import Foundation

/// 录制进度回调
public protocol StreamRecorderDelegate: AnyObject {
    func recorderDidStart(_ recorder: StreamRecorderEngine)
    func recorder(_ recorder: StreamRecorderEngine, didUpdateProgress progress: RecordingProgress)
    func recorder(_ recorder: StreamRecorderEngine, didFinishWithResult result: RecordingResult)
    func recorder(_ recorder: StreamRecorderEngine, didFailWithError error: Error)
}

/// 录制进度
public struct RecordingProgress {
    public let currentTime: Double  // 当前已录制时长（秒）
    public let totalDuration: Double // 总时长（秒）
    public let bytesWritten: Int64   // 已写入字节数
    public let bitrate: Double       // 当前码率 (kbps)
    
    public var percentage: Double {
        guard totalDuration > 0 else { return 0 }
        return min(currentTime / totalDuration * 100, 100)
    }
}

/// 录制结果
public struct RecordingResult {
    public let outputPath: String
    public let duration: Double
    public let fileSize: Int64
    public let hasVideo: Bool
    public let hasAudio: Bool
    public let videoInfo: VideoInfo?
    public let audioInfo: AudioInfo?
    public let audioLevel: AudioLevel?
}

public struct VideoInfo {
    public let codec: String
    public let width: Int
    public let height: Int
    public let fps: Double
    public let pixelFormat: String
}

public struct AudioInfo {
    public let codec: String
    public let sampleRate: Int
    public let channels: Int
}

public struct AudioLevel {
    public let meanVolume: Double  // dB
    public let maxVolume: Double   // dB
    public let isSilent: Bool
}

public enum RecordingError: Error, LocalizedError {
    case invalidURL
    case noFFmpeg
    case noMediaTracks
    case processFailed(Int)
    case outputNotFound
    case unknown(String)
    
    public var errorDescription: String? {
        switch self {
        case .invalidURL: return "无效的 URL"
        case .noFFmpeg: return "未找到 ffmpeg，请安装: brew install ffmpeg"
        case .noMediaTracks: return "未找到任何媒体轨道"
        case .processFailed(let code): return "录制失败 (exit code: \(code))"
        case .outputNotFound: return "输出文件不存在"
        case .unknown(let msg): return msg
        }
    }
}

/// 录制引擎协议
public protocol StreamRecorderEngine: AnyObject {
    var delegate: StreamRecorderDelegate? { get set }
    var isRecording: Bool { get }
    
    func start(url: URL, outputPath: String, duration: Double) async throws
    func stop()
}