/*
NAME
  mtsSender_test.go

DESCRIPTION
  mtsSender_test.go contains tests that validate the functionalilty of the
  mtsSender under senders.go. Tests include checks that the mtsSender is
  segmenting sends correctly, and also that it can correct discontinuities.

AUTHORS
  Saxon A. Nelson-Milton <saxon@ausocean.org>

LICENSE
  mtsSender_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 revid

import (
	"errors"
	"fmt"
	"testing"
	"time"

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

	"bitbucket.org/ausocean/av/stream/mts"
	"bitbucket.org/ausocean/av/stream/mts/meta"
	"bitbucket.org/ausocean/utils/logger"
	"bitbucket.org/ausocean/utils/ring"
)

// Ring buffer sizes and read/write timeouts.
const (
	rbSize        = 100
	rbElementSize = 150000
	wTimeout      = 10 * time.Millisecond
	rTimeout      = 10 * time.Millisecond
)

// sender simulates sending of video data, creating discontinuities if
// testDiscontinuities is set to true.
type sender struct {
	buf                 [][]byte
	testDiscontinuities bool
	discontinuityAt     int
	currentPkt          int
}

// send takes d and neglects if testDiscontinuities is true, returning an error,
// otherwise d is appended to senders buf.
func (ts *sender) send(d []byte) error {
	if ts.testDiscontinuities && ts.currentPkt == ts.discontinuityAt {
		ts.currentPkt++
		return errors.New("could not send")
	}
	cpy := make([]byte, len(d))
	copy(cpy, d)
	ts.buf = append(ts.buf, cpy)
	ts.currentPkt++
	return nil
}

// log implements the required logging func for some of the structs in use
// within tests.
func log(lvl int8, msg string, args ...interface{}) {
	var l string
	switch lvl {
	case logger.Warning:
		l = "warning"
	case logger.Debug:
		l = "debug"
	case logger.Info:
		l = "info"
	case logger.Error:
		l = "error"
	case logger.Fatal:
		l = "fatal"
	}
	msg = l + ": " + msg
	for i := 0; i < len(args); i++ {
		msg += " %v"
	}
	fmt.Printf(msg, args)
}

// tstPacker implements io.Writer and handles the writing of data to the
// ringBuffer used in tests.
type tstPacker struct {
	rb *ring.Buffer
}

// Write writes to tstPacker's ringBuffer.
func (p *tstPacker) Write(d []byte) (int, error) {
	n, err := p.rb.Write(d)
	p.rb.Flush()
	return n, err
}

// TestSegment ensures that the mtsSender correctly segments data into clips
// based on positioning of PSI in the mtsEncoder's output stream.
func TestSegment(t *testing.T) {
	mts.Meta = meta.New()
	// Create ringBuffer, sender, loadsender and the MPEGTS encoder.
	rb := ring.NewBuffer(rbSize, rbElementSize, wTimeout)
	tstSender := &sender{}
	loadSender := newMtsSender(tstSender, log)
	packer := &tstPacker{rb: rb}
	encoder := mts.NewEncoder(packer, 25)

	// Turn time based PSI writing off for encoder.
	const psiSendCount = 10
	encoder.TimeBasedPsi(false, psiSendCount)

	const noOfPacketsToWrite = 100
	for i := 0; i < noOfPacketsToWrite; i++ {
		// Insert a payload so that we check that the segmentation works correctly
		// in this regard. Packet no will be used.
		encoder.Encode([]byte{byte(i)})
		rb.Flush()

		for {
			next, err := rb.Next(rTimeout)
			if err != nil {
				break
			}

			err = loadSender.load(next)
			if err != nil {
				t.Fatalf("Unexpected err: %v\n", err)
			}

			err = loadSender.send()
			if err != nil {
				t.Fatalf("Unexpected err: %v\n", err)
			}
			loadSender.release()
		}
	}

	result := tstSender.buf
	expectData := 0
	for clipNo, clip := range result {
		t.Logf("Checking clip: %v\n", clipNo)
		// Check that the clip is of expected length.
		clipLen := len(clip)
		if clipLen != psiSendCount*mts.PacketSize {
			t.Fatalf("Clip %v is not correct length. Got: %v Want: %v\n Clip: %v\n", clipNo, clipLen, psiSendCount*mts.PacketSize, clip)
		}

