/*
NAME
  rtmp.go

DESCRIPTION
  See Readme.md

AUTHORS
  Saxon Nelson-Milton <saxon@ausocean.org>
  Dan Kortschak <dan@ausocean.org>
  Alan Noble <alan@ausocean.org>

LICENSE
  rtmp.go is Copyright (C) 2017-2019 the Australian Ocean Lab (AusOcean)

  It is free software: you can redistribute it and/or modify them
  under the terms of the GNU General Public License as published by the
  Free Software Foundation, either version 3 of the License, or (at your
  option) any later version.

  It is distributed in the hope that it will be useful, but WITHOUT
  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
  for more details.

  You should have received a copy of the GNU General Public License
  along with revid in gpl.txt. If not, see http://www.gnu.org/licenses.

  Derived from librtmp under the GNU Lesser General Public License 2.1
  Copyright (C) 2005-2008 Team XBMC http://www.xbmc.org
  Copyright (C) 2008-2009 Andrej Stepanchuk
  Copyright (C) 2009-2010 Howard Chu
*/

package rtmp

import (
	"bytes"
	"encoding/binary"
	"errors"
	"io"
	"math/rand"
	"net"
	"strconv"
	"time"
)

const (
	pkg         = "rtmp:"
	minDataSize = 11
)

const (
	setDataFrame = "@setDataFrame"

	av__checkbw                         = "_checkbw"
	av__onbwcheck                       = "_onbwcheck"
	av__onbwdone                        = "_onbwdone"
	av__result                          = "_result"
	av_app                              = "app"
	av_audioCodecs                      = "audioCodecs"
	av_capabilities                     = "capabilities"
	av_close                            = "close"
	av_code                             = "code"
	av_connect                          = "connect"
	av_createStream                     = "createStream"
	av_deleteStream                     = "deleteStream"
	av_FCPublish                        = "FCPublish"
	av_FCUnpublish                      = "FCUnpublish"
	av_flashVer                         = "flashVer"
	av_fpad                             = "fpad"
	av_level                            = "level"
	av_live                             = "live"
	av_NetConnection_Connect_InvalidApp = "NetConnection.Connect.InvalidApp"
	av_NetStream_Failed                 = "NetStream.Failed"
	av_NetStream_Pause_Notify           = "NetStream.Pause.Notify"
	av_NetStream_Play_Complete          = "NetStream.Play.Complete"
	av_NetStream_Play_Failed            = "NetStream.Play.Failed"
	av_NetStream_Play_PublishNotify     = "NetStream.Play.PublishNotify"
	av_NetStream_Play_Start             = "NetStream.Play.Start"
	av_NetStream_Play_Stop              = "NetStream.Play.Stop"
	av_NetStream_Play_StreamNotFound    = "NetStream.Play.StreamNotFound"
	av_NetStream_Play_UnpublishNotify   = "NetStream.Play.UnpublishNotify"
	av_NetStream_Publish_Start          = "NetStream.Publish.Start"
	av_NetStream_Seek_Notify            = "NetStream.Seek.Notify"
	av_nonprivate                       = "nonprivate"
	av_objectEncoding                   = "objectEncoding"
	av_onBWDone                         = "onBWDone"
	av_onFCSubscribe                    = "onFCSubscribe"
	av_onFCUnsubscribe                  = "onFCUnsubscribe"
	av_onStatus                         = "onStatus"
	av_pageUrl                          = "pageUrl"
	av_ping                             = "ping"
	av_play                             = "play"
	av_playlist_ready                   = "playlist_ready"
	av_publish                          = "publish"
	av_releaseStream                    = "releaseStream"
	av_secureToken                      = "secureToken"
	av_set_playlist                     = "set_playlist"
	av_swfUrl                           = "swfUrl"
	av_tcUrl                            = "tcUrl"
	av_type                             = "type"
	av_videoCodecs                      = "videoCodecs"
	av_videoFunction                    = "videoFunction"
)

// RTMP protocol strings.
var rtmpProtocolStrings = [...]string{
	"rtmp",
	"rtmpt",
	"rtmpe",
	"rtmpte",
	"rtmps",
	"rtmpts",
	"",
	"",
	"rtmfp",
}

