/*
NAME
  encoder_test.go

AUTHOR
  Trek Hopton <trek@ausocean.org>
  Saxon A. Nelson-Milton <saxon@ausocean.org>

LICENSE
  encoder_test.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 in gpl.txt.
  If not, see http://www.gnu.org/licenses.
*/

package mts

import (
	"bytes"
	"io"
	"io/ioutil"
	"testing"

	"github.com/Comcast/gots/packet"
	"github.com/Comcast/gots/pes"

	"bitbucket.org/ausocean/av/container/mts/meta"
)

type nopCloser struct{ io.Writer }

func (nopCloser) Close() error { return nil }

type destination struct {
	packets [][]byte
}

func (d *destination) Write(p []byte) (int, error) {
	tmp := make([]byte, PacketSize)
	copy(tmp, p)
	d.packets = append(d.packets, tmp)
	return len(p), nil
}

// TestEncodeVideo checks that we can correctly encode some dummy data into a
// valid MPEG-TS stream. This checks for correct MPEG-TS headers and also that the
// original data is stored correctly and is retreivable.
func TestEncodeVideo(t *testing.T) {
	Meta = meta.New()

	const dataLength = 440
	const numOfPackets = 3
	const stuffingLen = 100

	// Generate test data.
	data := make([]byte, 0, dataLength)
	for i := 0; i < dataLength; i++ {
		data = append(data, byte(i))
	}

	// Expect headers for PID 256 (video)
	// NB: timing fields like PCR are neglected.
	expectedHeaders := [][]byte{
		{
			0x47, // Sync byte.
			0x41, // TEI=0, PUSI=1, TP=0, PID=00001 (256).
			0x00, // PID(Cont)=00000000.
			0x30, // TSC=00, AFC=11(adaptation followed by payload), CC=0000(0).
			0x07, // AFL= 7.
			0x50, // DI=0,RAI=1,ESPI=0,PCRF=1,OPCRF=0,SPF=0,TPDF=0, AFEF=0.
		},
		{
			0x47, // Sync byte.
			0x01, // TEI=0, PUSI=0, TP=0, PID=00001 (256).
			0x00, // PID(Cont)=00000000.
			0x31, // TSC=00, AFC=11(adaptation followed by payload), CC=0001(1).
			0x01, // AFL= 1.
			0x00, // DI=0,RAI=0,ESPI=0,PCRF=0,OPCRF=0,SPF=0,TPDF=0, AFEF=0.
		},
		{
			0x47, // Sync byte.
			0x01, // TEI=0, PUSI=0, TP=0, PID=00001 (256).
			0x00, // PID(Cont)=00000000.
			0x32, // TSC=00, AFC=11(adaptation followed by payload), CC=0010(2).
			0x57, // AFL= 1+stuffingLen.
			0x00, // DI=0,RAI=0,ESPI=0,PCRF=1,OPCRF=0,SPF=0,TPDF=0, AFEF=0.
		},
	}

	// Create the dst and write the test data to encoder.
	dst := &destination{}
	_, err := NewEncoder(nopCloser{dst}, 25, Video).Write(data)
	if err != nil {
		t.Fatalf("could not write data to encoder, failed with err: %v\n", err)
	}

	// Check headers.
	var expectedIdx int
	for _, p := range dst.packets {
		// Get PID.
		var _p packet.Packet
		copy(_p[:], p)
		pid := packet.Pid(&_p)
		if pid == VideoPid {
			// Get mts header, excluding PCR.
			gotHeader := p[0:6]
			wantHeader := expectedHeaders[expectedIdx]
			if !bytes.Equal(gotHeader, wantHeader) {
				t.Errorf("did not get expected header for idx: %v.\n Got: %v\n Want: %v\n", expectedIdx, gotHeader, wantHeader)
			}
			expectedIdx++
		}
	}

	// Gather payload data from packets to form the total PES packet.
	var pesData []byte
	for _, p := range dst.packets {
		var _p packet.Packet
		copy(_p[:], p)
		pid := packet.Pid(&_p)
		if pid == VideoPid {
			payload, err := packet.Payload(&_p)
			if err != nil {
				t.Fatalf("could not get payload from mts packet, failed with err: %v\n", err)
			}
			pesData = append(pesData, payload...)
		}
	}

