//
//  VoicePlayerManager.swift
//  QuickLocation
//
//  Created by 八条 on 2026/6/5.
//

import AVFoundation

final class VoicePlayerManager {

    static let shared = VoicePlayerManager()

    private var player: AVPlayer?
    private var timeObserver: Any?
    private var currentURL: String?
    private var onStateChange: ((State) -> Void)?
    private var onFinished: (() -> Void)?

    enum State { case idle, playing, paused }

    private(set) var state: State = .idle

    private init() {}

    func play(urlString: String,
              playbackView: VoicePlaybackView,
              onStateChange: @escaping (State) -> Void,
              onFinished: @escaping () -> Void) {
        // Stop current if different source
        if currentURL != urlString {
            stop()
        }

        guard let url = URL(string: urlString) else { return }
        currentURL = urlString
        self.onStateChange = onStateChange
        self.onFinished = onFinished

        if player == nil {
            player = AVPlayer(url: url)
        }

        if state == .paused {
            player?.play()
            state = .playing
            onStateChange(.playing)
            playbackView.play()
        } else {
            player?.replaceCurrentItem(with: AVPlayerItem(url: url))
            player?.play()
            state = .playing
            onStateChange(.playing)
            playbackView.play()

            if let obs = timeObserver {
                player?.removeTimeObserver(obs)
            }
            timeObserver = player?.addPeriodicTimeObserver(forInterval: CMTime(value: 1, timescale: 10),
                                                            queue: .main) { [weak self] time in
                guard let self = self,
                      let duration = self.player?.currentItem?.duration,
                      duration.isValid, !duration.isIndefinite,
                      CMTimeCompare(time, duration) >= 0 else { return }
                self.stop()
                self.onFinished?()
            }
        }
    }

    func isCurrent(url: String) -> Bool { currentURL == url }

    func pause() {
        player?.pause()
        state = .paused
        onStateChange?(.paused)
    }

    func stop() {
        player?.pause()
        player?.replaceCurrentItem(with: nil)
        if let obs = timeObserver {
            player?.removeTimeObserver(obs)
            timeObserver = nil
        }
        let prevFinished = onFinished
        onStateChange = nil
        onFinished = nil
        player = nil
        currentURL = nil
        state = .idle
        prevFinished?()
    }
}

protocol VoicePlaybackView: AnyObject {
    func play()
    func stop()
}