger => Self::new_int(code, val as i32),
            _ => Err(INVALID_PROPERTY_ID.into()),
        }
    }

    /// Creates a 4-byte integer property
    pub fn new_u32(code: PropertyCode, val: u32) -> Result<Property> {
        match code.property_type() {
            PropertyType::FourByteInteger => Self::new_int(code, val as i32),
            _ => Err(INVALID_PROPERTY_ID.into()),
        }
    }

    /// Creates a new integer property.
    ///
    /// This works for any sized integer type, from byte on up.
    pub fn new_int(code: PropertyCode, val: i32) -> Result<Property> {
        let value = match code.property_type() {
            PropertyType::Byte => {
                if val & !0xFF != 0 {
                    bail!(INVALID_PROPERTY_ID);
                }
                Value { byte: val as u8 }
            }
            PropertyType::TwoByteInteger => {
                if val & !0xFFFF != 0 {
                    return Err(INVALID_PROPERTY_ID.into());
                }
                Value {
                    integer2: val as u16,
                }
            }
            PropertyType::FourByteInteger | PropertyType::VariableByteInteger => Value {
                integer4: val as u32,
            },
            _ => return Err(INVALID_PROPERTY_ID.into()),
        };

        Ok(Property {
            cprop: ffi::MQTTProperty {
                identifier: code as Code,
                value,
            },
        })
    }

    /// Creates a new binary property.
    pub fn new_binary<V>(code: PropertyCode, bin: V) -> Result<Property>
    where
        V: Into<Binary>,
    {
        if code.property_type() != PropertyType::BinaryData {
            return Err(INVALID_PROPERTY_ID.into());
        }

        let mut v = bin.into();
        v.shrink_to_fit();

        let n = v.len();
        let p = v.as_mut_ptr() as *mut c_char;
        mem::forget(v);

        Ok(Property::new_string_binary(code, p, n, ptr::null_mut(), 0))
    }

    /// Creates a new string property.
    pub fn new_string(code: PropertyCode, s: &str) -> Result<Property> {
        if code.property_type() != PropertyType::Utf8EncodedString {
            return Err(INVALID_PROPERTY_ID.into());
        }

        let n = s.len();
        let p = CString::new(s).unwrap().into_raw();

        Ok(Property::new_string_binary(code, p, n, ptr::null_mut(), 0))
    }

    /// Creates a new string pair property.
    pub fn new_string_pair(code: PropertyCode, key: &str, val: &str) -> Result<Property> {
        if code.property_type() != PropertyType::Utf8StringPair {
            return Err(INVALID_PROPERTY_ID.into());
        }

        let nkey = key.len();
        let pkey = CString::new(key).unwrap().into_raw();

        let nval = val.len();
        let pval = CString::new(val).unwrap().into_raw();

        Ok(Property::new_string_binary(code, pkey, nkey, pval, nval))
    }

    /// Creates a property from a C lib MQTTProperty struct.
    fn from_c_property(cprop: &ffi::MQTTProperty) -> Result<Property> {
        let mut cprop = *cprop;
        let typ = match PropertyCode::new(cprop.identifier).map(|c| c.property_type()) {
            Some(typ) => typ,
            None => return Err(INVALID_PROPERTY_ID.into()),
        };

        unsafe {
            let mut pdata = cprop.value.__bindgen_anon_1.data.data;
            let n = cprop.value.__bindgen_anon_1.data.len as usize;

            match typ {
                PropertyType::BinaryData => {
                    if pdata.is_null() {
                        return Err(INVALID_PROPERTY_ID.into());
                    }
                    let v = Vec::from_raw_parts(pdata, n, n);
                    let mut vc = v.clone();
                    pdata = vc.as_mut_ptr() as *mut c_char;
                    mem::forget(v);
                    mem::forget(vc);
                }
                PropertyType::Utf8EncodedString => {
                    if pdata.is_null() {
                        return Err(INVALID_PROPERTY_ID.into());
                    }
                    let v = Vec::from_raw_parts(pdata as *mut u8, n, n);
                    let sr = CString::new(v.clone());
                    if sr.is_err() {
                        return Err(INVALID_PROPERTY_ID.into());
                    }
                    pdata = sr.unwrap().into_raw();
                    mem::forget(v);
                }
                PropertyType::Utf8StringPair => {
                    let pvalue = cprop.value.__bindgen_anon_1.value.data;
                    if pdata.is_null() || pvalue.is_null() {
                        return Err(INVALID_PROPERTY_ID.into());
                    }

                    let v = Vec::from_raw_parts(pdata as *mut u8, n, n);
                    let sr = CString::new(v.clone());
                    if sr.is_err() {
                        return Err(INVALID_PROPERTY_ID.into());
                    }
                    pdata = sr.unwrap().into_raw();
                    mem::forget(v);

                    let n = cprop.value.__bindgen_anon_1.value.len as usize;
                    let v = Vec::from_raw_parts(pvalue as *mut u8, n, n);
                    let sr = CString::new(v.clone());
                    if sr.is_err() {
                        return Err(INVALID_PROPERTY_ID.into());
                    }
                    cprop.value.__bindgen_anon_1.value.data = sr.unwrap().into_raw();
                    mem::forget(v);
                }
                _ => (),
            }