// RTMP errors.
var (
	errUnknownScheme = errors.New("rtmp: unknown scheme")
	errConnected     = errors.New("rtmp: already connected")
	errNotConnected  = errors.New("rtmp: not connected")
	errHandshake     = errors.New("rtmp: handshake failed")
	errConnSend      = errors.New("rtmp: connection send error")
	errConnStream    = errors.New("rtmp: connection stream error")
	errInvalidHeader = errors.New("rtmp: invalid header")
	errInvalidBody   = errors.New("rtmp: invalid body")
	errTinyPacket    = errors.New("rtmp: packet too small")
	errEncoding      = errors.New("rtmp: encoding error")
	errDecoding      = errors.New("rtmp: decoding error")
	errCopying       = errors.New("rtmp: copying error")
)

// setupURL parses the RTMP URL.
func setupURL(s *Session, addr string) (err error) {
	s.link.protocol, s.link.host, s.link.port, s.link.app, s.link.playpath, err = parseURL(addr)
	if err != nil {
		return err
	}

	if s.link.tcUrl == "" {
		if s.link.app != "" {
			s.link.tcUrl = rtmpProtocolStrings[s.link.protocol] + "://" + s.link.host + ":" + strconv.Itoa(int(s.link.port)) + "/" + s.link.app
			s.link.lFlags |= RTMP_LF_FTCU
		} else {
			s.link.tcUrl = addr
		}
	}

	if s.link.port == 0 {
		switch {
		case (s.link.protocol & RTMP_FEATURE_SSL) != 0:
			s.link.port = 433
			s.log(FatalLevel, pkg+"SSL not supported")
		case (s.link.protocol & RTMP_FEATURE_HTTP) != 0:
			s.link.port = 80
		default:
			s.link.port = 1935
		}
	}
	return nil
}

// connect establishes an RTMP connection.
func connect(s *Session) error {
	addr, err := net.ResolveTCPAddr("tcp4", s.link.host+":"+strconv.Itoa(int(s.link.port)))
	if err != nil {
		return err
	}
	s.link.conn, err = net.DialTCP("tcp4", nil, addr)
	if err != nil {
		s.log(WarnLevel, pkg+"dial failed", "error", err.Error())
		return err
	}
	s.log(DebugLevel, pkg+"connected")
	err = handshake(s)
	if err != nil {
		s.log(WarnLevel, pkg+"handshake failed", "error", err.Error())
		return errHandshake
	}
	s.log(DebugLevel, pkg+"handshaked")
	err = sendConnectPacket(s)
	if err != nil {
		s.log(WarnLevel, pkg+"sendConnect failed", "error", err.Error())
		return errConnSend
	}
	return nil
}

// connectStream reads a packet and handles it
func connectStream(s *Session) error {
	var err error
	for !s.isPlaying && s.isConnected() {
		pkt := packet{}
		err = readPacket(s, &pkt)
		if err != nil {
			break
		}
		if pkt.bodySize == 0 {
			continue
		}
		if pkt.packetType == RTMP_PACKET_TYPE_AUDIO ||
			pkt.packetType == RTMP_PACKET_TYPE_VIDEO ||
			pkt.packetType == RTMP_PACKET_TYPE_INFO {
			s.log(DebugLevel, pkg+"got packet before play; ignoring")
			continue
		}

		err = handlePacket(s, &pkt)
		if err != nil {
			break
		}
	}

	if !s.isPlaying {
		return err
	}
	return nil
}

// handlePacket handles a packet that the client has received.
// NB: cases have been commented out that are not currently used by AusOcean
func handlePacket(s *Session, pkt *packet) error {
	switch pkt.packetType {

	case RTMP_PACKET_TYPE_CHUNK_SIZE:
		if pkt.bodySize >= 4 {
			s.inChunkSize = int32(C_AMF_DecodeInt32(pkt.body[:4]))
		}

	case RTMP_PACKET_TYPE_BYTES_READ_REPORT:
		s.serverBW = int32(C_AMF_DecodeInt32(pkt.body[:4]))

