import UIKit
import AVFoundation

/**
 * 带内边距的标签
 */
class PaddingLabel: UILabel {
    var padding: UIEdgeInsets
    
    init(padding: UIEdgeInsets) {
        self.padding = padding
        super.init(frame: .zero)
    }
    
    required init?(coder: NSCoder) {
        self.padding = UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0)
        super.init(coder: coder)
    }
    
    override func drawText(in rect: CGRect) {
        super.drawText(in: rect.inset(by: padding))
    }
    
    override var intrinsicContentSize: CGSize {
        let size = super.intrinsicContentSize
        return CGSize(width: size.width + padding.left + padding.right,
                      height: size.height + padding.top + padding.bottom)
    }
}

/**
 * 对话画中画视图
 * 
 * 用于在画中画模式下显示用户和AI的对话内容
 */
@available(iOS 13.0, *)
class DialogPipView: UIView {
    
    // 视频播放器图层（必须有，否则画中画无法工作）
    private var playerLayer: AVPlayerLayer?
    private var player: AVPlayer?
    
    // 对话显示视图
    private let dialogView = UIView()
    
    // 用户消息标签
    private let userMessageLabel: PaddingLabel = {
        let label = PaddingLabel(padding: UIEdgeInsets(top: 8, left: 8, bottom: 8, right: 8))
        label.font = UIFont.systemFont(ofSize: 14)
        label.textColor = UIColor.white
        label.numberOfLines = 0
        label.backgroundColor = UIColor(red: 0.2, green: 0.2, blue: 0.2, alpha: 0.7)
        label.layer.cornerRadius = 8
        label.layer.masksToBounds = true
        label.textAlignment = .left
        label.isHidden = true
        return label
    }()
    
    // AI助手消息标签
    private let assistantMessageLabel: PaddingLabel = {
        let label = PaddingLabel(padding: UIEdgeInsets(top: 8, left: 8, bottom: 8, right: 8))
        label.font = UIFont.systemFont(ofSize: 14)
        label.textColor = UIColor.white
        label.numberOfLines = 0
        label.backgroundColor = UIColor(red: 0.0, green: 0.4, blue: 0.8, alpha: 0.7)
        label.layer.cornerRadius = 8
        label.layer.masksToBounds = true
        label.textAlignment = .left
        label.isHidden = true
        return label
    }()
    
    // 初始化
    override init(frame: CGRect) {
        super.init(frame: frame)
        setupView()
    }
    
    required init?(coder: NSCoder) {
        super.init(coder: coder)
        setupView()
    }
    
    // 设置视图
    private func setupView() {
        backgroundColor = UIColor.black
        
        // 添加对话视图
        addSubview(dialogView)
        dialogView.frame = bounds
        dialogView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
        
        // 添加用户消息标签
        dialogView.addSubview(userMessageLabel)
        userMessageLabel.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            userMessageLabel.leadingAnchor.constraint(equalTo: dialogView.leadingAnchor, constant: 8),
            userMessageLabel.trailingAnchor.constraint(equalTo: dialogView.trailingAnchor, constant: -8),
            userMessageLabel.topAnchor.constraint(equalTo: dialogView.topAnchor, constant: 10),
        ])
        
        // 添加AI助手消息标签
        dialogView.addSubview(assistantMessageLabel)
        assistantMessageLabel.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            assistantMessageLabel.leadingAnchor.constraint(equalTo: dialogView.leadingAnchor, constant: 8),
            assistantMessageLabel.trailingAnchor.constraint(equalTo: dialogView.trailingAnchor, constant: -8),
            assistantMessageLabel.topAnchor.constraint(equalTo: userMessageLabel.bottomAnchor, constant: 10),
            assistantMessageLabel.bottomAnchor.constraint(lessThanOrEqualTo: dialogView.bottomAnchor, constant: -10)
        ])
    }
    
    // 创建并返回视频图层
    func setupDialogLayer() -> AVPlayerLayer {
        // 创建无声视频，用于支持画中画功能
        let playerItem = createSilentVideoPlayerItem()
        player = AVPlayer(playerItem: playerItem)
        player?.actionAtItemEnd = .none
        player?.play()
        
        // 创建视频图层
        let layer = AVPlayerLayer(player: player)
        layer.frame = bounds
        layer.videoGravity = .resizeAspectFill
        
        // 将视频图层放在最底层
        self.layer.insertSublayer(layer, at: 0)
        playerLayer = layer
        
        // 注册通知，确保视频循环播放
        NotificationCenter.default.addObserver(self,
                                              selector: #selector(playerItemDidReachEnd),
                                              name: .AVPlayerItemDidPlayToEndTime,
                                              object: player?.currentItem)
        
        return layer
    }
    
    // 创建无声视频用于支持画中画
    private func createSilentVideoPlayerItem() -> AVPlayerItem {
        // 创建一个简单的黑色视频，足够支持画中画但不会占用太多资源
        let composition = AVMutableComposition()
        
        // 添加视频轨道
        let videoTrack = composition.addMutableTrack(withMediaType: .video, preferredTrackID: kCMPersistentTrackID_Invalid)
        
