Add basic client (#56)

Author: Chrisbattarbee

.cursorrules

@@ -0,0 +1,9 @@
+This repository is an implementation of a golang  model context protocol sdk.
+
+Project docs are available in the docs folder.
+
+Model context prtocol docs are available at https://modelcontextprotocol.io
+
+Write tests for all new functionality.
+
+Use go test to run tests after adding new functionality.

.gitignore

@@ -1 +1,2 @@
-.idea
+.idea
+.vscode

client.go

@@ -0,0 +1,269 @@
+package mcp_golang
+
+import (
+	"context"
+	"encoding/json"
+
+	"github.com/metoro-io/mcp-golang/internal/protocol"
+	"github.com/metoro-io/mcp-golang/internal/tools"
+	"github.com/metoro-io/mcp-golang/transport"
+	"github.com/pkg/errors"
+)
+
+// Client represents an MCP client that can connect to and interact with MCP servers
+type Client struct {
+	transport    transport.Transport
+	protocol     *protocol.Protocol
+	capabilities *ServerCapabilities
+	initialized  bool
+}
+
+// NewClient creates a new MCP client with the specified transport
+func NewClient(transport transport.Transport) *Client {
+	return &Client{
+		transport: transport,
+		protocol:  protocol.NewProtocol(nil),
+	}
+}
+
+// Initialize connects to the server and retrieves its capabilities
+func (c *Client) Initialize(ctx context.Context) (*InitializeResponse, error) {
+	if c.initialized {
+		return nil, errors.New("client already initialized")
+	}
+
+	err := c.protocol.Connect(c.transport)
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to connect transport")
+	}
+
+	// Make initialize request to server
+	response, err := c.protocol.Request(ctx, "initialize", nil, nil)
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to initialize")
+	}
+
+	responseBytes, ok := response.(json.RawMessage)
+	if !ok {
+		return nil, errors.New("invalid response type")
+	}
+
+	var initResult InitializeResponse
+	err = json.Unmarshal(responseBytes, &initResult)
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to unmarshal initialize response")
+	}
+
+	c.capabilities = &initResult.Capabilities
+	c.initialized = true
+	return &initResult, nil
+}
+
+// ListTools retrieves the list of available tools from the server
+func (c *Client) ListTools(ctx context.Context, cursor *string) (*tools.ToolsResponse, error) {
+	if !c.initialized {
+		return nil, errors.New("client not initialized")
+	}
+
+	params := map[string]interface{}{
+		"cursor": cursor,
+	}
+
+	response, err := c.protocol.Request(ctx, "tools/list", params, nil)
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to list tools")
+	}
+
+	responseBytes, ok := response.(json.RawMessage)
+	if !ok {
+		return nil, errors.New("invalid response type")
+	}
+
+	var toolsResponse tools.ToolsResponse
+	err = json.Unmarshal(responseBytes, &toolsResponse)
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to unmarshal tools response")
+	}
+
+	return &toolsResponse, nil
+}
+
+// CallTool calls a specific tool on the server with the provided arguments
+func (c *Client) CallTool(ctx context.Context, name string, arguments any) (*ToolResponse, error) {
+	if !c.initialized {
+		return nil, errors.New("client not initialized")
+	}
+
+	argumentsJson, err := json.Marshal(arguments)
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to marshal arguments")
+	}
+
+	params := baseCallToolRequestParams{
+		Name:      name,
+		Arguments: argumentsJson,
+	}
+
+	response, err := c.protocol.Request(ctx, "tools/call", params, nil)
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to call tool")
+	}
+
+	responseBytes, ok := response.(json.RawMessage)
+	if !ok {
+		return nil, errors.New("invalid response type")
+	}
+
+	var toolResponse ToolResponse
+	err = json.Unmarshal(responseBytes, &toolResponse)
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to unmarshal tool response")
+	}
+
+	return &toolResponse, nil
+}
+
+// ListPrompts retrieves the list of available prompts from the server
+func (c *Client) ListPrompts(ctx context.Context, cursor *string) (*ListPromptsResponse, error) {
+	if !c.initialized {
+		return nil, errors.New("client not initialized")
+	}
+
+	params := map[string]interface{}{
+		"cursor": cursor,
+	}
+
+	response, err := c.protocol.Request(ctx, "prompts/list", params, nil)
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to list prompts")
+	}
+
+	responseBytes, ok := response.(json.RawMessage)
+	if !ok {
+		return nil, errors.New("invalid response type")
+	}
+
+	var promptsResponse ListPromptsResponse
+	err = json.Unmarshal(responseBytes, &promptsResponse)
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to unmarshal prompts response")
+	}
+
+	return &promptsResponse, nil
+}
+
+// GetPrompt retrieves a specific prompt from the server
+func (c *Client) GetPrompt(ctx context.Context, name string, arguments any) (*PromptResponse, error) {
+	if !c.initialized {
+		return nil, errors.New("client not initialized")
+	}
+
+	argumentsJson, err := json.Marshal(arguments)
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to marshal arguments")
+	}
+
+	params := baseGetPromptRequestParamsArguments{
+		Name:      name,
+		Arguments: argumentsJson,
+	}
+
+	response, err := c.protocol.Request(ctx, "prompts/get", params, nil)
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to get prompt")
+	}
+
+	responseBytes, ok := response.(json.RawMessage)
+	if !ok {
+		return nil, errors.New("invalid response type")
+	}
+
+	var promptResponse PromptResponse
+	err = json.Unmarshal(responseBytes, &promptResponse)
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to unmarshal prompt response")
+	}
+
+	return &promptResponse, nil
+}
+
+// ListResources retrieves the list of available resources from the server
+func (c *Client) ListResources(ctx context.Context, cursor *string) (*ListResourcesResponse, error) {
+	if !c.initialized {
+		return nil, errors.New("client not initialized")
+	}
+
+	params := map[string]interface{}{
+		"cursor": cursor,
+	}
+
+	response, err := c.protocol.Request(ctx, "resources/list", params, nil)
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to list resources")
+	}
+
+	responseBytes, ok := response.(json.RawMessage)
+	if !ok {
+		return nil, errors.New("invalid response type")
+	}
+
+	var resourcesResponse ListResourcesResponse
+	err = json.Unmarshal(responseBytes, &resourcesResponse)
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to unmarshal resources response")
+	}
+
+	return &resourcesResponse, nil
+}
+
+// ReadResource reads a specific resource from the server
+func (c *Client) ReadResource(ctx context.Context, uri string) (*ResourceResponse, error) {
+	if !c.initialized {
+		return nil, errors.New("client not initialized")
+	}
+
+	params := readResourceRequestParams{
+		Uri: uri,
+	}
+
+	response, err := c.protocol.Request(ctx, "resources/read", params, nil)
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to read resource")
+	}
+
+	responseBytes, ok := response.(json.RawMessage)
+	if !ok {
+		return nil, errors.New("invalid response type")
+	}
+
+	var resourceResponse resourceResponseSent
+	err = json.Unmarshal(responseBytes, &resourceResponse)
+	if err != nil {
+		return nil, errors.Wrap(err, "failed to unmarshal resource response")
+	}
+
+	if resourceResponse.Error != nil {
+		return nil, resourceResponse.Error
+	}
+
+	return resourceResponse.Response, nil
+}
+
+// Ping sends a ping request to the server to check connectivity
+func (c *Client) Ping(ctx context.Context) error {
+	if !c.initialized {
+		return errors.New("client not initialized")
+	}
+
+	_, err := c.protocol.Request(ctx, "ping", nil, nil)
+	if err != nil {
+		return errors.Wrap(err, "failed to ping server")
+	}
+
+	return nil
+}
+
+// GetCapabilities returns the server capabilities obtained during initialization
+func (c *Client) GetCapabilities() *ServerCapabilities {
+	return c.capabilities
+}

