NavidromeApp/Shared/Audio/AudioPlayer.swift

import Foundation
import AVFoundation
import Combine
import MediaPlayer
import Accelerate
import os
#if os(iOS)
import UIKit
#endif

/// Shared audio player with real FFT visualizer for local files
class AudioPlayer: NSObject, ObservableObject {
    
    static let shared = AudioPlayer()
    
    // MARK: - Published State
    @Published var currentSong: Song?
    @Published var queue: [Song] = []
    @Published var queueIndex: Int = 0
    @Published var isPlaying = false
    // currentTime and duration are NOT @Published — updating them 10x/sec
    // would cause every view with @EnvironmentObject audioPlayer to re-render,
    // killing gesture recognizers across the entire app.
    // Views that need these (NowPlayingView, MiniPlayerBar) poll them directly
    // via their own Timer/TimelineView.
    var currentTime: TimeInterval = 0
    var duration: TimeInterval = 0
    @Published var volume: Float = 0.8
    @Published var repeatMode: RepeatMode = .off
    @Published var shuffleEnabled = false
    // audioLevels is NOT @Published — avoids 60fps SwiftUI state thrashing
    // Visualizer pulls directly via AudioPlayer.shared.currentLevels()
    // No lock needed: writes happen on main thread (Timer callbacks),
    // reads happen from view body. A one-frame-stale read is imperceptible.
    nonisolated(unsafe) private var _audioLevels: [Float] = Array(repeating: 0, count: 30)
    
    /// Current visualizer levels (called from TimelineView body)
    func currentLevels() -> [Float] {
        _audioLevels
    }
    
    /// Write visualizer levels (called from timers/taps on main thread)
    private func setLevels(_ levels: [Float]) {
        _audioLevels = levels
    }
    
    @Published var isUsingRealFFT = false
    @Published var isUsingOfflineVis = false
    @Published var offlineVisProgress: Float = 0
    @Published var sourcePlaylistId: String?
    @Published var sourcePlaylistName: String?
    
    enum RepeatMode {
        case off, all, one
    }
    
    // MARK: - AVPlayer (for streaming)
    private var player: AVPlayer?
    private var playerItem: AVPlayerItem?
    private var timeObserver: Any?
    
    // MARK: - AVAudioEngine (for local files with FFT)
    private var audioEngine: AVAudioEngine?
    private var enginePlayerNode: AVAudioPlayerNode?
    private var engineTimeTimer: Timer?
    private var engineFile: AVAudioFile?
    private var engineStartFrame: AVAudioFramePosition = 0
    private var scheduleGeneration: Int = 0
    private var nowPlayingSyncTimer: Timer?
    
    #if os(iOS)
    /// When true, SmartCrossfadeManager owns playback instead of the local player/engine
    private var isUsingCrossfade = false
    #endif
    
    // MARK: - FFT (radix-2, vDSP_fft_zrip)
    private var fftSetup: FFTSetup?
    // Written from audio render thread, read from Timer on main thread.
    // No lock needed: stale FFT frame is imperceptible at 30fps.
    nonisolated(unsafe) private var rawFFTLevels: [Float] = Array(repeating: 0, count: 512)
    
    // MARK: - Level Simulation (for streams)
    private var levelTimer: Timer?
    private var targetLevels: [Float] = Array(repeating: 0, count: 30)
    private var internalLevels: [Float] = Array(repeating: 0, count: 30)
    private var publishCounter: Int = 0
    private var lastTargetPhase: Int = 0
    
    // MARK: - Offline Visualizer
    #if os(iOS)
    private var offlineVisFrames: [[Float]] = []
    private var offlineVisTimer: Timer?
    private var offlineVisFPS: Double = 30.0
    #endif
    
    // MARK: - Now Playing Artwork
    private var cachedArtwork: MPMediaItemArtwork?
    private var cachedArtworkCoverArtId: String?
    
    private var cancellables = Set<AnyCancellable>()
    
    // MARK: - Init
    
    private override init() {
        // Radix-2 FFT setup for 1024 samples (log2(1024) = 10)
        fftSetup = vDSP_create_fftsetup(10, Int32(kFFTRadix2))
        super.init()
        configureAudioSession()
        setupRemoteControls()
    }
    
    // MARK: - Audio Session
    
    private func alog(_ msg: String) {
        #if os(iOS)
        DebugLogger.shared.log(msg, category: "Audio")
        #else
        print("[Audio] \(msg)")
        #endif
    }
    
    private func configureAudioSession() {
        #if os(iOS)
        do {
            let session = AVAudioSession.sharedInstance()
            try session.setCategory(.playback, mode: .default, options: [])
        } catch {
            print("Audio session category failed: \(error)")
        }
        #elseif os(watchOS)
        do {
            let session = AVAudioSession.sharedInstance()
            try session.setCategory(.playback, mode: .default, policy: .longFormAudio)
        } catch {
            print("watchOS audio session category failed: \(error)")
        }
        #endif
    }
    
    private func activateAudioSession() {
        do {
            try AVAudioSession.sharedInstance().setActive(true)
        } catch {
            print("Audio session activation failed: \(error)")
        }
    }
    
