iOS 1.0 RC 2: Plex streams under upload caps, shuffle and album radio stations, Recently Added list, photo covers, crossfade

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

ios/Stemify/Playback/PlaybackManager.swift

@@ -64,13 +64,14 @@ private struct SavedQueue: Codable {
     var positionMs: Int64 = 0
     var repeatMode: RepeatMode = .Off
     var mix: [String: StemSetting] = [:]
+    var station: PlaybackManager.Station?
 
-    init(items: [QueueItem], unshuffled: [QueueItem]?, index: Int, positionMs: Int64, repeatMode: RepeatMode, mix: [String: StemSetting]) {
+    init(items: [QueueItem], unshuffled: [QueueItem]?, index: Int, positionMs: Int64, repeatMode: RepeatMode, mix: [String: StemSetting], station: PlaybackManager.Station?) {
         self.items = items; self.unshuffled = unshuffled; self.index = index
-        self.positionMs = positionMs; self.repeatMode = repeatMode; self.mix = mix
+        self.positionMs = positionMs; self.repeatMode = repeatMode; self.mix = mix; self.station = station
     }
 
-    enum CodingKeys: String, CodingKey { case items, unshuffled, index, positionMs, repeatMode = "repeat", mix }
+    enum CodingKeys: String, CodingKey { case items, unshuffled, index, positionMs, repeatMode = "repeat", mix, station }
 
     init(from decoder: Decoder) throws {
         let c = try decoder.container(keyedBy: CodingKeys.self)
@@ -80,6 +81,7 @@ private struct SavedQueue: Codable {
         positionMs = (try? c.decode(Int64.self, forKey: .positionMs)) ?? 0
         repeatMode = (try? c.decode(RepeatMode.self, forKey: .repeatMode)) ?? .Off
         mix = (try? c.decode([String: StemSetting].self, forKey: .mix)) ?? [:]
+        station = try? c.decode(PlaybackManager.Station.self, forKey: .station)
     }
 }
 
@@ -203,37 +205,92 @@ final class PlaybackManager: StemEngineListener, @unchecked Sendable {
     }
     private func changed() {
         listeners.values.forEach { $0() }
-        topUpRadio()
+        topUpStation()
     }
 
-    /// Album radio: every album in the library in random order, each played whole and in track order.
-    /// Only the next album is fetched, once the queue is nearly played out.
-    @ObservationIgnored private var radioDeck: [Album]?
-    @ObservationIgnored private var radioBusy = false
+    /// Endless queues that top themselves up as they play.
+    /// Album radio (Plexamp's Random Album Radio): every album in the library in one shuffled order,
+    /// each played whole and in track order. The next several albums sit in the queue up front and
+    /// more are added, in deck order, as they play out.
+    /// Song radio: random songs from the whole library, fetched from the server a batch at a time
+    /// (Library Radio and Songs > Shuffle), so nothing has to load the whole library first.
+    enum Station: Codable, Equatable { case albums([String]), songs }
+    @ObservationIgnored private var station: Station?
+    @ObservationIgnored private var stationGen = 0
+    @ObservationIgnored private var stationBusy = false
+    private static let radioAlbumsAhead = 8
+    private static let radioAlbumsLow = 3
+    private static let radioSongsBatch = 100
+    private static let radioSongsLow = 25
+
+    private func setStation(_ s: Station?) { station = s; stationGen += 1; stationBusy = false }
+
+    private func albumDeck() async throws -> [String] {
+        var deck = (try? await plex.albums().map(\.ratingKey)) ?? []
+        if deck.isEmpty { deck = try await plex.randomAlbums(500).map(\.ratingKey) }
+        return deck.shuffled()
+    }
+
+    /// Tracks of [keys] in that order, fetched in parallel. Albums that fail or are empty are skipped.
+    private func albumTracks(_ keys: [String]) async -> [Track] {
+        let plex = plex
+        let lists = await withTaskGroup(of: (Int, [Track]).self) { group in
+            for (i, k) in keys.enumerated() { group.addTask { (i, (try? await plex.albumTracks(k)) ?? []) } }
+            var out = [[Track]](repeating: [], count: keys.count)
+            for await (i, t) in group { out[i] = t }
+            return out
+        }
+        return lists.flatMap { $0 }
+    }
 
     func startAlbumRadio() async throws {
-        var deck = try await plex.albums().shuffled()
+        var deck = try await albumDeck()
+        // The first album alone so music starts right away, then the rest of the look-ahead.
         var first: [Track] = []
-        while first.isEmpty, !deck.isEmpty { first = (try? await plex.albumTracks(deck.removeLast().ratingKey)) ?? [] }
-        if first.isEmpty { return }
+        while first.isEmpty, !deck.isEmpty { first = await albumTracks([deck.removeFirst()]) }
+        if first.isEmpty { throw RadioEmpty() }
         playTracks(first)
-        radioDeck = deck
+        setStation(.albums(deck))
+        topUpStation()
     }
 
