import SwiftUI
import AVFoundation
import Combine
#if os(macOS)
import AppKit
#endif

/// 播放队列项
struct MediaItem: Identifiable, Equatable {
    let id: String
    var url: URL
    var name: String
    var mediaType: String
    static func == (lhs: MediaItem, rhs: MediaItem) -> Bool { lhs.id == rhs.id }
}

/// 循环模式
enum RepeatMode: String, CaseIterable {
    case none = "不循环"
    case single = "单曲循环"
    case all = "列表循环"
    
    var icon: String {
        switch self {
        case .none: return "➡️"
        case .single: return "🔂"
        case .all: return "🔁"
        }
    }
    
    var next: RepeatMode {
        switch self {
        case .none: return .single
        case .single: return .all
        case .all: return .none
        }
    }
}

@MainActor
final class PlayerBridge: ObservableObject {
    
    // MARK: - Published状态
    @Published var showURLDialog = false
    @Published var showTrackDialog = false
    @Published var toastMessage: String?
    @Published var availableTracks: [String] = []
    @Published var currentTrackIndex: Int = 0
    @Published var isFullscreen = false
    @Published var showToolbar = false
    @Published var isPlaying = false
    @Published var currentTimeText = "00:00"
    @Published var totalTimeText = "00:00"
    @Published var currentTrackLabel = "🎵 Track 1"
    @Published var volume: Float = 1.0
    @Published var progressRatio: Double = 0
    @Published var cachedDuration: Double = 0
    @Published var queue: [MediaItem] = []
    @Published var currentIndex: Int = -1
    @Published var repeatMode: RepeatMode = .all
    
    // MARK: - 内部状态
    let player = AVPlayer()
    private var timeObserver: Any?
    private var itemStatusObserver: NSKeyValueObservation?
    private var cancellables = Set<AnyCancellable>()
    private var preferredTrackIndex: Int = 0
    
    #if os(macOS)
    private var fullscreenWindow: NSWindow?
    private var playlistWindow: NSWindow?
    #endif
    
    // MARK: - 初始化
    func setup() {
        player.volume = volume
        
        setupTimeObserver()
        setupPlaybackStatusObserver()
        setupEndObserver()
    }
    
    // MARK: - 播放控制
    func togglePlayPause() {
        if player.timeControlStatus == .playing {
            player.pause()
            isPlaying = false
        } else {
            player.play()
            isPlaying = true
        }
    }
    
    func playPrev() {
        guard !queue.isEmpty else { return }
        let idx = (currentIndex - 1 + queue.count) % queue.count
        playIndex(idx)
    }
    
    func playNext() {
        guard !queue.isEmpty else { return }
        switch repeatMode {
        case .none:
            if currentIndex < queue.count - 1 { playIndex(currentIndex + 1) }
        case .single:
            player.seek(to: .zero); player.play()
        case .all:
            playIndex((currentIndex + 1) % queue.count)
        }
    }
    
    func playIndex(_ index: Int) {
        guard index >= 0 && index < queue.count else { return }
        currentIndex = index
        let item = queue[index]
        
        let playerItem = AVPlayerItem(url: item.url)
        player.replaceCurrentItem(with: playerItem)
        player.play()
        isPlaying = true
        
        cachedDuration = 0
        progressRatio = 0
        currentTimeText = "00:00"
        totalTimeText = "00:00"
        
        itemStatusObserver = playerItem.observe(\.status, options: [.new]) { [weak self] pi, _ in
            if pi.status == .readyToPlay {
                Task { @MainActor in self?.loadDuration(pi) }
            }
        }
        
        loadTrackInfo(playerItem)
        showToast("正在播放: \(item.name)")
    }
    
    // MARK: - 播放结束
    private func setupEndObserver() {
        NotificationCenter.default.addObserver(
            forName: .AVPlayerItemDidPlayToEndTime, object: nil, queue: .main
        ) { [weak self] _ in
            Task { @MainActor in self?.onPlaybackEnded() }
        }
    }
    
    private func onPlaybackEnded() {
        switch repeatMode {
        case .none:
            if currentIndex < queue.count - 1 { playNext() } else { isPlaying = false }
        case .single:
            player.seek(to: .zero); player.play()
        case .all:
            playNext()
        }
    }
    