    // MARK: - Playback Controls
    
    func play(song: Song, fromQueue: [Song]? = nil, at index: Int = 0, playlistId: String? = nil, playlistName: String? = nil) {
        if let q = fromQueue {
            queue = shuffleEnabled ? q.shuffled() : q
            queueIndex = index
            sourcePlaylistId = playlistId
            sourcePlaylistName = playlistName
            
            // Prefetch Smart DJ profiles for upcoming tracks
            #if os(iOS)
            if CompanionSettings.shared.smartDJEnabled {
                let upcoming = Array(queue.dropFirst(index).prefix(10))
                Task { await CompanionAPIService().prefetchProfiles(for: upcoming) }
            }
            #endif
        }
        
        currentSong = song
        alog("Playing: \(song.title) by \(song.artist ?? "Unknown")")
        
        // Stop radio buffer if switching from radio to music
        if isRadioStream {
            isRadioStream = false
            radioStreamURL = nil
            #if os(iOS)
            RadioStreamBuffer.shared.stopBuffering()
            isPlayingFromBuffer = false
            #endif
        }
        
        #if os(iOS)
        // Smart DJ Crossfade path — dual-AVPlayer engine handles everything
        let crossfade = SmartCrossfadeManager.shared
        if crossfade.isEnabled && CompanionSettings.shared.smartDJEnabled && !isRadioStream {
            if let url = crossfade.resolveURL(for: song) {
                stopAll()
                isUsingCrossfade = true
                
                // Wire callbacks
                crossfade.timeUpdate = { [weak self] time, dur in
                    self?.currentTime = time
                    self?.duration = dur
                }
                crossfade.needsNextTrack = { [weak self] in
                    self?.prepareNextForCrossfade()
                }
                
                crossfade.playSong(song, url: url)
                isPlaying = true
                
                // Set AudioPlayer.player to the active crossfade player
                // so Lock Screen controls and visualizer still work
                player = crossfade.activePlayer
                
                // Safety: if boundary observer doesn't fire (short track, bad profile),
                // this catches the natural end and advances normally
                NotificationCenter.default.removeObserver(self, name: .AVPlayerItemDidPlayToEndTime, object: nil)
                NotificationCenter.default.addObserver(
                    self, selector: #selector(playerDidFinish),
                    name: .AVPlayerItemDidPlayToEndTime, object: crossfade.activePlayer.currentItem
                )
                
                updateNowPlayingInfo()
                fetchAndSetArtwork(coverArtId: song.coverArt)
                startLevelSimulation()
                
                // Load offline visualizer for crossfade path too
                if VisualizerSettings.shared.realAudioAnalysis {
                    loadOfflineVisualizer(songId: song.id, url: url)
                }
                
                // Prepare next track in standby
                prepareNextForCrossfade()
                return
            }
        }
        isUsingCrossfade = false
        #endif
        
        // Check for offline version first
        if let localURL = OfflineManager.shared.localURL(for: song.id) {
            #if os(iOS)
            if VisualizerSettings.shared.realAudioAnalysis {
                // Use AVPlayer for reliable playback + offline vis for the visualizer
                playWithAVPlayer(localURL)
                loadOfflineVisualizer(songId: song.id, url: localURL)
            } else {
                playWithAVPlayer(localURL)
            }
            #else
            playWithAVPlayer(localURL)
            #endif
        } else {
            #if os(iOS)
            // Check prefetch cache — already downloaded in background
            if let prefetchURL = AudioPreFetcher.shared.prefetchedURL(for: song.id, suffix: song.suffix) {
                alog("Playing from prefetch cache")
                playWithAVPlayer(prefetchURL)
                if VisualizerSettings.shared.realAudioAnalysis {
                    loadOfflineVisualizer(songId: song.id, url: prefetchURL)
                }
            } else {
                let quality = StreamingQuality.shared
                let streamURL = ServerManager.shared.client.streamURL(
                    songId: song.id,
                    format: quality.format,
                    maxBitRate: quality.maxBitRate
                )
                if let url = streamURL {
                    playWithAVPlayer(url)
                }
            }
            #else
            let streamURL = ServerManager.shared.client.streamURL(
                songId: song.id,
                format: "mp3",
                maxBitRate: 192
            )
            if let url = streamURL {
                playWithAVPlayer(url)
            }
            #endif
        }
        
        // Scrobble
        Task {
            try? await ServerManager.shared.client.scrobble(id: song.id, submission: false)
        }
        
        // Pre-fetch next tracks for instant playback
        #if os(iOS)
        AudioPreFetcher.shared.prefetchUpcoming(queue: queue, currentIndex: queueIndex)
        #endif
    }
    
    /// Play a radio stream from a direct URL
    func playRadio(song: Song, streamURL: URL) {
        alog("Radio: \(song.title) → \(streamURL.absoluteString)")
        currentSong = song
        queue = [song]
        queueIndex = 0
        isRadioStream = true
        radioStreamURL = streamURL
        
