/*
DESCRIPTION
  treatment is a netsender client intended to provide audio playback control,
  and speaker health checking by reversing signal and recording using revid.

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

LICENSE
  Copyright (C) 2020 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 treatment is a program for playing and recording audio through a common
// speaker unit.
package main

import (
	"bytes"
	"flag"
	"fmt"
	"io"
	"os/exec"
	"strconv"
	"sync"
	"time"

	"bitbucket.org/ausocean/av/container/mts"
	"bitbucket.org/ausocean/av/container/mts/meta"
	"bitbucket.org/ausocean/av/revid"
	"bitbucket.org/ausocean/av/revid/config"
	"bitbucket.org/ausocean/iot/pi/gpio"
	"bitbucket.org/ausocean/iot/pi/netlogger"
	"bitbucket.org/ausocean/iot/pi/netsender"
	"bitbucket.org/ausocean/utils/logger"
	"github.com/kidoman/embd"
	_ "github.com/kidoman/embd/host/rpi"
	lumberjack "gopkg.in/natefinch/lumberjack.v2"
)

// Copyright information prefixed to all metadata.
const (
	metaPreambleKey  = "copyright"
	metaPreambleData = "ausocean.org/license/content2020"
)

// Logging configuration.
const (
	logPath      = "/var/log/netsender/netsender.log"
	logMaxSize   = 500 // MB
	logMaxBackup = 10
	logMaxAge    = 28 // days
	logVerbosity = logger.Info
	logSuppress  = true
)

// Misc constants.
const (
	netSendRetryTime = 5 * time.Second
	defaultSleepTime = 60 // Seconds
	pkg              = "rv: "
	minAmpVolume     = 0
	maxAmpVolume     = 63
	volAddr          = 0x4B
	i2cPort          = 1
)

// Treatment modes.
const (
	modePaused    = "Paused"
	modeTreatment = "Play"
	modeCheck     = "Check"
)

// Variable map to send to netreceiver/vidgrind.
var varMap = map[string]string{
	"mode":          "enum:Paused,Play,Check",
	"AudioFilePath": "string",
}

func main() {
	mts.Meta = meta.NewWith([][2]string{{metaPreambleKey, metaPreambleData}})

	// Set up the player command with audio file path.
	filePtr := flag.String("path", "/home/pi/audio.wav", "Path to sound file we wish to play.")
	flag.Parse()

	// Create lumberjack logger to handle logging to file.
	fileLog := &lumberjack.Logger{
		Filename:   logPath,
		MaxSize:    logMaxSize,
		MaxBackups: logMaxBackup,
		MaxAge:     logMaxAge,
	}

	// Create netlogger to handle logging to cloud.
	netLog := netlogger.New()

	// Create logger that we call methods on to log, which in turn writes to the
	// lumberjack and netloggers.
	log := logger.New(logVerbosity, io.MultiWriter(fileLog, netLog), logSuppress)

	if *filePtr == "" {
		log.Fatal("no file path provided, check usage")
	}

	// The netsender client will handle communication with netreceiver and GPIO stuff.
	log.Debug("initialising netsender client")
	ns, err := netsender.New(log, gpio.InitPin, nil, gpio.WritePin, netsender.WithVarTypes(varMap))
	if err != nil {
		log.Fatal("could not initialise netsender client", "error", err)
	}

	// Revid will handle the recording and sending of audio for sound checking.
	log.Debug("initialising revid")
	rv, err := revid.New(config.Config{Logger: log}, ns)
	if err != nil {
		log.Fatal("could not initialise revid", "error", err)
	}

	// Start the control loop.
	log.Debug("starting control loop")
	run(rv, ns, filePtr, log, netLog)
}

// run starts a control loop that runs netsender, sends logs, checks for var changes, and
// if var changes, changes current mode (paused,audio playback or soundcheck)
func run(rv *revid.Revid, ns *netsender.Sender, file *string, l *logger.Logger, nl *netlogger.Logger) {
	var (
		wg        sync.WaitGroup
		audioQuit chan struct{}
		treating  bool
		vs        int
	)

	for {
		l.Debug("running netsender")
		err := ns.Run()
		if err != nil {
			l.Warning("run failed. Retrying...", "error", err)
			time.Sleep(netSendRetryTime)
			continue
		}

		l.Debug("sending logs")
		err = nl.Send(ns)
		if err != nil {
			l.Warning(pkg+"Logs could not be sent", "error", err)
		}

		l.Debug("checking varsum")
		newVs := ns.VarSum()
		if vs == newVs {
			sleep(ns, l)
			continue
		}
		vs = newVs
		l.Info("varsum changed", "vs", vs)

		l.Debug("getting new vars")
		vars, err := ns.Vars()
		if err != nil {
			l.Error(pkg+"netSender failed to get vars", "error", err)
			time.Sleep(netSendRetryTime)
			continue
		}
		l.Info("got new vars", "vars", vars)

