import SwiftUI
import AVFoundation

struct PlayerView: View {
    @EnvironmentObject var engine: PlayerEngine
    @State private var showControls = true
    @State private var isSeeking = false
    @State private var controlsTimer: Timer?
    @FocusState private var focused: Bool
    
    var body: some View {
        ZStack {
            Color.black
            
            if engine.currentItem != nil {
                PlayerLayerView(player: engine.player)
                    .onTapGesture {
                        toggleControls()
                    }
                
                if showControls {
                    controlsOverlay
                        .transition(.opacity)
                }
            } else {
                emptyState
            }
        }
        .ignoresSafeArea(.all, edges: engine.isFullscreen ? .all : [])
        .onAppear {
            focused = true
            resetControlsTimer()
        }
    }
    
    // MARK: - 空状态
    
    private var emptyState: some View {
        VStack(spacing: 16) {
            Image(systemName: "play.rectangle.on.rectangle")
                .font(.system(size: 64))
                .foregroundStyle(.secondary)
            Text("添加文件开始播放")
                .font(.title3)
                .foregroundStyle(.secondary)
            Text("支持 MP4, MKV, AVI, M4V, MOV, MP3, FLAC, M3U8 等格式")
                .font(.caption)
                .foregroundStyle(.tertiary)
        }
    }
    
    // MARK: - 控制层
    
    private var controlsOverlay: some View {
        VStack {
            // 顶部栏: 标题 + 全屏按钮
            HStack {
                if let item = engine.currentItem {
                    Text(item.name)
                        .font(.headline)
                        .lineLimit(1)
                        .padding(.horizontal, 12)
                        .padding(.vertical, 6)
                        .background(.ultraThinMaterial, in: Capsule())
                }
                Spacer()
                
                Button {
                    engine.toggleFullscreen()
                } label: {
                    Image(systemName: engine.isFullscreen ? "arrow.down.right.and.arrow.up.left" : "arrow.up.left.and.arrow.down.right")
                        .font(.title3)
                        .padding(10)
                        .background(.ultraThinMaterial, in: Circle())
                }
                .buttonStyle(.plain)
            }
            .padding(.horizontal, 20)
            .padding(.top, 12)
            
            Spacer()
            
            // 底部控制区
            VStack(spacing: 12) {
                // 进度条
                progressSection
                // 按钮行
                buttonRow
            }
            .padding(.horizontal, 20)
            .padding(.bottom, 16)
            .padding(.vertical, 12)
            .background(
                LinearGradient(
                    colors: [.clear, .black.opacity(0.6)],
                    startPoint: .top, endPoint: .bottom
                )
            )
        }
    }
    
    // MARK: - 进度条
    
    private var progressSection: some View {
        VStack(spacing: 4) {
            Slider(
                value: Binding(
                    get: { isSeeking ? engine.currentTime : engine.currentTime },
                    set: { newValue in
                        engine.currentTime = newValue
                        isSeeking = true
                    }
                ),
                in: 0...max(engine.duration, 0.1)
            ) { editing in
                if !editing {
                    engine.seek(to: engine.currentTime)
                    isSeeking = false
                }
            }
            #if os(iOS)
            .tint(.white)
            #else
            .tint(.accentColor)
            #endif
            
            HStack {
                Text(PlayerEngine.formatTime(engine.currentTime))
                    .font(.caption.monospacedDigit())
                Spacer()
                Text(PlayerEngine.formatTime(engine.duration))
                    .font(.caption.monospacedDigit())
            }
            .foregroundStyle(.white.opacity(0.8))
        }
    }
    
    // MARK: - 按钮行
    
    private var buttonRow: some View {
        HStack(spacing: 24) {
            // 音轨
            Menu {
                ForEach(Array(engine.audioTracks.enumerated()), id: \.offset) { idx, track in
                    Button {
                        engine.selectAudioTrack(track)
                    } label: {
                        HStack {
                            Text(track.displayName.isEmpty ? "音轨 \(idx + 1)" : track.displayName)
                            if track == engine.selectedAudioTrack {
                                Image(systemName: "checkmark")
                            }
                        }
                    }
                }
            } label: {
                Image(systemName: "waveform")
                    .font(.title3)
            }
            .buttonStyle(.plain)
            .disabled(engine.audioTracks.count <= 1)
            
            Spacer()
            
            // 上一个
            Button { engine.playPrevious() } label: {
                Image(systemName: "backward.fill")
                    .font(.title2)
            }
            .buttonStyle(.plain)
            
            // 快退
            Button { engine.seekBackward() } label: {
                Image(systemName: "gobackward.10")
                    .font(.title2)
            }
            .buttonStyle(.plain)
            
            // 播放/暂停
            Button { engine.togglePlay() } label: {
                Image(systemName: engine.isPlaying ? "pause.circle.fill" : "play.circle.fill")
                    .font(.system(size: 44))
            }
            .buttonStyle(.plain)
            
            // 快进
            Button { engine.seekForward() } label: {
                Image(systemName: "goforward.10")
                    .font(.title2)
            }
            .buttonStyle(.plain)
            
            // 下一个
            Button { engine.playNext() } label: {
                Image(systemName: "forward.fill")
                    .font(.title2)
            }
            .buttonStyle(.plain)
            
            Spacer()
            
            // 循环
            Button {
                engine.repeatMode = engine.repeatMode.next
            } label: {
                Image(systemName: engine.repeatMode.icon)
                    .font(.title3)
                    .overlay(alignment: .bottom) {
                        if engine.repeatMode != .none {
                            Circle()
                                .fill(.blue)
                                .frame(width: 4, height: 4)
                                .offset(y: -4)
                        }
                    }
            }
            .buttonStyle(.plain)
        }
        .foregroundStyle(.white)
    }
    
    // MARK: - 辅助
    
    private func toggleControls() {
        withAnimation(.easeInOut(duration: 0.2)) {
            showControls.toggle()
        }
        resetControlsTimer()
    }
    
    private func resetControlsTimer() {
        controlsTimer?.invalidate()
        controlsTimer = Timer.scheduledTimer(withTimeInterval: 4, repeats: false) { _ in
            Task { @MainActor in
                withAnimation(.easeInOut(duration: 0.3)) {
                    showControls = false
                }
            }
        }
    }
}