/*
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

// TODO: do error handling using logger


import (
	"bufio"
	"bytes"
	"crypto/md5"
	"encoding/binary"
	"encoding/hex"
	"flag"
	"fmt"
	"io"
	"io/ioutil"
	"log"
	"math/rand"
	"net"
	"net/http"
	"os"
	"os/exec"
	"runtime"
	"strconv"
	"strings"
	"time"
	"errors"
	"log"
	"/tools"
	"ioutil"

	"bitbucket.org/ausocean/av/ringbuffer"

	"github.com/Comcast/gots/packet"
	"github.com/Comcast/gots/packet/adaptationfield"
	"github.com/Comcast/gots/psi"
)

// defaults and networking consts
const (
	clipDuration       = 1 // s
	defaultPID         = 256
	defaultFrameRate   = 25
	defaultHTTPOutput  = "http://localhost:8080?"
	defaultUDPOutput   = "udp://0.0.0.0:16384"
	defaultRTPOutput   = "rtp://0.0.0.0:16384"
	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         = 1000 / clipDuration
	bitrateOutputDelay = 60 // s
	httpTimeOut        = 5  // s
	motionThreshold    = "0.0025"
	qscale             = "3"
)

type RevidInst interface {
	Run()
	Stop()
	ChangeState(newConfig Config) err
}

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
}

func NewRevidInstance(config Config)(r *revid, err error){
	ringBuffer = ringbuffer.NewRingBuffer(bufferSize, mp2tPacketSize*mp2tMaxPackets)
	r.Error = log.New(os.Stderr, "ERROR: ",log.Ldat|log.Ltime|log.Lshortfile)
	r.expectCC = -1
	r.dumpCC = -1
	r.dumpPCRBase = 0
}

func(r *revidInst) Run(){
	isRunning = true
	go r.input()
	go r.output()
}

func(r *revidInst) Stop(){
	r.isRunning = false
}

// input handles the reading from the specified input
func (r *revid)input(input string, output string) {
	// (re)initialize globals
	r.expectCC = -1
	r.dumpCC = -1
	r.dumpPCRBase = 0

	converter := tscreator.NewTsCreator(framesPerSec)
	go converter.Convert()
	h264Parser := h264.NewH264Parser(converter.NalInputChan)
	go h264Parser.Parse()

	var err error
	var inputBuffer *Reader
	switch(r.config.input){
	case raspivid:
		cmd := exec.Command("raspivid -o -")
		stdout, _ := cmd.StdoutPipe()
		err = cmd.Start()
		inputReader = bufio.NewReader(stdout)
		if err != nil {
			r.Error.Println(err.Error())
			return
		}
	default:
		r.Error.Println("Input not valid!")
	}
	clipSize := 0
	packetCount := 0
	now := time.Now()
	prevTime := now
	for r.isRunning {
		var h264Data []byte
		if h264Data, err = ioutil.ReadAll(inputReader); err != nil {
			r.Error.Println(err.Error())
		}
		h264Parser.SendInputData(h264Data)

		if clip, err := ringBuffer.Get(); err != nil {
			r.Error.Println(err.Error())
			return
		} else {
			for {
				upperBound := clipSize + mp2tPacketSize
				// get ts packet from converter
				clip = (<-converter.TsChan).ToByteSlice()
				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 := ringBuffer.DoneWriting(clipSize); err != nil {
						r.Error.Println(err.Error())
						return
					}
					clipSize = 0
					packetCount = 0
					prevTime = now
					break
				}
			}
		}
	}
}

// output handles the writing to specified output
func (r *revid)output(output string) {
	for r.isRunning {
		if clip, err := ringBuffer.Read(); err == nil {
			fmt.Println(clip)
			for err = sendClip(clip, output, conn); err != nil; {
				r.Error.Println(err.Error())
				err = sendClip(clip, output, conn)
			}
			if err := ringBuffer.DoneReading(); err != nil {
				r.Error.Println(err.Error())
			}
		}
	}
}

// sendClipToFile writes a video clip to a /tmp file.
func sendClipToFile(clip []byte, _ string, _ net.Conn) error {

	return nil
}

// sendClipToHTPP posts a video clip via HTTP, using a new TCP connection each time.
func sendClipToHTTP(clip []byte, output string, _ net.Conn) 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 err
}

// sendClipToUDP sends a video clip over UDP.
func sendClipToUDP(clip []byte, _ string, conn net.Conn) error {
	size := udpPackets * mp2tPacketSize
	fmt.Printf("Sending %d UDP packets of size %d (%d bytes)\n", len(clip)/size, size, len(clip))
	for offset := 0; offset < len(clip); offset += size {
		pkt := clip[offset : offset+size]
		_, err := conn.Write(pkt)
		if err != nil {
			return fmt.Errorf("UDP write error %s. Is your player listening?", err)
		}
	}
	return nil
}