voice-cat/clients/apple/Sources/VoiceCatCore/VoiceCatClient.swift

// Swift binding invariants: native config strings outlive the handle, destroy joins callback
// threads before deallocation, and callback payloads are copied before main-queue delivery.
// See docs/architecture.md §4 for the complete binding contract.

import VoiceCatC
import Foundation

/// Swift-idiomatic alias for the C `vc_pcm_sink_cb` function-pointer type from
/// `voicecat.h`. Exposed publicly so consumers (`VoiceCatMac`, tests) can declare a sink
/// callback without directly importing the `VoiceCatC` C module. Mirrors the C# wrapper's
/// `VcPcmSinkCallback` delegate.
public typealias VoiceCatPcmSinkCallback = vc_pcm_sink_cb

/// Swift-idiomatic alias for the C `vc_mixed_output_cb` function-pointer type from `voicecat.h`
/// — the external mixed-output sink used by the iOS VPIO path (see `setMixedOutputSink`).
public typealias VoiceCatMixedOutputCallback = vc_mixed_output_cb

/// The Swift wrapper around `vc_client*`. Owns the native handle for its entire lifetime;
/// `deinit` destroys it. Events and level meters are delivered on the main queue via the
/// `onEvent` / `onLevel` closures.
///
/// Thread-safety: the public methods are not thread-safe — call them from the main thread
/// (the standard AppKit/SwiftUI pattern). The internal event/level buffers are thread-safe
/// (lock-protected) because they're written from the core's event thread.
public final class VoiceCatClient {

    // MARK: - Stored properties

    private var handle: OpaquePointer?

    /// Unretained callback context; destroying the handle joins callback threads first.
    private var selfPointer: UnsafeMutableRawPointer {
        Unmanaged.passUnretained(self).toOpaque()
    }

    /// The core retains these pointers for the handle's lifetime.
    private var clientNamePtr: UnsafeMutablePointer<CChar>?
    private var clientVersionPtr: UnsafeMutablePointer<CChar>?
    private var tofuStorePathPtr: UnsafeMutablePointer<CChar>?

    // MARK: - Event / level delivery (main-queue)

    /// Called on the main queue for every event, in order, never coalesced. Set this from
    /// the main thread (AppKit/SwiftUI) to drive your UI.
    public var onEvent: ((VoiceCatEvent) -> Void)?

    /// Called on the main queue with the latest RMS level per stream_id since the last drain.
    /// Intermediate values are coalesced (only the latest per stream_id is delivered).
    public var onLevel: ((UInt32, Float) -> Void)?

    private let bufferLock = NSLock()
    private var eventBuffer: [VoiceCatEvent] = []
    private var levelSamples: [UInt32: Float] = [:]
    private var drainScheduled = false

    // MARK: - Init / deinit

    public init(config: VoiceCatConfig) {
        self.clientNamePtr = strdup(config.clientName)
        self.clientVersionPtr = strdup(config.clientVersion)
        self.tofuStorePathPtr = config.tofuStorePath.flatMap { strdup($0) }
        self.handle = nil  // placeholder — set below after callbacks are wired

        var nativeConfig = vc_config()
        nativeConfig.client_name = UnsafePointer(clientNamePtr)
        nativeConfig.client_version = UnsafePointer(clientVersionPtr)
        nativeConfig.log_level = config.logLevel.cValue
        nativeConfig.tofu_store_path = UnsafePointer(tofuStorePathPtr)

        let callbacks = Callbacks.make(user: selfPointer)
        self.handle = vc_client_create(&nativeConfig, callbacks)

        if handle == nil {
            free(clientNamePtr); clientNamePtr = nil
            free(clientVersionPtr); clientVersionPtr = nil
            if let tofuStorePathPtr { free(tofuStorePathPtr); self.tofuStorePathPtr = nil }
            fatalError("vc_client_create returned nil")
        }
    }

    deinit {
        if let handle {
            // Joins every internal thread synchronously — no callbacks can fire after this
            // returns, so the selfPointer and config-string pointers are safe to free.
            vc_client_destroy(handle)
            self.handle = nil
        }
        // Free config strings AFTER destroy (the core may have been reading them up until
        // destroy joined the io thread).
        free(clientNamePtr); clientNamePtr = nil
        free(clientVersionPtr); clientVersionPtr = nil
        if let tofuStorePathPtr { free(tofuStorePathPtr); self.tofuStorePathPtr = nil }
    }