	case RTMP_PACKET_TYPE_CONTROL:
		s.log(FatalLevel, pkg+"unsupported packet type RTMP_PACKET_TYPE_CONTROL")

	case RTMP_PACKET_TYPE_SERVER_BW:
		s.serverBW = int32(C_AMF_DecodeInt32(pkt.body[:4]))

	case RTMP_PACKET_TYPE_CLIENT_BW:
		s.clientBW = int32(C_AMF_DecodeInt32(pkt.body[:4]))
		if pkt.bodySize > 4 {
			s.clientBW2 = pkt.body[4]
		} else {
			s.clientBW2 = 0xff
		}

	case RTMP_PACKET_TYPE_AUDIO:
		s.log(FatalLevel, pkg+"unsupported packet type RTMP_PACKET_TYPE_AUDIO")

	case RTMP_PACKET_TYPE_VIDEO:
		s.log(FatalLevel, pkg+"unsupported packet type RTMP_PACKET_TYPE_VIDEO")

	case RTMP_PACKET_TYPE_FLEX_MESSAGE:
		s.log(FatalLevel, pkg+"unsupported packet type RTMP_PACKET_TYPE_FLEX_MESSAGE")

	case RTMP_PACKET_TYPE_INFO:
		s.log(FatalLevel, pkg+"unsupported packet type RTMP_PACKET_TYPE_INFO")

	case RTMP_PACKET_TYPE_INVOKE:
		err := handleInvoke(s, pkt.body[:pkt.bodySize])
		if err != nil {
			// This will never happen with the methods we implement.
			s.log(WarnLevel, pkg+"unexpected error from handleInvoke", "error", err.Error())
			return err
		}

	case RTMP_PACKET_TYPE_FLASH_VIDEO:
		s.log(FatalLevel, pkg+"unsupported packet type RTMP_PACKET_TYPE_FLASH_VIDEO")

	default:
		s.log(WarnLevel, pkg+"unknown packet type", "type", pkt.packetType)
	}
	return nil
}

func readN(s *Session, buf []byte) error {
	err := s.link.conn.SetReadDeadline(time.Now().Add(time.Second * time.Duration(s.link.timeout)))
	if err != nil {
		return err
	}
	n, err := io.ReadFull(s.link.conn, buf)
	if err != nil {
		s.log(DebugLevel, pkg+"read failed", "error", err.Error())
		return err
	}
	s.nBytesIn += int32(n)
	if s.nBytesIn > (s.nBytesInSent + s.clientBW/10) {
		err := sendBytesReceived(s)
		if err != nil {
			return err
		}
	}
	return nil
}

func writeN(s *Session, buf []byte) error {
	//ToDo: consider using a different timeout for writes than for reads
	err := s.link.conn.SetWriteDeadline(time.Now().Add(time.Second * time.Duration(s.link.timeout)))
	if err != nil {
		return err
	}
	_, err = s.link.conn.Write(buf)
	if err != nil {
		s.log(WarnLevel, pkg+"write failed", "error", err.Error())
		return err
	}
	return nil
}

func sendConnectPacket(s *Session) error {
	var pbuf [4096]byte
	pkt := packet{
		channel:    RTMP_CHANNEL_CONTROL,
		headerType: RTMP_PACKET_SIZE_LARGE,
		packetType: RTMP_PACKET_TYPE_INVOKE,
		header:     pbuf[:],
		body:       pbuf[RTMP_MAX_HEADER_SIZE:],
	}
	enc := pkt.body

	enc = C_AMF_EncodeString(enc, av_connect)
	if enc == nil {
		return errEncoding
	}
	s.numInvokes += 1
	enc = C_AMF_EncodeNumber(enc, float64(s.numInvokes))
	if enc == nil {
		return errEncoding
	}
	enc[0] = AMF_OBJECT
	enc = enc[1:]

	enc = C_AMF_EncodeNamedString(enc, av_app, s.link.app)
	if enc == nil {
		return errEncoding
	}
	if s.link.protocol&RTMP_FEATURE_WRITE != 0 {
		enc = C_AMF_EncodeNamedString(enc, av_type, av_nonprivate)
		if enc == nil {
			return errEncoding
		}
	}

