package mixer

import (
	"errors"
	"fmt"
	"math"
	"sync"

	"github.com/veandco/go-sdl2/mix"
	"github.com/veandco/go-sdl2/sdl"
	"radiantwavetech.com/radiantwave/internal/db"
	"radiantwavetech.com/radiantwave/internal/logger"
)

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

	currentMusic *mix.Music
	currentPath  string
	currentLoops int

	currentVolume float64

	defaultFreq      = 48000
	defaultFormat    = uint16(sdl.AUDIO_F32)
	defaultChannels  = 2
	defaultChunkSize = 1024
	defaultAllow     = sdl.AUDIO_ALLOW_ANY_CHANGE

	refreshCacheCallback func()

	persistConfigCallback func(*db.AppConfig) error
)

// Init initializes SDL audio + SDL_mixer. Safe to call multiple times.
// persistConfig persists the given config (used to save the selected audio
// device across restarts); it may be nil, in which case device selections are
// not saved.
func Init(cfg *db.AppConfig, onUpdate func(), persistConfig func(*db.AppConfig) error) error {
	mu.Lock()
	defer mu.Unlock()
	if inited {
		return nil
	}

	refreshCacheCallback = onUpdate
	persistConfigCallback = persistConfig

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

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

	// A stored "default" (the first-run seed) is the system default.
	deviceName := cfg.SelectedAudioDevice
	if deviceName == "" || deviceName == "default" {
		deviceName = ""
	} else {
		// Honor a persisted device selection by resolving it against the
		// currently enumerated devices, falling back to the system default if
		// it is no longer present.
		if resolved, ok := resolvePreferredDevice(deviceName); ok {
			deviceName = resolved
		} else {
			logger.Warning("Selected audio device %q not found; using system default", cfg.SelectedAudioDevice)
			deviceName = ""
		}
	}
	if err := openDeviceLocked(deviceName); err != nil {
		sdl.QuitSubSystem(sdl.INIT_AUDIO)
		return err
	}

	currentVolume = cfg.SavedVolume
	v := int(math.Round(currentVolume * float64(mix.MAX_VOLUME)))
	mix.VolumeMusic(v)

	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 != "" {
			// 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 {
	if !cfg.AudioEnabled {
		return nil
	}

	mu.Lock()
	defer mu.Unlock()

	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")
	}

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

	m, err := mix.LoadMUS(path)
	if err != nil {
		return fmt.Errorf("LoadMUS(%q): %w", path, err)
	}
	currentMusic = m
	currentPath = path
	if loopForever {
		currentLoops = -1
	} else {
		currentLoops = 0
	}

	v := int(math.Round(currentVolume * float64(mix.MAX_VOLUME)))
	mix.VolumeMusic(v)
	logger.Info("Current volume is %d", v)

	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)
	}

	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()
}

// SetVolume sets the SDL_mixer music volume to level (0.0–1.0), mapped onto
// SDL_mixer's 0–128 scale (mix.MAX_VOLUME). This is relative to the OS audio
// sink, which the kiosk shell pins to 100%, so in-app volume is 0–100% of the
// sink output.
func SetVolume(level float64) error {
	if level < 0 || level > 1 {
		return fmt.Errorf("volume must be between 0.0 and 1.0, got %f", level)
	}
	mu.Lock()
	defer mu.Unlock()
	if !inited {
		return errors.New("audio mixer not initialized")
	}
	currentVolume = level
	v := int(math.Round(level * float64(mix.MAX_VOLUME)))
	mix.VolumeMusic(v)
	return nil
}

// ConvertVolume converts a desired volume percentage (0%, 25%, 33%, 90%, etc) to
// the float64 value needed to pass to SetVolume 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
}

// 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")
	}

	oldDevice := CurrentDevice()
	if newName == "" {
		newName = ""
	}

	wasPlaying := mix.PlayingMusic()
	savedPath := currentPath
	savedLoops := currentLoops

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

	if deviceOpen {
		mix.CloseAudio()
		deviceOpen = false
	}

	if err := openDeviceLocked(newName); err != nil {
		if restoreErr := openDeviceLocked(oldDevice); restoreErr != nil {
			logger.Error("Failed to switch to device: %s", oldDevice)
		}
		return err
	}

	if cfg != nil {
		// Persist whatever device is actually open (openDeviceLocked falls
		// back to the system default if the requested name cannot be opened).
		cfg.SelectedAudioDevice = CurrentDevice()
		if persistConfigCallback != nil {
			if err := persistConfigCallback(cfg); err != nil {
				logger.Error("Failed to persist audio device selection: %v", err)
			}
		}
		currentVolume = cfg.SavedVolume
		v := int(math.Round(cfg.SavedVolume * float64(mix.MAX_VOLUME)))
		mix.VolumeMusic(v)
	}

	if wasPlaying && savedPath != "" {
		m, err := mix.LoadMUS(savedPath)
		if err != nil {
			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()
		sdl.QuitSubSystem(sdl.INIT_AUDIO)
		inited = false
	}
}