import MusicKit       // Catalog, auth, playback
import MediaPlayer    // MPRemoteCommandCenter, MPNowPlayingInfoCenter

func requestMusicAccess() async -> MusicAuthorization.Status {
    let status = await MusicAuthorization.request()
    switch status {
    case .authorized:
        // Full access to MusicKit APIs
        break
    case .denied, .restricted:
        // Show guidance to enable in Settings
        break
    case .notDetermined:
        break
    @unknown default:
        break
    }
    return status
}
 
// Check current status without prompting
let current = MusicAuthorization.currentStatus

func searchCatalog(term: String) async throws -> MusicItemCollection<Song> {
    var request = MusicCatalogSearchRequest(term: term, types: [Song.self])
    request.limit = 25
 
    let response = try await request.response()
    return response.songs
}

for song in songs {
    print("\(song.title) by \(song.artistName)")
    if let artwork = song.artwork {
        let url = artwork.url(width: 300, height: 300)
        // Load artwork from url
    }
}

func checkSubscription() async throws -> Bool {
    let subscription = try await MusicSubscription.current
    return subscription.canPlayCatalogContent
}
 
// Observe subscription changes
func observeSubscription() async {
    for await subscription in MusicSubscription.subscriptionUpdates {
        if subscription.canPlayCatalogContent {
            // Enable full playback UI
        } else {
            // Show subscription offer
        }
    }
}

import MusicKit
import SwiftUI
 
struct MusicOfferView: View {
    @State private var showOffer = false
 
    var body: some View {
        Button("Subscribe to Apple Music") {
            Task {
                let subscription = try? await MusicSubscription.current
                showOffer = subscription?.canBecomeSubscriber == true
            }
        }
        .musicSubscriptionOffer(
            isPresented: $showOffer,
            options: .default,
            onLoadCompletion: { error in
                if let error {
                    // Surface loading errors in app UI or diagnostics.
                    print(error)
                }
            }
        )
    }
}

let player = ApplicationMusicPlayer.shared
 
func playSong(_ song: Song) async throws {
    player.queue = [song]
    try await player.play()
}
 
func pause() {
    player.pause()
}
 
func skipToNext() async throws {
    try await player.skipToNextEntry()
}

func observePlayback() {
    // player.state is an @Observable property
    let state = player.state
    switch state.playbackStatus {
    case .playing:
        break
    case .paused:
        break
    case .stopped, .interrupted, .seekingForward, .seekingBackward:
        break
    @unknown default:
        break
    }
}

// Initialize with multiple items
func playAlbum(_ album: Album) async throws {
    player.queue = [album]
    try await player.play()
}
 
// Append songs to the existing queue
func appendToQueue(_ songs: [Song]) async throws {
    try await player.queue.insert(songs, position: .tail)
}
 
// Insert song to play next
func playNext(_ song: Song) async throws {
    try await player.queue.insert(song, position: .afterCurrentEntry)
}

import MediaPlayer
 
func updateNowPlaying(title: String, artist: String, duration: TimeInterval, elapsed: TimeInterval) {
    var info = [String: Any]()
    info[MPMediaItemPropertyTitle] = title
    info[MPMediaItemPropertyArtist] = artist
    info[MPMediaItemPropertyPlaybackDuration] = duration
    info[MPNowPlayingInfoPropertyElapsedPlaybackTime] = elapsed
    info[MPNowPlayingInfoPropertyPlaybackRate] = 1.0
    info[MPNowPlayingInfoPropertyMediaType] = MPNowPlayingInfoMediaType.audio.rawValue
 
    MPNowPlayingInfoCenter.default().nowPlayingInfo = info
}
 
func clearNowPlaying() {
    MPNowPlayingInfoCenter.default().nowPlayingInfo = nil
}

func setArtwork(_ image: UIImage) {
    let artwork = MPMediaItemArtwork(boundsSize: image.size) { _ in image }
    var info = MPNowPlayingInfoCenter.default().nowPlayingInfo ?? [:]
    info[MPMediaItemPropertyArtwork] = artwork
    MPNowPlayingInfoCenter.default().nowPlayingInfo = info
}

func setupRemoteCommands() {
    let center = MPRemoteCommandCenter.shared()
 
    center.playCommand.addTarget { _ in
        resumePlayback()
        return .success
    }
 
    center.pauseCommand.addTarget { _ in
        pausePlayback()
        return .success
    }
 
    center.nextTrackCommand.addTarget { _ in
        skipToNext()
        return .success
    }
 
    center.previousTrackCommand.addTarget { _ in
        skipToPrevious()
        return .success
    }
 
    // Disable commands you do not support
    center.seekForwardCommand.isEnabled = false
    center.seekBackwardCommand.isEnabled = false
}

func enableScrubbing() {
    let center = MPRemoteCommandCenter.shared()
    center.changePlaybackPositionCommand.addTarget { event in
        guard let positionEvent = event as? MPChangePlaybackPositionCommandEvent else {
            return .commandFailed
        }
        seek(to: positionEvent.positionTime)
        return .success
    }
}

// WRONG: MusicKit App Service not enabled for this bundle ID
 
// CORRECT: Enable MusicKit App Service in the developer portal,
// set the matching bundle ID, then add NSAppleMusicUsageDescription.
let status = await MusicAuthorization.request()

// WRONG
func play(_ song: Song) async throws {
    player.queue = [song]
    try await player.play() // Fails if no subscription
}
 
// CORRECT
func play(_ song: Song) async throws {
    let sub = try await MusicSubscription.current
    guard sub.canPlayCatalogContent else {
        showSubscriptionOffer()
        return
    }
    player.queue = [song]
    try await player.play()
}

// WRONG: Modifies the user's Music app queue
let player = SystemMusicPlayer.shared
 
// CORRECT: App-scoped playback
let player = ApplicationMusicPlayer.shared

// WRONG: Set once and forget
updateNowPlaying(title: firstSong.title, ...)
 
// CORRECT: Update on every track change
func onTrackChanged(_ song: Song) {
    updateNowPlaying(
        title: song.title,
        artist: song.artistName,
        duration: song.duration ?? 0,
        elapsed: 0
    )
}

// WRONG
center.skipForwardCommand.addTarget { _ in .commandFailed }
 
// CORRECT
center.skipForwardCommand.isEnabled = false