	if s.link.flashVer != "" {
		enc = C_AMF_EncodeNamedString(enc, av_flashVer, s.link.flashVer)
		if enc == nil {
			return errEncoding
		}
	}
	if s.link.swfUrl != "" {
		enc = C_AMF_EncodeNamedString(enc, av_swfUrl, s.link.swfUrl)
		if enc == nil {
			return errEncoding
		}
	}

	if s.link.tcUrl != "" {
		enc = C_AMF_EncodeNamedString(enc, av_tcUrl, s.link.tcUrl)
		if enc == nil {
			return errEncoding
		}
	}

	if s.link.protocol&RTMP_FEATURE_WRITE == 0 {
		enc = C_AMF_EncodeNamedBoolean(enc, av_fpad, false)
		if enc == nil {
			return errEncoding
		}
		enc = C_AMF_EncodeNamedNumber(enc, av_capabilities, 15)
		if enc == nil {
			return errEncoding
		}
		enc = C_AMF_EncodeNamedNumber(enc, av_audioCodecs, s.audioCodecs)
		if enc == nil {
			return errEncoding
		}
		enc = C_AMF_EncodeNamedNumber(enc, av_videoCodecs, s.videoCodecs)
		if enc == nil {
			return errEncoding
		}
		enc = C_AMF_EncodeNamedNumber(enc, av_videoFunction, 1)
		if enc == nil {
			return errEncoding
		}
		if s.link.pageUrl != "" {
			enc = C_AMF_EncodeNamedString(enc, av_pageUrl, s.link.pageUrl)
			if enc == nil {
				return errEncoding
			}
		}
	}

	if s.encoding != 0.0 || s.sendEncoding {
		enc = C_AMF_EncodeNamedNumber(enc, av_objectEncoding, s.encoding)
		if enc == nil {
			return errEncoding
		}
	}

	copy(enc, []byte{0, 0, AMF_OBJECT_END})
	enc = enc[3:]

	// add auth string
	if s.link.auth != "" {
		enc = C_AMF_EncodeBoolean(enc, s.link.lFlags&RTMP_LF_AUTH != 0)
		if enc == nil {
			return errEncoding
		}
		enc = C_AMF_EncodeString(enc, s.link.auth)
		if enc == nil {
			return errEncoding
		}
	}

	for i := range s.link.extras.o_props {
		enc = C_AMF_PropEncode(&s.link.extras.o_props[i], enc)
		if enc == nil {
			return errEncoding
		}
	}

	pkt.bodySize = uint32((len(pbuf) - RTMP_MAX_HEADER_SIZE) - len(enc))

	return sendPacket(s, &pkt, true) // response expected
}

func sendCreateStream(s *Session) error {
	var pbuf [256]byte
	pkt := packet{
		channel:    RTMP_CHANNEL_CONTROL,
		headerType: RTMP_PACKET_SIZE_MEDIUM,
		packetType: RTMP_PACKET_TYPE_INVOKE,
		header:     pbuf[:],
		body:       pbuf[RTMP_MAX_HEADER_SIZE:],
	}
	enc := pkt.body

	enc = C_AMF_EncodeString(enc, av_createStream)
	if enc == nil {
		return errEncoding
	}
	s.numInvokes++
	enc = C_AMF_EncodeNumber(enc, float64(s.numInvokes))
	if enc == nil {
		return errEncoding
	}
	enc[0] = AMF_NULL
	enc = enc[1:]

	pkt.bodySize = uint32((len(pbuf) - RTMP_MAX_HEADER_SIZE) - len(enc))

	return sendPacket(s, &pkt, true) // response expected
}

func sendReleaseStream(s *Session) error {
	var pbuf [1024]byte
	pkt := packet{
		channel:    RTMP_CHANNEL_CONTROL,
		headerType: RTMP_PACKET_SIZE_MEDIUM,
		packetType: RTMP_PACKET_TYPE_INVOKE,
		header:     pbuf[:],
		body:       pbuf[RTMP_MAX_HEADER_SIZE:],
	}
	enc := pkt.body

