import AVFoundation
#if os(macOS)
import AppKit

/// 视频源录制器：从 AVPlayerItemVideoOutput 抓帧，用 AVAssetWriter 写入文件
@MainActor
final class PlayerRecorder: NSObject {
    
    private var writer: AVAssetWriter?
    private var videoInput: AVAssetWriterInput?
    private var audioInput: AVAssetWriterInput?
    private var timer: Timer?
    private var startDate: Date?
    private var displayLink: CVDisplayLink?
    private var weakOutput: AVPlayerItemVideoOutput?
    
    @Published var isRecording = false
    @Published var durationText = "00:00"
    
    var onRecordingSaved: ((URL) -> Void)?
    var onError: ((String) -> Void)?
    
    private var tempURL: URL?
    
    private var saveDirectory: URL {
        let movies = FileManager.default.urls(for: .moviesDirectory, in: .userDomainMask).first!
        let dir = movies.appendingPathComponent("MiniPlayer", isDirectory: true)
        try? FileManager.default.createDirectory(at: dir, withIntermediateDirectories: true)
        return dir
    }
    
    /// 开始录制（从 videoOutput 抓帧）
    func startRecording(from output: AVPlayerItemVideoOutput) {
        guard !isRecording else { return }
        
        weakOutput = output
        
        // 创建临时文件
        let formatter = DateFormatter()
        formatter.dateFormat = "yyyy-MM-dd_HH-mm-ss"
        let filename = "Recording_\(formatter.string(from: Date())).mp4"
        let url = saveDirectory.appendingPathComponent(filename)
        tempURL = url
        
        do {
            writer = try AVAssetWriter(outputURL: url, fileType: .mp4)
        } catch {
            onError?("Cannot create writer: \(error.localizedDescription)")
            return
        }
        
        // 视频输入
        let videoSettings: [String: Any] = [
            AVVideoCodecKey: AVVideoCodecType.h264,
            AVVideoWidthKey: 1920,
            AVVideoHeightKey: 1080
        ]
        let vInput = AVAssetWriterInput(mediaType: .video, outputSettings: videoSettings)
        vInput.expectsMediaDataInRealTime = true
        if writer?.canAdd(vInput) == true {
            writer?.add(vInput)
            videoInput = vInput
        }
        
        writer?.startWriting()
        writer?.startSession(atSourceTime: .zero)
        
        isRecording = true
        startTimer()
        startCaptureLoop()
    }
    
    /// 停止录制
    func stopRecording() {
        guard isRecording else { return }
        isRecording = false
        stopTimer()
        stopCaptureLoop()
        
        videoInput?.markAsFinished()
        audioInput?.markAsFinished()
        
        writer?.finishWriting { [weak self] in
            Task { @MainActor in
                guard let self = self else { return }
                if let url = self.tempURL {
                    self.showSaveDialog(tempURL: url)
                }
            }
        }
    }
    
    // MARK: - 抓帧循环
    private func startCaptureLoop() {
        let queue = DispatchQueue(label: "recorder.capture")
        videoInput?.requestMediaDataWhenReady(on: queue) { [weak self] in
            self?.captureFrame()
        }
    }
    
    private func captureFrame() {
        guard let output = weakOutput, let input = videoInput, input.isReadyForMoreMediaData else { return }
        
        let time = output.itemTime(forHostTime: CACurrentMediaTime())
        if output.hasNewPixelBuffer(forItemTime: time), let pb = output.copyPixelBuffer(forItemTime: time, itemTimeForDisplay: nil) {
            let sampleBuffer = createSampleBuffer(from: pb, time: time)
            if let sb = sampleBuffer {
                input.append(sb)
            }
        }
    }
    
    private func createSampleBuffer(from pixelBuffer: CVPixelBuffer, time: CMTime) -> CMSampleBuffer? {
        var info = CMSampleTimingInfo()
        info.presentationTimeStamp = time
        info.duration = CMTime(value: 1, timescale: 30)
        
        var formatDescription: CMFormatDescription?
        CMVideoFormatDescriptionCreateForImageBuffer(allocator: kCFAllocatorDefault, imageBuffer: pixelBuffer, formatDescriptionOut: &formatDescription)
        
        guard let fd = formatDescription else { return nil }
        
        var sampleBuffer: CMSampleBuffer?
        CMSampleBufferCreateReadyWithImageBuffer(allocator: kCFAllocatorDefault, imageBuffer: pixelBuffer, formatDescription: fd, sampleTiming: &info, sampleBufferOut: &sampleBuffer)
        return sampleBuffer
    }
    
    private func stopCaptureLoop() {
        // requestMediaDataWhenReady 会在 isReadyForMoreMediaData=false 时停止
    }
    
    // MARK: - Timer
    private func startTimer() {
        startDate = Date()
        durationText = "00:00"
        timer = Timer.scheduledTimer(withTimeInterval: 1.0, repeats: true) { [weak self] _ in
            Task { @MainActor in
                guard let self = self, let start = self.startDate else { return }
                let elapsed = Int(Date().timeIntervalSince(start))
                let m = elapsed / 60
                let s = elapsed % 60
                let h = m / 60
                if h > 0 {
                    self.durationText = String(format: "%d:%02d:%02d", h, m % 60, s)
                } else {
                    self.durationText = String(format: "%02d:%02d", m, s)
                }
            }
        }
    }
    
    private func stopTimer() {
        timer?.invalidate()
        timer = nil
        startDate = nil
        durationText = "00:00"
    }
    
    // MARK: - 保存对话框
    private func showSaveDialog(tempURL: URL) {
        let panel = NSSavePanel()
        panel.nameFieldStringValue = tempURL.lastPathComponent
        panel.allowedContentTypes = [.mpeg4Movie]
        panel.directoryURL = saveDirectory
        panel.title = "Save Recording"
        
        panel.begin { [weak self] response in
            guard let self = self else { return }
            if response == .OK, let destURL = panel.url {
                do {
                    if FileManager.default.fileExists(atPath: destURL.path) {
                        try FileManager.default.removeItem(at: destURL)
                    }
                    try FileManager.default.moveItem(at: tempURL, to: destURL)
                    self.onRecordingSaved?(destURL)
                } catch {
                    self.onError?("Save failed: \(error.localizedDescription)")
                }
            } else {
                try? FileManager.default.removeItem(at: tempURL)
            }
        }
    }
}

#endif