    // MARK: - 时间更新
    private func setupTimeObserver() {
        let interval = CMTime(seconds: 0.5, preferredTimescale: 600)
        timeObserver = player.addPeriodicTimeObserver(forInterval: interval, queue: .main) { [weak self] time in
            Task { @MainActor in self?.updateTimeDisplay(time: time) }
        }
    }
    
    private func updateTimeDisplay(time: CMTime) {
        let current = time.seconds
        var total = player.currentItem?.duration.seconds ?? 0
        
        if !total.isFinite || total <= 0 { total = cachedDuration }
        else { cachedDuration = total }
        
        currentTimeText = formatTime(current)
        if total.isFinite && total > 0 {
            totalTimeText = formatTime(total)
            progressRatio = max(0, min(1, current / total))
        }
    }
    
    private func loadDuration(_ item: AVPlayerItem) {
        Task {
            if let dur = try? await item.asset.load(.duration) {
                let secs = dur.seconds
                if secs.isFinite && secs > 0 {
                    cachedDuration = secs
                    totalTimeText = formatTime(secs)
                }
            }
        }
    }
    
    private func formatTime(_ seconds: Double) -> String {
        guard seconds.isFinite && seconds >= 0 else { return "00:00" }
        let h = Int(seconds) / 3600
        let m = (Int(seconds) % 3600) / 60
        let s = Int(seconds) % 60
        if h > 0 { return String(format: "%d:%02d:%02d", h, m, s) }
        return String(format: "%02d:%02d", m, s)
    }
    
    // MARK: - 音量
    func adjustVolume(by delta: Float) {
        volume = max(0, min(1, volume + delta))
        player.volume = volume
    }
    
    func setVolume(_ val: Float) {
        volume = max(0, min(1, val))
        player.volume = volume
    }
    
    // MARK: - 音轨
    private func loadTrackInfo(_ item: AVPlayerItem) {
        Task {
            guard let group = try? await item.asset.loadMediaSelectionGroup(for: .audible) else {
                availableTracks = ["Track 1"]
                currentTrackIndex = 0
                updateTrackLabel()
                return
            }
            let options = group.options
            availableTracks = options.enumerated().map { idx, _ in "Track \(idx + 1)" }
            var targetIndex = preferredTrackIndex
            if targetIndex >= options.count { targetIndex = 0 }
            item.select(options[targetIndex], in: group)
            currentTrackIndex = targetIndex
            updateTrackLabel()
        }
    }
    
    func selectTrack(index: Int) {
        guard let item = player.currentItem else { return }
        Task {
            guard let group = try? await item.asset.loadMediaSelectionGroup(for: .audible),
                  index < group.options.count else { return }
            item.select(group.options[index], in: group)
            currentTrackIndex = index
            preferredTrackIndex = index
            updateTrackLabel()
        }
    }
    
    private func updateTrackLabel() {
        currentTrackLabel = "🎵 Track \(currentTrackIndex + 1)/\(max(availableTracks.count, 1))"
    }
    
    // MARK: - 循环模式
    func cycleRepeatMode() {
        repeatMode = repeatMode.next
        showToast("循环模式: \(repeatMode.rawValue)")
    }
    
    // MARK: - 全屏（视频内容全屏，非窗口全屏）
    func toggleFullscreen() {
        #if os(macOS)
        if let fw = fullscreenWindow {
            fw.close()
            fullscreenWindow = nil
            isFullscreen = false
            NSApp.activate(ignoringOtherApps: true)
            return
        }
        
        guard let screen = NSScreen.main else { return }
        let win = NSWindow(contentRect: screen.frame, styleMask: .borderless, backing: .buffered, defer: false)
        win.level = .screenSaver
        win.backgroundColor = .black
        win.collectionBehavior = [.canJoinAllSpaces, .fullScreenAuxiliary]
        win.hasShadow = false
        
        // 使用纯 NSView + AVPlayerLayer，避免 SwiftUI 桥接崩溃
        let playerView = FullscreenPlayerView(frame: screen.frame)
        playerView.player = player
        win.contentView = playerView
        win.makeKeyAndOrderFront(nil)
        // 确保键盘事件（Escape退出）能被接收
        win.makeFirstResponder(playerView)
        NSApp.activate(ignoringOtherApps: true)
        fullscreenWindow = win
        isFullscreen = true
        #endif
    }
    