            // Lengths are the same as the originals
            cprop.value.__bindgen_anon_1.data.data = pdata;
        }
        Ok(Property { cprop })
    }

    /// Creates a new string, string pair, or binary property given the raw
    /// pointers and sizes.
    /// This is a low-level, internal call to create a preperty that contains
    /// dynamic data. It does no error checking; it simply assembles the
    /// struct.
    fn new_string_binary(
        code: PropertyCode,
        pdata: *mut c_char,
        ndata: usize,
        pval: *mut c_char,
        nval: usize,
    ) -> Property {
        Property {
            cprop: ffi::MQTTProperty {
                identifier: code as Code,
                value: Value {
                    __bindgen_anon_1: ffi::MQTTProperty__bindgen_ty_1__bindgen_ty_1 {
                        data: LenString {
                            len: ndata as c_int,
                            data: pdata,
                        },
                        value: LenString {
                            len: nval as c_int,
                            data: pval,
                        },
                    },
                },
            },
        }
    }

    /// Gets the MQTT code for the property.
    pub fn property_code(&self) -> PropertyCode {
        PropertyCode::new(self.cprop.identifier).unwrap()
    }

    /// Gets the type of this property.
    pub fn property_type(&self) -> PropertyType {
        self.property_code().property_type()
    }

    /// Gets the any::TypeId of this property.
    pub fn type_of(&self) -> TypeId {
        self.property_type().type_of()
    }

    /// Gets the property value
    pub fn get<T>(&self) -> Option<T>
    where
        T: Any + 'static + Send + Default,
    {
        let mut v = T::default();
        let x: &mut dyn Any = &mut v;

        if let Some(val) = x.downcast_mut::<u8>() {
            if let Some(n) = self.get_byte() {
                *val = n;
                return Some(v);
            }
        }
        else if let Some(val) = x.downcast_mut::<u16>() {
            if let Some(n) = self.get_u16() {
                *val = n;
                return Some(v);
            }
        }
        else if let Some(val) = x.downcast_mut::<u32>() {
            if let Some(n) = self.get_u32() {
                *val = n;
                return Some(v);
            }
        }
        else if let Some(val) = x.downcast_mut::<i32>() {
            if let Some(n) = self.get_int() {
                *val = n;
                return Some(v);
            }
        }
        else if let Some(val) = x.downcast_mut::<Binary>() {
            if let Some(n) = self.get_binary() {
                *val = n;
                return Some(v);
            }
        }
        else if let Some(val) = x.downcast_mut::<String>() {
            if let Some(n) = self.get_string() {
                *val = n;
                return Some(v);
            }
        }
        else if let Some(val) = x.downcast_mut::<(String, String)>() {
            if let Some(n) = self.get_string_pair() {
                *val = n;
                return Some(v);
            }
        }
        None
    }

    /// Gets the property value as a byte.
    pub fn get_byte(&self) -> Option<u8> {
        match self.property_type() {
            PropertyType::Byte => Some(unsafe { self.cprop.value.byte }),
            _ => None,
        }
    }

    /// Gets the property value as a u16.
    pub fn get_u16(&self) -> Option<u16> {
        match self.property_type() {
            PropertyType::TwoByteInteger => Some(unsafe { self.cprop.value.integer2 }),
            _ => None,
        }
    }

    /// Gets the property value as a u16.
    pub fn get_u32(&self) -> Option<u32> {
        match self.property_type() {
            PropertyType::FourByteInteger => Some(unsafe { self.cprop.value.integer4 }),
            _ => None,
        }
    }

    /// Gets the property value as an integer.
    /// This extracts an integer value from the property. It works with any
    /// of the int types, one, two, or four bytes.
    /// If the Property contains an integer type it will be returned as
    /// Some(val), otherwise it will return None.
    pub fn get_int(&self) -> Option<i32> {
        unsafe {
            match self.property_type() {
                PropertyType::Byte => Some(self.cprop.value.byte as i32),
                PropertyType::TwoByteInteger => Some(self.cprop.value.integer2 as i32),
                PropertyType::FourByteInteger | PropertyType::VariableByteInteger => {
                    Some(self.cprop.value.integer4 as i32)
                }
                _ => None,
            }
        }
    }

    /// Gets the property value as a binary blob.
    pub fn get_binary(&self) -> Option<Binary> {
        unsafe {
            if self.property_type() == PropertyType::BinaryData {
                let n = self.cprop.value.__bindgen_anon_1.data.len as usize;
                let p = self.cprop.value.__bindgen_anon_1.data.data as *mut u8;
                let v = Vec::from_raw_parts(p, n, n);
                let vc = v.clone();
                mem::forget(v);
                Some(vc)
            }
            else {
                None
            }
        }
    }