	enc = C_AMF_EncodeString(enc, av_releaseStream)
	if enc == nil {
		return errEncoding
	}
	s.numInvokes++
	enc = C_AMF_EncodeNumber(enc, float64(s.numInvokes))
	if enc == nil {
		return errEncoding
	}
	enc[0] = AMF_NULL
	enc = enc[1:]
	enc = C_AMF_EncodeString(enc, s.link.playpath)
	if enc == nil {
		return errEncoding
	}
	pkt.bodySize = uint32((len(pbuf) - RTMP_MAX_HEADER_SIZE) - len(enc))

	return sendPacket(s, &pkt, false)
}

func sendFCPublish(s *Session) error {
	var pbuf [1024]byte
	pkt := packet{
		channel:    RTMP_CHANNEL_CONTROL,
		headerType: RTMP_PACKET_SIZE_MEDIUM,
		packetType: RTMP_PACKET_TYPE_INVOKE,
		header:     pbuf[:],
		body:       pbuf[RTMP_MAX_HEADER_SIZE:],
	}
	enc := pkt.body

	enc = C_AMF_EncodeString(enc, av_FCPublish)
	if enc == nil {
		return errEncoding
	}
	s.numInvokes++
	enc = C_AMF_EncodeNumber(enc, float64(s.numInvokes))
	if enc == nil {
		return errEncoding
	}
	enc[0] = AMF_NULL
	enc = enc[1:]
	enc = C_AMF_EncodeString(enc, s.link.playpath)
	if enc == nil {
		return errEncoding
	}

	pkt.bodySize = uint32((len(pbuf) - RTMP_MAX_HEADER_SIZE) - len(enc))

	return sendPacket(s, &pkt, false)
}

func sendFCUnpublish(s *Session) error {
	var pbuf [1024]byte
	pkt := packet{
		channel:    RTMP_CHANNEL_CONTROL,
		headerType: RTMP_PACKET_SIZE_MEDIUM,
		packetType: RTMP_PACKET_TYPE_INVOKE,
		header:     pbuf[:],
		body:       pbuf[RTMP_MAX_HEADER_SIZE:],
	}
	enc := pkt.body

	enc = C_AMF_EncodeString(enc, av_FCUnpublish)
	if enc == nil {
		return errEncoding
	}
	s.numInvokes++
	enc = C_AMF_EncodeNumber(enc, float64(s.numInvokes))
	if enc == nil {
		return errEncoding
	}
	enc[0] = AMF_NULL
	enc = enc[1:]
	enc = C_AMF_EncodeString(enc, s.link.playpath)
	if enc == nil {
		return errEncoding
	}

	pkt.bodySize = uint32((len(pbuf) - RTMP_MAX_HEADER_SIZE) - len(enc))

	return sendPacket(s, &pkt, false)
}

func sendPublish(s *Session) error {
	var pbuf [1024]byte
	pkt := packet{
		channel:    RTMP_CHANNEL_SOURCE,
		headerType: RTMP_PACKET_SIZE_LARGE,
		packetType: RTMP_PACKET_TYPE_INVOKE,
		header:     pbuf[:],
		body:       pbuf[RTMP_MAX_HEADER_SIZE:],
	}
	enc := pkt.body

	enc = C_AMF_EncodeString(enc, av_publish)
	if enc == nil {
		return errEncoding
	}
	s.numInvokes++
	enc = C_AMF_EncodeNumber(enc, float64(s.numInvokes))
	if enc == nil {
		return errEncoding
	}
	enc[0] = AMF_NULL
	enc = enc[1:]
	enc = C_AMF_EncodeString(enc, s.link.playpath)
	if enc == nil {
		return errEncoding
	}
	enc = C_AMF_EncodeString(enc, av_live)
	if enc == nil {
		return errEncoding
	}

	pkt.bodySize = uint32((len(pbuf) - RTMP_MAX_HEADER_SIZE) - len(enc))

