feat: add Chromecast playback support

2026-10-13 17:31:37 +02:00
parent 74b4bfe6c1
commit bb777b0ecd
22 changed files with 3299 additions and 115 deletions
@@ -0,0 +1,145 @@
+import Foundation
+
+struct CastMediaInput: Sendable {
+    let videoURL: String
+    let videoHeaders: String
+    let audioURL: String?
+    let audioHeaders: String?
+    let local: Bool
+    let restricted: Bool
+    let live: Bool
+    let duration: Double
+    let subtitles: [ResolvedSubtitle]
+}
+
+struct CastMediaDescription: Sendable {
+    let url: URL
+    let contentType: String
+    let duration: Double
+    let live: Bool
+    let tracks: [CastTextTrack]
+}
+
+struct CastTextTrack: Sendable {
+    let id: Int
+    let url: URL
+    let language: String
+    let label: String
+}
+
+private struct CastDeliveryError: LocalizedError {
+    let errorDescription: String? = "Could not deliver cast media. Check the connection and media compatibility. Private details are redacted."
+}
+
+// A start task retains this owner until native probing returns. Cancellation never
+// frees a handle in use; destruction and worker joins always run off the main actor.
+private final class CastMediaLifetime: @unchecked Sendable {
+    let handle: OpaquePointer
+    init(input: CastMediaInput) throws {
+        var error = [CChar](repeating: 0, count: 512)
+        let result = input.videoURL.withCString { video in
+            input.videoHeaders.withCString { headers in
+                (input.audioURL ?? "").withCString { audio in
+                    (input.audioHeaders ?? "").withCString { audioHeaders in
+                        var source = CastMediaSource(video_url: video, video_headers: headers,
+                            audio_url: audio, audio_headers: audioHeaders, local: input.local,
+                            restricted: input.restricted, live: input.live, duration: input.duration)
+                        return cast_media_create(&source, &error)
+                    }
+                }
+            }
+        }
+        guard let result else { throw CastDeliveryError() }
+        handle = result
+    }
+    func cancel() { cast_media_cancel(handle) }
+    func start(host: String) throws -> (String, Double) {
+        var url = [CChar](repeating: 0, count: 512)
+        var error = [CChar](repeating: 0, count: 512)
+        var duration = 0.0
+        guard host.withCString({ cast_media_start(handle, $0, &url, &duration, &error) }) else {
+            throw CastDeliveryError()
+        }
+        return (url.withUnsafeBufferPointer { String(cString: $0.baseAddress!) }, duration)
+    }
+    func subtitle(id: Int, data: Data) throws -> URL {
+        var url = [CChar](repeating: 0, count: 512)
+        let success = data.withUnsafeBytes {
+            cast_media_subtitle(handle, Int32(id), $0.baseAddress, $0.count, &url)
+        }
+        guard success, let result = URL(string: url.withUnsafeBufferPointer { String(cString: $0.baseAddress!) }) else { throw CastDeliveryError() }
+        return result
+    }
+    deinit {
+        // Capture an explicitly Sendable owner instead of crossing an actor with a pointer.
+        let cleanup = CastMediaCleanup(handle: handle)
+        DispatchQueue.global(qos: .utility).async { cast_media_destroy(cleanup.handle) }
+    }
+}
+private struct CastMediaCleanup: @unchecked Sendable { let handle: OpaquePointer }
+
+@MainActor final class CastMediaServer {
+    private var lifetime: CastMediaLifetime?
+    private var operation: Task<CastMediaDescription, Error>?
+
+    init() {}
+
+    func start(input: CastMediaInput, receiverHost: String) async throws -> CastMediaDescription {
+        stop()
+        guard input.subtitles.count <= 32 else { throw CastDeliveryError() }
+        let owner = try CastMediaLifetime(input: input)
+        lifetime = owner
+        let task = Task.detached(priority: .userInitiated) {
+            do {
+                let (text, duration) = try owner.start(host: receiverHost)
+                try Task.checkCancellation()
+                guard let url = URL(string: text) else { throw CastDeliveryError() }
+                var tracks: [CastTextTrack] = []
+                for (index, subtitle) in input.subtitles.enumerated() {
+                    try Task.checkCancellation()
+                    let data = try await WebVTTDocument.loadData(url: subtitle.url, headers: subtitle.headers)
+                    guard let text = String(data: data, encoding: .utf8) else { throw CastDeliveryError() }
+                    _ = try WebVTTDocument.parse(text)
+                    let trackURL = try owner.subtitle(id: index + 1, data: data)
+                    tracks.append(CastTextTrack(id: index + 1, url: trackURL,
+                        language: subtitle.language, label: subtitle.label))
+                }
+                try Task.checkCancellation()
+                return CastMediaDescription(url: url, contentType: "application/vnd.apple.mpegurl",
+                    duration: duration, live: input.live, tracks: tracks)
+            } catch {
+                owner.cancel()
+                if Task.isCancelled { throw CancellationError() }
+                throw CastDeliveryError()
+            }
+        }
+        operation = task
+        do {
+            let result = try await withTaskCancellationHandler {
+                try await task.value
+            } onCancel: {
+                owner.cancel()
+                task.cancel()
+            }
+            guard lifetime === owner else { throw CancellationError() }
+            operation = nil
+            return result
+        } catch {
+            if lifetime === owner { stop() }
+            if error is CancellationError { throw error }
+            throw CastDeliveryError()
+        }
+    }
+
+    func stop() {
+        operation?.cancel()
+        operation = nil
+        lifetime?.cancel()
+        lifetime = nil
+    }
+
+    deinit {
+        operation?.cancel()
+        lifetime?.cancel()
+    }
+}