package xmlrpc

import (

	"errors"

	"fmt"

	"io/ioutil"

	"net/http"

	"net/http/cookiejar"

	"net/rpc"

	"net/url"

	"sync"

)

type Client struct {

	*rpc.Client

}

// clientCodec is rpc.ClientCodec interface implementation.

type clientCodec struct {

	// url presents url of xmlrpc service

	url *url.URL

	// httpClient works with HTTP protocol

	httpClient *http.Client

	// cookies stores cookies received on last request

	cookies http.CookieJar

	// responses presents map of active requests. It is required to return request id, that

	// rpc.Client can mark them as done.

	responses map[uint64]*http.Response

	mutex     sync.Mutex

	response Response

	// ready presents channel, that is used to link request and it`s response.

	ready chan uint64

	// close notifies codec is closed.

	close chan uint64

}

func (codec *clientCodec) WriteRequest(request *rpc.Request, args interface{}) (err error) {

	httpRequest, err := NewRequest(codec.url.String(), request.ServiceMethod, args)

	if err != nil {

		return err

	}

	if codec.cookies != nil {

		for _, cookie := range codec.cookies.Cookies(codec.url) {

			httpRequest.AddCookie(cookie)

		}

	}

	var httpResponse *http.Response

	httpResponse, err = codec.httpClient.Do(httpRequest)

	if err != nil {

		return err

	}

	if codec.cookies != nil {

		codec.cookies.SetCookies(codec.url, httpResponse.Cookies())

	}

	codec.mutex.Lock()

	codec.responses[request.Seq] = httpResponse

	codec.mutex.Unlock()

	codec.ready <- request.Seq

	return nil

}

func (codec *clientCodec) ReadResponseHeader(response *rpc.Response) (err error) {

	var seq uint64

	select {

	case seq = <-codec.ready:

	case <-codec.close:

		return errors.New("codec is closed")

	}

	response.Seq = seq

	codec.mutex.Lock()

	httpResponse := codec.responses[seq]

	delete(codec.responses, seq)

	codec.mutex.Unlock()

	defer httpResponse.Body.Close()

	if httpResponse.StatusCode < 200 || httpResponse.StatusCode >= 300 {

		response.Error = fmt.Sprintf("request error: bad status code - %d", httpResponse.StatusCode)

		return nil

	}

	body, err := ioutil.ReadAll(httpResponse.Body)

	if err != nil {

		response.Error = err.Error()

		return nil

	}

	resp := Response(body)

	if err := resp.Err(); err != nil {

		response.Error = err.Error()

		return nil

	}

	codec.response = resp

	return nil

}

func (codec *clientCodec) ReadResponseBody(v interface{}) (err error) {

	if v == nil {

		return nil

	}

	return codec.response.Unmarshal(v)

}

func (codec *clientCodec) Close() error {

	if transport, ok := codec.httpClient.Transport.(*http.Transport); ok {

		transport.CloseIdleConnections()

	}

	close(codec.close)

	return nil

}

// NewClient returns instance of rpc.Client object, that is used to send request to xmlrpc service.

func NewClient(requrl string, transport http.RoundTripper) (*Client, error) {

	if transport == nil {

		transport = http.DefaultTransport

	}

	httpClient := &http.Client{Transport: transport}

	jar, err := cookiejar.New(nil)

	if err != nil {

		return nil, err

	}

	u, err := url.Parse(requrl)

	if err != nil {

		return nil, err

	}

	codec := clientCodec{

		url:        u,

		httpClient: httpClient,

		close:      make(chan uint64),

		ready:      make(chan uint64),

		responses:  make(map[uint64]*http.Response),

		cookies:    jar,

	}

	return &Client{rpc.NewClientWithCodec(&codec)}, nil

}