        #if os(iOS)
        // Resolve playlist URLs (.pls, .m3u, .asx) to actual stream URLs, then play
        // Buffering is NOT started automatically — user taps LIVE to enable it
        if RadioStreamBuffer.isPlaylistURL(streamURL) {
            alog("Radio: resolving playlist URL...")
            Task {
                let resolved = await RadioStreamBuffer.resolveStreamURL(streamURL)
                await MainActor.run {
                    self.radioStreamURL = resolved
                    self.playWithAVPlayer(resolved)
                }
            }
        } else {
            playWithAVPlayer(streamURL)
        }
        #else
        playWithAVPlayer(streamURL)
        #endif
    }
    
    /// Whether current playback is a radio stream (for buffer/scrub behavior)
    @Published var isRadioStream = false
    private(set) var radioStreamURL: URL?
    
    #if os(iOS)
    /// Switch radio playback from live to buffered file for scrubbing
    private var isPlayingFromBuffer = false
    
    func radioSeekBack(to secondsFromStart: TimeInterval) {
        guard isRadioStream, let bufferURL = RadioStreamBuffer.shared.bufferPlaybackURL else { return }
        
        RadioStreamBuffer.shared.isLive = false
        
        // Guard: don't seek to exactly 0 — can break partial file reads
        let seekTime = max(0.1, secondsFromStart)
        
        if isPlayingFromBuffer {
            // Already on buffer — just seek within it
            let cmTime = CMTime(seconds: seekTime, preferredTimescale: 600)
            player?.seek(to: cmTime) { [weak self] _ in
                self?.player?.play()
            }
        } else {
            // First switch: swap AVPlayer to the buffer file
            isPlayingFromBuffer = true
            let asset = AVURLAsset(url: bufferURL)
            let item = AVPlayerItem(asset: asset)
            player?.replaceCurrentItem(with: item)
            
            let cmTime = CMTime(seconds: seekTime, preferredTimescale: 600)
            player?.seek(to: cmTime) { [weak self] _ in
                self?.player?.play()
            }
        }
    }
    
    /// Jump back to live radio
    func radioGoLive() {
        guard isRadioStream, let liveURL = radioStreamURL else { return }
        RadioStreamBuffer.shared.isLive = true
        isPlayingFromBuffer = false
        
        let asset = AVURLAsset(url: liveURL)
        let item = AVPlayerItem(asset: asset)
        player?.replaceCurrentItem(with: item)
        player?.play()
    }
    #endif
    
    #if os(iOS)
    /// Set now playing artwork from a UIImage (for radio station custom covers)
    func setNowPlayingArtwork(image: UIImage) {
        let artwork = MPMediaItemArtwork(boundsSize: image.size) { _ in image }
        cachedArtwork = artwork
        cachedArtworkCoverArtId = currentSong?.id
        updateNowPlayingInfo()
    }
    #endif
    
    // MARK: - AVPlayer Path (streams + fallback)
    
    private func playWithAVPlayer(_ url: URL) {
        alog("AVPlayer path: \(url.scheme ?? "file")://...\(url.lastPathComponent)")
        stopAll()
        
        // Reset audio session to pure playback (fixes radio→music conflict)
        do {
            try AVAudioSession.sharedInstance().setCategory(.playback, mode: .default, options: [])
            try AVAudioSession.sharedInstance().setActive(true)
        } catch {
            print("Audio session reset failed: \(error)")
        }
        
        isUsingRealFFT = false
        
        let asset = AVURLAsset(url: url)
        playerItem = AVPlayerItem(asset: asset)
        
        if player == nil {
            player = AVPlayer(playerItem: playerItem)
        } else {
            player?.replaceCurrentItem(with: playerItem)
        }
        
        player?.volume = volume
        player?.play()
        isPlaying = true
        
        // Time observer
        let interval = CMTime(seconds: 0.1, preferredTimescale: 600)
        timeObserver = player?.addPeriodicTimeObserver(forInterval: interval, queue: .main) { [weak self] time in
            guard let self = self else { return }
            self.currentTime = time.seconds
            if let dur = self.playerItem?.duration.seconds, !dur.isNaN {
                self.duration = dur
            }
        }
        
        // Periodic Now Playing info sync (keeps Dynamic Island/Lock Screen in sync)
        nowPlayingSyncTimer?.invalidate()
        nowPlayingSyncTimer = Timer.scheduledTimer(withTimeInterval: 5.0, repeats: true) { [weak self] _ in
            guard let self = self, self.isPlaying else { return }
            self.updateNowPlayingInfo()
        }
        
        NotificationCenter.default.removeObserver(self, name: .AVPlayerItemDidPlayToEndTime, object: nil)
        NotificationCenter.default.addObserver(self, selector: #selector(playerDidFinish), name: .AVPlayerItemDidPlayToEndTime, object: playerItem)
        
        updateNowPlayingInfo()
        fetchAndSetArtwork(coverArtId: currentSong?.coverArt)
        startLevelSimulation()
    }
    