    // MARK: - 文件操作
    func openFileDialog() {
        #if os(macOS)
        let panel = NSOpenPanel()
        panel.canChooseFiles = true
        panel.canChooseDirectories = false
        panel.allowsMultipleSelection = true
        panel.allowedContentTypes = [
            .movie, .video, .audio, .mpeg4Movie, .quickTimeMovie, .avi, .mp3, .wav, .mpeg4Audio
        ]
        if panel.runModal() == .OK {
            for url in panel.urls {
                addItem(url: url, name: url.lastPathComponent, type: "file")
            }
        }
        #endif
    }
    
    func addURL(_ urlString: String) {
        guard let url = URL(string: urlString) else { showToast("无效URL"); return }
        let name = url.lastPathComponent.isEmpty ? (url.host ?? urlString) : url.lastPathComponent
        let type = urlString.contains(".m3u8") ? "stream" : "url"
        addItem(url: url, name: name, type: type)
    }
    
    private func addItem(url: URL, name: String, type: String) {
        queue.append(MediaItem(id: UUID().uuidString, url: url, name: name, mediaType: type))
        if queue.count == 1 { playIndex(0) }
    }
    
    func removeItem(at index: Int) {
        guard index >= 0 && index < queue.count else { return }
        let wasPlaying = (index == currentIndex)
        queue.remove(at: index)
        if wasPlaying {
            if queue.isEmpty {
                currentIndex = -1
                player.replaceCurrentItem(with: nil)
                currentTimeText = "00:00"; totalTimeText = "00:00"; progressRatio = 0
            } else {
                currentIndex = min(index, queue.count - 1)
                playIndex(currentIndex)
            }
        } else if index < currentIndex {
            currentIndex -= 1
        }
    }
    
    // MARK: - 播放列表窗口
    @Published var showPlaylistSheet = false
    
    func togglePlaylistWindow() {
        #if os(macOS)
        if let win = playlistWindow, win.isVisible {
            win.close(); playlistWindow = nil; return
        }
        let win = NSWindow(
            contentRect: NSRect(x: 0, y: 0, width: 400, height: 500),
            styleMask: [.titled, .closable, .resizable], backing: .buffered, defer: false
        )
        win.title = "播放列表 (\(queue.count))"
        win.isReleasedWhenClosed = false
        win.center()
        win.contentView = NSHostingView(rootView: PlaylistWindowView(bridge: self))
        win.makeKeyAndOrderFront(nil)
        playlistWindow = win
        #else
        showPlaylistSheet.toggle()
        #endif
    }
    
    // MARK: - Toast
    private func showToast(_ message: String) {
        toastMessage = message
        DispatchQueue.main.asyncAfter(deadline: .now() + 2) { [weak self] in
            if self?.toastMessage == message { self?.toastMessage = nil }
        }
    }
    
    // MARK: - 播放状态
    private func setupPlaybackStatusObserver() {
        player.publisher(for: \.timeControlStatus)
            .receive(on: DispatchQueue.main)
            .sink { [weak self] status in
                self?.isPlaying = (status == .playing)
            }
            .store(in: &cancellables)
    }
    
    deinit {
        if let observer = timeObserver { player.removeTimeObserver(observer) }
        itemStatusObserver?.invalidate()
    }
}

// MARK: - 全屏专用 NSView（纯 AppKit，不经过 SwiftUI）
#if os(macOS)
import AppKit

class FullscreenPlayerView: NSView {
    var player: AVPlayer? {
        get { (layer as? AVPlayerLayer)?.player }
        set { (layer as? AVPlayerLayer)?.player = newValue }
    }
    
    override init(frame: NSRect) {
        super.init(frame: frame)
        wantsLayer = true
        let playerLayer = AVPlayerLayer()
        playerLayer.videoGravity = .resizeAspect
        layer = playerLayer
    }
    
    required init?(coder: NSCoder) { fatalError() }
    
    override var acceptsFirstResponder: Bool { true }
    
    override func layout() {
        super.layout()
        (layer as? AVPlayerLayer)?.frame = bounds
    }
    
    override func mouseDown(with event: NSEvent) {
        if event.clickCount == 2 {
            // 双击退出全屏 — 通过通知
            NotificationCenter.default.post(name: .init("ExitFullscreen"), object: nil)
        } else {
            // 单击播放/暂停
            if let p = player {
                if p.timeControlStatus == .playing { p.pause() } else { p.play() }
            }
        }
    }
    
    override func keyDown(with event: NSEvent) {
        if event.keyCode == 53 { // Escape
            NotificationCenter.default.post(name: .init("ExitFullscreen"), object: nil)
        }
    }
}
#endif