    /// Gets the property value as a string.
    pub fn get_string(&self) -> Option<String> {
        unsafe {
            if self.property_type() == PropertyType::Utf8EncodedString {
                let s = CString::from_raw(self.cprop.value.__bindgen_anon_1.data.data);
                let sc = s.clone();
                s.into_raw();
                sc.into_string().ok()
            }
            else {
                None
            }
        }
    }

    /// Gets the property value as a string pair.
    pub fn get_string_pair(&self) -> Option<(String, String)> {
        unsafe {
            if self.property_type() == PropertyType::Utf8StringPair {
                let s = CString::from_raw(self.cprop.value.__bindgen_anon_1.data.data);
                let sc = s.clone();
                s.into_raw();
                let keyopt = sc.into_string().ok();

                let s = CString::from_raw(self.cprop.value.__bindgen_anon_1.value.data);
                let sc = s.clone();
                s.into_raw();
                let valopt = sc.into_string().ok();
                keyopt.and_then(|key| valopt.map(|val| (key, val)))
            }
            else {
                None
            }
        }
    }
}

impl Drop for Property {
    /// Drops the property.
    /// For string any binary types, the heap memory will be freed.
    fn drop(&mut self) {
        unsafe {
            match self.property_type() {
                PropertyType::BinaryData => {
                    debug!(
                        "Dropping binary property: {:?}",
                        self.cprop.value.__bindgen_anon_1.data.data
                    );
                    let n = self.cprop.value.__bindgen_anon_1.data.len as usize;
                    let _ = Vec::from_raw_parts(self.cprop.value.__bindgen_anon_1.data.data, n, n);
                }
                PropertyType::Utf8EncodedString => {
                    debug!(
                        "Dropping string property: {:?}",
                        self.cprop.value.__bindgen_anon_1.data.data
                    );
                    let _ = CString::from_raw(self.cprop.value.__bindgen_anon_1.data.data);
                }
                PropertyType::Utf8StringPair => {
                    debug!(
                        "Dropping string pair property: {:?}, {:?}",
                        self.cprop.value.__bindgen_anon_1.data.data,
                        self.cprop.value.__bindgen_anon_1.value.data
                    );
                    let _ = CString::from_raw(self.cprop.value.__bindgen_anon_1.data.data);
                    let _ = CString::from_raw(self.cprop.value.__bindgen_anon_1.value.data);
                }
                _ => (),
            }
        }
    }
}

impl Clone for Property {
    /// Creates a clone of the property.
    /// For string any binary properties, this also clones the heap memory
    /// so that each property is managing separate allocations.
    fn clone(&self) -> Self {
        let mut cprop = self.cprop;

        unsafe {
            match self.property_type() {
                PropertyType::BinaryData => {
                    // TODO: Can we just do a low-level mem copy?
                    let n = cprop.value.__bindgen_anon_1.data.len as usize;
                    let v = Vec::from_raw_parts(cprop.value.__bindgen_anon_1.data.data, n, n);
                    let mut vc = v.clone();
                    let p = vc.as_mut_ptr() as *mut c_char;
                    cprop.value.__bindgen_anon_1.data.data = p;
                    mem::forget(v);
                    mem::forget(vc);
                }
                PropertyType::Utf8EncodedString => {
                    let s = CString::from_raw(cprop.value.__bindgen_anon_1.data.data);
                    let sc = s.clone();
                    s.into_raw();
                    cprop.value.__bindgen_anon_1.data.data = sc.into_raw();
                }
                PropertyType::Utf8StringPair => {
                    let s = CString::from_raw(cprop.value.__bindgen_anon_1.data.data);
                    let sc = s.clone();
                    cprop.value.__bindgen_anon_1.data.data = sc.into_raw();
                    s.into_raw();

                    let s = CString::from_raw(cprop.value.__bindgen_anon_1.value.data);
                    let sc = s.clone();
                    cprop.value.__bindgen_anon_1.value.data = sc.into_raw();
                    s.into_raw();
                }
                _ => (),
            }
        }
        Property { cprop }
    }
}

/////////////////////////////////////////////////////////////////////////////
// Properties

/// A collection of MQTT v5 properties.
///
/// This is a collection of properties that can be added to outgoing packets
/// or retrieved from incoming packets.
#[derive(Debug)]
pub struct Properties {
    pub(crate) cprops: ffi::MQTTProperties,
}

impl Properties {
    /// Creates a new, empty collection of properties.
    pub fn new() -> Self {
        Properties::default()
    }

    pub fn from_c_struct(cprops: &ffi::MQTTProperties) -> Self {
        // This does a deep copy in the C lib
        let cprops = unsafe { ffi::MQTTProperties_copy(cprops) };
        Properties { cprops }
    }

    /// Determines if the property list has no items in it.
    pub fn is_empty(&self) -> bool {
        self.cprops.count == 0
    }

    /// Gets the number of property items in the collection.
    pub fn len(&self) -> usize {
        self.cprops.count as usize
    }

    /// Gets the number of bytes required for the serialized list on
    /// the wire.
    pub fn byte_len(&self) -> usize {
        let p = &self.cprops as *const _ as *mut ffi::MQTTProperties;
        unsafe { ffi::MQTTProperties_len(p) as usize }
    }

