package player

import (
	"os"
	"os/exec"
	"sync"
	"time"
)

// Player handles alarm sound playback by shelling out to system audio tools.
type Player struct {
	mu     sync.Mutex
	stopCh chan struct{}
	doneCh chan struct{}
}

func New() *Player {
	return &Player{}
}

// resolveSound finds the actual file path for a sound. Returns "" if no file found.
func resolveSound(path string) string {
	if path != "default" && path != "" {
		if _, err := os.Stat(path); err == nil {
			return path
		}
		return ""
	}
	candidates := []string{
		"/usr/share/sounds/freedesktop/stereo/alarm-clock-elapsed.oga",
		"/usr/share/sounds/gnome/default/alerts/bark.ogg",
		"/usr/share/sounds/sound-icons/trumpet-12.wav",
	}
	for _, c := range candidates {
		if _, err := os.Stat(c); err == nil {
			return c
		}
	}
	return ""
}

// findPlayer returns the name and arg builder for the first available audio player.
func findPlayer() (string, func(string) []string) {
	players := []struct {
		name string
		args func(string) []string
	}{
		{"paplay", func(f string) []string { return []string{f} }},
		{"aplay", func(f string) []string { return []string{f} }},
		{"mpv", func(f string) []string { return []string{"--no-video", "--no-terminal", f} }},
		{"ffplay", func(f string) []string { return []string{"-nodisp", "-autoexit", f} }},
	}
	for _, pl := range players {
		if _, err := exec.LookPath(pl.name); err == nil {
			return pl.name, pl.args
		}
	}
	return "", nil
}

// PlayLoop starts playing a sound file in a loop until Stop() is called.
func (p *Player) PlayLoop(path string) {
	p.Stop() // kill any previous playback and wait for it to finish

	p.mu.Lock()
	p.stopCh = make(chan struct{})
	p.doneCh = make(chan struct{})
	stopCh := p.stopCh
	doneCh := p.doneCh
	p.mu.Unlock()

	resolved := resolveSound(path)
	if resolved == "" {
		go p.bellLoop(stopCh, doneCh)
		return
	}

	name, argsFn := findPlayer()
	if name == "" {
		os.Stdout.WriteString("\a")
		close(doneCh)
		return
	}

	go p.audioLoop(name, argsFn, resolved, stopCh, doneCh)
}

// audioLoop runs the audio player in a loop. The goroutine fully owns the
// process — no other goroutine touches cmd. Coordination is only via channels.
func (p *Player) audioLoop(name string, argsFn func(string) []string, path string, stopCh, doneCh chan struct{}) {
	defer close(doneCh)

	for {
		// Check if we should stop before starting a new process
		select {
		case <-stopCh:
			return
		default:
		}

		cmd := exec.Command(name, argsFn(path)...)
		cmd.Stdout = nil
		cmd.Stderr = nil

		if err := cmd.Start(); err != nil {
			return
		}

		// Wait for either the process to finish or a stop signal
		processDone := make(chan error, 1)
		go func() {
			processDone <- cmd.Wait()
		}()

		select {
		case <-stopCh:
			// Kill the process and wait for it to exit
			_ = cmd.Process.Kill()
			<-processDone
			return
		case <-processDone:
			// Process finished naturally, loop again after a brief pause
		}

		// Pause between loops
		select {
		case <-stopCh:
			return
		case <-time.After(300 * time.Millisecond):
		}
	}
}

func (p *Player) bellLoop(stopCh, doneCh chan struct{}) {
	defer close(doneCh)
	ticker := time.NewTicker(2 * time.Second)
	defer ticker.Stop()
	os.Stdout.WriteString("\a")
	for {
		select {
		case <-stopCh:
			return
		case <-ticker.C:
			os.Stdout.WriteString("\a")
		}
	}
}

// Stop stops any currently playing sound and waits for the playback goroutine to exit.
func (p *Player) Stop() {
	p.mu.Lock()
	stopCh := p.stopCh
	doneCh := p.doneCh
	p.stopCh = nil
	p.doneCh = nil
	p.mu.Unlock()

	if stopCh != nil {
		close(stopCh)
	}
	if doneCh != nil {
		<-doneCh // wait for goroutine to actually finish
	}
}