// This layer of the XMPP protocol translates between bytes and XMLish

// structures.

package xmpp

import (

	"encoding/xml"

	"fmt"

	"io"

	"log"

	"reflect"

	"strings"

)

// Read bytes from a reader, unmarshal them as XML into structures of

// the appropriate type, and send those structures on a channel.

func (cl *Client) recvXml(r io.Reader, ch chan<- interface{},

	extStanza map[xml.Name]reflect.Type) {

	defer close(ch)

	// This trick loads our namespaces into the parser.

	nsstr := fmt.Sprintf(`<a xmlns="%s" xmlns:stream="%s">`,

		NsClient, NsStream)

	nsrdr := strings.NewReader(nsstr)

	p := xml.NewDecoder(io.MultiReader(nsrdr, r))

	p.Token()

Loop:

	for {

		// Sniff the next token on the stream.

		t, err := p.Token()

		if t == nil {

			if err != io.EOF {

				cl.setError(fmt.Errorf("recv: %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 {

				cl.setError(fmt.Errorf("recv: %v", err))

				break Loop

			}

			ch <- st

			continue

		case "stream error", NsStream + " error":

			obj = &streamError{}

		case NsStream + " features":

			obj = &Features{}

		case NsTLS + " proceed", NsTLS + " failure":

			obj = &starttls{}

		case NsSASL + " challenge", NsSASL + " failure",

			NsSASL + " success":

			obj = &auth{}

		case NsClient + " iq":

			obj = &Iq{}

		case NsClient + " message":

			obj = &Message{}

		case NsClient + " presence":

			obj = &Presence{}

		default:

			obj = &Generic{}

			if Debug {

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

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

			}

		}

		// Read the complete XML stanza.

		err = p.DecodeElement(obj, &se)

		if err != nil {

			cl.setError(fmt.Errorf("recv: %v", err))

			break Loop

		}

		// If it's a Stanza, we try to unmarshal its innerxml

		// into objects of the appropriate respective

		// types. This is specified by our extensions.

		if st, ok := obj.(Stanza); ok {

			err = parseExtended(st.GetHeader(), extStanza)

			if err != nil {

				cl.setError(fmt.Errorf("recv: %v", err))

				break Loop

			}

		}

		// Put it on the channel.

		ch <- obj

	}

}

func parseExtended(st *Header, extStanza map[xml.Name]reflect.Type) error {

	// Now parse the stanza's innerxml to find the string that we

	// can unmarshal this nested element from.

	reader := strings.NewReader(st.Innerxml)

	p := xml.NewDecoder(reader)

	for {

		t, err := p.Token()

		if err == io.EOF {

			break

		}

		if err != nil {

			return err

		}

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

			if typ, ok := extStanza[se.Name]; ok {

				nested := reflect.New(typ).Interface()

				// Unmarshal the nested element and

				// stuff it back into the stanza.

				err := p.DecodeElement(nested, &se)

				if err != nil {

					return err

				}

				st.Nested = append(st.Nested, nested)

			}

		}

	}

	return nil

}

// Receive structures on a channel, marshal them to XML, and send the

// bytes on a writer.

func (cl *Client) sendXml(w io.Writer, ch <-chan interface{}) {

	defer func(w io.Writer) {

		if c, ok := w.(io.Closer); ok {

			c.Close()

		}

	}(w)

	enc := xml.NewEncoder(w)

	for obj := range ch {

		if st, ok := obj.(*stream); ok {

			_, err := w.Write([]byte(st.String()))

			if err != nil {

				cl.setError(fmt.Errorf("send: %v", err))

				break

			}

		} else {

			err := enc.Encode(obj)

			if err != nil {

				cl.setError(fmt.Errorf("send: %v", err))

				break

			}

		}

	}

}