/*
NAME
  RtpToTsConverter.go - provides utilities for the conversion of Rtp packets
  to equivalent MpegTs packets.

DESCRIPTION
  See Readme.md

AUTHOR
  Saxon Nelson-Milton <saxon.milton@gmail.com>

LICENSE
  RtpToTsConverter.go is Copyright (C) 2017 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 [GNU licenses](http://www.gnu.org/licenses).
*/

package tsgenerator

import (
	_ "fmt"
	_"os"
	"../mpegts"
	"../pes"
	"../tools"
	"../rtp"
)

type TsGenerator interface {
	Generate()
}

type tsGenerator struct {
	TsChan          <-chan *mpegts.MpegTsPacket
	tsChan          chan<- *mpegts.MpegTsPacket
	InputChan       chan<- rtp.RtpPacket
	inputChan       <-chan rtp.RtpPacket
	NalInputChan    chan<- []byte
	nalInputChan    <-chan []byte
	currentTsPacket *mpegts.MpegTsPacket
	payloadByteChan chan byte
	currentCC       byte
	currentPtsTime			float64
	currentPcrTime 			float64
	fps							uint
	isGenerating bool
}

func NewTsGenerator(fps uint) (g *tsGenerator) {
	g = new(tsGenerator)
	tsChan := make(chan *mpegts.MpegTsPacket, 100)
	g.TsChan = tsChan
	g.tsChan = tsChan
	inputChan := make(chan rtp.RtpPacket, 100)
	g.InputChan = inputChan
	g.inputChan = inputChan
	nalInputChan := make(chan []byte, 10000)
	g.NalInputChan = nalInputChan
	g.nalInputChan = nalInputChan
	g.currentCC = 0
	g.fps = fps
	g.currentPcrTime = .0
	g.currentPtsTime = .7
	return
}

func (g *tsGenerator) genPts()(pts uint64){
	pts = uint64(g.currentPtsTime * float64(90000))
	g.currentPtsTime += 1.0/float64(g.fps)
	return
}

func (g *tsGenerator) genPcr()(pcr uint64){
	pcr = uint64(g.currentPcrTime * float64(90000))
	g.currentPcrTime += 1.0/float64(g.fps)
	return
}

func (g *tsGenerator) Stop(){
	g.isGenerating = false
}

func (g *tsGenerator) Generate() {
	g.isGenerating = true
	pesPktChan := make(chan []byte, 1000)
	payloadByteChan := make(chan byte, 100000)
	var rtpBuffer [](*rtp.RtpPacket)
	for g.isGenerating {
		select {
		default:
		case rtpPacket := <-g.inputChan:
			rtpBuffer = append(rtpBuffer, &rtpPacket)
			if len(rtpBuffer) > 2 {
				// if there's something weird going on with sequence numbers then
				// insertion sort
				if rtpPacket.SequenceNumber < rtpBuffer[len(rtpBuffer)-2].SequenceNumber {
					for i := 1; i < len(rtpBuffer); i++ {
						for j := i; j > 0 && rtpBuffer[j].SequenceNumber < rtpBuffer[j-1].SequenceNumber; j-- {
							temp := rtpBuffer[j]
							rtpBuffer[j] = rtpBuffer[j-1]
							rtpBuffer[j-1] = temp
						}
					}
				}
			}

			if len(rtpBuffer) > 200 {
				for tools.GetOctectType(rtpBuffer[0]) != 7 {
					rtpBuffer = rtpBuffer[1:]
				}
				sps := make([]byte, len(rtpBuffer[0].Payload))
				copy(sps[:], rtpBuffer[0].Payload[:])
				rtpBuffer = rtpBuffer[1:]
				pps := make([]byte, len(rtpBuffer[0].Payload))
				copy(pps[:], rtpBuffer[0].Payload[:])
				rtpBuffer = rtpBuffer[1:]
				sei := make([]byte, len(rtpBuffer[0].Payload))
				copy(sei[:], rtpBuffer[0].Payload[:])
				rtpBuffer = rtpBuffer[1:]
				for tools.GetOctectType(rtpBuffer[0]) != 7 {
					switch tools.GetOctectType(rtpBuffer[0]) {
					case 28:
						if tools.GetStartBit(rtpBuffer[0]) == 1 {
							var buffer []byte
							buffer = append(buffer, []byte{0x00, 0x00, 0x01}...)
							buffer = append(buffer, []byte{0x09, 0x10}...)
							buffer = append(buffer, []byte{0x00, 0x00, 0x01}...)
							buffer = append(buffer, sps...)
							buffer = append(buffer, []byte{0x00, 0x00, 0x01}...)
							buffer = append(buffer, pps...)
							buffer = append(buffer, []byte{0x00, 0x00, 0x01}...)
							buffer = append(buffer, sei...)
							buffer = append(buffer, []byte{0x00, 0x00, 0x01}...)
							buffer = append(buffer, rtpBuffer[0].Payload[0]&0xE0|rtpBuffer[0].Payload[1]&0x1F)
							buffer = append(buffer, rtpBuffer[0].Payload[2:]...)
							rtpBuffer = rtpBuffer[1:]
							for {
								buffer = append(buffer, rtpBuffer[0].Payload[2:]...)
								if tools.GetEndBit(rtpBuffer[0]) == 1 {
									rtpBuffer = rtpBuffer[1:]
									g.NalInputChan <- buffer
									break
								}
								rtpBuffer = rtpBuffer[1:]
							}
						}
					case 1:
						var buffer []byte
						buffer = append(buffer, []byte{0x00, 0x00, 0x01}...)
						buffer = append(buffer, []byte{0x09, 0x10}...)
						buffer = append(buffer, []byte{0x00, 0x00, 0x01}...)
						buffer = append(buffer, sps...)
						buffer = append(buffer, []byte{0x00, 0x00, 0x01}...)
						buffer = append(buffer, pps...)
						buffer = append(buffer, []byte{0x00, 0x00, 0x01}...)
						buffer = append(buffer, sei...)
						buffer = append(buffer, []byte{0x00, 0x00, 0x01}...)
						buffer = append(buffer, rtpBuffer[0].Payload[0]&0xE0|rtpBuffer[0].Payload[1]&0x1F)
						buffer = append(buffer, rtpBuffer[0].Payload[2:]...)
						rtpBuffer = rtpBuffer[1:]
						g.NalInputChan <- buffer
					default:
					}
				}
			}
		case nalUnit := <-g.nalInputChan:
			pesPkt := pes.PESPacket{
				StreamID: 0xE0,
				PDI: byte(2),
				PTS: g.genPts(),
				Data: nalUnit,
				HeaderLength: 5,
			}
			pesPktChan <- pesPkt.ToByteSlice()
		case pesPkt := <-pesPktChan:
			for ii := range pesPkt {
				payloadByteChan <- pesPkt[ii]
			}
			pusi := true
			for len(payloadByteChan) > 0 {
				pkt := mpegts.MpegTsPacket{
					PUSI: pusi,
					PID: 256,
					RAI: pusi,
					CC: g.currentCC,
					AFC: byte(3),
					PCRF: pusi,
				}
				pkt.FillPayload(payloadByteChan)
				if pusi {
					pkt.PCR = g.genPcr()
					pusi = false
				}
				if g.currentCC++; g.currentCC > 15 {
					g.currentCC = 0
				}
				g.tsChan <- &pkt
			}
		}
	}
}