// This layer of the XMPP protocol reads XMLish structures and

// responds to them. It negotiates TLS and authentication.

package xmpp

import (

	"encoding/xml"

	"fmt"

)

// Callback to handle a stanza with a particular id.

type callback struct {

	id string

	// Return true means pass this to the application

	f func(Stanza) bool

}

// Receive XMPP stanzas from the client and send them on to the

// remote. Don't allow the client to send us any stanzas until

// negotiation has completed.  This loop is paused until resource

// binding is complete. Otherwise the app might inject something

// inappropriate into our negotiations with the server. The control

// channel controls this loop's activity.

func sendStream(sendXml chan<- interface{}, recvXmpp <-chan Stanza,

	control <-chan sendCmd) {

	defer close(sendXml)

	var input <-chan Stanza

	for {

		select {

		case cmd := <-control:

			switch cmd {

			case sendDeny:

				input = nil

			case sendAllow:

				input = recvXmpp

			case sendAbort:

				return

			default:

				panic(fmt.Sprintf("unknown cmd %d", cmd))

			}

		case x, ok := <-input:

			if !ok {

				return

			}

			if x == nil {

				Info.Log("Refusing to send nil stanza")

				continue

			}

			sendXml <- x

		}

	}

}

// Receive XMLish structures, handle all the stream-related ones, and

// send XMPP stanzas on to the client.

func (cl *Client) recvStream(recvXml <-chan interface{}, sendXmpp chan<- Stanza) {

	defer close(sendXmpp)

	handlers := make(map[string]func(Stanza) bool)

	for {

		select {

		case h := <-cl.handlers:

			handlers[h.id] = h.f

		case x, ok := <-recvXml:

			if !ok {

				return

			}

			switch obj := x.(type) {

			case *stream:

				// Do nothing.

			case *streamError:

				cl.handleStreamError(obj)

			case *Features:

				cl.handleFeatures(obj)

			case *starttls:

				cl.handleTls(obj)

			case *auth:

				cl.handleSasl(obj)

			case Stanza:

				send := true

				id := obj.GetHeader().Id

				if handlers[id] != nil {

					f := handlers[id]

					delete(handlers, id)

					send = f(obj)

				}

				if send {

					sendXmpp <- obj

				}

			default:

				Warn.Logf("Unhandled non-stanza: %T %#v", x, x)

			}

		}

	}

}

func (cl *Client) handleStreamError(se *streamError) {

	Info.Logf("Received stream error: %v", se)

	cl.inputControl <- sendAbort

}

func (cl *Client) handleFeatures(fe *Features) {

	cl.Features = fe

	if fe.Starttls != nil {

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

			Local: "starttls"}}

		cl.sendXml <- start

		return

	}

	if len(fe.Mechanisms.Mechanism) > 0 {

		cl.chooseSasl(fe)

		return

	}

	if fe.Bind != nil {

		cl.bind()

		return

	}

}

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

	cl.layer1.startTls(&cl.tlsConfig)

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

	// session.

	cl.sendXml <- &stream{To: cl.Jid.Domain, Version: XMPPVersion}

}

// Send a request to bind a resource. RFC 3920, section 7.

func (cl *Client) bind() {

	res := cl.Jid.Resource

	bindReq := &bindIq{}

	if res != "" {

		bindReq.Resource = &res

	}

	msg := &Iq{Header: Header{Type: "set", Id: NextId(),

		Nested: []interface{}{bindReq}}}

	f := func(st Stanza) bool {

		iq, ok := st.(*Iq)

		if !ok {

			Warn.Log("non-iq response")

		}

		if iq.Type == "error" {

			Warn.Log("Resource binding failed")

			return false

		}

		var bindRepl *bindIq

		for _, ele := range iq.Nested {

			if b, ok := ele.(*bindIq); ok {

				bindRepl = b

				break

			}

		}

		if bindRepl == nil {

			Warn.Logf("Bad bind reply: %#v", iq)

			return false

		}

		jidStr := bindRepl.Jid

		if jidStr == nil || *jidStr == "" {

			Warn.Log("Can't bind empty resource")

			return false

		}

		jid := new(JID)

		if err := jid.Set(*jidStr); err != nil {

			Warn.Logf("Can't parse JID %s: %s", *jidStr, err)

			return false

		}

		cl.Jid = *jid

		Info.Logf("Bound resource: %s", cl.Jid.String())

		cl.bindDone()

		return false

	}

	cl.SetCallback(msg.Id, f)

	cl.sendXml <- msg

}

// Register a callback to handle the next XMPP stanza (iq, message, or

// presence) with a given id. The provided function will not be called

// more than once. If it returns false, the stanza will not be made

// available on the normal Client.Recv channel. The callback must not

// read from that channel, as deliveries on it cannot proceed until

// the handler returns true or false.

func (cl *Client) SetCallback(id string, f func(Stanza) bool) {

	h := &callback{id: id, f: f}

	cl.handlers <- h

}