/*
 *   Copyright (C) 2021 Arsen Musayelyan
 *
 *   This program is free software: you can redistribute it and/or modify
 *   it 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.
 *
 *   This program 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 this program.  If not, see <https://www.gnu.org/licenses/>.
 */

package main

import (
	"bufio"
	"bytes"
	ds "github.com/asticode/go-astideepspeech"
	"github.com/gen2brain/malgo"
	flag "github.com/spf13/pflag"
	"net"
	"os"
	"os/signal"
	"path/filepath"
	"strconv"
	"strings"
	"syscall"
	"time"
)

var verbose *bool
var execDir string
var configDir string

func main() {
	// Configure environment (paths to resources)
	var gopath, confPath string
	gopath, configDir, execDir, confPath = configEnv()

	// Define and parse command line flags
	tfLogLevel := flag.Int("tf-log-level", 2, "Log level for TensorFlow")
	verbose = flag.BoolP("verbose", "v", false, "Log more events")
	showDecode := flag.BoolP("show-decode", "d", false, "Show text to speech decodes")
	configPath := flag.StringP("config", "c", confPath, "Location of trident TOML config")
	modelPath := flag.StringP("model", "m", filepath.Join(execDir, "deepspeech.pbmm"), "Path to DeepSpeech model")
	scorerPath := flag.StringP("scorer", "s", filepath.Join(execDir, "deepspeech.scorer"), "Path to DeepSpeech scorer")
	socketPath := flag.StringP("socket", "S", filepath.Join(configDir, "trident.sock"), "Path to UNIX socket for IPC")
	GOPATH := flag.String("gopath", gopath, "GOPATH for use with plugins")
	flag.Parse()

	// Set TensorFlow log level to specified level (default 2)
	_ = os.Setenv("TF_CPP_MIN_LOG_LEVEL", strconv.Itoa(*tfLogLevel))

	// Get and parse TOML config
	config, err := getConfig(*configPath)
	if err != nil {
		log.Fatal().Err(err).Msg("Error getting TOML config")
	}

	// Create new channel storing os.Signal
	sigChannel := make(chan os.Signal, 1)
	// Notify channel upon reception of specified signals
	signal.Notify(sigChannel,
		syscall.SIGINT,
		syscall.SIGTERM,
		syscall.SIGHUP,
		syscall.SIGQUIT,
	)
	// Create new goroutine to handle signals gracefully
	go func() {
		// Wait for signal
		sig := <-sigChannel
		// Log reception of signal
		log.Info().Str("signal", sig.String()).Msg("Received signal, shutting down")
		// If IPC is enabled in the config, remove the UNIX socket
		if config.IPCEnabled {
			_ = os.RemoveAll(*socketPath)
		}
		// Exit with code 0
		os.Exit(0)
	}()

	// Create new DeepSpeech model
	model, err := ds.New(*modelPath)
	if err != nil {
		log.Fatal().Err(err).Msg("Error opening DeepSpeech model")
	}

	// Initialize available plugins
	plugins := initPlugins(*GOPATH)

	// If IPC is enabled in config
	if config.IPCEnabled {
		// Remove UNIX socket ignoring error
		_ = os.RemoveAll(*socketPath)
		// Listen on UNIX socket
		ln, err := net.Listen("unix", *socketPath)
		if err != nil {
			log.Fatal().Err(err).Msg("Error listening on UNIX socket")
		}
		go func() {
			for {
				// Accept any connection when it arrives
				conn, err := ln.Accept()
				if err != nil {
					log.Fatal().Err(err).Msg("Error accepting connection")
				}
				go func(conn net.Conn) {
					// Close connection at end of function
					defer conn.Close()
					// Create new scanner for connection (default is ScanLines)
					scanner := bufio.NewScanner(conn)
					// Scan until EOF
					for scanner.Scan() {
						// If error encountered, return from function
						if scanner.Err() != nil {
							return
						}
						// Get text from scanner
						input := scanner.Text()
						// Attempt to match text to action and return action
						action, ok := getAction(config, &input)
						// If match founc
						if ok {
							// Log performing action
							log.Info().Str("action", action.Name).Str("source", "socket").Msg("Performing action")
							// Perform returned action
							done, err := performAction(action, &input, plugins)
							if err != nil {
								log.Warn().Err(err).Str("action", action.Name).Msg("Error performing configured action")
							}
							// If action complete, close connection and return
							if done {
								conn.Close()
								return
							}
						}
					}
				}(conn)
			}
		}()
	}

	// Initialize audio context
	ctx, err := malgo.InitContext(nil, malgo.ContextConfig{}, func(message string) {
		log.Warn().Msg(message)
	})
	if err != nil {
		log.Fatal().Err(err).Msg("Error initializing malgo context")
	}
	// Uninitialize and free at end of function
	defer func() {
		_ = ctx.Uninit()
		ctx.Free()
	}()