    // MARK: - Internal: event/level enqueue (called from the core's event thread)

    /// Called by Callbacks.onEvent on the core's event thread. Buffers the event and
    /// schedules a coalesced main-queue drain.
    internal func enqueueEvent(_ event: VoiceCatEvent) {
        bufferLock.lock()
        eventBuffer.append(event)
        let shouldSchedule = !drainScheduled
        drainScheduled = true
        bufferLock.unlock()
        if shouldSchedule {
            DispatchQueue.main.async { [weak self] in self?.drain() }
        }
    }

    /// Called by Callbacks.onLevel on the core's event thread. Coalesces to latest-per-stream
    /// and schedules a coalesced main-queue drain.
    internal func enqueueLevel(_ streamId: UInt32, _ rms: Float) {
        bufferLock.lock()
        levelSamples[streamId] = rms
        let shouldSchedule = !drainScheduled
        drainScheduled = true
        bufferLock.unlock()
        if shouldSchedule {
            DispatchQueue.main.async { [weak self] in self?.drain() }
        }
    }

    /// Drains buffered events + coalesced levels on the main queue. Only one drain is
    /// scheduled at a time (debounced via `drainScheduled`).
    private func drain() {
        bufferLock.lock()
        let events = eventBuffer
        eventBuffer.removeAll()
        let levels = levelSamples
        levelSamples.removeAll()
        drainScheduled = false
        bufferLock.unlock()

        for event in events { onEvent?(event) }
        for (streamId, rms) in levels { onLevel?(streamId, rms) }
    }

    // MARK: - Lifecycle (statics)

    /// The core's version string (e.g. "VoiceCat 0.0.1 (protocol v1)"). Static literal — never freed.
    public static var versionString: String {
        String(cString: vc_version_string())
    }

    /// Human-readable description of a result code. Static literal — never freed.
    public static func resultString(_ code: VoiceCatResult) -> String {
        String(cString: vc_result_string(code.cValue))
    }

    // MARK: - Connection & auth (async; results via onEvent)

    @discardableResult
    public func connect(host: String, port: UInt16) -> VoiceCatResult {
        VoiceCatResult(vc_connect(handle, host, port))
    }

    @discardableResult
    public func disconnect() -> VoiceCatResult {
        VoiceCatResult(vc_disconnect(handle))
    }

    @discardableResult
    public func authenticateGuest(_ nickname: String) -> VoiceCatResult {
        VoiceCatResult(vc_authenticate_guest(handle, nickname))
    }

    @discardableResult
    public func authenticateUser(_ username: String, password: String) -> VoiceCatResult {
        VoiceCatResult(vc_authenticate_user(handle, username, password))
    }

    // MARK: - TOFU server-identity gate

    /// Accept or reject the pending server-identity check. Call after a `.serverIdentity`
    /// event. `accept=true` on firstConnect/mismatch updates the pin file and proceeds;
    /// `accept=false` aborts (emits `.disconnected` with `.crypto`). See docs/security.md §1.1.
    @discardableResult
    public func confirmServerIdentity(accept: Bool) -> VoiceCatResult {
        VoiceCatResult(vc_confirm_server_identity(handle, accept ? 1 : 0))
    }

    /// The Ed25519 identity fingerprint from ServerHello, hex-formatted — DISPLAY ONLY, not
    /// the value the TOFU gate pins on (see docs/security.md §1.1). Empty if not yet available.
    /// Uses the two-call idiom: query size with nil buffer, then allocate + fetch.
    public func getServerIdentityDisplay() -> String {
        var len: Int = 0
        _ = vc_get_server_identity_display(handle, nil, 0, &len)
        if len == 0 { return "" }
        let buf = UnsafeMutablePointer<CChar>.allocate(capacity: len + 1)
        defer { buf.deallocate() }
        _ = vc_get_server_identity_display(handle, buf, len + 1, &len)
        return String(cString: buf)
    }

