import SwiftUI
import AVFoundation

// MARK: - 跨平台AVPlayer渲染

#if os(iOS)
import UIKit

struct VideoPlayerRepresentable: UIViewRepresentable {
    let player: AVPlayer
    
    func makeUIView(context: Context) -> PlayerUIView {
        let view = PlayerUIView()
        view.player = player
        return view
    }
    
    func updateUIView(_ uiView: PlayerUIView, context: Context) {
        uiView.player = player
    }
}

class PlayerUIView: UIView {
    override static var layerClass: AnyClass { AVPlayerLayer.self }
    
    var player: AVPlayer? {
        get { (layer as? AVPlayerLayer)?.player }
        set { (layer as? AVPlayerLayer)?.player = newValue }
    }
    
    override var contentMode: UIView.ContentMode {
        get { (layer as? AVPlayerLayer)?.videoGravity == .resizeAspectFill ? .scaleAspectFill : .scaleAspectFit }
        set {
            (layer as? AVPlayerLayer)?.videoGravity = newValue == .scaleAspectFill ? .resizeAspectFill : .resizeAspect
        }
    }
}

#elseif os(macOS)
import AppKit

struct VideoPlayerRepresentable: NSViewRepresentable {
    let player: AVPlayer
    
    func makeCoordinator() -> Coordinator { Coordinator() }
    
    class Coordinator {
        weak var view: PlayerNSView?
    }
    
    func makeNSView(context: Context) -> PlayerNSView {
        let view = PlayerNSView()
        view.player = player
        context.coordinator.view = view
        return view
    }
    
    func updateNSView(_ nsView: PlayerNSView, context: Context) {
        // 只在 player 引用变化时设置（Coordinator 确保不重复设置）
        if nsView.player !== player {
            nsView.player = player
        }
    }
}

class PlayerNSView: NSView {
    // 使用 makeBackingLayer 让 AppKit 管理 AVPlayerLayer 作为 backing layer
    override func makeBackingLayer() -> CALayer { AVPlayerLayer() }
    
    private var playerLayer: AVPlayerLayer { layer as! AVPlayerLayer }
    
    override init(frame: NSRect) {
        super.init(frame: frame)
        wantsLayer = true
        playerLayer.videoGravity = .resizeAspect
    }
    
    required init?(coder: NSCoder) { fatalError() }
    
    var player: AVPlayer? {
        get { playerLayer.player }
        set { playerLayer.player = newValue }
    }
}
#endif