add mcp (Model Context Protocol) support

pkg/mcp/model_context_protocol.go

@@ -0,0 +1,218 @@
+package mcp
+
+import (
+	"encoding/base64"
+	"encoding/json"
+
+	"github.com/invopop/jsonschema"
+)
+
+// MCPProtocolVersion defines the type for Model Context Protocol (MCP) version
+type MCPProtocolVersion string
+
+// MCP Protocol Versions
+const (
+	MCPProtocolVersion20250618 MCPProtocolVersion = "2025-06-18"
+	MCPProtocolVersion20250326 MCPProtocolVersion = "2025-03-26"
+	MCPProtocolVersion20241105 MCPProtocolVersion = "2024-11-05"
+)
+
+// LatestSupportedMCPVersion defines the latest supported version of Model Context Protocol (MCP)
+const LatestSupportedMCPVersion = MCPProtocolVersion20250618
+
+// SupportedMCPVersion defines a map of supported MCP versions
+var SupportedMCPVersion = map[MCPProtocolVersion]bool{
+	MCPProtocolVersion20250618: true,
+	MCPProtocolVersion20250326: true,
+	MCPProtocolVersion20241105: true,
+}
+
+// MCPInitializeRequest defines the request structure for initializing the MCP connection
+type MCPInitializeRequest struct {
+	ProtocolVersion string             `json:"protocolVersion"`
+	ClientInfo      *MCPImplementation `json:"clientInfo"`
+}
+
+// MCPInitializeResponse defines the response structure for the MCP initialization request
+type MCPInitializeResponse struct {
+	ProtocolVersion string             `json:"protocolVersion"`
+	Capabilities    *MCPCapabilities   `json:"capabilities"`
+	ServerInfo      *MCPImplementation `json:"serverInfo"`
+}
+
+// MCPCapabilities defines the capabilities of the MCP server
+type MCPCapabilities struct {
+	Resources *MCPResourceCapabilities `json:"resources,omitempty"`
+	Tools     *MCPToolCapabilities     `json:"tools,omitempty"`
+	Prompts   *MCPPromptCapabilities   `json:"prompts,omitempty"`
+}
+
+// MCPImplementation defines the client/server information structure sent in the MCP initialization request/response
+type MCPImplementation struct {
+	Name    string `json:"name"`
+	Title   string `json:"title,omitempty"`
+	Version string `json:"version"`
+}
+
+// MCPResourceCapabilities defines the capabilities related to resources in the MCP
+type MCPResourceCapabilities struct {
+	Subscribe   bool `json:"subscribe"`
+	ListChanged bool `json:"listChanged"`
+}
+
+// MCPToolCapabilities defines the capabilities related to tools in the MCP
+type MCPToolCapabilities struct {
+	ListChanged bool `json:"listChanged"`
+}
+
+// MCPPromptCapabilities defines the capabilities related to prompts in the MCP
+type MCPPromptCapabilities struct {
+	ListChanged bool `json:"listChanged"`
+}
+
+// MCPListResourcesResponse defines the response structure for listing resources in the MCP
+type MCPListResourcesResponse struct {
+	Resources  []*MCPResource `json:"resources"`
+	NextCursor string         `json:"nextCursor,omitempty"`
+}
+
+// MCPResource defines the structure of a resource in the MCP
+type MCPResource struct {
+	URI         string `json:"uri"`
+	Name        string `json:"name"`
+	Size        int    `json:"size,omitempty"`
+	MimeType    string `json:"mimeType,omitempty"`
+	Title       string `json:"title,omitempty"`
+	Description string `json:"description,omitempty"`
+}
+
+// MCPReadResourceRequest defines the request structure for reading a resource in the MCP
+type MCPReadResourceRequest struct {
+	URI string `json:"uri"`
+}
+
+// MCPReadResourceResponse defines the response structure for reading a resource in the MCP
+type MCPReadResourceResponse[T MCPTextResourceContents | MCPBlobResourceContents] struct {
+	Contents []*T `json:"contents"`
+}
+
+// MCPTextResourceContents defines the text contents structure of a resource in the MCP
+type MCPTextResourceContents struct {
+	URI      string `json:"uri"`
+	Text     string `json:"text"`
+	MimeType string `json:"mimeType,omitempty"`
+}
+
+// MCPBlobResourceContents defines the blob contents structure of a resource in the MCP