    // MARK: - AVAudioEngine Path (local files with real FFT)
    
    private func playLocalWithEngine(_ url: URL) {
        #if os(iOS)
        alog("Engine path: \(url.lastPathComponent)")
        activateAudioSession()
        stopAll()
        
        isUsingRealFFT = true
        
        do {
            let file = try AVAudioFile(forReading: url)
            engineFile = file
            
            let engine = AVAudioEngine()
            let playerNode = AVAudioPlayerNode()
            
            engine.attach(playerNode)
            engine.connect(playerNode, to: engine.mainMixerNode, format: file.processingFormat)
            
            // Install FFT tap on the mixer output
            let format = engine.mainMixerNode.outputFormat(forBus: 0)
            engine.mainMixerNode.installTap(onBus: 0, bufferSize: 1024, format: format) { [weak self] buffer, _ in
                self?.processFFT(buffer: buffer)
            }
            
            try engine.start()
            
            // Schedule file and play
            scheduleGeneration += 1
            let gen = scheduleGeneration
            playerNode.scheduleFile(file, at: nil) { [weak self] in
                DispatchQueue.main.async {
                    guard let self = self, self.scheduleGeneration == gen else { return }
                    self.playerDidFinishEngine()
                }
            }
            playerNode.play()
            
            self.audioEngine = engine
            self.enginePlayerNode = playerNode
            self.engineStartFrame = 0
            isPlaying = true
            
            // Duration from file
            duration = Double(file.length) / file.processingFormat.sampleRate
            
            // Time tracking for engine (accounts for seek offset)
            engineTimeTimer = Timer.scheduledTimer(withTimeInterval: 0.1, repeats: true) { [weak self] _ in
                guard let self = self, let node = self.enginePlayerNode,
                      let file = self.engineFile,
                      let nodeTime = node.lastRenderTime,
                      let playerTime = node.playerTime(forNodeTime: nodeTime) else { return }
                let sampleRate = file.processingFormat.sampleRate
                let offsetSeconds = Double(self.engineStartFrame) / sampleRate
                self.currentTime = offsetSeconds + Double(playerTime.sampleTime) / playerTime.sampleRate
            }
            
            // Publish FFT levels at ~30fps (smoothing already applied in processFFT)
            levelTimer = Timer.scheduledTimer(withTimeInterval: 1.0/30.0, repeats: true) { [weak self] _ in
                guard let self = self else { return }
                let levels = self.rawFFTLevels
                self.setLevels(levels)
            }
            
            updateNowPlayingInfo()
            fetchAndSetArtwork(coverArtId: currentSong?.coverArt)
            
        } catch {
            alog("Engine failed: \(error.localizedDescription), falling back to AVPlayer")
            playWithAVPlayer(url)
        }
        #endif
    }
    
    // MARK: - FFT Processing
    
    #if os(iOS)
    private func processFFT(buffer: AVAudioPCMBuffer) {
        guard let fftSetup = fftSetup else { return }
        guard let channelData = buffer.floatChannelData?[0] else { return }
        
        let frameCount = buffer.frameLength
        let fftSize: vDSP_Length = 1024
        let log2n: vDSP_Length = 10
        guard frameCount >= fftSize else { return }
        
        let halfSize = Int(fftSize / 2)
        
        // 1. Hann window
        var windowed = [Float](repeating: 0, count: Int(fftSize))
        var window = [Float](repeating: 0, count: Int(fftSize))
        vDSP_hann_window(&window, fftSize, Int32(vDSP_HANN_NORM))
        vDSP_vmul(channelData, 1, window, 1, &windowed, 1, fftSize)
        
        // 2-3. FFT with safe pointers
        var realp = [Float](repeating: 0, count: halfSize)
        var imagp = [Float](repeating: 0, count: halfSize)
        var magnitudes = [Float](repeating: 0, count: halfSize)
        
        realp.withUnsafeMutableBufferPointer { realpBuf in
            imagp.withUnsafeMutableBufferPointer { imagpBuf in
                var splitComplex = DSPSplitComplex(
                    realp: realpBuf.baseAddress!,
                    imagp: imagpBuf.baseAddress!
                )
                
                windowed.withUnsafeBytes { rawBuffer in
                    let complexPtr = rawBuffer.bindMemory(to: DSPComplex.self).baseAddress!
                    vDSP_ctoz(complexPtr, 2, &splitComplex, 1, vDSP_Length(halfSize))
                }
                
                vDSP_fft_zrip(fftSetup, &splitComplex, 1, log2n, FFTDirection(FFT_FORWARD))
                vDSP_zvmags(&splitComplex, 1, &magnitudes, 1, vDSP_Length(halfSize))
            }
        }
        
        // 4. Normalize by N² and take sqrt for amplitude
        let fftSizeF = Float(fftSize)
        var scale: Float = 1.0 / (fftSizeF * fftSizeF)
        vDSP_vsmul(magnitudes, 1, &scale, &magnitudes, 1, vDSP_Length(halfSize))
        