	// Set device configuration options
	deviceConfig := malgo.DefaultDeviceConfig(malgo.Capture)
	deviceConfig.Capture.Format = malgo.FormatS16
	deviceConfig.Capture.Channels = 1
	deviceConfig.Playback.Format = malgo.FormatS16
	deviceConfig.Playback.Channels = 1
	deviceConfig.SampleRate = uint32(model.SampleRate())
	deviceConfig.Alsa.NoMMap = 1

	// Create new buffer to store audio samples
	captured := &bytes.Buffer{}
	onRecvFrames := func(_, sample []byte, _ uint32) {
		// Upon receipt of sample, write to buffer
		captured.Write(sample)
	}
	log.Info().Msg("Listening to audio events")
	// Initialize audio device using configuration options
	device, err := malgo.InitDevice(ctx.Context, deviceConfig, malgo.DeviceCallbacks{
		Data: onRecvFrames,
	})
	if err != nil {
		log.Fatal().Err(err).Msg("Error initializing audio device")
	}
	// Uninitialize at end of function
	defer device.Uninit()

	// Start capture device (begin recording)
	err = device.Start()
	if err != nil {
		log.Fatal().Err(err).Msg("Error starting capture device")
	}

	// Set DeepSpeech scorer
	err = model.EnableExternalScorer(*scorerPath)
	if err != nil {
		log.Fatal().Err(err).Msg("Error opening DeepSpeech scorer")
	}

	// Create new stream for DeepSpeech model
	sttStream, err := model.NewStream()
	if err != nil {
		log.Fatal().Err(err).Msg("Error creating DeepSpeech stream")
	}
	// Create a safe stream using sync.Mutex
	safeStream := &SafeStream{Stream: sttStream}

	// Create goroutine to clean stream every minute
	go func() {
		for {
			time.Sleep(20 * time.Second)
			// Lock mutex of stream
			safeStream.Lock()
			// Reset stream and buffer
			resetStream(safeStream, model, captured)
			if *verbose {
				log.Debug().Msg("1m passed; cleaning stream")
			}
			// Unlock mutex of stream
			safeStream.Unlock()
		}
	}()

	var tts string
	listenForActivation := true
	for {
		time.Sleep(200 * time.Millisecond)
		// Convert captured raw audio to slice of int16
		slice, err := convToInt16Slice(captured)
		if err != nil {
			log.Fatal().Err(err).Msg("Error converting captured audio feed")
		}
		// Reset buffer
		captured.Reset()
		// Lock mutex of stream
		safeStream.Lock()
		// Feed converted audio to stream
		safeStream.FeedAudioContent(slice)
		// Decode stream without destroying
		tts, err = safeStream.IntermediateDecode()
		if err != nil {
			log.Fatal().Err(err).Msg("Error intermediate decoding stream")
		}
		if *showDecode {
			log.Debug().Msg("TTS Decode: " + tts)
		}
		// If decoded string contains activation phrase and listenForActivation is true
		if strings.Contains(tts, config.ActivationPhrase) && listenForActivation {
			// Play activation tone
			err = playActivationTone(ctx)
			if err != nil {
				log.Fatal().Err(err).Msg("Error playing activation tone")
			}
			// Log detection of activation phrase
			log.Info().Msg("Activation phrase detected")
			// Reset stream and buffer
			resetStream(safeStream, model, captured)
			// Create new goroutine to listen for commands
			go func() {
				// Disable activation
				listenForActivation = false
				// Enable activation at end of function
				defer func() {
					listenForActivation = true
				}()
				// Create timeout channel to trigger after configured time
				timeout := time.After(config.ActivationTime)
			activationLoop:
				for {
					time.Sleep(100 * time.Millisecond)
					select {
					// If timeout has elapsed
					case <-timeout:
						log.Warn().Msg("Unknown command")
						break activationLoop
					// If timeout has not elapsed
					default:
						// Attempt to match decoded string to action
						action, ok := getAction(config, &tts)
						// If match found
						if ok {
							// Keep listening if user is talking
							for {
								// Get length of text to speech string
								ttsLen := len(tts)
								time.Sleep(time.Second)
								// If length has not changed
								if ttsLen == len(tts) {
									// Break out of for loop
									break
								}
							}
							// Log performing action
							log.Info().Str("action", action.Name).Str("source", "voice").Msg("Performing action")
							// Perform action matched by getAction()
							done, err := performAction(action, &tts, plugins)
							if err != nil {
								log.Warn().Err(err).Str("action", action.Name).Msg("Error performing configured action")
							}
							// If action is complete
							if done {
								// Lock mutex of stream
								safeStream.Lock()
								// Reset stream and buffer
								resetStream(safeStream, model, captured)
								// Unlock mutex of stream
								safeStream.Unlock()
								// Return from goroutine
								return
							}
						}
					}
				}
			}()
		}
		// Unlock mutex of stream
		safeStream.Unlock()
	}
}

// Function to reset stream and buffer
func resetStream(s *SafeStream, model *ds.Model, captured *bytes.Buffer) {
	// Reset buffer
	captured.Reset()
	// Discard stream (workaround for lack of Clear function)
	s.Discard()
	// Create new stream, setting it to same location as old
	s.Stream, _ = model.NewStream()
}