/*
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"
	"fmt"
	"io"
	"io/ioutil"
	"net"
	"net/http"
	"os"
	"os/exec"
	"strconv"
	"time"
	"errors"

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

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

// Misc constants
const (
	clipDuration    = 1                   // s
	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
	packetsPerFrame = 7
	h264BufferSize  = 500000
	bitrateTime     = 60
	mjpegParserInChanLen= 10000
)

// Log Types
const (
	Error   = "Error"
	Warning = "Warning"
	Info    = "Info"
	Debug   = "Debug"
)

// Config provides parameters relevant to a revid instance. A new config must
// be passed to the constructor.
type Config struct {
	Input          uint8
	InputCodec 		uint8
	Output         uint8
	OutputFileName string
	InputFileName  string
	Height         string
	Width          string
	FrameRate      string
	HttpAddress    string
	Quantization   string
	Timeout 				string
	Packetization   uint8
	IntraRefreshPeriod string
	Logger         smartLogger.LogInstance
}

// Enums for config struct
const (
	raspivid  = 1
	rtp       = 2
	h264Codec = 3
	file      = 4
	httpOut   = 5
	h264      = 6
	mjpeg     = 7
	none = 8
	mpegts = 9
)

// Default config settings
const (
	defaultFrameRate = "25"
	defaultWidth = "1280"
	defaultHeight = "720"
	defaultIntraRefreshPeriod = "100"
)

// RevidInst provides methods to control a revidInst session; providing methods
// to start, stop and change the state of an instance using the Config struct.
type RevidInst interface {
	Start()
	Stop()
	ChangeState(newconfig Config) error
	GetConfigRef() *Config
	Log(logType, m string)
	IsRunning() bool
}


// The revidInst struct provides fields to describe the state of a RevidInst.
type revidInst struct {
	ffmpegPath  string
	tempDir     string
	ringBuffer  ringbuffer.RingBuffer
	config      Config
	isRunning   bool
	outputFile  *os.File
	inputFile   *os.File
	generator   tsgenerator.TsGenerator
	parser  parser.Parser
	cmd         *exec.Cmd
	inputReader *bufio.Reader
	mjpegOutputChan chan []byte
}

// NewRevidInstance returns a pointer to a new revidInst with the desired
// configuration, and/or an error if construction of the new instant was not
// successful.
func NewRevidInstance(config Config) (r *revidInst, err error) {
	r = new(revidInst)
	r.ringBuffer = ringbuffer.NewRingBuffer(bufferSize, mp2tPacketSize*mp2tMaxPackets)
	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
		}
	}
	switch r.config.InputCodec {
	case h264:
		r.parser = parser.NewH264Parser()
	case mjpeg:
		r.parser = parser.NewMJPEGParser(mjpegParserInChanLen)
	}
	switch r.config.Packetization {
	case none:
		r.parser.SetOutputChan(r.mjpegOutputChan)
	case mpegts:
		frameRateAsInt, _ := strconv.Atoi(r.config.FrameRate)
		r.generator = tsgenerator.NewTsGenerator(uint(frameRateAsInt))
		r.parser.SetOutputChan(r.generator.GetNalInputChan())
		r.generator.Start()
	}
	r.parser.Start()
	go r.packClips()
	r.Log(Info, "New revid instance created! config is:")
	r.Log(Info, fmt.Sprintf("%v", r.config))
	return
}

// GetConfigRef returns a pointer to the revidInst's Config struct object
func (r *revidInst) GetConfigRef() *Config {
	return &r.config
}