content_api.go

@@ -3,6 +3,7 @@ package mcp_golang
 import (
 	"encoding/json"
 	"fmt"
+
 	"github.com/tidwall/sjson"
 )
 
@@ -111,9 +112,43 @@ type Content struct {
 	Annotations      *Annotations
 }
 
+func (c *Content) UnmarshalJSON(b []byte) error {
+	type typeWrapper struct {
+		Type             ContentType       `json:"type" yaml:"type" mapstructure:"type"`
+		Text             *string           `json:"text" yaml:"text" mapstructure:"text"`
+		Image            *string           `json:"image" yaml:"image" mapstructure:"image"`
+		Annotations      *Annotations      `json:"annotations" yaml:"annotations" mapstructure:"annotations"`
+		EmbeddedResource *EmbeddedResource `json:"resource" yaml:"resource" mapstructure:"resource"`
+	}
+	var tw typeWrapper
+	err := json.Unmarshal(b, &tw)
+	if err != nil {
+		return err
+	}
+	switch tw.Type {
+	case ContentTypeText:
+		c.Type = ContentTypeText
+	case ContentTypeImage:
+		c.Type = ContentTypeImage
+	case ContentTypeEmbeddedResource:
+		c.Type = ContentTypeEmbeddedResource
+	default:
+		return fmt.Errorf("unknown content type: %s", tw.Type)
+	}
+
+	switch c.Type {
+	case ContentTypeText:
+		c.TextContent = &TextContent{Text: *tw.Text}
+	default:
+		return fmt.Errorf("unknown content type: %s", c.Type)
+	}
+
+	return nil
+}
+
 // Custom JSON marshaling for ToolResponse Content
 func (c Content) MarshalJSON() ([]byte, error) {
-	rawJson := []byte{}
+	var rawJson []byte
 
 	switch c.Type {
 	case ContentTypeText: