package main

import (
	"fmt"
	"os"
	"os/exec"
	"os/signal"
	"strings"
	"syscall"

	mqtt "github.com/eclipse/paho.mqtt.golang"
	"gopkg.in/yaml.v3"
)

var config = Config{}

var onCommandMessage mqtt.MessageHandler = func(client mqtt.Client, msg mqtt.Message) {
	value := string(msg.Payload())

	fmt.Printf("Requested %s\n", value)

	soundDef, found := config.Player.Sounds[value]

	if !found {
		soundDef, found = config.Player.Sounds["default"]
		if !found {
			fmt.Fprintf(os.Stderr, "No config entry found\n")
			return
		}
	}

	token := client.Publish(config.Mqtt.StateTopic, 0, false, "playing")
	token.Wait()

	var args []string
	var program string

	if soundDef.Program == "" {
		program = config.Player.DefaultProgram

		args = make([]string, len(config.Player.DefaultArgs))
		copy(args, config.Player.DefaultArgs)

		args = append(args, soundDef.Args...)
	} else {
		program = soundDef.Program
		args = make([]string, len(soundDef.Args))
		copy(args, soundDef.Args)
	}

	for i := range args {
		args[i] = strings.ReplaceAll(args[i], "{payload}", value)
	}

	fmt.Printf("Running %v %v\n", program, args)
	cmd := exec.Command(program, args...)
	cmd.Stderr = os.Stderr

	stdout, err := cmd.Output()

	out := strings.TrimSpace(string(stdout))

	if err != nil {
		fmt.Fprintf(os.Stderr, "Execution error: %v\n", err.Error())
	}

	if out != "" {
		fmt.Printf("Command output: %s\n", out)
	}

	token = client.Publish(config.Mqtt.StateTopic, 0, false, "stopped")
	token.Wait()
}

var onConnected mqtt.OnConnectHandler = func(client mqtt.Client) {
	fmt.Println("Connected")

	token := client.Subscribe(config.Mqtt.CommandTopic, 1, onCommandMessage)
	token.Wait()
}

var onDisconnected mqtt.ConnectionLostHandler = func(client mqtt.Client, err error) {
	fmt.Fprintf(os.Stderr, "Connection lost: %v\n", err)
}

func main() {
	if len(os.Args) < 2 {
		fmt.Fprintf(os.Stderr, "Usage: %s config.yaml\n", os.Args[0])
		os.Exit(2)
	}

	yamlData, err := os.ReadFile(os.Args[1])

	if err != nil {
		panic(err.Error())
	}

	yamlStr := os.ExpandEnv(string(yamlData))
	err = yaml.Unmarshal([]byte(yamlStr), &config)

	if err != nil {
		panic(err.Error())
	}

	opts := mqtt.NewClientOptions()
	opts.AddBroker(config.Mqtt.Address)
	opts.SetClientID(config.Mqtt.ClientId)
	opts.SetUsername(config.Mqtt.Username)
	opts.SetPassword(config.Mqtt.Password)
	opts.SetAutoReconnect(true)

	opts.OnConnect = onConnected
	opts.OnConnectionLost = onDisconnected
	client := mqtt.NewClient(opts)

	if token := client.Connect(); token.Wait() && token.Error() != nil {
		panic(token.Error())
	}

	// wait forever for interrupt
	exit := make(chan os.Signal, 1)
	defer close(exit)
	signal.Notify(exit, syscall.SIGINT, syscall.SIGTERM)
	<-exit

	client.Disconnect(250)
}