        // sqrt for perceptual scaling
        for i in 0..<halfSize {
            magnitudes[i] = sqrt(magnitudes[i])
        }
        
        // 5. Push raw 512-bin magnitudes — visualizer handles binning & smoothing
        let finalMagnitudes = magnitudes
        rawFFTLevels = finalMagnitudes
    }
    #endif
    
    // MARK: - Engine Finish
    
    private func playerDidFinishEngine() {
        if repeatMode == .one, let file = engineFile, let node = enginePlayerNode {
            node.stop()
            node.scheduleFile(file, at: nil) { [weak self] in
                DispatchQueue.main.async { self?.playerDidFinishEngine() }
            }
            node.play()
        } else {
            next()
        }
    }
    
    // MARK: - Transport
    
    func togglePlayPause() {
        if isPlaying {
            pause()
        } else {
            resume()
        }
    }
    
    func pause() {
        #if os(iOS)
        if isUsingCrossfade {
            SmartCrossfadeManager.shared.pause()
            isPlaying = false
            stopOfflineVisTimer()
            updateNowPlayingInfo()
            return
        }
        #endif
        // Always pause both — only one is active, pausing nil is a no-op
        player?.pause()
        enginePlayerNode?.pause()
        isPlaying = false
        #if os(iOS)
        stopOfflineVisTimer()
        #endif
        updateNowPlayingInfo()
    }
    
    func resume() {
        #if os(iOS)
        if isUsingCrossfade {
            SmartCrossfadeManager.shared.resume()
            isPlaying = true
            updateNowPlayingInfo()
            return
        }
        #endif
        // Resume whichever player path is active
        if isUsingRealFFT, !isUsingOfflineVis, let node = enginePlayerNode {
            // Engine path (real-time FFT on local file without offline vis)
            node.play()
        } else {
            // AVPlayer path (streams, downloads with offline vis, everything else)
            player?.play()
        }
        isPlaying = true
        #if os(iOS)
        if isUsingOfflineVis {
            startOfflineVisSync()
        }
        #endif
        updateNowPlayingInfo()
    }
    
    func next() {
        guard !queue.isEmpty else { return }
        if repeatMode == .all {
            queueIndex = (queueIndex + 1) % queue.count
        } else {
            queueIndex = min(queueIndex + 1, queue.count - 1)
        }
        play(song: queue[queueIndex])
    }
    
    func previous() {
        if currentTime > 3 {
            seek(to: 0)
        } else {
            queueIndex = max(queueIndex - 1, 0)
            play(song: queue[queueIndex])
        }
    }
    
    #if os(iOS)
    /// Loads the next queue track into the crossfade standby player.
    /// If no next track exists, SmartCrossfadeManager will self-crossfade.
    private func prepareNextForCrossfade() {
        let crossfade = SmartCrossfadeManager.shared
        guard crossfade.isEnabled, !queue.isEmpty else { return }
        
        // Always wire the callback first
        crossfade.needsNextTrack = { [weak self] in
            guard let self = self else { return }
            
            // Check if there's actually a next track to advance to
            let hasNext: Bool
            if self.repeatMode == .all {
                hasNext = true
            } else {
                hasNext = self.queueIndex + 1 < self.queue.count
            }
            
            if hasNext {
                // Advance queue
                if self.repeatMode == .all {
                    self.queueIndex = (self.queueIndex + 1) % self.queue.count
                } else {
                    self.queueIndex = min(self.queueIndex + 1, self.queue.count - 1)
                }
                self.currentSong = self.queue[self.queueIndex]
            }
            // else: self-crossfade — keep same song, don't advance
            
            self.player = crossfade.activePlayer
            self.updateNowPlayingInfo()
            self.fetchAndSetArtwork(coverArtId: self.currentSong?.coverArt)
            
            // Prepare the NEXT next track (or self-crossfade again)
            self.prepareNextForCrossfade()
        }
        
        // Now check if there's actually a next track to prepare
        let nextIdx: Int
        if repeatMode == .all {
            nextIdx = (queueIndex + 1) % queue.count
        } else {
            nextIdx = queueIndex + 1
            guard nextIdx < queue.count else {
                // No next track — SmartCrossfadeManager will self-crossfade
                alog("SmartDJ: no next track — will self-crossfade")
                return
            }
        }
        
        let nextSong = queue[nextIdx]
        guard let url = crossfade.resolveURL(for: nextSong) else { return }
        
        alog("SmartDJ: preparing \(nextSong.title) in standby")
        crossfade.prepareNext(nextSong, url: url)
    }
    #endif
    
    func seek(to time: TimeInterval) {
        #if os(iOS)
        if isUsingCrossfade {
            SmartCrossfadeManager.shared.seek(to: time)
            currentTime = time
            updateNowPlayingInfo()
            return
        }
        #endif
        let wasPaused = !isPlaying
        
        if let node = enginePlayerNode, let file = engineFile, let engine = audioEngine {
            let sampleRate = file.processingFormat.sampleRate
            let startFrame = AVAudioFramePosition(time * sampleRate)
            let totalFrames = file.length
            guard startFrame >= 0, startFrame < totalFrames else { return }
            let remainingFrames = AVAudioFrameCount(totalFrames - startFrame)
            
