// Copyright 2011 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.

// This file contains the three layers of processing for the

// communication with the server: transport (where TLS happens), XML

// (where strings are converted to go structures), and Stream (where

// we respond to XMPP events on behalf of the library client).

package xmpp

import (

	"crypto/tls"

	"io"

	"log"

	"net"

	"os"

	"time"

	"xml"

)

func (cl *Client) readTransport(w io.Writer) {

	defer tryClose(cl.socket, w)

	cl.socket.SetReadTimeout(1e8)

	p := make([]byte, 1024)

	for {

		if cl.socket == nil {

			cl.waitForSocket()

		}

		nr, err := cl.socket.Read(p)

		if nr == 0 {

			if errno, ok := err.(*net.OpError) ; ok {

				if errno.Timeout() {

					continue

				}

			}

			log.Printf("read: %s", err.String())

			break

		}

		nw, err := w.Write(p[:nr])

		if nw < nr {

			log.Println("read: %s", err.String())

			break

		}

	}

}

func (cl *Client) writeTransport(r io.Reader) {

	defer tryClose(r, cl.socket)

	p := make([]byte, 1024)

	for {

		nr, err := r.Read(p)

		if nr == 0 {

			log.Printf("write: %s", err.String())

			break

		}

		nw, err := cl.socket.Write(p[:nr])

		if nw < nr {

			log.Println("write: %s", err.String())

			break

		}

	}

}

func readXml(r io.Reader, ch chan<- interface{}) {

	if debug {

		pr, pw := io.Pipe()

		go tee(r, pw, "S: ")

		r = pr

	}

	defer tryClose(r, ch)

	p := xml.NewParser(r)

	for {

		// Sniff the next token on the stream.

		t, err := p.Token()

		if t == nil {

			if err != os.EOF {

				log.Printf("read: %v", err)

			}

			break

		}

		var se xml.StartElement

		var ok bool

		if se, ok = t.(xml.StartElement) ; !ok {

			continue

		}

		// Allocate the appropriate structure for this token.

		var obj interface{}

		switch se.Name.Space + " " + se.Name.Local {

		case nsStream + " stream":

			st, err := parseStream(se)

			if err != nil {

				log.Printf("unmarshal stream: %v",

					err)

				break

			}

			ch <- st

			continue

		case "stream error", nsStream + " error":

			obj = &StreamError{}

		case nsStream + " features":

			obj = &Features{}

		case nsTLS + " proceed", nsTLS + " failure":

			obj = &starttls{}

		default:

			obj = &Unrecognized{}

			log.Printf("Ignoring unrecognized: %s %s\n",

				se.Name.Space, se.Name.Local)

		}

		// Read the complete XML stanza.

		err = p.Unmarshal(obj, &se)

		if err != nil {

			log.Printf("unmarshal: %v", err)

			break

		}

		// Put it on the channel.

		ch <- obj

	}

}

func writeXml(w io.Writer, ch <-chan interface{}) {

	if debug {

		pr, pw := io.Pipe()

		go tee(pr, w, "C: ")

		w = pw

	}

	defer tryClose(w, ch)

	for obj := range ch {

		err := xml.Marshal(w, obj)

		if err != nil {

			log.Printf("write: %v", err)

			break

		}

	}

}

func writeText(w io.Writer, ch <-chan *string) {

	if debug {

		pr, pw := io.Pipe()

		go tee(pr, w, "C: ")

		w = pw

	}

	defer tryClose(w, ch)

	for str := range ch {

		_, err := w.Write([]byte(*str))

		if err != nil {

			log.Printf("writeStr: %v", err)

			break

		}

	}

}

func (cl *Client) readStream(srvIn <-chan interface{}, srvOut, cliOut chan<- interface{}) {

	defer tryClose(srvIn, cliOut)

	for x := range srvIn {

		switch obj := x.(type) {

		case *Stream:

			handleStream(obj)

		case *Features:

			handleFeatures(obj, srvOut)

		case *starttls:

			cl.handleTls(obj)

		default:

			cliOut <- x

		}

	}

}

func writeStream(srvOut chan<- interface{}, cliIn <-chan interface{}) {

	defer tryClose(srvOut, cliIn)

	for x := range cliIn {

		srvOut <- x

	}

}

func handleStream(ss *Stream) {

}

func handleFeatures(fe *Features, srvOut chan<- interface{}) {

	if fe.Starttls != nil {

		start := &starttls{XMLName: xml.Name{Space: nsTLS,

			Local: "starttls"}}

		srvOut <- start

	}

}

// readTransport() is running concurrently. We need to stop it,

// negotiate TLS, then start it again. It calls waitForSocket() in

// its inner loop; see below.

func (cl *Client) handleTls(t *starttls) {

	tcp := cl.socket

	// Set the socket to nil, and wait for the reader routine to

	// signal that it's paused.

	cl.socket = nil

	cl.socketSync.Add(1)

	cl.socketSync.Wait()

	// Negotiate TLS with the server.

	tls := tls.Client(tcp, nil)

	// Make the TLS connection available to the reader, and wait

	// for it to signal that it's working again.

	cl.socketSync.Add(1)

	cl.socket = tls

	cl.socketSync.Wait()

	// Reset the read timeout on the (underlying) socket so the

	// reader doesn't get woken up unnecessarily.

	tcp.SetReadTimeout(0)

	log.Println("TLS negotiation succeeded.")

	// Now re-send the initial handshake message to start the new

	// session.

	hsOut := &Stream{To: cl.Jid.Domain, Version: Version}

	cl.xmlOut <- hsOut

}

// Synchronize with handleTls(). Called from readTransport() when

// cl.socket is nil.

func (cl *Client) waitForSocket() {

	// Signal that we've stopped reading from the socket.

	cl.socketSync.Done()

	// Wait until the socket is available again.

	for cl.socket == nil {

		time.Sleep(1e8)

	}

	// Signal that we're going back to the read loop.

	cl.socketSync.Done()

}