	return sendPacket(s, &pkt, true) // response expected
}

func sendDeleteStream(s *Session, dStreamId float64) error {
	var pbuf [256]byte
	pkt := packet{
		channel:    RTMP_CHANNEL_CONTROL,
		headerType: RTMP_PACKET_SIZE_MEDIUM,
		packetType: RTMP_PACKET_TYPE_INVOKE,
		header:     pbuf[:],
		body:       pbuf[RTMP_MAX_HEADER_SIZE:],
	}
	enc := pkt.body

	enc = C_AMF_EncodeString(enc, av_deleteStream)
	if enc == nil {
		return errEncoding
	}
	s.numInvokes++
	enc = C_AMF_EncodeNumber(enc, float64(s.numInvokes))
	if enc == nil {
		return errEncoding
	}
	enc[0] = AMF_NULL
	enc = enc[1:]
	enc = C_AMF_EncodeNumber(enc, dStreamId)
	if enc == nil {
		return errEncoding
	}
	pkt.bodySize = uint32((len(pbuf) - RTMP_MAX_HEADER_SIZE) - len(enc))

	/* no response expected */
	return sendPacket(s, &pkt, false)
}

// sendBytesReceived tells the server how many bytes the client has received.
func sendBytesReceived(s *Session) error {
	var pbuf [256]byte
	pkt := packet{
		channel:    RTMP_CHANNEL_BYTES_READ,
		headerType: RTMP_PACKET_SIZE_MEDIUM,
		packetType: RTMP_PACKET_TYPE_BYTES_READ_REPORT,
		header:     pbuf[:],
		body:       pbuf[RTMP_MAX_HEADER_SIZE:],
	}
	enc := pkt.body

	s.nBytesInSent = s.nBytesIn
	enc = C_AMF_EncodeInt32(enc, s.nBytesIn)
	if enc == nil {
		return errEncoding
	}
	pkt.bodySize = 4

	return sendPacket(s, &pkt, false)
}

func sendCheckBW(s *Session) error {
	var pbuf [256]byte
	pkt := packet{
		channel:    RTMP_CHANNEL_CONTROL,
		headerType: RTMP_PACKET_SIZE_LARGE,
		packetType: RTMP_PACKET_TYPE_INVOKE,
		header:     pbuf[:],
		body:       pbuf[RTMP_MAX_HEADER_SIZE:],
	}
	enc := pkt.body

	enc = C_AMF_EncodeString(enc, av__checkbw)
	if enc == nil {
		return errEncoding
	}
	s.numInvokes++
	enc = C_AMF_EncodeNumber(enc, float64(s.numInvokes))
	if enc == nil {
		return errEncoding
	}
	enc[0] = AMF_NULL
	enc = enc[1:]

	pkt.bodySize = uint32((len(pbuf) - RTMP_MAX_HEADER_SIZE) - len(enc))

	return sendPacket(s, &pkt, false)
}

func eraseMethod(m []method, i int) []method {
	copy(m[i:], m[i+1:])
	m[len(m)-1] = method{}
	return m[:len(m)-1]
}

// int handleInvoke handles a packet invoke request
// Side effects: s.isPlaying set to true upon av_NetStream_Publish_Start
func handleInvoke(s *Session, body []byte) error {
	if body[0] != 0x02 {
		return errInvalidBody
	}
	var obj C_AMFObject
	nRes := C_AMF_Decode(&obj, body, 0)
	if nRes < 0 {
		return errDecoding
	}

	meth := C_AMFProp_GetString(C_AMF_GetProp(&obj, "", 0))
	s.log(DebugLevel, pkg+"invoking method "+meth)
	txn := C_AMFProp_GetNumber(C_AMF_GetProp(&obj, "", 1))

	switch meth {
	case av__result:
		var methodInvoked string
		for i, m := range s.methodCalls {
			if float64(m.num) == txn {
				methodInvoked = m.name
				s.methodCalls = eraseMethod(s.methodCalls, i)
				break
			}
		}
		if methodInvoked == "" {
			s.log(WarnLevel, pkg+"received result without matching request", "id", txn)
			goto leave
		}
		s.log(DebugLevel, pkg+"received result for "+methodInvoked)

		switch methodInvoked {
		case av_connect:
			if s.link.token != "" {
				s.log(FatalLevel, pkg+"no support for link token")