		// Configure revid based on the vars.
		l.Debug("updating revid configuration")
		err = rv.Update(vars)
		if err != nil {
			l.Warning(pkg+"couldn't update revid", "error", err)
			sleep(ns, l)
			continue
		}
		l.Info("revid successfully reconfigured")

		l.Debug("checking amplifier volume")
		v := vars["AmpVolume"]
		if v != "" {
			vol, err := strconv.ParseInt(v, 10, 8)
			if err != nil {
				l.Error(pkg+"failed to parse amplifier volume", "error", err)
			} else if vol < minAmpVolume || vol > maxAmpVolume {
				l.Error(fmt.Sprintf("%s invalid amplifier volume, must be between %v and %v", pkg, minAmpVolume, maxAmpVolume), "volume", vol)
			} else {
				bus := embd.NewI2CBus(i2cPort)
				err := bus.WriteByte(volAddr, byte(vol))
				if err != nil {
					l.Error(pkg+"failed to write amplifier volume", "error", err)
				}
			}
		}

		l.Debug("checking mode")
		switch ns.Mode() {
		case modePaused:
			stopAudio(&wg, &treating, audioQuit)
			l.Info("mode is Paused, stopping revid")
			rv.Stop()
		case modeTreatment:
			l.Debug("checking audio file path")
			f := vars["AudioFilePath"]
			if f != "" && *file != f {
				file = &f
				l.Info("updated audio file path, stopping audio", "AudioFilePath", f)
				stopAudio(&wg, &treating, audioQuit)
			}
			if !treating {
				l.Info("starting audio treatment")
				rv.Stop()
				audioQuit = make(chan struct{})
				treating = true
				wg.Add(1)
				go playAudio(file, audioQuit, &wg, l)
			}
		case modeCheck:
			stopAudio(&wg, &treating, audioQuit)
			l.Info("sound checking")
			err = rv.Start()
			if err != nil {
				l.Error("could not start revid", "error", err)
				ns.SetMode(modePaused, &vs)
				sleep(ns, l)
				continue
			}
		default:
			l.Warning("mode is not valid", "mode", ns.Mode())

		}
		l.Info("revid updated with new mode")
		sleep(ns, l)
	}
}

// playAudio is intended to be run as a routine. It will repeatedly play an audio file until
// a signal is received to return. The entire audio file is played before the termination
// signal chan is checked.
func playAudio(file *string, quit chan struct{}, wg *sync.WaitGroup, l *logger.Logger) {
	var numPlays int
	for {
		cmd := exec.Command(audioCmd, *file)
		// We'd like to see what the playback software is outputting, so pipe
		// stdout and stderr.
		outPipe, err := cmd.StdoutPipe()
		if err != nil {
			l.Error("failed to pipe stdout", "error", err)
		}
		errPipe, err := cmd.StderrPipe()
		if err != nil {
			l.Error("failed to pipe stderr", "error", err)
		}

		// Start playback of the audio file.
		err = cmd.Start()
		if err != nil {
			l.Error("start failed", "error", err)
			continue
		}
		numPlays++
		l.Debug("playing audio", "numPlays", numPlays)

		// Copy any std out to a buffer for logging.
		var outBuff bytes.Buffer
		go func() {
			_, err = io.Copy(&outBuff, outPipe)
			if err != nil {
				l.Error("failed to copy out pipe", "error", err)
			}
		}()

		// Copy any std error to a buffer for logging.
		var errBuff bytes.Buffer
		go func() {
			_, err = io.Copy(&errBuff, errPipe)
			if err != nil {
				l.Error("failed to copy error pipe", "error", err)
			}
		}()

		// Wait for playback to complete.
		err = cmd.Wait()
		if err != nil {
			l.Error("failed to wait for execution finish", "error", err)
		}
		l.Debug("stdout received", "stdout", string(outBuff.Bytes()))

		// If there was any errors on stderr, log them.
		if errBuff.Len() != 0 {
			l.Error("errors from stderr", "stderr", string(errBuff.Bytes()))
		}

		// Check for audio signal halt.
		// TODO: work out better way to do this. Doing it this way means we have to wait for
		// the audio file to finish playing.
		select {
		case <-quit:
			wg.Done()
			return
		default:
		}
	}
}

// stopAudio signals to the playAudio routine to terminate and then waits for it to
// do so.
func stopAudio(wg *sync.WaitGroup, treating *bool, signal chan struct{}) {
	if !*treating {
		return
	}
	close(signal)
	wg.Wait()
	*treating = false
}

// sleep uses a delay to halt the program based on the monitoring period
// netsender parameter (mp) defined in the netsender.conf config.
func sleep(ns *netsender.Sender, l *logger.Logger) {
	l.Debug("sleeping")
	t, err := strconv.Atoi(ns.Param("mp"))
	if err != nil {
		l.Error(pkg+"could not get sleep time, using default", "error", err)
		t = defaultSleepTime
	}
	time.Sleep(time.Duration(t) * time.Second)
	l.Debug("finished sleeping")
}

// checkPath wraps the use of lookPath to check the existence of executables
// that will be used by the audio looper.
func checkPath(cmd string, l *logger.Logger) {
	path, err := exec.LookPath(cmd)
	if err != nil {
		l.Fatal(fmt.Sprintf("couldn't find %s", cmd), "error", err)
	}
	l.Debug(fmt.Sprintf("found %s", cmd), "path", path)
}