-    private func topUpRadio() {
-        guard radioDeck != nil, !radioBusy, queue.count - index < 3 else { return }
-        radioBusy = true
-        Task { @MainActor in
-            defer { radioBusy = false }
-            while var deck = radioDeck, !deck.isEmpty {
-                let album = deck.removeLast()
-                radioDeck = deck
-                if let t = try? await plex.albumTracks(album.ratingKey), !t.isEmpty, radioDeck != nil {
-                    addToQueue(t)
-                    return
-                }
+    func startSongRadio() async throws {
+        let first = try await plex.randomTracks(Self.radioSongsBatch)
+        if first.isEmpty { throw RadioEmpty() }
+        playTracks(first)
+        setStation(.songs)
+    }
+
+    struct RadioEmpty: LocalizedError { var errorDescription: String? { "No music found in your library" } }
+
+    private func topUpStation() {
+        guard let st = station, !stationBusy, index >= 0, index < queue.count else { return }
+        let gen = stationGen
+        switch st {
+        case .albums(let saved):
+            let ahead = Set(queue[index...].map { $0.track.albumKey ?? $0.track.album }).count
+            guard ahead <= Self.radioAlbumsLow else { return }
+            stationBusy = true
+            Task { @MainActor in
+                defer { if gen == stationGen { stationBusy = false } }
+                var deck = saved
+                if deck.isEmpty { deck = (try? await albumDeck()) ?? [] }
+                let take = Array(deck.prefix(Self.radioAlbumsAhead + 1 - ahead))
+                deck.removeFirst(take.count)
+                let tracks = await albumTracks(take)
+                guard gen == stationGen else { return }
+                station = .albums(deck)
+                addToQueue(tracks)
+            }
+        case .songs:
+            guard queue.count - index <= Self.radioSongsLow else { return }
+            stationBusy = true
+            Task { @MainActor in
+                defer { if gen == stationGen { stationBusy = false } }
+                let have = Set(queue.map(\.track.ratingKey))
+                guard let more = try? await plex.randomTracks(Self.radioSongsBatch), gen == stationGen else { return }
+                addToQueue(more.filter { !have.contains($0.ratingKey) })
             }
-            if radioDeck != nil, let all = try? await plex.albums(), !all.isEmpty { radioDeck = all.shuffled() }
         }
     }
 
@@ -263,7 +320,7 @@ final class PlaybackManager: StemEngineListener, @unchecked Sendable {
 
     func playTracks(_ tracks: [Track], mixes: [[String: StemSetting]]? = nil, start: Int = 0, shuffle doShuffle: Bool = false) {
         if tracks.isEmpty { return }
-        radioDeck = nil
+        setStation(nil)
         let items = items(tracks, mixes)
         if doShuffle {
             unshuffled = items
@@ -332,6 +389,7 @@ final class PlaybackManager: StemEngineListener, @unchecked Sendable {
     }
 
     func clearUpNext() {
+        setStation(nil)
         guard index >= 0 else { return }
         queue = Array(queue.prefix(index + 1))
         unshuffled = nil
@@ -454,6 +512,7 @@ final class PlaybackManager: StemEngineListener, @unchecked Sendable {
         reportTimeline("stopped")
         currentToken = -1
         queued = [:]
+        setStation(nil)
         queue = []
         index = -1
         current = nil
@@ -649,15 +708,18 @@ final class PlaybackManager: StemEngineListener, @unchecked Sendable {
     }
 
     private func openDetached(_ track: Track, _ startMs: Int64) async throws -> (TrackSession, StemEntry?) {
-        try await withCheckedThrowingContinuation { cont in
+        // Plain Plex files need a playback session first, or a Remote Access upload limit fails them.
+        var stream: URL?
+        if stems.find(track) == nil, !cache.isComplete(Self.plexKey(track)) { stream = await plex.streamUrl(track) }
+        return try await withCheckedThrowingContinuation { [stream] cont in
             DispatchQueue.global(qos: .userInitiated).async { [self] in
-                cont.resume(with: Result { try open(track, startMs) })
+                cont.resume(with: Result { try open(track, startMs, stream: stream) })
             }
         }
     }
 
