/*
DESCRIPTION
  rvcl is command line interface for revid. The user can provide configuration
  by passing a JSON string directly, or by specifying a file containing the JSON.

AUTHORS
  Saxon A. Nelson-Milton <saxon@ausocean.org>
  Dan Kortschak <dan@ausocean.org>
  Scott Barnard <scott@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
  along with revid in gpl.txt. If not, see http://www.gnu.org/licenses.

USAGE
  User may providied path to a config JSON file using the 'config-file' flag.
  For example, to stream a H.264 file to youtube we will need to create a file
  containing configuration JSON:
  {
    "Input":"file",
    "InputPath":"<path to h264 file>",
    "Output":"rtmp",
    "RtmpUrl":"<rtmp url>",
    "FileFPS":"25"
  }

  Then, using rvcl we can stream:

  ./rvcl -config-file="config.json"

  We can also use the 'config' flag to directly pass JSON as a string.
  NB: Quotations must have backslashes, '\', proceeding them for rvcl to consider
  the string valid JSON. For example, to play a file to youtube using the JSON
  config described above, we would do the following:

  ./rvcl -config="{\"Input\":\"file\",\"InputPath\":\"<file path>\",
    \"Output\":\"rtmp\",\"RtmpUrl\":\"<rtmp url>\",\"FileFPS\":\"25\"}"

  rvcl passes given variables to revid i.e. all variables defined by revid are
  valid. See revid config package i.e. bitbucket.org/ausocean/av/revid/config for
  revid specific variables, and see AVDevice implementations i.e.
  bitbucket.org/ausocean/av/device for input device specific variables.
*/

// rvcl is a command line interface for revid.
package main

import (
	"encoding/json"
	"flag"
	"fmt"
	"io"
	"os"
	"runtime/pprof"

	"gopkg.in/natefinch/lumberjack.v2"

	"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/netsender"
	"bitbucket.org/ausocean/utils/logger"
)

// Copyright information prefixed to all metadata.
const (
	metaPreambleKey  = "copyright"
	metaPreambleData = "ausocean.org/license/content2019"
)

// Logging configuration.
const (
	logMaxSize    = 500 // MB
	logMaxBackups = 10
	logMaxAge     = 28 // days
	logLevel      = logger.Debug
	logPath       = "/var/log/netsender/netsender.log"
	logSuppress   = false
)

// Misc consts.
const (
	pkg         = "rvcl: "
	profilePath = "rvcl.prof"
)

// canProfile is set to false with revid-cli is built with "-tags profile".
var canProfile = false

// The logger that will be used throughout.
var log *logger.Logger

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

	// If built with profile tag, we will start CPU profiling.
	if canProfile {
		profile()
		defer pprof.StopCPUProfile()
	}

	// User can provide config through single JSON string flag, or through JSON file.
	var (
		configPtr     = flag.String("config", "", "Provide configuration JSON to revid (see readme for further information).")
		configFilePtr = flag.String("config-file", "", "Location of revid configuration file (see readme for further information).")
	)
	flag.Parse()

	// Create config map according to flags or file, and panic if both are defined.
	var (
		cfg map[string]string
		err error
	)
	switch {
	case *configPtr != "" && *configFilePtr != "": // This doesn't make sense so panic.
		panic("cannot define both command-line config and file config")
	case *configPtr != "": // Decode JSON file to map.
		err = json.Unmarshal([]byte(*configPtr), &cfg)
		if err != nil {
			panic(fmt.Sprintf("could not decode JSON config: %w", err))
		}
	case *configFilePtr != "": // Decode JSON string to map from command line flag.
		f, err := os.Open(*configFilePtr)
		if err != nil {
			panic(fmt.Sprintf("could not open config file: %w", err))
		}
		err = json.NewDecoder(f).Decode(&cfg)
		if err != nil {
			panic(fmt.Sprintf("could not decode JSON config: %w", err))
		}
	default: // No config information has been provided; give empty map to force defaults.
		cfg = map[string]string{}
	}

	// Create logger that methods will be called on by the netsender client and
	// revid to log messages. Logs will go the lumberjack logger to handle file
	// writing of messages.
	log = logger.New(
		logLevel,
		io.MultiWriter(
			&lumberjack.Logger{
				Filename:   logPath,
				MaxSize:    logMaxSize, // MB
				MaxBackups: logMaxBackups,
				MaxAge:     logMaxAge, // days
			},
		),
		logSuppress,
	)

	// Create a netsender client. This is used only for HTTP sending of media
	// in this binary.
	ns, err := netsender.New(log, nil, nil, nil, nil)
	if err != nil {
		log.Log(logger.Fatal, pkg+"could not initialise netsender client: "+err.Error())
	}

	rv, err := revid.New(config.Config{Logger: log}, ns)
	if err != nil {
		panic(fmt.Sprintf("could not create revid: %w", err))
	}

	// Configure revid with configuration map obtained through flags or file.
	// If config is empty, defaults will be adopted by revid.
	err = rv.Update(cfg)
	if err != nil {
		panic(fmt.Sprintf("could not update revid config: %w", err))
	}

	err = rv.Start()
	if err != nil {
		panic(fmt.Sprintf("could not start revid: %w", err))
	}

	// Run indefinitely.
	select {}
}

// profile creates a file to hold CPU profile metrics and begins CPU profiling.
func profile() {
	f, err := os.Create(profilePath)
	if err != nil {
		log.Log(logger.Fatal, pkg+"could not create CPU profile", "error", err.Error())
	}
	if err := pprof.StartCPUProfile(f); err != nil {
		log.Log(logger.Fatal, pkg+"could not start CPU profile", "error", err.Error())
	}
}