//go:build windows

package audio

import (
	"encoding/binary"
	"fmt"
	"log"
	"sync"
	"time"
	"unsafe"

	"github.com/go-ole/go-ole"
	"github.com/moutend/go-wca/pkg/wca"
)

// Player handles WASAPI audio playback with mixing support
type Player struct {
	client       *wca.IAudioClient
	renderClient *wca.IAudioRenderClient
	waveFormat   *wca.WAVEFORMATEX
	bufferSize   uint32
	volume       float32
	muted        bool
	mu           sync.Mutex
	running      bool
	stopChan     chan struct{}

	// User buffers for mixing
	// map[SenderID] -> AudioQueue
	userBuffers map[uint16][]int16

	// User EQs (DSP Filters)
	userEQs map[uint16]*EQChain

	// User settings
	userSettings map[uint16]*UserSettings
	bufferMu     sync.Mutex
}

// NewPlayer creates a new WASAPI audio player
func NewPlayer() (*Player, error) {
	// Initialize COM
	ole.CoInitializeEx(0, ole.COINIT_APARTMENTTHREADED)
	log.Printf("[Audio] Windows/WASAPI initializing...")

	var deviceEnumerator *wca.IMMDeviceEnumerator
	if err := wca.CoCreateInstance(
		wca.CLSID_MMDeviceEnumerator,
		0,
		wca.CLSCTX_ALL,
		wca.IID_IMMDeviceEnumerator,
		&deviceEnumerator,
	); err != nil {
		return nil, fmt.Errorf("failed to create device enumerator: %w", err)
	}
	defer deviceEnumerator.Release()

	var device *wca.IMMDevice
	if err := deviceEnumerator.GetDefaultAudioEndpoint(wca.ERender, wca.EConsole, &device); err != nil {
		return nil, fmt.Errorf("failed to get default render device: %w", err)
	}
	defer device.Release()

	var audioClient *wca.IAudioClient
	if err := device.Activate(wca.IID_IAudioClient, wca.CLSCTX_ALL, nil, &audioClient); err != nil {
		return nil, fmt.Errorf("failed to activate audio client: %w", err)
	}

	waveFormat := &wca.WAVEFORMATEX{
		WFormatTag:      wca.WAVE_FORMAT_PCM,
		NChannels:       1,
		NSamplesPerSec:  48000,
		WBitsPerSample:  16,
		NBlockAlign:     2,
		NAvgBytesPerSec: 96000,
		CbSize:          0,
	}

	duration := wca.REFERENCE_TIME(100 * 10000) // 100ms buffer
	if err := audioClient.Initialize(
		wca.AUDCLNT_SHAREMODE_SHARED,
		wca.AUDCLNT_STREAMFLAGS_AUTOCONVERTPCM|wca.AUDCLNT_STREAMFLAGS_SRC_DEFAULT_QUALITY,
		duration,
		0,
		waveFormat,
		nil,
	); err != nil {
		audioClient.Release()
		return nil, fmt.Errorf("failed to initialize audio client: %w", err)
	}

	var bufferSize uint32
	if err := audioClient.GetBufferSize(&bufferSize); err != nil {
		audioClient.Release()
		return nil, fmt.Errorf("failed to get buffer size: %w", err)
	}

	var renderClient *wca.IAudioRenderClient
	if err := audioClient.GetService(wca.IID_IAudioRenderClient, &renderClient); err != nil {
		audioClient.Release()
		return nil, fmt.Errorf("failed to get render client: %w", err)
	}

	return &Player{
		client:       audioClient,
		renderClient: renderClient,
		waveFormat:   waveFormat,
		bufferSize:   bufferSize,
		volume:       1.0,
		muted:        false,
		stopChan:     make(chan struct{}),
		userBuffers:  make(map[uint16][]int16),
		userEQs:      make(map[uint16]*EQChain),
		userSettings: make(map[uint16]*UserSettings),
	}, nil
}

// Start begins audio playback
func (p *Player) Start() error {
	p.mu.Lock()
	if p.running {
		p.mu.Unlock()
		return nil
	}
	p.running = true
	p.stopChan = make(chan struct{})
	p.mu.Unlock()

	if err := p.client.Start(); err != nil {
		return fmt.Errorf("failed to start audio client: %w", err)
	}

	go p.playbackLoop()
	return nil
}

// Stop stops audio playback
func (p *Player) Stop() {
	p.mu.Lock()
	if !p.running {
		p.mu.Unlock()
		return
	}
	p.running = false
	p.mu.Unlock()

	close(p.stopChan)
	p.client.Stop()
}

// Close releases all resources
func (p *Player) Close() {
	p.Stop()
	if p.renderClient != nil {
		p.renderClient.Release()
	}
	if p.client != nil {
		p.client.Release()
	}
	ole.CoUninitialize()
}