        // 创建一个简单的黑色视频，持续10秒
        let videoSize = CGSize(width: 640, height: 480)
        let duration = CMTime(seconds: 10, preferredTimescale: 600)
        
        // 创建一个黑色图像
        UIGraphicsBeginImageContextWithOptions(videoSize, true, 0)
        UIColor.black.setFill()
        UIRectFill(CGRect(origin: .zero, size: videoSize))
        let blackImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        
        // 创建黑色图像的视频
        let settings = [
            AVVideoCodecKey: AVVideoCodecType.h264,
            AVVideoWidthKey: videoSize.width,
            AVVideoHeightKey: videoSize.height
        ] as [String : Any]
        
        let writerInput = AVAssetWriterInput(mediaType: .video, outputSettings: settings)
        let adaptor = AVAssetWriterInputPixelBufferAdaptor(assetWriterInput: writerInput, sourcePixelBufferAttributes: nil)
        
        if let pixelBuffer = createPixelBuffer(fromImage: blackImage!, size: videoSize) {
            let attributes: [String: Any] = [
                kCVPixelBufferPixelFormatTypeKey as String: kCVPixelFormatType_32ARGB,
                kCVPixelBufferWidthKey as String: videoSize.width,
                kCVPixelBufferHeightKey as String: videoSize.height
            ]
            
            // 创建一个5秒的黑色视频
            let assetWriter = try! AVAssetWriter(outputURL: URL(fileURLWithPath: NSTemporaryDirectory()).appendingPathComponent("temp.mov"), fileType: .mov)
            assetWriter.add(writerInput)
            assetWriter.startWriting()
            assetWriter.startSession(atSourceTime: .zero)
            
            let frameCount = 50 // 5秒，10fps
            let frameDuration = CMTime(value: 1, timescale: 10)
            
            writerInput.requestMediaDataWhenReady(on: DispatchQueue.global()) {
                for i in 0..<frameCount {
                    while !writerInput.isReadyForMoreMediaData {}
                    
                    let presentationTime = CMTime(value: CMTimeValue(i), timescale: 10)
                    adaptor.append(pixelBuffer, withPresentationTime: presentationTime)
                }
                
                writerInput.markAsFinished()
                assetWriter.finishWriting {}
            }
            
            // 等待视频写入完成
            while assetWriter.status == .writing {}
            
            // 创建AVPlayerItem
            let asset = AVAsset(url: assetWriter.outputURL)
            return AVPlayerItem(asset: asset)
        }
        
        // 如果上面的方法失败，创建一个简单的默认项
        let emptyItem = AVPlayerItem(url: URL(fileURLWithPath: ""))
        return emptyItem
    }
    
    // 从UIImage创建像素缓冲区
    private func createPixelBuffer(fromImage image: UIImage, size: CGSize) -> CVPixelBuffer? {
        var pixelBuffer: CVPixelBuffer?
        let attrs = [
            kCVPixelBufferCGImageCompatibilityKey: kCFBooleanTrue,
            kCVPixelBufferCGBitmapContextCompatibilityKey: kCFBooleanTrue
        ] as CFDictionary
        
        let status = CVPixelBufferCreate(
            kCFAllocatorDefault,
            Int(size.width),
            Int(size.height),
            kCVPixelFormatType_32ARGB,
            attrs,
            &pixelBuffer
        )
        
        guard status == kCVReturnSuccess, let buffer = pixelBuffer else {
            return nil
        }
        
        CVPixelBufferLockBaseAddress(buffer, [])
        let context = CGContext(
            data: CVPixelBufferGetBaseAddress(buffer),
            width: Int(size.width),
            height: Int(size.height),
            bitsPerComponent: 8,
            bytesPerRow: CVPixelBufferGetBytesPerRow(buffer),
            space: CGColorSpaceCreateDeviceRGB(),
            bitmapInfo: CGImageAlphaInfo.noneSkipFirst.rawValue
        )
        
        context?.draw(image.cgImage!, in: CGRect(x: 0, y: 0, width: size.width, height: size.height))
        CVPixelBufferUnlockBaseAddress(buffer, [])
        
        return buffer
    }
    
    // 视频播放结束处理
    @objc private func playerItemDidReachEnd(notification: Notification) {
        // 循环播放视频
        player?.seek(to: .zero)
        player?.play()
    }
    
    // 更新对话内容
    func updateDialogContent(userMessage: String, assistantMessage: String) {
        // 设置用户消息
        if !userMessage.isEmpty {
            userMessageLabel.text = "用户: \(userMessage)"
            userMessageLabel.isHidden = false
        } else {
            userMessageLabel.isHidden = true
        }
        
        // 设置AI助手消息
        if !assistantMessage.isEmpty {
            assistantMessageLabel.text = "AI助手: \(assistantMessage)"
            assistantMessageLabel.isHidden = false
        } else {
            assistantMessageLabel.isHidden = true
        }
        
        // 更新布局
        setNeedsLayout()
    }
    
    // 布局子视图
    override func layoutSubviews() {
        super.layoutSubviews()
        
        // 调整视频图层大小
        playerLayer?.frame = bounds
    }
    
    // 释放资源
    deinit {
        NotificationCenter.default.removeObserver(self)
        player?.pause()
        player = nil
    }
}