+type MCPBlobResourceContents struct {
+	URI      string `json:"uri"`
+	Blob     string `json:"blob"` // Base64 encoded content of the resource
+	MimeType string `json:"mimeType,omitempty"`
+}
+
+// MCPListToolsResponse defines the response structure for listing tools in the MCP
+type MCPListToolsResponse struct {
+	Tools      []*MCPTool `json:"tools"`
+	NextCursor string     `json:"nextCursor,omitempty"`
+}
+
+// MCPTool defines the structure of a tool in the MCP
+type MCPTool struct {
+	Name         string             `json:"name"`
+	InputSchema  *jsonschema.Schema `json:"inputSchema"`
+	OutputSchema *jsonschema.Schema `json:"outputSchema"`
+	Title        string             `json:"title,omitempty"`
+	Description  string             `json:"description,omitempty"`
+}
+
+// MCPCallToolRequest defines the request structure for listing tools in the MCP
+type MCPCallToolRequest struct {
+	Name      string          `json:"name"`
+	Arguments json.RawMessage `json:"arguments,omitempty"`
+}
+
+// MCPCallToolResponse defines the response structure for calling a tool in the MCP
+type MCPCallToolResponse[T MCPTextContent | MCPImageContent | MCPAudioContent | MCPResourceLink | MCPEmbeddedResource] struct {
+	Content []*T `json:"content"`
+	IsError bool `json:"isError,omitempty"`
+}
+
+// MCPTextContent defines the text content structure used in MCP
+type MCPTextContent struct {
+	Type string `json:"type"`
+	Text string `json:"text"`
+}
+
+// MCPImageContent defines the image content structure used in MCP
+type MCPImageContent struct {
+	Type     string `json:"type"`
+	MimeType string `json:"mimeType"`
+	Data     string `json:"data"` // Base64 encoded content for binary data
+}
+
+// MCPAudioContent defines the audio content structure used in MCP
+type MCPAudioContent struct {
+	Type     string `json:"type"`
+	MimeType string `json:"mimeType"`
+	Data     string `json:"data"` // Base64 encoded content for binary data
+}
+
+// MCPResourceLink defines the resource link content structure used in MCP
+type MCPResourceLink struct {
+	URI         string `json:"uri"`
+	Type        string `json:"type"`
+	Name        string `json:"name"`
+	Size        int    `json:"size,omitempty"`
+	MimeType    string `json:"mimeType,omitempty"`
+	Title       string `json:"title,omitempty"`
+	Description string `json:"description,omitempty"`
+}
+
+// MCPEmbeddedResource defines the embedded resource content structure used in MCP
+type MCPEmbeddedResource struct {
+	Type     string `json:"type"`
+	Resource any    `json:"resource"`
+}
+
+// NewMCPTextContent creates a new instance of MCPTextContent with the given text
+func NewMCPTextContent(text string) *MCPTextContent {
+	return &MCPTextContent{
+		Type: "text",
+		Text: text,
+	}
+}
+
+// NewMCPImageContent creates a new instance of MCPImageContent with the given data and MIME type
+func NewMCPImageContent(data []byte, mimeType string) *MCPImageContent {
+	return &MCPImageContent{
+		Type:     "image",
+		MimeType: mimeType,
+		Data:     base64.StdEncoding.EncodeToString(data),
+	}
+}
+
+// NewMCPAudioContent creates a new instance of MCPAudioContent with the given data and MIME type
+func NewMCPAudioContent(data []byte, mimeType string) *MCPAudioContent {
+	return &MCPAudioContent{
+		Type:     "audio",
+		MimeType: mimeType,
+		Data:     base64.StdEncoding.EncodeToString(data),
+	}
+}
+
+// NewMCPResourceLink creates a new instance of MCPResourceLink with the given parameters
+func NewMCPResourceLink(uri string, name string) *MCPResourceLink {
+	return &MCPResourceLink{
+		URI:  uri,
+		Type: "resource_link",
+		Name: name,
+	}
+}
+
+// NewMCPEmbeddedResource creates a new instance of MCPEmbeddedResource with the given resource
+func NewMCPEmbeddedResource[T MCPTextResourceContents | MCPBlobResourceContents](resource *T) *MCPEmbeddedResource {
+	return &MCPEmbeddedResource{
+		Type:     "resource",
+		Resource: resource,
+	}
+}