		// Also check that the first packet is a PAT.
		firstPkt := clip[:mts.PacketSize]
		var pkt [mts.PacketSize]byte
		copy(pkt[:], firstPkt)
		pid := (*packet.Packet)(&pkt).PID()
		if pid != mts.PatPid {
			t.Fatalf("First packet of clip %v is not pat, but rather: %v\n", clipNo, pid)
		}

		// Check that the clip data is okay.
		for i := 0; i < len(clip); i += mts.PacketSize {
			firstPkt := clip[i : i+mts.PacketSize]
			copy(pkt[:], firstPkt)
			p := (*packet.Packet)(&pkt)
			pid := p.PID()
			if pid == mts.VideoPid {
				payload, err := p.Payload()
				if err != nil {
					t.Fatalf("Unexpected err: %v\n", err)
				}

				// Parse PES from the MTS payload.
				pes, err := pes.NewPESHeader(payload)
				if err != nil {
					t.Fatalf("Unexpected err: %v\n", err)
				}

				// Get the data from the PES packet and convert to an int.
				data := int8(pes.Data()[0])

				// Calc expected data in the PES and then check.
				if data != int8(expectData) {
					t.Errorf("Did not get expected pkt data. ClipNo: %v, pktNoInClip: %v, Got: %v, want: %v\n", clipNo, i/mts.PacketSize, data, expectData)
				}
				expectData++
			}
		}
	}
}

func TestSendFailDiscontinuity(t *testing.T) {
	mts.Meta = meta.New()
	// Create ringBuffer sender, loadSender and the MPEGTS encoder.
	rb := ring.NewBuffer(rbSize, rbElementSize, wTimeout)
	const clipWithDiscontinuity = 3
	tstSender := &sender{testDiscontinuities: true, discontinuityAt: clipWithDiscontinuity}
	loadSender := newMtsSender(tstSender, log)
	packer := tstPacker{rb: rb}
	encoder := mts.NewEncoder(&packer, 25)

	// Turn time based PSI writing off for encoder.
	const psiSendCount = 10
	encoder.TimeBasedPsi(false, psiSendCount)

	const noOfPacketsToWrite = 100
	for i := 0; i < noOfPacketsToWrite; i++ {
		// Our payload will just be packet no.
		encoder.Encode([]byte{byte(i)})
		rb.Flush()

		for {
			next, err := rb.Next(rTimeout)
			if err != nil {
				break
			}

			err = loadSender.load(next)
			if err != nil {
				t.Fatalf("Unexpected err: %v\n", err)
			}

			loadSender.send()
			loadSender.release()
		}
	}

	result := tstSender.buf

	// First check that we have less clips as expected.
	expectedLen := (((noOfPacketsToWrite/psiSendCount)*2 + noOfPacketsToWrite) / psiSendCount) - 1
	gotLen := len(result)
	if gotLen != expectedLen {
		t.Errorf("We don't have one less clip as we should. Got: %v, want: %v\n", gotLen, expectedLen)
	}
	// Now check that the discontinuity indicator is set at the discontinuityClip PAT.
	disconClip := result[clipWithDiscontinuity]
	firstPkt := disconClip[:mts.PacketSize]
	var pkt [mts.PacketSize]byte
	copy(pkt[:], firstPkt)
	discon, err := (*packet.AdaptationField)((*packet.Packet)(&pkt)).Discontinuity()
	if err != nil {
		t.Fatalf("Unexpected err: %v\n", err)
	}

	if !discon {
		t.Fatalf("Did not get discontinuity indicator for PAT")
	}

}