    /// Removes all the items from the property list.
    pub fn clear(&mut self) {
        unsafe { ffi::MQTTProperties_free(&mut self.cprops) };
        self.cprops = ffi::MQTTProperties::default();
    }

    /// Adds a property to the colletion.
    pub fn push(&mut self, prop: Property) -> Result<()> {
        let rc = unsafe { ffi::MQTTProperties_add(&mut self.cprops, &prop.cprop) };
        if rc == 0 {
            mem::forget(prop);
            Ok(())
        }
        else {
            Err(rc.into())
        }
    }

    /// Adds a property to the collection given the property code and value.
    pub fn push_val<T>(&mut self, code: PropertyCode, val: T) -> Result<()>
    where
        T: Any + 'static,
    {
        self.push(Property::new(code, val)?)
    }

    /// Adds an single-byte property to the collection.
    pub fn push_byte(&mut self, code: PropertyCode, val: u8) -> Result<()> {
        self.push(Property::new_byte(code, val)?)
    }

    /// Adds an two-byte integer property to the collection.
    pub fn push_u16(&mut self, code: PropertyCode, val: u16) -> Result<()> {
        self.push(Property::new_u16(code, val)?)
    }

    /// Adds a four-byte integer property to the collection.
    pub fn push_u32(&mut self, code: PropertyCode, val: u32) -> Result<()> {
        self.push(Property::new_u32(code, val)?)
    }

    /// Adds an integer property to the collection.
    ///
    /// This works for any integer type.
    pub fn push_int(&mut self, code: PropertyCode, val: i32) -> Result<()> {
        self.push(Property::new_int(code, val)?)
    }

    /// Adds a binary property to the collection
    pub fn push_binary<V>(&mut self, code: PropertyCode, bin: V) -> Result<()>
    where
        V: Into<Binary>,
    {
        self.push(Property::new_binary(code, bin)?)
    }

    /// Adds a string property to the collection
    pub fn push_string(&mut self, code: PropertyCode, s: &str) -> Result<()> {
        self.push(Property::new_string(code, s)?)
    }

    /// Adds a string pair property to the collection
    pub fn push_string_pair(&mut self, code: PropertyCode, key: &str, val: &str) -> Result<()> {
        self.push(Property::new_string_pair(code, key, val)?)
    }

    /// Gets a property instance
    pub fn get(&self, code: PropertyCode) -> Option<Property> {
        self.get_at(code, 0)
    }

    /// Gets a property instance when there are possibly multiple values.
    pub fn get_at(&self, code: PropertyCode, idx: usize) -> Option<Property> {
        let ps = &self.cprops as *const _ as *mut ffi::MQTTProperties;
        unsafe {
            let p = ffi::MQTTProperties_getPropertyAt(ps, code as Code, idx as c_int);
            if !p.is_null() {
                Property::from_c_property(&*p).ok()
            }
            else {
                None
            }
        }
    }

    /// Gets an iterator for a property instance
    pub fn iter(&self, code: PropertyCode) -> PropertyIterator {
        PropertyIterator {
            props: self,
            code,
            idx: 0,
        }
    }

    /// Gets a value from the collection when there may be more than one
    /// for the code.
    pub fn get_val_at<T>(&self, code: PropertyCode, idx: usize) -> Option<T>
    where
        T: Any + 'static + Send + Default,
    {
        self.get_at(code, idx).and_then(|prop| prop.get())
    }

    /// Gets a value from the collection when there may be more than one
    /// for the code.
    pub fn get_val<T>(&self, code: PropertyCode) -> Option<T>
    where
        T: Any + 'static + Send + Default,
    {
        self.get_val_at(code, 0)
    }

    /// Gets an integer value of a specific property.
    pub fn get_int(&self, code: PropertyCode) -> Option<i32> {
        self.get(code).and_then(|prop| prop.get_int())
    }

    /// Gets an integer value of a specific value when there may be more than one.
    pub fn get_int_at(&self, code: PropertyCode, idx: usize) -> Option<i32> {
        self.get_at(code, idx).and_then(|prop| prop.get_int())
    }

    /// Gets a binary value of a specific property.
    pub fn get_binary(&self, code: PropertyCode) -> Option<Binary> {
        self.get(code).and_then(|prop| prop.get_binary())
    }

    /// Gets a binary value of a specific value when there may be more than one.
    pub fn get_binary_at(&self, code: PropertyCode, idx: usize) -> Option<Binary> {
        self.get_at(code, idx).and_then(|prop| prop.get_binary())
    }

    /// Gets a string value of a specific property.
    pub fn get_string(&self, code: PropertyCode) -> Option<String> {
        self.get(code).and_then(|prop| prop.get_string())
    }

    /// Gets a binary value of a specific value when there may be more than one.
    pub fn get_string_at(&self, code: PropertyCode, idx: usize) -> Option<String> {
        self.get_at(code, idx).and_then(|prop| prop.get_string())
    }