            scheduleGeneration += 1
            let gen = scheduleGeneration
            node.stop()
            
            node.scheduleSegment(file, startingFrame: startFrame, frameCount: remainingFrames, at: nil) { [weak self] in
                DispatchQueue.main.async {
                    guard let self = self, self.scheduleGeneration == gen else { return }
                    self.playerDidFinishEngine()
                }
            }
            
            if engine.isRunning {
                node.play()
                // If we were paused, immediately pause again (we only played to set position)
                if wasPaused {
                    node.pause()
                }
            }
            
            currentTime = time
            engineStartFrame = startFrame
            updateNowPlayingInfo()
        } else {
            currentTime = time // Update immediately for responsive UI
            let cmTime = CMTime(seconds: time, preferredTimescale: 600)
            player?.seek(to: cmTime) { [weak self] finished in
                guard let self = self, finished else { return }
                if wasPaused {
                    self.player?.pause()
                }
                self.updateNowPlayingInfo()
            }
        }
    }
    
    func seekToPercent(_ pct: Double) {
        seek(to: duration * pct)
    }
    
    func toggleShuffle() { shuffleEnabled.toggle() }
    
    func cycleRepeat() {
        switch repeatMode {
        case .off: repeatMode = .all
        case .all: repeatMode = .one
        case .one: repeatMode = .off
        }
    }
    
    // MARK: - Queue Management
    
    func playNext(_ song: Song) {
        let insertAt = queueIndex + 1
        if insertAt <= queue.count {
            queue.insert(song, at: insertAt)
        } else {
            queue.append(song)
        }
    }
    
    func playLater(_ song: Song) {
        queue.append(song)
    }
    
    func playNow(_ song: Song) {
        queue.insert(song, at: queueIndex + 1)
        queueIndex += 1
        play(song: song)
    }
    
    func playInstantMix(basedOn song: Song) {
        Task {
            let similar = try? await ServerManager.shared.client.getSimilarSongs2(id: song.id, count: 50)
            if let songs = similar, !songs.isEmpty {
                await MainActor.run {
                    self.play(song: songs[0], fromQueue: songs)
                }
            }
        }
    }
    
    @objc private func playerDidFinish() {
        if let song = currentSong {
            Task { try? await ServerManager.shared.client.scrobble(id: song.id) }
        }
        
        if repeatMode == .one {
            seek(to: 0)
            player?.play()
        } else {
            next()
        }
    }
    
    // MARK: - Now Playing Info Center
    
    private func updateNowPlayingInfo() {
        #if os(iOS)
        var info: [String: Any] = [:]
        info[MPMediaItemPropertyTitle] = currentSong?.title ?? "Unknown"
        info[MPMediaItemPropertyArtist] = currentSong?.artist ?? "Unknown"
        info[MPMediaItemPropertyAlbumTitle] = currentSong?.album ?? ""
        info[MPNowPlayingInfoPropertyElapsedPlaybackTime] = currentTime
        info[MPMediaItemPropertyPlaybackDuration] = duration
        info[MPNowPlayingInfoPropertyPlaybackRate] = isPlaying ? 1.0 : 0.0
        if let artwork = cachedArtwork {
            info[MPMediaItemPropertyArtwork] = artwork
        }
        MPNowPlayingInfoCenter.default().nowPlayingInfo = info
        #endif
    }
    
    private func fetchAndSetArtwork(coverArtId: String?) {
        #if os(iOS)
        guard let id = coverArtId else { return }
        if id == cachedArtworkCoverArtId, cachedArtwork != nil { return }
        
        // Check user-set custom cover first
        if let customImage = AlbumCoverStore.shared.loadCover(for: id) {
            let artwork = MPMediaItemArtwork(boundsSize: customImage.size) { _ in customImage }
            self.cachedArtwork = artwork
            self.cachedArtworkCoverArtId = id
            self.updateNowPlayingInfo()
            return
        }
        
        guard let url = ServerManager.shared.client.coverArtURL(id: id, size: 600) else { return }
        
        if let cached = ImageCache.shared.cachedImage(for: url) {
            let artwork = MPMediaItemArtwork(boundsSize: cached.size) { _ in cached }
            self.cachedArtwork = artwork
            self.cachedArtworkCoverArtId = id
            self.updateNowPlayingInfo()
            return
        }
        