     /// Opens every stem (or the original file) and waits for the decoders to know their format.
-    private func open(_ track: Track, _ startMs: Int64) throws -> (TrackSession, StemEntry?) {
+    private func open(_ track: Track, _ startMs: Int64, stream: URL? = nil) throws -> (TrackSession, StemEntry?) {
         let entry = stems.find(track)
         var sources: [(name: String, key: String, url: URL?, hint: String)] = []
         if let entry {
@@ -671,7 +733,7 @@ final class PlaybackManager: StemEngineListener, @unchecked Sendable {
         } else {
             guard let part = track.partKey else { throw PlainError("Plex has no file for this track") }
             let hint = track.partFile.map { ($0 as NSString).pathExtension } ?? track.codec ?? ""
-            sources.append(("mix", Self.plexKey(track), plex.partUrl(part), hint))
+            sources.append(("mix", Self.plexKey(track), stream ?? plex.partUrl(part), hint))
         }
         if sources.isEmpty { throw PlainError("No stems listed for this track") }
         let decoders = sources.map { src -> StemDecoder in
@@ -723,7 +785,7 @@ final class PlaybackManager: StemEngineListener, @unchecked Sendable {
                 return
             }
             self.queued[s.token] = (item.uid, entry)
-            self.engine.queueNext(s)
+            self.engine.queueNext(s, fadeMs: self.fadeMs(into: item.track))
             await self.precacheAhead(from: i)
         }
     }
@@ -746,6 +808,20 @@ final class PlaybackManager: StemEngineListener, @unchecked Sendable {
         }
     }
 
+    /// How long to crossfade from the current track into `next`, in ms.
+    private func fadeMs(into next: Track) -> Int {
+        let sec = settings.crossfadeSec
+        guard sec > 0 else { return 0 }
+        if settings.sweetFades, let a = current?.track.albumKey, a == next.albumKey { return 0 }
+        return sec * 1000
+    }
+
+    /// Applies a changed crossfade setting to the queued track.
+    func crossfadeChanged() {
+        guard let i = upcomingIndex() else { return }
+        engine.setNextFade(fadeMs(into: queue[i].track))
+    }
+
     private func requeueNext() {
         if currentToken >= 0 { prepareNext() }
     }
@@ -922,7 +998,7 @@ final class PlaybackManager: StemEngineListener, @unchecked Sendable {
             try? await Task.sleep(nanoseconds: 500_000_000)
             guard let self, !Task.isCancelled else { return }
             let snap = SavedQueue(items: self.queue, unshuffled: self.unshuffled, index: self.index,
-                                  positionMs: self.positionMs(), repeatMode: self.repeatMode, mix: self.mix)
+                                  positionMs: self.positionMs(), repeatMode: self.repeatMode, mix: self.mix, station: self.station)
             let file = self.queueFile
             DispatchQueue.global(qos: .utility).async {
                 guard let data = try? JSONEncoder().encode(snap) else { return }
@@ -934,7 +1010,7 @@ final class PlaybackManager: StemEngineListener, @unchecked Sendable {
     /// Saves right away, for when the app is about to be suspended.
     func flushSave() {
         saveTask?.cancel()
-        let snap = SavedQueue(items: queue, unshuffled: unshuffled, index: index, positionMs: positionMs(), repeatMode: repeatMode, mix: mix)
+        let snap = SavedQueue(items: queue, unshuffled: unshuffled, index: index, positionMs: positionMs(), repeatMode: repeatMode, mix: mix, station: station)
         if let data = try? JSONEncoder().encode(snap) { try? data.write(to: queueFile, options: .atomic) }
     }
 
@@ -945,6 +1021,7 @@ final class PlaybackManager: StemEngineListener, @unchecked Sendable {
         shuffle = saved.unshuffled != nil
         repeatMode = saved.repeatMode
         mix = saved.mix
+        station = saved.station
         nextUid = (saved.items.map(\.uid).max() ?? 0) + 1
         let i = min(max(saved.index, -1), saved.items.count - 1)
         index = i