    /// Gets a string pair for a specific property.
    pub fn get_string_pair(&self, code: PropertyCode) -> Option<(String, String)> {
        self.get(code).and_then(|prop| prop.get_string_pair())
    }

    /// Gets a string pair for a specific property when there may be more than one.
    pub fn get_string_pair_at(&self, code: PropertyCode, idx: usize) -> Option<(String, String)> {
        self.get_at(code, idx)
            .and_then(|prop| prop.get_string_pair())
    }

    /// Gets an iterator into the user property string pairs.
    pub fn user_iter(&self) -> StringPairIterator {
        StringPairIterator {
            props: self,
            code: PropertyCode::UserProperty,
            idx: 0,
        }
    }

    /// Searches for the specified key in the user properties and returns
    /// the value if found.
    pub fn find_user_property(&self, key: &str) -> Option<String> {
        for (k, v) in self.user_iter() {
            if k == key {
                return Some(v);
            }
        }
        None
    }
}

impl Default for Properties {
    fn default() -> Self {
        Properties {
            cprops: ffi::MQTTProperties::default(),
        }
    }
}

unsafe impl Send for Properties {}

impl Clone for Properties {
    /// Creates a clone of the property.
    /// For string any binary properties, this also clones the heap memory
    /// so that each property is managing separate allocations.
    fn clone(&self) -> Self {
        // This does a deep copy in the C lib
        let cprops = unsafe { ffi::MQTTProperties_copy(&self.cprops) };
        Properties { cprops }
    }
}

impl Drop for Properties {
    fn drop(&mut self) {
        // This deletes the collection and all the elements in it.
        unsafe { ffi::MQTTProperties_free(&mut self.cprops) };
    }
}

/// Iterator over the values for a speciifc property
pub struct PropertyIterator<'a> {
    props: &'a Properties,
    code: PropertyCode,
    idx: usize,
}

impl<'a> Iterator for PropertyIterator<'a> {
    type Item = Property;

    fn next(&mut self) -> Option<Self::Item> {
        let prop = self.props.get_at(self.code, self.idx);
        self.idx += 1;
        prop
    }
}

/// Iterator over the values for a speciifc property
pub struct StringPairIterator<'a> {
    props: &'a Properties,
    code: PropertyCode,
    idx: usize,
}

impl<'a> Iterator for StringPairIterator<'a> {
    type Item = (String, String);

    fn next(&mut self) -> Option<Self::Item> {
        let pair = self.props.get_string_pair_at(self.code, self.idx);
        self.idx += 1;
        pair
    }
}

/////////////////////////////////////////////////////////////////////////////
//                              Unit Tests
/////////////////////////////////////////////////////////////////////////////

#[cfg(test)]
mod tests {
    use super::*;
    use std::ffi::CStr;

    #[test]
    fn test_property_type_new() {
        assert_eq!(
            PropertyType::new(ffi::MQTTPropertyTypes_MQTTPROPERTY_TYPE_BYTE),
            Some(PropertyType::Byte)
        );
        assert_eq!(
            PropertyType::new(ffi::MQTTPropertyTypes_MQTTPROPERTY_TYPE_BINARY_DATA),
            Some(PropertyType::BinaryData)
        );

        assert_eq!(PropertyType::new(7), None);
    }

    #[test]
    fn test_property_code_new() {
        assert_eq!(
            PropertyCode::new(ffi::MQTTPropertyCodes_MQTTPROPERTY_CODE_PAYLOAD_FORMAT_INDICATOR),
            Some(PropertyCode::PayloadFormatIndicator)
        );
        assert_eq!(
            PropertyCode::new(ffi::MQTTPropertyCodes_MQTTPROPERTY_CODE_AUTHENTICATION_METHOD),
            Some(PropertyCode::AuthenticationMethod)
        );
        assert_eq!(
            PropertyCode::new(ffi::MQTTPropertyCodes_MQTTPROPERTY_CODE_USER_PROPERTY),
            Some(PropertyCode::UserProperty)
        );
    }

    #[test]
    fn test_property_generic_new() {
        let prop = Property::new(PropertyCode::ResponseTopic, 42u16);
        assert!(!prop.is_ok());

        //let prop = Property::new(PropertyCode::ResponseTopic, "events".to_string());
        //assert!(prop.is_ok());

        let prop = Property::new(PropertyCode::MaximumQos, 2u8);
        assert!(prop.is_ok());

        let topic = "data/temp".to_string();
        let prop = Property::new(PropertyCode::ResponseTopic, topic.clone()).unwrap();
        assert_eq!(prop.get_string(), Some(topic));

        let topic = "data/temp";
        let prop = Property::new(PropertyCode::ResponseTopic, topic).unwrap();
        assert_eq!(prop.get_string(), Some(topic.to_string()));
    }