// ChangeState swaps the current config of a revidInst with the passed
// configuration; checking validity and returning errors if not valid.
func (r *revidInst) ChangeState(config Config) error {
	switch config.Input {
	case rtp:
	case raspivid:
	case file:
	default:
		return errors.New("Bad input type defined in config!")
	}
	switch config.InputCodec {
	case h264:
	case mjpeg:
	default:
		return errors.New("Bad input format defined in config!")
	}
	switch config.Output {
	case httpOut:
	case file:
	default:
		return errors.New("Bad output type defined in config!")
	}
	if integer, err := strconv.Atoi(config.Width); integer < 0 || err != nil {
		return errors.New("Bad width defined in config!")
	}
	if integer, _ := strconv.Atoi(config.Width); integer == 0 {
		config.Width = defaultWidth
	}
	if integer, err := strconv.Atoi(config.Height); integer < 0 || err != nil {
		return errors.New("Bad height defined in config!")
	}
	if integer, _ := strconv.Atoi(config.Height); integer == 0 {
		config.Height = defaultHeight
	}
	if integer, err := strconv.Atoi(config.FrameRate); integer < 0 || err != nil {
		return errors.New("Bad FrameRate defined in config!")
	}
	if integer, _ := strconv.Atoi(config.FrameRate); integer == 0 {
		config.FrameRate = defaultFrameRate
	}
	if integer, err := strconv.Atoi(config.Timeout); integer < 0 || err != nil {
		return errors.New("Bad timeout define in config!")
	}
	if integer, err := strconv.Atoi(config.IntraRefreshPeriod); integer < 0 || err != nil {
		return errors.New("Bad intra refresh period defined in config!")
	}
	if integer, _ := strconv.Atoi(config.IntraRefreshPeriod); integer == 0 {
		config.IntraRefreshPeriod = defaultIntraRefreshPeriod
	}
	if integer, err := strconv.Atoi(config.Quantization); integer <= 0 || integer > 51 || err != nil {
		return errors.New("Bad quantization level defined in config!")
	}
	r.config = config
	return nil
}

// Log takes a logtype and message and tries to send this information to the
// logger provided in the revidInst config, if there is one, otherwise an
// error is returned.
func (r *revidInst) Log(logType, m string) error {
	if r.config.Logger != nil {
		r.config.Logger.Log(logType, m)
		return nil
	} else {
		return errors.New("No logger was defined in config for this instance!")
	}
}

// IsRunning returns true if the revidInst is currently running and false otherwise
func (r *revidInst) IsRunning() bool {
	return r.isRunning
}

// Start invokes a revidInst to start processing video from a defined input
// and packetising to a defined output.
func (r *revidInst) Start() {
	if r.isRunning {
		r.Log(Warning, "revidInst.Start() called but revid already running!")
		return
	}
	r.Log(Info, "Starting Revid!")
	switch r.config.Input {
	case raspivid:
		r.Log(Info, "Starting raspivid!")
		var codec string
		switch r.config.InputCodec{
		case h264:
			codec = "H264"
		case mjpeg:
			codec = "MJPEG"
		}
		r.cmd = exec.Command("raspivid",
			"-cd",	codec,
			"-o", 	"-",
			"-n",
			"-t", 	r.config.Timeout,
			"-b", 	"0",
			"-qp",	r.config.Quantization,
			"-w", 	r.config.Width,
			"-h", 	r.config.Height,
			"-fps", r.config.FrameRate,
			"-ih",
			"-g", 	r.config.IntraRefreshPeriod,
		)
		stdout, _ := r.cmd.StdoutPipe()
		err := r.cmd.Start()
		r.inputReader = bufio.NewReader(stdout)
		if err != nil {
			r.Log(Error, err.Error())
			return
		}
		r.isRunning = true
	case file:
		stats, err := r.inputFile.Stat()
		if err != nil {
			r.Log(Error, "Could not get input file stats!")
			r.Stop()
			return
		}
		data := make([]byte, stats.Size())
		_, err = r.inputFile.Read(data)
		if err != nil {
			r.Log(Error, err.Error())
			r.Stop()
			return
		}
		for i := range data {
			r.parser.GetInputChan() <- data[i]
		}
	}
	go r.readCamera()
	go r.outputClips()
}

// readCamera reads data from the defined camera while the revidInst is running.
func (r *revidInst)readCamera() {
	r.Log(Info, "Reading camera data!")
	for r.isRunning {
		data := make([]byte, 1)
		_, err := io.ReadFull(r.inputReader, data)
		switch {
		case err != nil && err.Error() == "EOF" && r.isRunning:
			r.Log(Error, "No data from camera!")
			time.Sleep(5 * time.Second)
		case err != nil && r.isRunning:
			r.Log(Error, err.Error())
		default:
			r.parser.GetInputChan()<-data[0]
		}
	}
	r.Log(Info, "Out of reading routine!")
}

// Stop halts any processing of video
func (r *revidInst) Stop() {
	if r.isRunning {
		r.Log(Info, "Stopping revid!")
		r.isRunning = false
		if r.cmd != nil {
			r.cmd.Process.Kill()
		}
	} else {
		r.Log(Warning, "revidInst.Stop() called but revid not running!")
	}
}

