// internal/audio/mixer/mixer.go
package mixer

import (
	"bufio"
	"bytes"
	"errors"
	"fmt"
	"os/exec"
	"strconv"
	"strings"
	"sync"

	"github.com/veandco/go-sdl2/mix"
	"github.com/veandco/go-sdl2/sdl"
	"rhemawavetech.com/rhemawave/internal/db"
	"rhemawavetech.com/rhemawave/internal/logger"
)

var (
	mu         sync.Mutex
	inited     bool
	deviceOpen bool
	deviceName string

	currentMusic *mix.Music
	currentPath  string
	currentLoops int // 0 = once, -1 = forever

	// Config knobs (could be made public or read from your config)
	defaultFreq      = 48000
	defaultFormat    = uint16(sdl.AUDIO_F32)
	defaultChannels  = 2
	defaultChunkSize = 1024
	defaultAllow     = sdl.AUDIO_ALLOW_ANY_CHANGE

	refreshCacheCallback func()
)

type Sink struct {
	ID        int
	Name      string
	Volume    float64
	IsDefault bool
}

// Init initializes SDL audio + SDL_mixer. Safe to call multiple times.
func Init(cfg *db.AppConfig, onUpdate func()) error {
	mu.Lock()
	defer mu.Unlock()
	if inited {
		return nil
	}

	refreshCacheCallback = onUpdate

	if err := sdl.InitSubSystem(sdl.INIT_AUDIO); err != nil {
		return fmt.Errorf("SDL audio init failed: %w", err)
	}

	// FIX 1: Initialize MP3 and OGG decoders
	err := mix.Init(mix.INIT_MP3 | mix.INIT_OGG)
	if err != nil {
		logger.Error("Failed to initialize MP3/OGG support: %v", err)
	}

	deviceName := cfg.SelectedAudioDevice
	if deviceName == "default" {
		deviceName = ""
	}
	if err := openDeviceLocked(deviceName); err != nil {
		sdl.QuitSubSystem(sdl.INIT_AUDIO)
		return err
	}

	SetAllSinkVolumes(cfg.SavedVolume)

	inited = true
	return nil
}

// openDeviceLocked tries to open the named device; if it fails and the name wasn't empty, falls back to default.
func openDeviceLocked(name string) error {
	if err := mix.OpenAudioDevice(defaultFreq, defaultFormat, defaultChannels, defaultChunkSize, name, defaultAllow); err != nil {
		if name != "" {
			// Log the failure of the requested device

			// Fallback to default device
			if err2 := mix.OpenAudioDevice(defaultFreq, defaultFormat, defaultChannels, defaultChunkSize, "", defaultAllow); err2 != nil {
				return fmt.Errorf("failed to open device %q and default device: %w", name, err2)
			}
			deviceName = "" // actually opened default
		} else {
			return fmt.Errorf("failed to open default audio device: %w", err)
		}
	} else {
		if name != "" {
		} else {
		}
		deviceName = name
	}
	deviceOpen = true
	return nil
}

// Play loads a WAV (as music) and plays it. If loopForever is true, loops forever.
// If something is already playing, it stops and replaces it.
func Play(path string, loopForever bool, cfg *db.AppConfig) error {
	// Check if audio is enabled or disabled
	if !cfg.AudioEnabled {
		return nil
	}

	// Lock the mutex
	mu.Lock()
	defer mu.Unlock()

	// Check if mixer has been initialized and that a device is open
	if !inited {
		logger.Error("audio mixer not initialized")
		return errors.New("audio mixer not initialized")
	}
	if !deviceOpen {
		if err := openDeviceLocked(""); err != nil {
			return fmt.Errorf("failed to open audio device: %w", err)
		}
	}
	if path == "" {
		logger.Error("empty audio path")
		return errors.New("empty audio path")
	}

	// Stop and free any prior music
	mix.HaltMusic()
	if currentMusic != nil {
		currentMusic.Free()
		currentMusic = nil
	}

	// Load the music file
	m, err := mix.LoadMUS(path)
	if err != nil {
		return fmt.Errorf("LoadMUS(%q): %w", path, err)
	}
	// Set current music to the loaded music file
	currentMusic = m
	currentPath = path
	if loopForever {
		currentLoops = -1
	} else {
		currentLoops = 0
	}

	mix.VolumeMusic(mix.MAX_VOLUME)
	volume := mix.VolumeMusic(-1)
	logger.Info("Current volume is %d", volume)

	if err := currentMusic.Play(currentLoops); err != nil {
		currentMusic.Free()
		currentMusic = nil
		logger.Error("music.Play failed: %v", err)
		return fmt.Errorf("music.Play: %w", err)
	}
	return nil
}