    #[test]
    fn test_new_property_byte() {
        let val = 1u8;

        let prop = Property::new_byte(PropertyCode::PayloadFormatIndicator, val).unwrap();

        unsafe {
            assert_eq!(
                prop.cprop.identifier,
                PropertyCode::PayloadFormatIndicator as Code
            );
            assert_eq!(prop.cprop.value.byte, val);
        }

        assert_eq!(prop.get_byte(), Some(val));
        assert_eq!(prop.get::<u8>(), Some(val));

        let val = 1i32;
        let prop = Property::new_int(PropertyCode::PayloadFormatIndicator, val).unwrap();

        unsafe {
            assert_eq!(
                prop.cprop.identifier,
                PropertyCode::PayloadFormatIndicator as Code
            );
            assert_eq!(prop.cprop.value.byte, val as u8);
        }

        assert_eq!(prop.get_int(), Some(val));
        assert_eq!(prop.get::<i32>(), Some(val));

        let res = Property::new_int(PropertyCode::PayloadFormatIndicator, 0x100);
        assert!(res.is_err());
    }

    #[test]
    fn test_new_property_u16() {
        let val = 1024u16;
        let prop = Property::new_u16(PropertyCode::ReceiveMaximum, val).unwrap();

        unsafe {
            assert_eq!(prop.cprop.identifier, PropertyCode::ReceiveMaximum as Code);
            assert_eq!(prop.cprop.value.integer2, val);
        }

        assert_eq!(prop.get_u16(), Some(val));
        assert_eq!(prop.get::<u16>(), Some(val));

        let val = 1024i32;
        let prop = Property::new_int(PropertyCode::ReceiveMaximum, val).unwrap();

        unsafe {
            assert_eq!(prop.cprop.identifier, PropertyCode::ReceiveMaximum as Code);
            assert_eq!(prop.cprop.value.integer2, val as u16);
        }

        assert_eq!(prop.get_int(), Some(val));
        assert_eq!(prop.get::<i32>(), Some(val));

        assert_eq!(prop.get_u16(), Some(val as u16));
        assert_eq!(prop.get::<u16>(), Some(val as u16));

        let res = Property::new_int(PropertyCode::ReceiveMaximum, 0x10000);
        assert!(res.is_err());
    }

    #[test]
    fn test_new_property_i32() {
        let val = 1024 * 1024;
        let prop = Property::new_int(PropertyCode::MessageExpiryInterval, val).unwrap();

        unsafe {
            assert_eq!(
                prop.cprop.identifier,
                PropertyCode::MessageExpiryInterval as Code
            );
            assert_eq!(prop.cprop.value.integer4, val as u32);
        }
    }

    #[test]
    fn test_new_property_binary() {
        let val = "12345"; // Anything that can be converted into Vec<u8>
        let prop = Property::new_binary(PropertyCode::CorrelationData, val).unwrap();

        // We should have non-null data pointer, null value pointer
        unsafe {
            assert!(!prop.cprop.value.__bindgen_anon_1.data.data.is_null());
            assert_eq!(prop.cprop.value.__bindgen_anon_1.data.len, 5);

            assert!(prop.cprop.value.__bindgen_anon_1.value.data.is_null());
            assert_eq!(prop.cprop.value.__bindgen_anon_1.value.len, 0);
        }
        assert_eq!(prop.get_binary(), Some(val.as_bytes().to_vec()));
        assert_eq!(prop.get::<Vec<u8>>(), Some(val.as_bytes().to_vec()));
    }

    #[test]
    fn test_new_property_string() {
        let val = "replies/myqueue";
        let prop = Property::new_string(PropertyCode::ResponseTopic, val).unwrap();

        // We should have non-null data pointer, null value pointer
        unsafe {
            assert!(!prop.cprop.value.__bindgen_anon_1.data.data.is_null());
            assert_eq!(
                prop.cprop.value.__bindgen_anon_1.data.len,
                val.len() as c_int
            );

            let s = CStr::from_ptr(prop.cprop.value.__bindgen_anon_1.data.data);
            assert_eq!(val, s.to_str().unwrap());

            assert!(prop.cprop.value.__bindgen_anon_1.value.data.is_null());
            assert_eq!(prop.cprop.value.__bindgen_anon_1.value.len, 0);
        }

        assert_eq!(prop.get_string(), Some(val.to_string()));
        assert_eq!(prop.get::<String>(), Some(val.to_string()));
    }

    #[test]
    fn test_new_property_string_pair() {
        let key = "mykey";
        let val = "myvalue";
        let prop = Property::new_string_pair(PropertyCode::UserProperty, key, val).unwrap();

        // We should have non-null data and value pointers
        unsafe {
            assert!(!prop.cprop.value.__bindgen_anon_1.data.data.is_null());
            assert_eq!(
                prop.cprop.value.__bindgen_anon_1.data.len,
                key.len() as c_int
            );

            let s = CStr::from_ptr(prop.cprop.value.__bindgen_anon_1.data.data);
            assert_eq!(key, s.to_str().unwrap());

            assert!(!prop.cprop.value.__bindgen_anon_1.value.data.is_null());
            assert_eq!(
                prop.cprop.value.__bindgen_anon_1.value.len,
                val.len() as c_int
            );

            let s = CStr::from_ptr(prop.cprop.value.__bindgen_anon_1.value.data);
            assert_eq!(val, s.to_str().unwrap());
        }

        assert_eq!(
            prop.get_string_pair(),
            Some((key.to_string(), val.to_string()))
        );
        assert_eq!(
            prop.get::<(String, String)>(),
            Some((key.to_string(), val.to_string()))
        );
    }

