package mcp

import "encoding/json"

// JSON-RPC 2.0 envelope types (the wire format MCP rides on). Notifications are
// requests with no id and must not receive a response.

type rpcRequest struct {
	JSONRPC string          `json:"jsonrpc"`
	ID      json.RawMessage `json:"id,omitempty"`
	Method  string          `json:"method"`
	Params  json.RawMessage `json:"params,omitempty"`
}

func (r *rpcRequest) isNotification() bool { return len(r.ID) == 0 }

type rpcResponse struct {
	JSONRPC string          `json:"jsonrpc"`
	ID      json.RawMessage `json:"id,omitempty"`
	Result  any             `json:"result,omitempty"`
	Error   *rpcError       `json:"error,omitempty"`
}

type rpcError struct {
	Code    int    `json:"code"`
	Message string `json:"message"`
	Data    any    `json:"data,omitempty"`
}

const (
	codeParseError     = -32700
	codeInvalidRequest = -32600
	codeMethodNotFound = -32601
	codeInvalidParams  = -32602
	codeInternalError  = -32603
)

func result(id json.RawMessage, v any) *rpcResponse {
	return &rpcResponse{JSONRPC: "2.0", ID: id, Result: v}
}

func errorResponse(id json.RawMessage, code int, msg string) *rpcResponse {
	return &rpcResponse{JSONRPC: "2.0", ID: id, Error: &rpcError{Code: code, Message: msg}}
}