// Stop stops playback. If fadeMs > 0, fades out asynchronously; otherwise halts immediately.
// It also frees the currently loaded music (so a new Play will reload).
func Stop(fadeMs int, cfg *db.AppConfig) {
	mu.Lock()
	defer mu.Unlock()
	if !inited {
		return
	}

	if fadeMs > 0 && mix.PlayingMusic() {
		_ = mix.FadeOutMusic(fadeMs) // async fade; we’ll still free below
	}

	mix.HaltMusic()
	if currentMusic != nil {
		currentMusic.Free()
		currentMusic = nil
	}
	currentPath = ""
	currentLoops = 0
}

// IsPlaying reports whether music is currently playing (or fading).
func IsPlaying() bool {
	mu.Lock()
	defer mu.Unlock()
	if !inited {
		return false
	}
	return mix.PlayingMusic()
}

// SetDefaultSinkVolume sets volume 0.0–1.0 on the default sink
func SetDefaultSinkVolume(level float64) error {
	if level < 0 || level > 1 {
		return fmt.Errorf("volume must be between 0.0 and 1.0, got %f", level)
	}
	pct := fmt.Sprintf("%.2f", level)
	cmd := exec.Command("wpctl", "set-volume", "@DEFAULT_AUDIO_SINK@", pct)
	if out, err := cmd.CombinedOutput(); err != nil {
		return fmt.Errorf("wpctl failed: %w\noutput: %s", err, out)
	}
	return nil
}

// listSinkIDs returns just the numeric IDs of all audio sinks.
func listSinkIDs() ([]int, error) {
	sinks, err := listSinks()
	if err != nil {
		return nil, err
	}
	ids := make([]int, len(sinks))
	for i, s := range sinks {
		ids[i] = s.ID
	}
	return ids, nil
}

// listSinks returns full Sink info for all audio sinks.
func listSinks() ([]Sink, error) {
	out, err := exec.Command("wpctl", "status").Output()
	if err != nil {
		return nil, fmt.Errorf("wpctl status: %w", err)
	}
	return parseSinks(out)
}

// SetAllSinkVolumes sets volume on every audio sink found via wpctl status
func SetAllSinkVolumes(level float64) error {
	ids, err := listSinkIDs()
	if err != nil {
		return err
	}
	pct := fmt.Sprintf("%.2f", level)
	for _, id := range ids {
		cmd := exec.Command("wpctl", "set-volume", strconv.Itoa(id), pct)
		if out, err := cmd.CombinedOutput(); err != nil {
			return fmt.Errorf("wpctl set-volume %d failed: %w\noutput: %s", id, err, out)
		}
	}
	return nil
}

// ConvertVolume converts a desired volume percentage (0%, 25%, 33%, 90%, etc) to
// the float64 value needed to pass to SetAllSinkVolumes 0..1.0
// Percentages should be passed as integers. 25% -> 25
func ConvertVolume(volPerc int) float64 {
	if volPerc == 0 {
		return 0.0
	}
	return float64(volPerc) / 100.0
}

// parseSinks parses the output of `wpctl status` and extracts audio sinks.
func parseSinks(data []byte) ([]Sink, error) {
	var sinks []Sink

	scanner := bufio.NewScanner(bytes.NewReader(data))

	inAudioSection := false
	inSinksSection := false

	for scanner.Scan() {
		line := scanner.Text()
		stripped := strings.TrimLeft(line, " │├└─")

		// Detect top-level sections: "Audio", "Video", "Settings", etc.
		// These are lines with no leading tree characters.
		if !strings.HasPrefix(line, " ") && !strings.HasPrefix(line, "│") {
			inAudioSection = strings.TrimSpace(line) == "Audio"
			inSinksSection = false
			continue
		}

		if !inAudioSection {
			continue
		}

		// Detect subsection headers within Audio
		if strings.Contains(stripped, "Sinks:") {
			inSinksSection = true
			continue
		}
		// Any other subsection header resets sink parsing
		if strings.HasSuffix(strings.TrimSpace(stripped), ":") {
			inSinksSection = false
			continue
		}

		if !inSinksSection {
			continue
		}

		sink, ok := parseSinkLine(stripped)
		if ok {
			sinks = append(sinks, sink)
		}
	}

	if err := scanner.Err(); err != nil {
		return nil, fmt.Errorf("scanning wpctl output: %w", err)
	}

	return sinks, nil
}

// parseSinkLine parses a single sink entry line like:
//
//	"*51. USB Audio   [vol: 1.00]"
//	"33. Built-in Audio Analog Stereo   [vol: 0.65]"
func parseSinkLine(s string) (Sink, bool) {
	s = strings.TrimSpace(s)
	if s == "" {
		return Sink{}, false
	}

	var sink Sink

	// Leading '*' marks the default sink
	if strings.HasPrefix(s, "*") {
		sink.IsDefault = true
		s = strings.TrimPrefix(s, "*")
		s = strings.TrimSpace(s)
	}

