// Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package jsonrpc

import (
	
	
	
	
	
)

var errMissingParams = errors.New("jsonrpc: request body missing params")

type serverCodec struct {
	dec *json.Decoder // for reading JSON values
	enc *json.Encoder // for writing JSON values
	c   io.Closer

	// temporary work space
	req serverRequest

	// JSON-RPC clients can use arbitrary json values as request IDs.
	// Package rpc expects uint64 request IDs.
	// We assign uint64 sequence numbers to incoming requests
	// but save the original request ID in the pending map.
	// When rpc responds, we use the sequence number in
	// the response to find the original request ID.
	mutex   sync.Mutex // protects seq, pending
	seq     uint64
	pending map[uint64]*json.RawMessage
}

// NewServerCodec returns a new rpc.ServerCodec using JSON-RPC on conn.
func ( io.ReadWriteCloser) rpc.ServerCodec {
	return &serverCodec{
		dec:     json.NewDecoder(),
		enc:     json.NewEncoder(),
		c:       ,
		pending: make(map[uint64]*json.RawMessage),
	}
}

type serverRequest struct {
	Method string           `json:"method"`
	Params *json.RawMessage `json:"params"`
	Id     *json.RawMessage `json:"id"`
}

func ( *serverRequest) () {
	.Method = ""
	.Params = nil
	.Id = nil
}

type serverResponse struct {
	Id     *json.RawMessage `json:"id"`
	Result interface{}      `json:"result"`
	Error  interface{}      `json:"error"`
}

func ( *serverCodec) ( *rpc.Request) error {
	.req.reset()
	if  := .dec.Decode(&.req);  != nil {
		return 
	}
	.ServiceMethod = .req.Method

	// JSON request id can be any JSON value;
	// RPC package expects uint64.  Translate to
	// internal uint64 and save JSON on the side.
	.mutex.Lock()
	.seq++
	.pending[.seq] = .req.Id
	.req.Id = nil
	.Seq = .seq
	.mutex.Unlock()

	return nil
}

func ( *serverCodec) ( interface{}) error {
	if  == nil {
		return nil
	}
	if .req.Params == nil {
		return errMissingParams
	}
	// JSON params is array value.
	// RPC params is struct.
	// Unmarshal into array containing struct for now.
	// Should think about making RPC more general.
	var  [1]interface{}
	[0] = 
	return json.Unmarshal(*.req.Params, &)
}

var null = json.RawMessage([]byte("null"))

func ( *serverCodec) ( *rpc.Response,  interface{}) error {
	.mutex.Lock()
	,  := .pending[.Seq]
	if ! {
		.mutex.Unlock()
		return errors.New("invalid sequence number in response")
	}
	delete(.pending, .Seq)
	.mutex.Unlock()

	if  == nil {
		// Invalid request so no id. Use JSON null.
		 = &null
	}
	 := serverResponse{Id: }
	if .Error == "" {
		.Result = 
	} else {
		.Error = .Error
	}
	return .enc.Encode()
}

func ( *serverCodec) () error {
	return .c.Close()
}

// ServeConn runs the JSON-RPC server on a single connection.
// ServeConn blocks, serving the connection until the client hangs up.
// The caller typically invokes ServeConn in a go statement.
func ( io.ReadWriteCloser) {
	rpc.ServeCodec(NewServerCodec())
}