import AVFoundation
import Foundation
import MediaPlayer

/// An internet radio stream the user saved in Browse > Web Radio.
struct WebStation: Codable, Hashable, Identifiable {
    var id = UUID().uuidString
    var name: String
    var url: String
}

/// Plays a web radio stream through AVPlayer, outside the stem engine. Starting a station pauses
/// the queue, and playing the queue again stops the station. Main-thread only, like PlaybackManager.
@Observable
final class WebRadio: @unchecked Sendable {
    private let pm: PlaybackManager
    @ObservationIgnored private let player = AVPlayer()
    @ObservationIgnored weak var nowPlaying: NowPlaying?

    private(set) var station: WebStation?
    private(set) var playing = false
    /// A station is loaded (playing or paused); the lock screen belongs to the radio.
    var active: Bool { station != nil }

    init(pm: PlaybackManager) {
        self.pm = pm
        player.automaticallyWaitsToMinimizeStalling = true
        pm.addListener { [weak self] in
            guard let self, self.active, pm.playWhenReady else { return }
            self.stop()
        }
    }

    func play(_ s: WebStation) {
        guard let url = URL(string: s.url) else { return }
        station = s
        if pm.playWhenReady { pm.pause() }
        let a = AVAudioSession.sharedInstance()
        try? a.setCategory(.playback, mode: .default, policy: .longFormAudio)
        try? a.setActive(true)
        player.replaceCurrentItem(with: AVPlayerItem(url: url))
        player.play()
        playing = true
        publish()
    }

    func resume() {
        guard active else { return }
        // Live streams go stale while paused; rejoin at the live edge.
        if let s = station { play(s) }
    }

    func pause() {
        player.pause()
        playing = false
        publish()
    }

    func toggle() { if playing { pause() } else { resume() } }

    func stop() {
        player.pause()
        player.replaceCurrentItem(with: nil)
        station = nil
        playing = false
        nowPlaying?.refresh()
    }

    private func publish() {
        guard let s = station else { return }
        let c = MPNowPlayingInfoCenter.default()
        c.nowPlayingInfo = [
            MPMediaItemPropertyTitle: s.name,
            MPMediaItemPropertyArtist: "Web Radio",
            MPNowPlayingInfoPropertyIsLiveStream: true,
            MPNowPlayingInfoPropertyPlaybackRate: playing ? 1.0 : 0.0,
        ]
        c.playbackState = playing ? .playing : .paused
    }
}