	// Expect "<id>. <name> ..."
	dotIdx := strings.Index(s, ".")
	if dotIdx < 0 {
		return Sink{}, false
	}

	idStr := strings.TrimSpace(s[:dotIdx])
	id, err := strconv.Atoi(idStr)
	if err != nil {
		return Sink{}, false
	}
	sink.ID = id

	rest := strings.TrimSpace(s[dotIdx+1:])

	// Extract [vol: X.XX] if present
	volStart := strings.Index(rest, "[vol:")
	if volStart >= 0 {
		sink.Name = strings.TrimSpace(rest[:volStart])
		volPart := rest[volStart:]
		// "[vol: 0.65]" or "[vol: 0.65 MUTED]"
		volPart = strings.TrimPrefix(volPart, "[vol:")
		volPart = strings.TrimRight(volPart, "]")
		volPart = strings.TrimSpace(volPart)
		fields := strings.Fields(volPart)
		if len(fields) > 0 {
			v, err := strconv.ParseFloat(fields[0], 64)
			if err == nil {
				sink.Volume = v
			}
		}
	} else {
		sink.Name = strings.TrimSpace(rest)
	}

	return sink, true
}

// ListDevices returns the list of available output device names (from core SDL).
func ListDevices() []string {
	mu.Lock()
	defer mu.Unlock()
	n := sdl.GetNumAudioDevices(false)
	if n <= 0 {
		return nil
	}
	out := make([]string, 0, n)
	for i := 0; i < n; i++ {
		if name := sdl.GetAudioDeviceName(i, false); name != "" {
			out = append(out, name)
		}
	}
	return out
}

// CurrentDevice returns the last requested/opened device name ("" means default).
func CurrentDevice() string {
	return deviceName
}

// SwitchDevice switches output devices, preserving volume and resuming playback of the current track/loop state if any.
func SwitchDevice(newName string, cfg *db.AppConfig) error {
	mu.Lock()
	defer mu.Unlock()

	if !inited {
		return errors.New("audio mixer not initialized")
	}

	// Log device switch attempt
	// Automatically defaults to "system default"
	oldDevice := CurrentDevice() // Which device is to be closed
	// SDL expects "" for default device, not "system default"
	if newName == "" {          // Which device is being switched to?
		newName = ""
	}

	// Capture current state
	wasPlaying := mix.PlayingMusic()
	savedPath := currentPath
	savedLoops := currentLoops

	// Stop and release current music before reopening device
	mix.HaltMusic()
	if currentMusic != nil {
		currentMusic.Free()
		currentMusic = nil
	}
	currentPath = ""
	currentLoops = 0

	// Close and reopen device
	if deviceOpen {
		mix.CloseAudio()
		deviceOpen = false
	}

	// Attempt to open the newName device
	if err := openDeviceLocked(newName); err != nil {
		// If error switching to new device, switch back to the old device
		// oldDevice is already "" for default (which openDeviceLocked expects)
		if restoreErr := openDeviceLocked(oldDevice); restoreErr != nil {
			// We should not hit an error when switching back, but if we do...
			logger.Error("Failed to switch to device: %s", oldDevice)
		}
		// Could not switch to the new device, return the error
		return err
	}

	// Restore saved volume after reopening device
	if cfg != nil {
		SetAllSinkVolumes(cfg.SavedVolume)
	}

	// Optionally resume previous track if there was one
	if wasPlaying && savedPath != "" {
		m, err := mix.LoadMUS(savedPath)
		if err != nil {
			// Don't fail the device switch just because reload failed
			return fmt.Errorf("device switched, but reloading %q failed: %w", savedPath, err)
		}
		currentMusic = m
		currentPath = savedPath
		currentLoops = savedLoops
		if err := currentMusic.Play(currentLoops); err != nil {
			currentMusic.Free()
			currentMusic = nil
			currentPath = ""
			currentLoops = 0
			return fmt.Errorf("device switched, but restarting playback failed: %w", err)
		}
	}

	logger.Info("Audio device switched to %s", newName)

	return nil
}

func GetVolume128() int {
	mu.Lock()
	defer mu.Unlock()
	return mix.VolumeMusic(-1)
}

// Shutdown fully tears everything down. Call at app exit.
func Shutdown() {
	mu.Lock()
	defer mu.Unlock()

	mix.HaltMusic()
	if currentMusic != nil {
		currentMusic.Free()
		currentMusic = nil
	}
	if deviceOpen {
		mix.CloseAudio()
		deviceOpen = false
	}

	if inited {
		mix.Quit() // Add this to clean up the decoders
		sdl.QuitSubSystem(sdl.INIT_AUDIO)
		inited = false
	}
}