import os

/// Distributes one producer's audio to several feeds (one per route).
///
/// `push` may run on a real-time thread: it only try-locks and otherwise uses the last known list.
public final class AudioFanout: @unchecked Sendable {
    private let feeds = OSAllocatedUnfairLock<[AudioFeed]>(initialState: [])
    private var cached: [AudioFeed] = [] // producer thread only

    public init() {}

    public func add(_ feed: AudioFeed) {
        feeds.withLock { $0.append(feed) }
    }

    public func remove(_ feed: AudioFeed) {
        feeds.withLock { $0.removeAll { $0 === feed } }
    }

    public var isEmpty: Bool { feeds.withLock { $0.isEmpty } }

    public func push(planar data: UnsafePointer<Float>, channelStride: Int, channels: Int, frames: Int, sampleRate: Double) {
        if let current = feeds.withLockIfAvailable({ $0 }) { cached = current }
        for feed in cached {
            feed.push(planar: data, channelStride: channelStride, channels: channels, frames: frames, sampleRate: sampleRate)
        }
    }
}