/*
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 packets

import (
  "fmt"
  "os"
)

type RtpToTsConverter interface {
  Convert()
}

type rtpToTsConverter struct {
  TsChan <-chan *MpegTsPacket
  tsChan chan<- *MpegTsPacket
  InputChan chan<- RtpPacket
  inputChan <-chan RtpPacket
  currentTsPacket *MpegTsPacket
  payloadByteChan chan byte
  currentCC byte
}

func NewRtpToTsConverter() (c *rtpToTsConverter) {
  c = new(rtpToTsConverter)
  tsChan := make(chan *MpegTsPacket,100)
  c.TsChan = tsChan
  c.tsChan = tsChan
  inputChan := make(chan RtpPacket,100)
  c.InputChan = inputChan
  c.inputChan = inputChan
  c.currentCC = 0
  return
}

func (c* rtpToTsConverter) Convert() {
    file,_ := os.Create("video")
  pesPktChan := make(chan []byte, 10000)
  pesDataChan := make(chan byte, 15000)
  nalAccessChan := make(chan []byte, 100)
  data := make(chan byte,10000)
  payloadByteChan := make(chan byte, 15000)
  // Get nal units from incoming rtp
  var sps []byte
  var pps []byte
  // Frist find sps
  for {
    rtpPacket := <-c.inputChan
    fragmentType := rtpPacket.Payload[0] & 0x1F
    if fragmentType == 7 {
      sps = make([]byte,4+len(rtpPacket.Payload))
      sps[0] = 0x00
      sps[1] = 0x00
      sps[2] = 0x00
      sps[3] = 0x01
      for i := range rtpPacket.Payload {
        sps[i+4] = rtpPacket.Payload[i]
      }
      break
    }
  }
  // now find pps
  for {
    rtpPacket := <-c.inputChan
    fragmentType := rtpPacket.Payload[0] & 0x1F
    if fragmentType == 8 {
      pps = make([]byte,4+len(rtpPacket.Payload))
      pps[0] = 0x00
      pps[1] = 0x00
      pps[2] = 0x00
      pps[3] = 0x01
      for i := range rtpPacket.Payload {
        pps[i+4] = rtpPacket.Payload[i]
      }
      break
    }
  }
  for {
    select {
    default:
    case rtpPacket := <-c.inputChan:
      threeNUBs := rtpPacket.Payload[0] & 0xE0
      fragmentType := rtpPacket.Payload[0] & 0x1F
      startBit := (rtpPacket.Payload[1] & 0x80)>>7
      fiveNUBs := rtpPacket.Payload[1] & 0x1F
      fragmentData := rtpPacket.Payload[2:]
      fmt.Printf("fragmentType: %v\n", fragmentType)
      if fragmentType == 28 {
        if startBit == 1 {
          if len(data) > 0 {
            dataArray := make([]byte, len(data))
            for ii:=0; len(data) > 0; ii++ {
              dataArray[ii] = <-data
            }
            fmt.Printf("data array size: %v\n", len(dataArray))
            nalAccessChan<-dataArray
            file.Write(dataArray)
          }
          // load sps into data
          for ii := range sps {
            data<-sps[ii]
          }
          // load pps into data
          for ii := range pps {
            data<-pps[ii]
          }
          buffer := make([]byte,5+len(fragmentData))
          buffer[0] = 0x00
          buffer[1] = 0x00
          buffer[2] = 0x00
          buffer[3] = 0x01
          buffer[4] = threeNUBs | fiveNUBs
          for i := range fragmentData {
            buffer[i+5] = fragmentData[i]
          }
          // load data into data chan
          for ii := range buffer {
            data<-buffer[ii]
          }
        } else {
          if len(data) > 0 {
            for ii := range fragmentData {
              data<-fragmentData[ii]
            }
          }
        }
      }
    case nalUnit := <-nalAccessChan:
      for ii := range nalUnit {
        pesDataChan<-nalUnit[ii]
      }
      pesDataChanLen := len(nalUnit)
      pesPkt := new(PESPacket)
      pesPkt.StreamID = 0xE0
      pesPkt.Length = uint16( 3 + pesDataChanLen )
      pesPkt.ScramblingControl = 0
      pesPkt.Priority = true
      pesPkt.DAI = false
      pesPkt.Copyright = false
      pesPkt.Original = true
      pesPkt.PDI = 0
      pesPkt.ESCR = false
      pesPkt.ESRate = false
      pesPkt.DSMTrickMode = false
      pesPkt.ACI = false
      pesPkt.CRC = false
      pesPkt.Ext = false
      pesPkt.HeaderLength = 0
      pesPkt.Data = make([]byte,pesDataChanLen)
      for ii:=0; ii<pesDataChanLen; ii++ {
        pesPkt.Data[ii] = <-pesDataChan
      }
      pesPktChan<-pesPkt.ToByteSlice()
    case pesPkt := <-pesPktChan:
      for ii:=range pesPkt {
        payloadByteChan<-pesPkt[ii]
      }
      firstPacket:=true
      for len(payloadByteChan) > 0 {
        lengthOfByteChan := len(payloadByteChan)
        c.currentTsPacket = new(MpegTsPacket)
        c.currentTsPacket.SyncByte = 0x47
        c.currentTsPacket.TEI = false
        c.currentTsPacket.PUSI = false
        if firstPacket  { // if it's the start of the payload
          c.currentTsPacket.PUSI = true
          firstPacket = false
        }
        c.currentTsPacket.Priority = false
        c.currentTsPacket.PID = 256
        c.currentTsPacket.TSC = 0
        c.currentTsPacket.CC = c.currentCC
        if c.currentCC++; c.currentCC > 15 { c.currentCC = 0 }
        payloadLength := 182
        if lengthOfByteChan < 182 {
          payloadLength = lengthOfByteChan
        }
        c.currentTsPacket.AFC = 3
        stuffingLength := 182-payloadLength
        c.currentTsPacket.AF = make([]byte,2 + stuffingLength) // adaptationfield flag length = 16
        c.currentTsPacket.AF[0] = byte(1 + stuffingLength)
        c.currentTsPacket.AF[1] = 0
        if c.currentTsPacket.PUSI {
          c.currentTsPacket.AF[1] = 0x00
        }
        for ii := 0; ii < stuffingLength; ii++ {
          c.currentTsPacket.AF[2+ii] = 0xFF
        }
        c.currentTsPacket.Payload = make([]byte, payloadLength)
        for ii:=0; ii < payloadLength; ii++ {
          c.currentTsPacket.Payload[ii] = <-payloadByteChan
        }
        c.tsChan<-c.currentTsPacket
      }
    }
  }
}