    // MARK: - Channels

    /// Join a channel. Result arrives as a `.joinResult` event (not via the return value,
    /// which only reflects "request queued"). `password` is for password-protected channels.
    @discardableResult
    public func joinChannel(_ channelId: UInt32, password: String? = nil) -> VoiceCatResult {
        VoiceCatResult(vc_join_channel(handle, channelId, password))
    }

    @discardableResult
    public func leaveChannel() -> VoiceCatResult {
        VoiceCatResult(vc_leave_channel(handle))
    }

    @discardableResult
    public func joinVoice() -> VoiceCatResult {
        VoiceCatResult(vc_join_voice(handle))
    }

    @discardableResult
    public func leaveVoice() -> VoiceCatResult {
        VoiceCatResult(vc_leave_voice(handle))
    }

    /// Pull the current channel tree. Re-call after `.channelList`/`.userJoined`/`.userLeft`/
    /// `.userUpdated` events. The native list is freed inside this call — callers never
    /// manage native lifetime.
    public func listChannels() -> [Channel] {
        var native = vc_channel_list()
        _ = vc_list_channels(handle, &native)
        return Marshaling.channels(&native)
    }

    public func listUsers() -> [User] {
        var native = vc_user_list()
        _ = vc_list_users(handle, &native)
        return Marshaling.users(&native)
    }

    public func listUserStreams(_ userId: UInt32) -> [StreamSummary] {
        var native = vc_stream_summary_list()
        let r = vc_list_user_streams(handle, userId, &native)
        guard r == VC_OK else { return [] }
        return Marshaling.streamSummaries(&native)
    }

    // MARK: - Local media streams

    /// Start a mic / screen-audio / aux stream. Returns `(result, streamId)` — `streamId`
    /// is non-zero on success. The `label` and `deviceId` C strings are only needed for the
    /// duration of the call (the core copies what it needs), so we use temporary strdup'd
    /// buffers freed via `defer`.
    @discardableResult
    public func startStream(_ descriptor: StreamDescriptor) -> (VoiceCatResult, UInt32) {
        var streamId: UInt32 = 0
        let labelPtr = strdup(descriptor.label)
        defer { free(labelPtr) }
        let deviceIdPtr = descriptor.deviceId.flatMap { strdup($0) }
        defer { if let deviceIdPtr { free(deviceIdPtr) } }

        var desc = vc_stream_desc()
        desc.kind = descriptor.kind.cValue
        desc.device_id = deviceIdPtr.map { UnsafePointer($0) }
        desc.label = UnsafePointer(labelPtr)
        desc.external_feed = descriptor.externalFeed ? 1 : 0

        let r = vc_stream_start(handle, &desc, &streamId)
        return (VoiceCatResult(r), streamId)
    }

    @discardableResult
    public func stopStream(_ streamId: UInt32) -> VoiceCatResult {
        VoiceCatResult(vc_stream_stop(handle, streamId))
    }

    @discardableResult
    public func setInputDevice(streamId: UInt32, deviceId: String?) -> VoiceCatResult {
        VoiceCatResult(vc_set_input_device(handle, streamId, deviceId))
    }

    /// Set the capture channel count for a local MIC stream (1 = mono, 2 = stereo interleaved).
    /// Takes effect on the next AudioEngine restart (immediately if already running). Used by
    /// the iOS `IOSAudioRouter` when the user picks stereo built-in mic capture.
    @discardableResult
    public func setCaptureChannels(streamId: UInt32, channels: UInt32) -> VoiceCatResult {
        VoiceCatResult(vc_set_capture_channels(handle, streamId, channels))
    }