			}
			if (s.link.protocol & RTMP_FEATURE_WRITE) != 0 {
				sendReleaseStream(s)
				sendFCPublish(s)
			} else {
				s.log(FatalLevel, pkg+"link protocol has no RTMP_FEATURE_WRITE")
			}

			sendCreateStream(s)
			if (s.link.protocol & RTMP_FEATURE_WRITE) == 0 {
				s.log(FatalLevel, pkg+"link protocol has no RTMP_FEATURE_WRITE")
			}

		case av_createStream:
			s.streamID = int32(C_AMFProp_GetNumber(C_AMF_GetProp(&obj, "", 3)))

			if s.link.protocol&RTMP_FEATURE_WRITE != 0 {
				sendPublish(s)
			} else {
				s.log(FatalLevel, pkg+"link protocol has no RTMP_FEATURE_WRITE")
			}

		case av_play, av_publish:
			s.log(FatalLevel, pkg+"unsupported method av_play/av_publish")
		}

	case av_onBWDone:
		if s.checkCounter == 0 { // ToDo: why is this always zero?
			sendCheckBW(s)
		}

	case av_onFCUnsubscribe, av_onFCSubscribe:
		s.log(FatalLevel, pkg+"unsupported method av_onFCUnsubscribe/av_onFCSubscribe")

	case av_ping:
		s.log(FatalLevel, pkg+"unsupported method av_ping")

	case av__onbwcheck:
		s.log(FatalLevel, pkg+"unsupported method av_onbwcheck")

	case av__onbwdone:
		s.log(FatalLevel, pkg+"unsupported method av_onbwdone")

	case av_close:
		s.log(FatalLevel, pkg+"unsupported method av_close")

	case av_onStatus:
		var obj2 C_AMFObject
		C_AMFProp_GetObject(C_AMF_GetProp(&obj, "", 3), &obj2)
		code := C_AMFProp_GetString(C_AMF_GetProp(&obj2, av_code, -1))
		level := C_AMFProp_GetString(C_AMF_GetProp(&obj2, av_level, -1))
		s.log(DebugLevel, pkg+"onStatus", "code", code, "level", level)

		switch code {
		case av_NetStream_Failed, av_NetStream_Play_Failed,
			av_NetStream_Play_StreamNotFound, av_NetConnection_Connect_InvalidApp:
			s.log(FatalLevel, pkg+"unsupported method av_NetStream/av_NetStream_Play_Failed/av_netSTream_Play_StreamNotFound/av_netConnection_Connect_invalidApp")

		case av_NetStream_Play_Start, av_NetStream_Play_PublishNotify:
			s.log(FatalLevel, pkg+"unsupported method av_NetStream_Play_Start/av_NetStream_Play_PublishNotify")

		case av_NetStream_Publish_Start:
			s.log(DebugLevel, pkg+"playing")
			s.isPlaying = true
			for i, m := range s.methodCalls {
				if m.name == av_publish {
					s.methodCalls = eraseMethod(s.methodCalls, i)
					break
				}
			}
			// ToDo: handle case when av_publish method not found

		case av_NetStream_Play_Complete, av_NetStream_Play_Stop, av_NetStream_Play_UnpublishNotify:
			s.log(FatalLevel, pkg+"unsupported method av_NetStream_Play_Complete/av_NetStream_Play_Stop/av_NetStream_Play_UnpublishNotify")

		case av_NetStream_Seek_Notify:
			s.log(FatalLevel, pkg+"unsupported method av_netStream_Seek_Notify")

		case av_NetStream_Pause_Notify:
			s.log(FatalLevel, pkg+"unsupported method av_NetStream_Pause_Notify")
		}

	case av_playlist_ready:
		s.log(FatalLevel, pkg+"unsupported method av_playlist_ready")

	default:
		s.log(FatalLevel, pkg+"unknown method "+meth)
	}
leave:
	C_AMF_Reset(&obj)
	return nil
}

func handshake(s *Session) error {
	var clientbuf [RTMP_SIG_SIZE + 1]byte
	clientsig := clientbuf[1:]