        Task {
            do {
                let (data, _) = try await URLSession.shared.data(from: url)
                guard let image = UIImage(data: data) else { return }
                ImageCache.shared.store(image, for: url)
                let artwork = MPMediaItemArtwork(boundsSize: image.size) { _ in image }
                await MainActor.run {
                    self.cachedArtwork = artwork
                    self.cachedArtworkCoverArtId = id
                    self.updateNowPlayingInfo()
                }
            } catch { }
        }
        #endif
    }
    
    private func setupRemoteControls() {
        #if os(iOS) || os(watchOS)
        let center = MPRemoteCommandCenter.shared()
        center.playCommand.addTarget { [weak self] _ in self?.resume(); return .success }
        center.pauseCommand.addTarget { [weak self] _ in self?.pause(); return .success }
        center.togglePlayPauseCommand.addTarget { [weak self] _ in self?.togglePlayPause(); return .success }
        center.nextTrackCommand.addTarget { [weak self] _ in self?.next(); return .success }
        center.previousTrackCommand.addTarget { [weak self] _ in
            self?.previous()
            return .success
        }
        center.changePlaybackPositionCommand.addTarget { [weak self] event in
            guard let posEvent = event as? MPChangePlaybackPositionCommandEvent else { return .commandFailed }
            self?.seek(to: posEvent.positionTime)
            return .success
        }
        #endif
    }
    
    // MARK: - Offline Visualizer Pipeline
    
    #if os(iOS)
    /// Load or generate cached visualizer data for a downloaded song
    private func loadOfflineVisualizer(songId: String, url: URL) {
        stopOfflineVisTimer()
        isUsingOfflineVis = false
        offlineVisProgress = 0
        offlineVisFPS = VisualizerSettings.shared.effectiveFPS
        let points = VisualizerSettings.shared.numberOfPoints
        let cutoff = VisualizerSettings.shared.frequencyCutoff
        
        Task {
            let storage = VisualizerStorageManager.shared
            let hasCache = await storage.hasCache(for: songId)
            
            if hasCache {
                alog("Offline vis: loading cache for \(songId)")
                if let frames = try? await storage.loadCache(for: songId) {
                    let normalized = Self.normalizeVisFrames(frames)
                    await MainActor.run {
                        self.offlineVisFrames = normalized
                        self.isUsingOfflineVis = true
                        self.isUsingRealFFT = true
                        self.offlineVisProgress = 1.0
                        self.startOfflineVisSync()
                    }
                }
            } else {
                // Try Companion API first (pre-computed server frames)
                var fetched = false
                if CompanionSettings.shared.isEnabled, let path = self.currentSong?.path {
                    do {
                        if let serverFrames = try await CompanionAPIService().fetchVisualizerFrames(relativePath: path) {
                            let normalized = Self.normalizeVisFrames(serverFrames)
                            try? await storage.saveCache(frames: serverFrames, for: songId)
                            alog("Offline vis: fetched \(serverFrames.count) frames from server")
                            await MainActor.run {
                                self.offlineVisFrames = normalized
                                self.isUsingOfflineVis = true
                                self.isUsingRealFFT = true
                                self.offlineVisProgress = 1.0
                                self.startOfflineVisSync()
                            }
                            fetched = true
                        }
                    } catch {
                        alog("Offline vis: server fetch failed, will analyze locally")
                    }
                }
                
                if !fetched {
                alog("Offline vis: analyzing \(songId)...")
                do {
                    let frames = try await OfflineAudioAnalyzer.shared.analyze(
                        url: url,
                        pointsCount: points,
                        fps: offlineVisFPS,
                        cutoff: cutoff
                    ) { [weak self] pct in
                        Task { @MainActor in
                            self?.offlineVisProgress = pct
                        }
                    }
                    
                    try? await storage.saveCache(frames: frames, for: songId)
                    let normalized = Self.normalizeVisFrames(frames)
                    alog("Offline vis: cached \(frames.count) frames for \(songId)")
                    
                    await MainActor.run {
                        self.offlineVisFrames = normalized
                        self.isUsingOfflineVis = true
                        self.isUsingRealFFT = true
                        self.offlineVisProgress = 1.0
                        self.startOfflineVisSync()
                    }
                } catch {
                    alog("Offline vis: analysis failed: \(error.localizedDescription)")
                    await MainActor.run {
                        self.startLevelSimulation()
                    }
                }
                } // end if !fetched
            }
        }
    }
    
    /// Normalize vis frames so the wave is always visible regardless of song loudness.
    /// Maps the 95th percentile peak to 0.8, preserving dynamics without clipping.
    private static func normalizeVisFrames(_ frames: [[Float]]) -> [[Float]] {
        guard !frames.isEmpty else { return frames }
        
        // Collect all non-zero values to find the peak
        var allValues: [Float] = []
        allValues.reserveCapacity(frames.count * (frames.first?.count ?? 20))
        for frame in frames {
            for v in frame where v > 0.001 {
                allValues.append(v)
            }
        }
        
        guard !allValues.isEmpty else { return frames }
        
        // Use 95th percentile instead of absolute max to avoid outlier spikes
        allValues.sort()
        let p95Index = min(Int(Float(allValues.count) * 0.95), allValues.count - 1)
        let p95 = allValues[p95Index]
        
        guard p95 > 0.001 else { return frames }
        
        let scale = 0.8 / p95
        
        return frames.map { frame in
            frame.map { min(1.0, $0 * scale) }
        }
    }
    