    // MARK: - External PCM feed / tap

    /// External PCM feed — drives a local stream's encode pipeline with caller-supplied PCM
    /// instead of (or in addition to) a hardware capture device. Intended for ReplayKit
    /// Broadcast Extension (iOS), ScreenCaptureKit (macOS), bots, and soundboard use cases.
    ///
    /// - Parameters:
    ///   - streamId: The stream returned by `startStream`. Must be active.
    ///   - pcm: Raw int16 PCM pointer. Caller must keep the buffer alive for the duration of the call.
    ///   - samplesPerChannel: Samples per channel (e.g. 960 for 20 ms @ 48 kHz).
    ///   - channels: 1 (mono) or 2 (stereo interleaved L/R).
    @discardableResult
    public func feedPcm(streamId: UInt32, pcm: UnsafePointer<Int16>,
                        samplesPerChannel: Int, channels: UInt32) -> VoiceCatResult {
        VoiceCatResult(vc_stream_feed_pcm(handle, streamId, pcm,
                                          samplesPerChannel, channels))
    }

    /// Convenience overload for feeding from a Swift `[Int16]` array.
    @discardableResult
    public func feedPcm(streamId: UInt32, pcm: [Int16],
                        samplesPerChannel: Int, channels: UInt32) -> VoiceCatResult {
        pcm.withUnsafeBufferPointer {
            feedPcm(streamId: streamId, pcm: $0.baseAddress!,
                    samplesPerChannel: samplesPerChannel, channels: channels)
        }
    }

    /// External PCM tap — receive decoded per-stream audio as raw int16 PCM before it
    /// reaches the hardware mix. Fires once per decoded Opus frame per remote stream.
    ///
    /// The callback is a C function pointer (`@convention(c)`) receiving:
    ///   `(user, userId, streamId, pcm, samplesPerChannel, channels, sampleRate)`
    ///
    /// Pass `nil` to disable (default). The callback MUST NOT block or allocate.
    @discardableResult
    public func setPcmSink(_ cb: VoiceCatPcmSinkCallback?, user: UnsafeMutableRawPointer?) -> VoiceCatResult {
        VoiceCatResult(vc_set_pcm_sink(handle, cb, user))
    }

    /// External mixed-output sink (iOS VPIO) — receives the FINAL mixed remote audio as int16
    /// PCM on the core's mixer-timer thread when external playback is enabled. The Swift VPIO
    /// renderer copies this into its ring and plays it through the voice-processing output so
    /// echo cancellation has its reference signal. Pass `nil` to disable. Mirrors
    /// `vc_set_mixed_output_sink`. The callback MUST NOT block or allocate.
    @discardableResult
    public func setMixedOutputSink(_ cb: VoiceCatMixedOutputCallback?,
                                   user: UnsafeMutableRawPointer?) -> VoiceCatResult {
        VoiceCatResult(vc_set_mixed_output_sink(handle, cb, user))
    }

    /// Enable/disable external-playback mode (iOS VPIO). When enabled, the core opens NO hardware
    /// playback device; it drives decode+mix on a timer and delivers the final mix via
    /// `setMixedOutputSink`. Apply before the engine starts, or follow with `audioRestart()` to
    /// apply to a running engine. Mirrors `vc_set_external_playback`.
    @discardableResult
    public func setExternalPlayback(_ enabled: Bool) -> VoiceCatResult {
        VoiceCatResult(vc_set_external_playback(handle, enabled ? 1 : 0))
    }

    @discardableResult
    public func setInputMode(_ mode: VoiceCatInputMode) -> VoiceCatResult {
        VoiceCatResult(vc_set_input_mode(handle, mode.cValue))
    }

    /// VAD threshold: normalized RMS 0.0–1.0 (default ~0.025). Takes effect immediately.
    @discardableResult
    public func setVadThreshold(_ threshold: Float) -> VoiceCatResult {
        VoiceCatResult(vc_set_vad_threshold(handle, threshold))
    }

    @discardableResult
    public func setPushToTalk(_ active: Bool) -> VoiceCatResult {
        VoiceCatResult(vc_set_push_to_talk(handle, active ? 1 : 0))
    }

    @discardableResult
    public func setSelfMute(micMuted: Bool, deafened: Bool) -> VoiceCatResult {
        VoiceCatResult(vc_set_self_mute(handle, micMuted ? 1 : 0, deafened ? 1 : 0))
    }

