import AVFoundation
import Foundation

/// 手表端录音：AVAudioRecorder 写 AAC .m4a，存在手表 Documents 里，停后交给 WatchSessionManager 传到 iPhone。
@MainActor
final class WatchRecorder: ObservableObject {
    @Published var isRecording = false
    @Published var elapsed: TimeInterval = 0

    private var recorder: AVAudioRecorder?
    private var timer: Timer?
    private var startDate: Date?
    private(set) var currentFileURL: URL?

    func requestPermission() async -> Bool {
        await withCheckedContinuation { continuation in
            AVAudioSession.sharedInstance().requestRecordPermission { granted in
                continuation.resume(returning: granted)
            }
        }
    }

    func start() throws {
        let session = AVAudioSession.sharedInstance()
        try session.setCategory(.record, mode: .default)
        try session.setActive(true)

        let fileName = "watch-note-\(Int(Date().timeIntervalSince1970)).m4a"
        let docs = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)[0]
        let url = docs.appendingPathComponent(fileName)
        currentFileURL = url

        let settings: [String: Any] = [
            AVFormatIDKey: Int(kAudioFormatMPEG4AAC),
            AVSampleRateKey: 44_100,
            AVNumberOfChannelsKey: 1,
            AVEncoderAudioQualityKey: AVAudioQuality.high.rawValue
        ]
        recorder = try AVAudioRecorder(url: url, settings: settings)
        recorder?.record()

        isRecording = true
        startDate = Date()
        elapsed = 0
        timer = Timer.scheduledTimer(withTimeInterval: 0.2, repeats: true) { [weak self] _ in
            Task { @MainActor in
                guard let self, let start = self.startDate else { return }
                self.elapsed = Date().timeIntervalSince(start)
            }
        }
    }

    /// 停止录音，返回录音文件 URL（nil 表示没录成）
    func stop() -> URL? {
        timer?.invalidate()
        timer = nil
        recorder?.stop()
        recorder = nil
        isRecording = false
        try? AVAudioSession.sharedInstance().setActive(false)
        return currentFileURL
    }
}