	// Get data from the PES packet and compare with the original data.
	pes, err := pes.NewPESHeader(pesData)
	if err != nil {
		t.Fatalf("got error from pes creation: %v\n", err)
	}
	_data := pes.Data()
	if !bytes.Equal(data, _data) {
		t.Errorf("did not get expected result.\n Got: %v\n Want: %v\n", data, _data)
	}
}

// TestEncodePcm tests the MPEG-TS encoder's ability to encode pcm audio data.
// It reads and encodes input pcm data into MPEG-TS, then decodes the MPEG-TS and compares the result to the input pcm.
func TestEncodePcm(t *testing.T) {
	Meta = meta.New()

	var buf bytes.Buffer
	sampleRate := 48000
	sampleSize := 2
	blockSize := 16000
	writeFreq := float64(sampleRate*sampleSize) / float64(blockSize)
	e := NewEncoder(nopCloser{&buf}, writeFreq, Audio)

	inPath := "../../../test/test-data/av/input/sweep_400Hz_20000Hz_-3dBFS_5s_48khz.pcm"
	inPcm, err := ioutil.ReadFile(inPath)
	if err != nil {
		t.Errorf("unable to read file: %v", err)
	}

	// Break pcm into blocks and encode to mts and get the resulting bytes.
	for i := 0; i < len(inPcm); i += blockSize {
		if len(inPcm)-i < blockSize {
			block := inPcm[i:]
			_, err = e.Write(block)
			if err != nil {
				t.Errorf("unable to write block: %v", err)
			}
		} else {
			block := inPcm[i : i+blockSize]
			_, err = e.Write(block)
			if err != nil {
				t.Errorf("unable to write block: %v", err)
			}
		}
	}
	clip := buf.Bytes()

	// Get the first MTS packet to check
	var pkt packet.Packet
	pesPacket := make([]byte, 0, blockSize)
	got := make([]byte, 0, len(inPcm))
	i := 0
	if i+PacketSize <= len(clip) {
		copy(pkt[:], clip[i:i+PacketSize])
	}

	// Loop through MTS packets until all the audio data from PES packets has been retrieved
	for i+PacketSize <= len(clip) {

		// Check MTS packet
		if !(pkt.PID() == audioPid) {
			i += PacketSize
			if i+PacketSize <= len(clip) {
				copy(pkt[:], clip[i:i+PacketSize])
			}
			continue
		}
		if !pkt.PayloadUnitStartIndicator() {
			i += PacketSize
			if i+PacketSize <= len(clip) {
				copy(pkt[:], clip[i:i+PacketSize])
			}
		} else {
			// Copy the first MTS payload
			payload, err := pkt.Payload()
			if err != nil {
				t.Errorf("unable to get MTS payload: %v", err)
			}
			pesPacket = append(pesPacket, payload...)

			i += PacketSize
			if i+PacketSize <= len(clip) {
				copy(pkt[:], clip[i:i+PacketSize])
			}

			// Copy the rest of the MTS payloads that are part of the same PES packet
			for (!pkt.PayloadUnitStartIndicator()) && i+PacketSize <= len(clip) {
				payload, err = pkt.Payload()
				if err != nil {
					t.Errorf("unable to get MTS payload: %v", err)
				}
				pesPacket = append(pesPacket, payload...)

				i += PacketSize
				if i+PacketSize <= len(clip) {
					copy(pkt[:], clip[i:i+PacketSize])
				}
			}
		}
		// Get the audio data from the current PES packet
		pesHeader, err := pes.NewPESHeader(pesPacket)
		if err != nil {
			t.Errorf("unable to read PES packet: %v", err)
		}
		got = append(got, pesHeader.Data()...)
		pesPacket = pesPacket[:0]
	}

	// Compare data from MTS with original data.
	if !bytes.Equal(got, inPcm) {
		t.Error("data decoded from mts did not match input data")
	}
}