/*
NAME
  revid - a testbed for re-muxing and re-directing video streams as MPEG-TS over various protocols.

DESCRIPTION
  See Readme.md

AUTHORS
  Alan Noble <anoble@gmail.com>
	Saxon A. Nelson-Milton <saxon.milton@gmail.com>

LICENSE
  revid is Copyright (C) 2017 Alan Noble.

  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).
*/

// revid is a testbed for re-muxing and re-directing video streams as MPEG-TS over various protocols.
package revid

import (
	"bufio"
	"bytes"
	"crypto/md5"
	"encoding/hex"
	"fmt"
	"io"
	"io/ioutil"
	"log"
	"net"
	"net/http"
	"os"
	"os/exec"
	"strconv"
	"time"

	"bitbucket.org/ausocean/av/h264"
	"bitbucket.org/ausocean/av/tsgenerator"

	"bitbucket.org/ausocean/av/ringbuffer"
)

// defaults and networking consts
const (
	clipDuration       = 1 // s
	defaultPID         = 256
	defaultFrameRate   = 25
	mp2tPacketSize     = 188                 // MPEG-TS packet size
	mp2tMaxPackets     = 2016 * clipDuration // # first multiple of 7 and 8 greater than 2000
	udpPackets         = 7                   // # of UDP packets per ethernet frame (8 is the max)
	rtpPackets         = 7                   // # of RTP packets per ethernet frame (7 is the max)
	rtpHeaderSize      = 12
	rtpSSRC            = 1 // any value will do
	bufferSize         = 100 / clipDuration
	httpTimeOut        = 5 // s
	motionThreshold    = "0.0025"
	qscale             = "3"
	defaultRaspividCmd = "raspivid -o -"
	framesPerSec       = 25
	packetsPerFrame    = 7
	h264BufferSize     = 500000
)

const (
	Raspivid  = 0
	Rtp       = 1
	H264Codec = 2
	File      = 4
	HttpOut   = 5
)

var cmd *exec.Cmd
var inputReader *bufio.Reader

type Config struct {
	Input          uint8
	InputCmd       string
	Output         uint8
	OutputFileName string
	InputFileName  string
	Height         string
	Width          string
	Bitrate        string
	FrameRate string
	HttpAddress string
}

type RevidInst interface {
	Start()
	Stop()
	ChangeState(newConfig Config) error
}

type revidInst struct {
	expectCC    int
	dumpCC      int
	dumpPCRBase uint64
	conn        net.Conn
	ffmpegPath  string
	tempDir     string
	ringBuffer  ringbuffer.RingBuffer
	config      Config
	isRunning   bool
	Error       *log.Logger
	outputFile  *os.File
	inputFile   *os.File
	generator   tsgenerator.TsGenerator
	h264Parser  h264.H264Parser
}

func NewRevidInstance(config Config) (r *revidInst, err error) {
	r = new(revidInst)
	r.ringBuffer = ringbuffer.NewRingBuffer(bufferSize, mp2tPacketSize*mp2tMaxPackets)
	r.Error = log.New(os.Stderr, "ERROR: ", log.Ldate|log.Ltime|log.Lshortfile)
	r.expectCC = -1
	r.dumpCC = -1
	r.dumpPCRBase = 0
	r.ChangeState(config)
	switch r.config.Output {
	case File:
		r.outputFile, err = os.Create(r.config.OutputFileName)
		if err != nil {
			return nil, err
		}
	}
	switch r.config.Input {
	case File:
		r.inputFile, err = os.Open(r.config.InputFileName)
		if err != nil {
			return nil, err
		}
	}
	r.generator = tsgenerator.NewTsGenerator(framesPerSec)
	r.h264Parser = h264.H264Parser{OutputChan: r.generator.GetNalInputChan()}
	// TODO: Need to create constructor for parser otherwise I'm going to break
	// something eventuallyl
	go r.h264Parser.Parse()
	go r.input()
	return
}

func (r *revidInst) ChangeState(newConfig Config) error {
	// TODO: check that the config is G
	r.config = newConfig
	return nil
}