    #[test]
    fn test_move_property_int() {
        let val = 1024 * 1024;

        let org_prop = Property::new_int(PropertyCode::MessageExpiryInterval, val).unwrap();
        unsafe {
            assert_eq!(
                org_prop.cprop.identifier,
                PropertyCode::MessageExpiryInterval as Code
            );
            assert_eq!(org_prop.cprop.value.integer4, val as u32);
        }

        let prop = org_prop;
        unsafe {
            assert_eq!(
                prop.cprop.identifier,
                PropertyCode::MessageExpiryInterval as Code
            );
            assert_eq!(prop.cprop.value.integer4, val as u32);
        }
    }

    #[test]
    fn test_move_property_binary() {
        let val = "12345"; // Anything that can be converted into Vec<u8>
        let org_prop = Property::new_binary(PropertyCode::CorrelationData, val).unwrap();

        let prop = org_prop;

        // We should have non-null data pointer, null value pointer
        unsafe {
            assert_eq!(prop.cprop.identifier, PropertyCode::CorrelationData as Code);

            assert!(!prop.cprop.value.__bindgen_anon_1.data.data.is_null());
            assert_eq!(prop.cprop.value.__bindgen_anon_1.data.len, 5);

            assert!(prop.cprop.value.__bindgen_anon_1.value.data.is_null());
            assert_eq!(prop.cprop.value.__bindgen_anon_1.value.len, 0);
        }
    }

    #[test]
    fn test_move_property_string() {
        let val = "replies/myqueue";
        let org_prop = Property::new_string(PropertyCode::ResponseTopic, val).unwrap();

        let prop = org_prop;

        unsafe {
            assert_eq!(prop.cprop.identifier, PropertyCode::ResponseTopic as Code);

            assert!(!prop.cprop.value.__bindgen_anon_1.data.data.is_null());
            assert_eq!(
                prop.cprop.value.__bindgen_anon_1.data.len,
                val.len() as c_int
            );

            assert!(prop.cprop.value.__bindgen_anon_1.value.data.is_null());
            assert_eq!(prop.cprop.value.__bindgen_anon_1.value.len, 0);
        }
    }

    #[test]
    fn test_clone_property_binary() {
        let val = "12345"; // Anything that can be converted into Vec<u8>
        let org_prop = Property::new_binary(PropertyCode::CorrelationData, val).unwrap();

        let prop = org_prop.clone();

        // We should have non-null data pointer, null value pointer
        unsafe {
            assert_eq!(prop.cprop.identifier, PropertyCode::CorrelationData as Code);

            assert!(!prop.cprop.value.__bindgen_anon_1.data.data.is_null());
            assert_eq!(prop.cprop.value.__bindgen_anon_1.data.len, 5);

            assert!(prop.cprop.value.__bindgen_anon_1.value.data.is_null());
            assert_eq!(prop.cprop.value.__bindgen_anon_1.value.len, 0);

            assert_ne!(
                org_prop.cprop.value.__bindgen_anon_1.data.data,
                prop.cprop.value.__bindgen_anon_1.data.data
            );
        }
    }

    #[test]
    fn test_clone_property_string() {
        let val = "replies/myqueue";
        let org_prop = Property::new_string(PropertyCode::ResponseTopic, val).unwrap();

        let prop = org_prop;

        unsafe {
            assert_eq!(prop.cprop.identifier, PropertyCode::ResponseTopic as Code);

            assert!(!prop.cprop.value.__bindgen_anon_1.data.data.is_null());
            assert_eq!(
                prop.cprop.value.__bindgen_anon_1.data.len,
                val.len() as c_int
            );

            assert!(prop.cprop.value.__bindgen_anon_1.value.data.is_null());
            assert_eq!(prop.cprop.value.__bindgen_anon_1.value.len, 0);
        }
    }

    /////////////////////////////////////////////////////////////////////////

    #[test]
    fn test_properties_default() {
        let props = Properties::default();

        assert!(props.is_empty());
        assert_eq!(props.len(), 0);

        // Empty list needs 1 byte for zero len byte
        assert_eq!(props.byte_len(), 1);
    }

    #[test]
    fn test_properties_push() {
        let mut props = Properties::new();

        let val = 1;
        let prop = Property::new_int(PropertyCode::PayloadFormatIndicator, val).unwrap();

        props.push(prop).unwrap();

        assert_eq!(props.len(), 1);
        assert!(!props.is_empty());
    }

    #[test]
    fn test_properties_push_val() {
        let mut props = Properties::new();

        props
            .push_val(PropertyCode::ResponseTopic, "responses/somewhere")
            .unwrap();

        assert!(!props.is_empty());
        assert_eq!(props.len(), 1);

        props
            .push_val(PropertyCode::CorrelationData, b"12345")
            .unwrap();
        assert_eq!(props.len(), 2);
    }