// PlayPCM adds audio samples to a specific user's buffer
func (p *Player) PlayPCM(senderID uint16, samples []int16) {
	if p.muted {
		return
	}

	p.bufferMu.Lock()
	defer p.bufferMu.Unlock()

	// Check per-user mute
	if settings, ok := p.userSettings[senderID]; ok && settings.Muted {
		return
	}

	// Apply EQ Filters if gains are non-zero
	p.ensureEQ(senderID)

	// Check if any band has gain != 0
	hasActiveEQ := false
	if settings, ok := p.userSettings[senderID]; ok && len(settings.Gains) == 5 {
		for _, g := range settings.Gains {
			if g != 0 {
				hasActiveEQ = true
				break
			}
		}
	}

	// Apply filters if needed
	// Note: We should probably process always if we want smooth transitions,
	// but for optimization we skip if all 0.
	// However, skipping might cause clicks if we jump from filtered to non-filtered state abruptly.
	// For "Pro" audio, always process. For TUI app, let's process if active.
	if hasActiveEQ {
		if eq, ok := p.userEQs[senderID]; ok {
			// Update gains from settings
			// (Ideally we only do this on change, but doing it here ensures sync)
			gains := p.userSettings[senderID].Gains
			for i, g := range gains {
				eq.SetGain(i, g)
			}

			// Process in-place (conceptually) - actually implementation creates new slice
			samples = eq.Process(samples)
		}
	} else {
		// Even if not active, we might want to reset filters if they were active before?
		// Or just leave them alone.
	}

	// Calculate EQ bands for visualization
	// We do this BEFORE appending to buffer to ensure we have visual feedback even if buffer is full/lagging
	// This is a "fire and forget" calculation for UI
	bands := CalculateEQBands(samples, 48000)

	// Update user settings with new bands
	if _, ok := p.userSettings[senderID]; !ok {
		p.userSettings[senderID] = &UserSettings{Volume: 1.0, Muted: false}
	}
	p.userSettings[senderID].EQBands = bands

	// Append to user's specific buffer
	// This ensures sequential playback for the same user
	p.userBuffers[senderID] = append(p.userBuffers[senderID], samples...)

	// Limit buffer size per user to avoid memory leaks if stalled
	if len(p.userBuffers[senderID]) > 48000*2 { // 2 seconds max
		// Drop oldest
		drop := len(p.userBuffers[senderID]) - 48000
		p.userBuffers[senderID] = p.userBuffers[senderID][drop:]
	}
}

// SetVolume sets playback volume (0.0 to 1.0)
func (p *Player) SetVolume(vol float32) {
	if vol < 0 {
		vol = 0
	}
	if vol > 1.0 {
		vol = 1.0
	}
	p.mu.Lock()
	p.volume = vol
	p.mu.Unlock()
}

// GetVolume returns current volume (0.0 to 1.0)
func (p *Player) GetVolume() float32 {
	p.mu.Lock()
	defer p.mu.Unlock()
	return p.volume
}

// SetMuted sets mute state
func (p *Player) SetMuted(muted bool) {
	p.mu.Lock()
	p.muted = muted
	p.mu.Unlock()
}

func (p *Player) IsMuted() bool {
	p.mu.Lock()
	defer p.mu.Unlock()
	return p.muted
}

// SetUserVolume sets volume for a specific user (1.0 is default)
func (p *Player) SetUserVolume(clientID uint16, vol float32) {
	p.bufferMu.Lock()
	defer p.bufferMu.Unlock()

	if _, ok := p.userSettings[clientID]; !ok {
		p.userSettings[clientID] = &UserSettings{Volume: 1.0, Muted: false}
	}
	p.userSettings[clientID].Volume = vol
}

// SetUserMuted sets mute state for a specific user
func (p *Player) SetUserMuted(clientID uint16, muted bool) {
	p.bufferMu.Lock()
	defer p.bufferMu.Unlock()

	if _, ok := p.userSettings[clientID]; !ok {
		p.userSettings[clientID] = &UserSettings{Volume: 1.0, Muted: false}
	}
	p.userSettings[clientID].Muted = muted
}

