// 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 package implements a simple XMPP client according to RFCs 3920

// and 3921, plus the various XEPs at http://xmpp.org/protocols/.

package xmpp

import (

	"bytes"

	"fmt"

	"io"

	"os"

	"xml"

)

const (

	// Version of RFC 3920 that we implement.

	Version = "1.0"

	nsStreams = "urn:ietf:params:xml:ns:xmpp-streams"

)

// JID represents an entity that can communicate with other

// entities. It looks like node@domain/resource. Node and resource are

// sometimes optional.

type JID struct {

	Node *string

	Domain string

	Resource *string

}

var _ fmt.Stringer = &JID{}

// XMPP's <stream:stream> XML element

type Stream struct {

	to string `xml:"attr"`

	from string `xml:"attr"`

	id string `xml:"attr"`

	lang string `xml:"attr"`

	version string `xml:"attr"`

}

var _ xml.Marshaler = &Stream{}

type StreamError struct {

	cond definedCondition

	text errText

}

var _ xml.Marshaler = &StreamError{}

type definedCondition struct {

	// Must always be in namespace nsStreams

	XMLName xml.Name

}

type errText struct {

	XMLName xml.Name

	Lang string

	text string `xml:"chardata"`

}

var _ xml.Marshaler = &errText{}

func (jid *JID) String() string {

	result := jid.Domain

	if jid.Node != nil {

		result = *jid.Node + "@" + result

	}

	if jid.Resource != nil {

		result = result + "/" + *jid.Resource

	}

	return result

}

func (s *Stream) MarshalXML() ([]byte, os.Error) {

	buf := bytes.NewBuffer(nil)

	buf.WriteString("<stream:stream")

	writeField(buf, "to", s.to)

	writeField(buf, "from", s.from)

	writeField(buf, "id", s.id)

	writeField(buf, "xml:lang", s.lang)

	writeField(buf, "version", s.version)

	buf.WriteString(">")

	// We never write </stream:stream>

	return buf.Bytes(), nil

}

func (s *StreamError) MarshalXML() ([]byte, os.Error) {

	buf := bytes.NewBuffer(nil)

	buf.WriteString("<stream:error>")

	xml.Marshal(buf, s.cond)

	xml.Marshal(buf, s.text)

	buf.WriteString("</stream:error>")

	return buf.Bytes(), nil

}

func (e *errText) MarshalXML() ([]byte, os.Error) {

	buf := bytes.NewBuffer(nil)

	buf.WriteString("<text")

	writeField(buf, "xmlns", nsStreams)

	writeField(buf, "xml:lang", e.Lang)

	buf.WriteString(">")

	xml.Escape(buf, []byte(e.text))

	buf.WriteString("</text>")

	return buf.Bytes(), nil

}

func writeField(w io.Writer, field, value string) {

	if value != "" {

		io.WriteString(w, " ")

		io.WriteString(w, field)

		io.WriteString(w, `="`)

		xml.Escape(w, []byte(value))

		io.WriteString(w, `"`)

	}

}