    #[test]
    fn test_properties_get_int() {
        let code = PropertyCode::PayloadFormatIndicator;

        let mut props = Properties::new();

        let val = 1;
        let org_prop = Property::new_int(code, val).unwrap();

        props.push(org_prop).unwrap();

        let prop = props.get(code).unwrap();
        assert_eq!(prop.get_int().unwrap(), val);
        //assert_eq!(prop.get_val::<i32>().unwrap(), val);
    }

    #[test]
    fn test_properties_multiple() {
        let code = PropertyCode::UserProperty;

        let mut props = Properties::new();

        props
            .push(Property::new_string_pair(code, "user0", "val0").unwrap())
            .unwrap();
        props
            .push(Property::new_string_pair(code, "user1", "val1").unwrap())
            .unwrap();
        props
            .push(Property::new_string_pair(code, "user2", "val2").unwrap())
            .unwrap();

        assert!(!props.is_empty());
        assert_eq!(props.len(), 3);

        assert_eq!(
            props.get_string_pair_at(code, 0).unwrap(),
            ("user0".to_string(), "val0".to_string())
        );
        assert_eq!(
            props.get_string_pair_at(code, 1).unwrap(),
            ("user1".to_string(), "val1".to_string())
        );
        assert_eq!(
            props.get_string_pair_at(code, 2).unwrap(),
            ("user2".to_string(), "val2".to_string())
        );

        assert_eq!(
            props.get_val::<(String, String)>(code),
            Some(("user0".to_string(), "val0".to_string()))
        );
        assert_eq!(
            props.get_val_at::<(String, String)>(code, 1),
            Some(("user1".to_string(), "val1".to_string()))
        );
        assert_eq!(
            props.get_val_at::<(String, String)>(code, 2),
            Some(("user2".to_string(), "val2".to_string()))
        );

        assert_eq!(props.get_string_pair_at(code, 3), None);
    }

    #[test]
    fn test_properties_iterator() {
        let code = PropertyCode::UserProperty;

        let mut props = Properties::new();

        props.push_string_pair(code, "user0", "val0").unwrap();
        props.push_string_pair(code, "user1", "val1").unwrap();
        props.push_string_pair(code, "user2", "val2").unwrap();

        let mut it = props.iter(code);

        assert_eq!(
            it.next().and_then(|prop| prop.get_string_pair()),
            Some(("user0".to_string(), "val0".to_string()))
        );
        assert_eq!(
            it.next().and_then(|prop| prop.get_string_pair()),
            Some(("user1".to_string(), "val1".to_string()))
        );
        assert_eq!(
            it.next().and_then(|prop| prop.get_string_pair()),
            Some(("user2".to_string(), "val2".to_string()))
        );

        assert_eq!(it.next().and_then(|prop| prop.get_string_pair()), None);
    }

    #[test]
    fn test_properties_user_iterator() {
        let code = PropertyCode::UserProperty;

        let mut props = Properties::new();

        props.push_string_pair(code, "user0", "val0").unwrap();
        props.push_string_pair(code, "user1", "val1").unwrap();
        props.push_string_pair(code, "user2", "val2").unwrap();

        let mut it = props.user_iter();

        assert_eq!(it.next(), Some(("user0".to_string(), "val0".to_string())));
        assert_eq!(it.next(), Some(("user1".to_string(), "val1".to_string())));
        assert_eq!(it.next(), Some(("user2".to_string(), "val2".to_string())));

        assert_eq!(it.next(), None);
    }

    #[test]
    fn test_properties_user_find() {
        let code = PropertyCode::UserProperty;

        let mut props = Properties::new();

        props
            .push(Property::new_string_pair(code, "user0", "val0").unwrap())
            .unwrap();
        props
            .push(Property::new_string_pair(code, "user1", "val1").unwrap())
            .unwrap();
        props
            .push(Property::new_string_pair(code, "user2", "val2").unwrap())
            .unwrap();

        assert_eq!(props.find_user_property("user0"), Some("val0".to_string()));
        assert_eq!(props.find_user_property("user1"), Some("val1".to_string()));
        assert_eq!(props.find_user_property("user2"), Some("val2".to_string()));
        assert_eq!(props.find_user_property("user3"), None);
    }

    #[test]
    fn test_properties_macro() {
        // Zero length
        let props = properties![];
        assert!(props.is_empty());

        // Some different properties
        let props = properties! {
            PropertyCode::ResponseTopic => "responses/somewhere",
            PropertyCode::CorrelationData => b"12345",
            PropertyCode::MaximumQos => 1,
        };

        println!("{:?}", props);
        assert!(!props.is_empty());
        assert_eq!(3, props.len());
        assert_eq!(
            Some(b"12345".to_vec()),
            props.get_val::<Vec<u8>>(PropertyCode::CorrelationData)
        );

        let props = properties! {
            PropertyCode::SessionExpiryInterval => 60,
        };

        assert_eq!(1, props.len());
        assert_eq!(
            Some(60),
            props.get_val::<i32>(PropertyCode::SessionExpiryInterval)
        );
    }
}