// GetUserSettings gets current volume and mute state for user
func (p *Player) GetUserSettings(clientID uint16) (float32, bool) {
	p.bufferMu.Lock()
	defer p.bufferMu.Unlock()

	if settings, ok := p.userSettings[clientID]; ok {
		return settings.Volume, settings.Muted
	}
	return 1.0, false
}

// GetEQBands returns the current 5-band EQ values for a user (0.0-1.0)
func (p *Player) GetEQBands(clientID uint16) []float64 {
	p.bufferMu.Lock()
	defer p.bufferMu.Unlock()

	if settings, ok := p.userSettings[clientID]; ok {
		return settings.EQBands
	}
	return nil
}

// SetUserGain sets the EQ gain for a specific band (0-4) and user.
// Gain is in dB (e.g. -12.0 to +12.0)
func (p *Player) SetUserGain(clientID uint16, bandIdx int, gainDb float64) {
	p.bufferMu.Lock()
	defer p.bufferMu.Unlock()

	p.ensureUserSettings(clientID)

	// Ensure Gains slice exists
	if len(p.userSettings[clientID].Gains) != 5 {
		p.userSettings[clientID].Gains = make([]float64, 5)
	}

	if bandIdx >= 0 && bandIdx < 5 {
		p.userSettings[clientID].Gains[bandIdx] = gainDb
	}
}

// GetUserGain returns the gain for a band
func (p *Player) GetUserGain(clientID uint16, bandIdx int) float64 {
	p.bufferMu.Lock()
	defer p.bufferMu.Unlock()

	if settings, ok := p.userSettings[clientID]; ok {
		if len(settings.Gains) > bandIdx {
			return settings.Gains[bandIdx]
		}
	}
	return 0.0
}

func (p *Player) ensureUserSettings(clientID uint16) {
	if _, ok := p.userSettings[clientID]; !ok {
		p.userSettings[clientID] = &UserSettings{
			Volume: 1.0,
			Muted:  false,
			Gains:  make([]float64, 5),
		}
	}
}

func (p *Player) ensureEQ(clientID uint16) {
	if _, ok := p.userEQs[clientID]; !ok {
		// New EQ chain
		// Assume 48000 Hz, would be better to pass actual stream rate
		p.userEQs[clientID] = NewEQChain(48000)
	}
}

func (p *Player) playbackLoop() {
	ticker := time.NewTicker(10 * time.Millisecond)
	defer ticker.Stop()

	for {
		select {
		case <-p.stopChan:
			return
		case <-ticker.C:
			p.writeFrame()
		}
	}
}

func (p *Player) writeFrame() {
	for {
		var padding uint32
		if err := p.client.GetCurrentPadding(&padding); err != nil {
			return
		}

		available := p.bufferSize - padding
		if available < frameSamples {
			return
		}

		p.bufferMu.Lock()

		// Mix audio from all active user buffers
		mixed := make([]int32, frameSamples)
		activeUsers := 0
		hasAnyAudio := false

		for id, buf := range p.userBuffers {
			if len(buf) > 0 {
				hasAnyAudio = true
				activeUsers++
				// Take up to frameSamples from this user
				toTake := frameSamples
				if len(buf) < frameSamples {
					toTake = len(buf)
				}

				for i := 0; i < toTake; i++ {
					sample := int32(buf[i])

					// Apply user volume if set
					if settings, ok := p.userSettings[id]; ok {
						sample = int32(float32(sample) * settings.Volume)
					}

					mixed[i] += sample
				}

				// Advance buffer
				if len(buf) <= frameSamples {
					delete(p.userBuffers, id)
				} else {
					p.userBuffers[id] = buf[frameSamples:]
				}
			}
		}

		p.bufferMu.Unlock()

		// If no audio is playing, don't write anything (keep buffer empty for lower latency when audio starts)
		if !hasAnyAudio {
			return
		}

		// Get WASAPI buffer
		var buffer *byte
		if err := p.renderClient.GetBuffer(uint32(frameSamples), &buffer); err != nil {
			return
		}

		p.mu.Lock()
		vol := p.volume
		p.mu.Unlock()

		// Write mixed samples with clipping protection and volume application
		bufSlice := unsafe.Slice(buffer, int(frameSamples)*2)
		for i := 0; i < int(frameSamples); i++ {
			val := mixed[i]

			// Apply master volume
			val = int32(float32(val) * vol)

			// Hard clipping
			if val > 32767 {
				val = 32767
			} else if val < -32768 {
				val = -32768
			}
			binary.LittleEndian.PutUint16(bufSlice[i*2:], uint16(val))
		}

		p.renderClient.ReleaseBuffer(uint32(frameSamples), 0)
	}
}