import Foundation
import AVKit
import Combine

#if os(iOS)
/// 画中画（Picture-in-Picture）控制器
/// 封装 AVPictureInPictureController，管理 PiP 生命周期
@MainActor
final class PiPController: NSObject, ObservableObject {
    
    @Published var isPiPActive = false
    @Published var isPiPSupported = false
    
    private var pipController: AVPictureInPictureController?
    private weak var playerLayer: AVPlayerLayer?
    private var pipPossibleObservation: NSKeyValueObservation?
    
    /// 用 AVPlayerLayer 初始化 PiP 控制器
    func setup(with playerLayer: AVPlayerLayer) {
        // 避免重复初始化
        guard pipController == nil else { return }
        
        self.playerLayer = playerLayer
        
        guard AVPictureInPictureController.isPictureInPictureSupported() else {
            NSLog("[MiniPlayer] PiP not supported on this device")
            isPiPSupported = false
            return
        }
        
        isPiPSupported = true
        
        guard let pip = AVPictureInPictureController(playerLayer: playerLayer) else {
            NSLog("[MiniPlayer] PiP controller creation returned nil")
            isPiPSupported = false
            return
        }
        pip.delegate = self
        self.pipController = pip
        
        // KVO 观察 isPictureInPicturePossible 变化
        pipPossibleObservation = pip.observe(\.isPictureInPicturePossible, options: [.new]) { [weak self] controller, _ in
            let possible = controller.isPictureInPicturePossible
            NSLog("[MiniPlayer] PiP possible changed: %d", possible)
            Task { @MainActor in
                // 触发 UI 刷新（按钮状态可能需要更新）
                self?.objectWillChange.send()
            }
        }
        
        NSLog("[MiniPlayer] PiP controller initialized, possible=%d", pip.isPictureInPicturePossible)
    }
    
    /// 切换画中画状态
    func togglePiP() {
        guard let pip = pipController else {
            NSLog("[MiniPlayer] PiP controller not initialized")
            return
        }
        
        NSLog("[MiniPlayer] togglePiP: active=%d, possible=%d", pip.isPictureInPictureActive, pip.isPictureInPicturePossible)
        
        if pip.isPictureInPictureActive {
            pip.stopPictureInPicture()
        } else if pip.isPictureInPicturePossible {
            pip.startPictureInPicture()
        } else {
            NSLog("[MiniPlayer] PiP not possible — check: 1) player has content 2) Xcode project has 'Audio, AirPlay, and Picture in Picture' background mode enabled in Signing & Capabilities")
        }
    }
    
    /// 当前是否可以启动 PiP
    var canStartPiP: Bool {
        pipController?.isPictureInPicturePossible ?? false
    }
    
    deinit {
        pipPossibleObservation = nil
        pipController?.delegate = nil
    }
}

// MARK: - AVPictureInPictureControllerDelegate
extension PiPController: AVPictureInPictureControllerDelegate {
    
    nonisolated func pictureInPictureControllerWillStartPictureInPicture(_ pictureInPictureController: AVPictureInPictureController) {
        NSLog("[MiniPlayer] PiP will start")
        Task { @MainActor in self.isPiPActive = true }
    }
    
    nonisolated func pictureInPictureControllerDidStartPictureInPicture(_ pictureInPictureController: AVPictureInPictureController) {
        NSLog("[MiniPlayer] PiP did start")
    }
    
    nonisolated func pictureInPictureControllerWillStopPictureInPicture(_ pictureInPictureController: AVPictureInPictureController) {
        NSLog("[MiniPlayer] PiP will stop")
    }
    
    nonisolated func pictureInPictureControllerDidStopPictureInPicture(_ pictureInPictureController: AVPictureInPictureController) {
        NSLog("[MiniPlayer] PiP did stop")
        Task { @MainActor in self.isPiPActive = false }
    }
    
    nonisolated func pictureInPictureController(_ pictureInPictureController: AVPictureInPictureController, failedToStartPictureInPictureWithError error: Error) {
        NSLog("[MiniPlayer] PiP failed to start: \(error.localizedDescription)")
    }
    
    nonisolated func pictureInPictureController(_ pictureInPictureController: AVPictureInPictureController, restoreUserInterfaceForPictureInPictureStopWithCompletionHandler completionHandler: @escaping (Bool) -> Void) {
        // 用户点击 PiP 窗口的恢复按钮时调用
        // 返回 true 表示我们已处理恢复（回到 app 内播放）
        NSLog("[MiniPlayer] PiP restore requested")
        completionHandler(true)
    }
}
#endif