/*
DESCRIPTION
  Looper is a program that loops an audio file.

AUTHORS
  Ella Pietraroia <ella@ausocean.org>
  Scott Barnard <scott@ausocean.org>
  Saxon Nelson-Milton <saxon@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 looper is a bare bones program for repeated playback of an audio file.
package main

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

	"bitbucket.org/ausocean/iot/pi/netlogger"
	"bitbucket.org/ausocean/iot/pi/netsender"
	"bitbucket.org/ausocean/iot/pi/sds"
	"bitbucket.org/ausocean/utils/logging"
	"gopkg.in/natefinch/lumberjack.v2"
)

// Logging related constants.
const (
	logPath      = "/var/log/audiolooper/audiolooper.log"
	logMaxSize   = 500 // MB
	logMaxBackup = 10
	logMaxAge    = 28 // days
	logVerbosity = logging.Debug
	logSuppress  = true
)

// Netsender related consts.
const (
	netSendRetryTime = 5 * time.Second
	defaultSleepTime = 60 // Seconds
)

// Looper modes.
const (
	modeNormal = "Normal"
	modePaused = "Paused"
)

func main() {
	filePtr := flag.String("path", "", "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 a netlogger to deal with logging to cloud.
	nl := netlogger.New()

	// Create logger that we call methods on to l.
	l := logging.New(logVerbosity, io.MultiWriter(fileLog, nl), logSuppress)

	// Call initialisation code that is specific to the platform (pi 0 or 3).
	initCommand(l)

	// Create netsender client.
	ns, err := netsender.New(l, nil, readPin(), nil)
	if err != nil {
		l.Fatal("could not initialise netsender client", "error", err)
	}

	// This routine will deal with things that need to happen with the netsender client.
	go run(ns, l, nl)

	// Repeatedly play audio file.
	var numPlays int
	for {
		cmd := exec.Command(audioCmd, *filePtr)

		// 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.Error())
			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.Error())
		}
		l.Debug("stdout received", "stdout", string(outBuff.Bytes()))

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

// run is a routine to deal with netsender related tasks.
func run(ns *netsender.Sender, l logging.Logger, nl *netlogger.Logger) {
	var vs int
	for {
		err := ns.Run()
		if err != nil {
			l.Warning("Run Failed. Retrying...", "error", err)
			time.Sleep(netSendRetryTime)
			continue
		}

		err = nl.Send(ns)
		if err != nil {
			l.Warning("Logs could not be sent", "error", err.Error())
		}

		// If var sum hasn't changed we skip rest of loop.
		newVs := ns.VarSum()
		if vs == newVs {
			sleep(ns, l)
			continue
		}
		vs = newVs

		vars, err := ns.Vars()
		if err != nil {
			l.Error("netSender failed to get vars", "error", err)
			time.Sleep(netSendRetryTime)
			continue
		}

		// Configure looper based on vars.
		err = update(vars)
		if err != nil {
			l.Warning("couldn't update with new vars", "error", err)
			sleep(ns, l)
			continue
		}

		// TODO: consider handling of any modes ? We'd likely have paused and
		// normal for the audio looper.
		switch ns.Mode() {
		case modePaused:
		case modeNormal:
		}
	}
}

// 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 logging.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)
}

// 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 logging.Logger) {
	t, err := strconv.Atoi(ns.Param("mp"))
	if err != nil {
		l.Error("could not get sleep time, using default", "error", err)
		t = defaultSleepTime
	}
	time.Sleep(time.Duration(t) * time.Second)
}

// readPin provides a callback function of consistent signature for use by
// netsender to retrieve software defined pin values.
func readPin() func(pin *netsender.Pin) error {
	return func(pin *netsender.Pin) error {
		switch {
		case pin.Name == "X23":
			pin.Value = -1
		case pin.Name[0] == 'X':
			return sds.ReadSystem(pin)
		default:
			pin.Value = -1
		}
		return nil
	}
}

// update is currently a stub, but might used to update looper related params
// in future.
func update(v map[string]string) error {
	return nil
}