func (r *revidInst) Start() {
	r.isRunning = true
	go r.generator.Generate()
	switch r.config.Input {
	case Raspivid:
		cmd = exec.Command("raspivid", "-o", "-", "-n", "-t", "0", "-b",
			r.config.Bitrate, "-w", r.config.Width, "-h", r.config.Height, "-fps", r.config.FrameRate)
		stdout, _ := cmd.StdoutPipe()
		err := cmd.Start()
		inputReader = bufio.NewReader(stdout)
		if err != nil {
			r.Error.Println(err.Error())
			return
		}
	case File:
	default:
		r.Error.Println("Input not valid!")
	}
	var h264Data []byte
	switch r.config.Input {
	case Raspivid:
		go func() {
			for r.isRunning {
				h264Data = make([]byte, 1)
				_, err := io.ReadFull(inputReader, h264Data)
				if err != nil {
					if err.Error() == "EOF" {
						r.Error.Println("No data from camera!")
						time.Sleep(5*time.Second)
					} else {
						r.Error.Println(err.Error())
					}
				} else {
					r.h264Parser.InputByteChan <- h264Data[0]
				}
			}
		}()
	case File:
		stats, err := r.inputFile.Stat()
		if err != nil {
			panic("Could not get file stats!")
		}
		h264Data = make([]byte, stats.Size())
		_, err = r.inputFile.Read(h264Data)
		if err != nil {
			r.Error.Println(err.Error())
		}
		for i := range h264Data {
			r.h264Parser.InputByteChan <- h264Data[i]
		}
	}
	go r.output()
}

func (r *revidInst) Stop() {
	if r.isRunning {
		r.isRunning = false
		r.generator.Stop()
		cmd.Process.Kill()
	}
}

func (r *revidInst) input() {
	clipSize := 0
	packetCount := 0
	now := time.Now()
	prevTime := now
	fmt.Println("reading")
	for {
		if clip, err := r.ringBuffer.Get(); err != nil {
			r.Error.Println(err.Error())
			return
		} else {
			for {
				tsPacket := <-(r.generator.GetTsOutputChan())
				byteSlice, err := tsPacket.ToByteSlice()
				if err != nil {
					r.Error.Println(err.Error())
				}
				upperBound := clipSize + mp2tPacketSize
				copy(clip[clipSize:upperBound], byteSlice)
				packetCount++
				clipSize += mp2tPacketSize
				// send if (1) our buffer is full or (2) 1 second has elapsed and we have % packetsPerFrame
				now = time.Now()
				if (packetCount == mp2tMaxPackets) ||
					(now.Sub(prevTime) > clipDuration*time.Second && packetCount%packetsPerFrame == 0) {
					if err := r.ringBuffer.DoneWriting(clipSize); err != nil {
						r.Error.Println(err.Error())
						return
					}
					clipSize = 0
					packetCount = 0
					prevTime = now
					break
				}
			}
		}
	}
}

func (r *revidInst) output() {
	for r.isRunning {
		if clip, err := r.ringBuffer.Read(); err == nil {
			switch r.config.Output {
			case File:
				r.outputFile.Write(clip)
			case HttpOut:
			for err := sendClipToHTTP(clip, r.config.HttpAddress); err != nil; {
				err = sendClipToHTTP(clip, r.config.HttpAddress)
			}
			default:
				r.Error.Println("No output?")
			}
			if err := r.ringBuffer.DoneReading(); err != nil {
				r.Error.Println(err.Error())
			}
		}
	}
}

// sendClipToHTPP posts a video clip via HTTP, using a new TCP connection each time.
func sendClipToHTTP(clip []byte, output string) error {
	timeout := time.Duration(httpTimeOut * time.Second)
	client := http.Client{
		Timeout: timeout,
	}
	hash := md5.Sum(clip)
	url := output + strconv.Itoa(len(clip)) + "." + hex.EncodeToString(hash[:]) // NB: append size.digest to output
	fmt.Printf("Posting %s (%d bytes)\n", url, len(clip))
	resp, err := client.Post(url, "video/mp2t", bytes.NewReader(clip)) // lighter than NewBuffer
	if err != nil {
		return fmt.Errorf("Error posting to %s: %s", output, err)
	}
	defer resp.Body.Close()
	body, err := ioutil.ReadAll(resp.Body)
	if err == nil {
		fmt.Printf("%s\n", body)
	}
	return nil
}