	var serversig [RTMP_SIG_SIZE]byte
	clientbuf[0] = RTMP_CHANNEL_CONTROL
	binary.BigEndian.PutUint32(clientsig, uint32(time.Now().UnixNano()/1000000))
	copy(clientsig[4:8], []byte{0, 0, 0, 0})

	for i := 8; i < RTMP_SIG_SIZE; i++ {
		clientsig[i] = byte(rand.Intn(256))
	}

	err := writeN(s, clientbuf[:])
	if err != nil {
		return err
	}
	s.log(DebugLevel, pkg+"handshake sent")

	var typ [1]byte
	err = readN(s, typ[:])
	if err != nil {
		return err
	}
	s.log(DebugLevel, pkg+"handshake received")

	if typ[0] != clientbuf[0] {
		s.log(WarnLevel, pkg+"handshake type mismatch", "sent", clientbuf[0], "received", typ)
	}
	err = readN(s, serversig[:])
	if err != nil {
		return err
	}

	// decode server response
	suptime := binary.BigEndian.Uint32(serversig[:4])
	s.log(DebugLevel, pkg+"server uptime", "uptime", suptime)

	// 2nd part of handshake
	err = writeN(s, serversig[:])
	if err != nil {
		return err
	}

	err = readN(s, serversig[:])
	if err != nil {
		return err
	}

	if !bytes.Equal(serversig[:RTMP_SIG_SIZE], clientbuf[1:RTMP_SIG_SIZE+1]) {
		s.log(WarnLevel, pkg+"signature mismatch", "serversig", serversig[:RTMP_SIG_SIZE], "clientsig", clientbuf[1:RTMP_SIG_SIZE+1])
	}
	return nil
}

// write prepares data to write then sends it.
func (s *Session) write(buf []byte) error {
	pkt := packet{
		channel: RTMP_CHANNEL_SOURCE,
		info:    s.streamID,
	}
	var enc []byte

	for len(buf) != 0 {
		if pkt.bytesRead == 0 {
			if len(buf) < minDataSize {
				return errTinyPacket
			}

			if buf[0] == 'F' && buf[1] == 'L' && buf[2] == 'V' {
				buf = buf[13:]
			}

			pkt.packetType = buf[0]
			buf = buf[1:]
			pkt.bodySize = C_AMF_DecodeInt24(buf[:3])
			buf = buf[3:]
			pkt.timestamp = C_AMF_DecodeInt24(buf[:3])
			buf = buf[3:]
			pkt.timestamp |= uint32(buf[0]) << 24
			buf = buf[4:]

			headerType := uint8(RTMP_PACKET_SIZE_MEDIUM)
			switch pkt.packetType {
			case RTMP_PACKET_TYPE_VIDEO, RTMP_PACKET_TYPE_AUDIO:
				if pkt.timestamp == 0 {
					headerType = RTMP_PACKET_SIZE_LARGE
				}
			case RTMP_PACKET_TYPE_INFO:
				headerType = RTMP_PACKET_SIZE_LARGE
				pkt.bodySize += 16
			}

			resizePacket(&pkt, pkt.bodySize, headerType)

			enc = pkt.body[:pkt.bodySize]
			if pkt.packetType == RTMP_PACKET_TYPE_INFO {
				enc = C_AMF_EncodeString(enc, setDataFrame)
				if enc == nil {
					return errEncoding
				}
				pkt.bytesRead = uint32(len(pkt.body) - len(enc))
			}

		} else {
			enc = pkt.body[:pkt.bodySize][pkt.bytesRead:]
		}
		num := int(pkt.bodySize - pkt.bytesRead)
		if num > len(buf) {
			num = len(buf)
		}

		copy(enc[:num], buf[:num])
		pkt.bytesRead += uint32(num)
		buf = buf[num:]
		if pkt.bytesRead == pkt.bodySize {
			err := sendPacket(s, &pkt, false)
			pkt.body = nil
			pkt.bytesRead = 0
			if err != nil {
				return err
			}
			if len(buf) < 4 {
				return nil
			}
			buf = buf[4:]
		}
	}
	return nil
}