/*
NAME
  PES.go -
DESCRIPTION
  See Readme.md

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

LICENSE
  PES.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

type PESPacket struct {
	StreamID          byte
	Length            uint16
	ScramblingControl byte
	Priority          bool
	DAI               bool // data alginment indicator
	Copyright         bool
	Original          bool
	PDI               byte // PTS DTS indicator
	ESCR              bool
	ESRate            bool
	DSMTrickMode      bool
	ACI               bool // additional copy info flag
	CRC               bool
	Ext               bool
	HeaderLength      byte
	OptFields         []byte
	Stuffing          []byte
	Data              []byte
}

func (p *PESPacket) ToByteSlice() (output []byte) {
	output = make([]byte, 6+p.Length)
	output[0] = 0x00
	output[1] = 0x00
	output[2] = 0x01
	output[3] = p.StreamID
	output[4] = byte(( p.Length & 0xFF00 ) >> 8)
	output[5] = byte( p.Length & 0x00FF )
	output[6] = 0x2 << 6 |
							p.ScramblingControl << 4 |
							boolToByte(p.Priority) << 3 |
							boolToByte(p.DAI) << 2 |
							boolToByte(p.Copyright) << 1 |
							boolToByte(p.Original)
	output[7] = p.PDI << 6 |
							boolToByte(p.ESCR) << 5 |
							boolToByte(p.ESRate) << 4 |
							boolToByte(p.DSMTrickMode) << 3 |
							boolToByte(p.ACI) << 2 |
							boolToByte(p.CRC) << 1 |
							boolToByte(p.Ext)
	output[8] = p.HeaderLength
	optFieldsOffset := 9+len(p.OptFields)
	copy(output[9:optFieldsOffset],p.OptFields)
	copy(output[optFieldsOffset:optFieldsOffset + len(p.Stuffing)],p.Stuffing)
	dataOffset := 9+int(p.HeaderLength)
	copy(output[dataOffset:dataOffset+len(p.Data)],p.Data)
	return
}