//
//  LivePlaybackViewModel.swift
//  suixinkan
//
//  Created by Codex on 2026/6/25.
//

import AVFoundation
import Foundation
import Combine

/// 直播播放地址解析器，避免把 RTMP 推流地址误当作播放地址。
enum LivePlaybackURLResolver {
    static func playableURL(from live: LiveEntity) -> URL? {
        playableURL(from: live.playbackURLCandidates)
    }

    static func playableURL(from candidates: [String]) -> URL? {
        for candidate in candidates {
            if let url = playableURL(from: candidate) {
                return url
            }
        }
        return nil
    }

    static func playableURL(from rawValue: String) -> URL? {
        let value = rawValue.liveTrimmed
        guard !value.isEmpty, let url = URL(string: value) else { return nil }
        guard let scheme = url.scheme?.lowercased(), scheme == "http" || scheme == "https" else { return nil }
        if url.pathExtension.lowercased() == "flv" {
            return nil
        }
        return url
    }
}

/// 播放器状态。
enum LivePlaybackState: Equatable {
    case empty
    case ready(URL)
    case playing(URL)
    case failed(String)
}

@MainActor
/// 直播播放器 ViewModel，管理系统播放器的 URL、播放和释放状态。
final class LivePlaybackViewModel: ObservableObject {
    @Published var state: LivePlaybackState = .empty
    @Published var errorMessage: String?

    @Published private(set) var player: AVPlayer?

    var playableURL: URL? {
        switch state {
        case .ready(let url), .playing(let url):
            url
        case .empty, .failed:
            nil
        }
    }

    var isPlaying: Bool {
        if case .playing = state { return true }
        return false
    }

    init(live: LiveEntity? = nil, urlString: String? = nil) {
        if let live {
            load(live: live)
        } else if let urlString {
            load(urlString: urlString)
        }
    }

    func load(live: LiveEntity) {
        load(url: LivePlaybackURLResolver.playableURL(from: live))
    }

    func load(urlString: String) {
        load(url: LivePlaybackURLResolver.playableURL(from: urlString))
    }

    func play() {
        guard let url = playableURL else { return }
        if player == nil {
            player = AVPlayer(url: url)
        }
        player?.play()
        state = .playing(url)
    }

    func pause() {
        guard let url = playableURL else { return }
        player?.pause()
        state = .ready(url)
    }

    func reload() {
        guard let url = playableURL else { return }
        releasePlayer()
        player = AVPlayer(url: url)
        state = .ready(url)
    }

    func release() {
        releasePlayer()
        if let url = playableURL {
            state = .ready(url)
        } else {
            state = .empty
        }
    }

    private func load(url: URL?) {
        releasePlayer()
        guard let url else {
            errorMessage = "暂无可播放地址"
            state = .empty
            return
        }
        errorMessage = nil
        player = AVPlayer(url: url)
        state = .ready(url)
    }

    private func releasePlayer() {
        player?.pause()
        player = nil
    }
}