// packClips takes data segments; whether that be tsPackets or jpeg frames and
// packs them into clips 1s long.
func (r *revidInst) packClips() {
	clipSize := 0
	packetCount := 0
	now := time.Now()
	prevTime := now
	for {
		if clip, err := r.ringBuffer.Get(); err != nil {
			r.Log(Error, err.Error())
			switch r.config.Packetization {
			case none:
				r.Log(Warning, "Clearing mjpeg chan!")
				for len(r.mjpegOutputChan) > 0 {
					<-(r.mjpegOutputChan)
				}
			case mpegts:
				r.Log(Warning, "Clearing TS chan!")
				for len(r.generator.GetTsOutputChan()) > 0 {
					<-(r.generator.GetTsOutputChan())
				}
			}
			time.Sleep(1 * time.Second)
		} else {
			for {
				switch r.config.Packetization {
				case none:
					frame := <-r.mjpegOutputChan
					upperBound := clipSize + len(frame)
					copy(clip[clipSize:upperBound], frame)
					packetCount ++
					clipSize += len(frame)
				case mpegts:
					tsPacket := <-(r.generator.GetTsOutputChan())
					tsByteSlice, err := tsPacket.ToByteSlice()
					if err != nil {
						r.Log(Error, err.Error())
					}
					upperBound := clipSize + mp2tPacketSize
					copy(clip[clipSize:upperBound], tsByteSlice)
					packetCount++
					clipSize += mp2tPacketSize
				}
				// send if (1) our buffer is full or (2) 1 second has elapsed and we have % packetsPerFrame
				now = time.Now()
				if now.Sub(prevTime) > clipDuration*time.Second && len(clip) > 0 {
					if err := r.ringBuffer.DoneWriting(clipSize); err != nil {
						r.Log(Error, err.Error())
						r.Log(Warning, "Dropping clip!")
					}
					clipSize = 0
					packetCount = 0
					prevTime = now
					break
				}
			}
		}
	}
}

// outputClips takes the clips produced in the packClips method and outputs them
// to the desired output defined in the revidInst config
func (r *revidInst) outputClips() {
	now := time.Now()
	prevTime := now
	bytes := 0
	delay := 0
	for r.isRunning {
		switch {
		case r.ringBuffer.GetNoOfElements() < 2:
			delay++
			time.Sleep(time.Duration(delay) * time.Millisecond)
		case delay > 10:
			delay -= 10
		}
		if clip, err := r.ringBuffer.Read(); err == nil {
			r.Log(Debug, fmt.Sprintf("Delay is: %v\n", delay))
			r.Log(Debug, fmt.Sprintf("Ring buffer size: %v\n", r.ringBuffer.GetNoOfElements()))
			switch r.config.Output {
			case file:
				r.outputFile.Write(clip)
			case httpOut:
				bytes += len(clip)
				for err := r.sendClipToHTTP(clip, r.config.HttpAddress); err != nil; {
					r.Log(Error, err.Error())
					r.Log(Warning, "Post failed trying again!")
					err = r.sendClipToHTTP(clip, r.config.HttpAddress)
				}
			default:
				r.Log(Error, "No output defined!")
			}
			if err := r.ringBuffer.DoneReading(); err != nil {
				r.Log(Error, err.Error())
			}
			now = time.Now()
			deltaTime := now.Sub(prevTime)
			if deltaTime > time.Duration(bitrateTime)*time.Second {
				r.Log(Info, fmt.Sprintf("Bitrate: %v bits/s\n", int64(float64(bytes*8)/float64(deltaTime/1e9))))
				r.Log(Info, fmt.Sprintf("Ring buffer size: %v\n", r.ringBuffer.GetNoOfElements()))
				prevTime = now
				bytes = 0
			}
		}
	}
}

// sendClipToHTTP takes a clip and an output url and posts through http. 
func (r *revidInst) sendClipToHTTP(clip []byte, output string) error {
	timeout := time.Duration(httpTimeOut * time.Second)
	client := http.Client{
		Timeout: timeout,
	}
	url := output + strconv.Itoa(len(clip))
	r.Log(Debug, fmt.Sprintf("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 {
		r.Log(Debug, fmt.Sprintf("%s\n", body))
	} else {
		r.Log(Error, err.Error())
	}
	return nil
}