    /// Sync cached frames to current playback time.
    /// Uses proportional mapping (time/duration → frame index) so it works
    /// regardless of what FPS the frames were analyzed at.
    private func startOfflineVisSync() {
        stopOfflineVisTimer()
        stopLevelTimer()
        
        let frameCount = offlineVisFrames.count
        alog("Offline vis sync: \(frameCount) frames, duration=\(String(format: "%.1f", duration))s")
        
        // Wait briefly for duration to become available if it's still 0
        if duration <= 0 {
            DispatchQueue.main.asyncAfter(deadline: .now() + 0.5) { [weak self] in
                self?.startOfflineVisSyncTimer()
            }
        } else {
            startOfflineVisSyncTimer()
        }
    }
    
    private func startOfflineVisSyncTimer() {
        stopOfflineVisTimer()
        
        offlineVisTimer = Timer.scheduledTimer(withTimeInterval: 1.0 / 30.0, repeats: true) { [weak self] _ in
            guard let self = self, self.isUsingOfflineVis, self.isPlaying else { return }
            let frames = self.offlineVisFrames
            guard !frames.isEmpty else { return }
            
            let dur = self.duration
            let time = self.currentTime
            
            // Map playback position to frame index proportionally
            let frameIndex: Int
            if dur > 0 {
                let pct = min(time / dur, 1.0)
                frameIndex = min(Int(pct * Double(frames.count)), frames.count - 1)
            } else {
                // Duration still unknown — estimate at 30fps
                frameIndex = min(Int(time * 30.0), frames.count - 1)
            }
            
            if frameIndex >= 0, frameIndex < frames.count {
                self.setLevels(frames[frameIndex])
            }
        }
    }
    
    private func stopOfflineVisTimer() {
        offlineVisTimer?.invalidate()
        offlineVisTimer = nil
    }
    #endif
    
    // MARK: - Simulated Level Animation (for streams)
    
    private func startLevelSimulation() {
        stopLevelTimer()
        levelTimer = Timer.scheduledTimer(withTimeInterval: 1.0/60.0, repeats: true) { [weak self] _ in
            guard let self = self, self.isPlaying else {
                if self?.internalLevels.contains(where: { $0 > 0.01 }) == true {
                    self?.internalLevels = Array(repeating: 0, count: 30)
                    self?.setLevels(self?.internalLevels ?? [])
                }
                return
            }
            
            let time = self.currentTime
            let phase = Int(time * 12)
            if phase != self.lastTargetPhase {
                self.lastTargetPhase = phase
                self.targetLevels = (0..<30).map { _ in
                    Float.random(in: 0.1...0.85)
                }
            }
            
            let smoothing: Float = 0.15
            self.internalLevels = zip(self.internalLevels, self.targetLevels).map { current, target in
                current + (target - current) * smoothing
            }
            
            self.publishCounter += 1
            if self.publishCounter % 2 == 0 {
                self.setLevels(self.internalLevels)
            }
        }
    }
    
    // MARK: - Cleanup
    
    private func stopLevelTimer() {
        levelTimer?.invalidate()
        levelTimer = nil
    }
    
    private func stopEngineTimer() {
        engineTimeTimer?.invalidate()
        engineTimeTimer = nil
    }
    
    private func stopEngine() {
        scheduleGeneration += 1 // invalidate all pending completions
        enginePlayerNode?.stop()
        audioEngine?.mainMixerNode.removeTap(onBus: 0)
        audioEngine?.stop()
        audioEngine = nil
        enginePlayerNode = nil
        engineFile = nil
        stopEngineTimer()
    }
    
    private func stopAVPlayer() {
        player?.pause()
        player?.replaceCurrentItem(with: nil)
        if let observer = timeObserver {
            player?.removeTimeObserver(observer)
            timeObserver = nil
        }
        playerItem = nil
    }
    
    /// Stop everything — called before starting new playback
    private func stopAll() {
        stopLevelTimer()
        nowPlayingSyncTimer?.invalidate()
        nowPlayingSyncTimer = nil
        #if os(iOS)
        stopOfflineVisTimer()
        if isUsingCrossfade {
            SmartCrossfadeManager.shared.stop()
            isUsingCrossfade = false
        }
        #endif
        stopEngine()
        stopAVPlayer()
        NotificationCenter.default.removeObserver(self, name: .AVPlayerItemDidPlayToEndTime, object: nil)
    }
    
    func stop() {
        stopAll()
        isPlaying = false
        currentSong = nil
        setLevels(Array(repeating: 0, count: 30))
        internalLevels = Array(repeating: 0, count: 30)
        rawFFTLevels = Array(repeating: 0, count: 512)
        isUsingRealFFT = false
        isUsingOfflineVis = false
        #if os(iOS)
        offlineVisFrames = []
        #endif
        if isRadioStream {
            isRadioStream = false
            radioStreamURL = nil
            #if os(iOS)
            RadioStreamBuffer.shared.stopBuffering()
            isPlayingFromBuffer = false
            #endif
        }
    }
    
    deinit {
        if let setup = fftSetup {
            vDSP_destroy_fftsetup(setup)
        }
        stop()
    }
}