    /// Global playback volume applied after mixing all remote streams. gain 0.0 = silent,
    /// 1.0 = unity (default), >1.0 amplifies. Always LOCAL — no protocol traffic. Mirrors the
    /// Windows client's `SetOutputVolume` and the C ABI `vc_set_output_volume`.
    @discardableResult
    public func setOutputVolume(_ gain: Float) -> VoiceCatResult {
        VoiceCatResult(vc_set_output_volume(handle, gain < 0 ? 0 : gain))
    }

    /// Send-side microphone input gain. Applied to captured MIC PCM before the VAD/PTT gate and
    /// Opus encode (so boosting a quiet mic also helps it cross the VAD threshold). gain 0.0 =
    /// silent, 1.0 = unity (default), >1.0 amplifies (clamped to int16). Always LOCAL.
    @discardableResult
    public func setInputGain(_ gain: Float) -> VoiceCatResult {
        VoiceCatResult(vc_set_input_gain(handle, gain < 0 ? 0 : gain))
    }

    /// Send-side microphone noise suppression (RNNoise). Denoises captured MIC PCM before the
    /// input gain and VAD/PTT gate, so everyone hears the cleaned signal (one pass for all
    /// listeners). MIC stream only, mono only; always LOCAL — no protocol traffic. Independent
    /// of the per-listener receive-side NR in `setRemoteStream` (docs/voice.md §10).
    @discardableResult
    public func setInputNoiseReduction(_ enable: Bool) -> VoiceCatResult {
        VoiceCatResult(vc_set_input_noise_reduction(handle, enable ? 1 : 0))
    }

    // MARK: - AVAudioSession interruption hooks (iOS)

    /// Pause miniaudio device I/O. Call when AVAudioSession interruption begins.
    @discardableResult
    public func audioSuspend() -> VoiceCatResult {
        VoiceCatResult(vc_audio_suspend(handle))
    }

    /// Resume miniaudio device I/O. Call after re-activating AVAudioSession.
    @discardableResult
    public func audioResume() -> VoiceCatResult {
        VoiceCatResult(vc_audio_resume(handle))
    }

    /// Full audio engine restart — uninitialize and re-initialize the capture and playback
    /// devices so they pick up a new AVAudioSession route. Call this AFTER reconfiguring
    /// AVAudioSession (setCategory, setPreferredInput, setPreferredPolarPattern, etc.) so the
    /// core's devices reopen against the new route. Unlike `audioSuspend()`/`audioResume()`
    /// (which only stop/start the existing devices, leaving them bound to the route that was
    /// active when they were opened), this fully re-initializes them. Safe to call when the
    /// engine is not running (it will just start it).
    @discardableResult
    public func audioRestart() -> VoiceCatResult {
        VoiceCatResult(vc_audio_restart(handle))
    }

    // MARK: - Receive-side, per remote stream (LOCAL — no protocol traffic; docs/voice.md §10)

    @discardableResult
    public func setRemoteStream(userId: UInt32, streamId: UInt32, gain: Float,
                                muted: Bool, noiseReduction: Bool) -> VoiceCatResult {
        VoiceCatResult(vc_set_remote_stream(handle, userId, streamId, gain,
                                            muted ? 1 : 0, noiseReduction ? 1 : 0))
    }

    public func getRemoteStream(userId: UInt32, streamId: UInt32) -> (VoiceCatResult, RemoteStreamState?) {
        var state = vc_remote_stream_state()
        let r = vc_get_remote_stream(handle, userId, streamId, &state)
        guard r == VC_OK else { return (VoiceCatResult(r), nil) }
        return (VoiceCatResult(r), Marshaling.remoteStreamState(state))
    }

    public func getStreamAudioConfig(userId: UInt32, streamId: UInt32) -> (VoiceCatResult, AudioConfig?) {
        var cfg = vc_audio_config()
        let r = vc_get_stream_audio_config(handle, userId, streamId, &cfg)
        guard r == VC_OK else { return (VoiceCatResult(r), nil) }
        return (VoiceCatResult(r), Marshaling.audioConfig(cfg))
    }

    // MARK: - Text

    @discardableResult
    public func sendText(scope: VoiceCatTextScope, targetId: UInt32, text: String) -> VoiceCatResult {
        VoiceCatResult(vc_send_text(handle, scope.cValue, targetId, text))
    }

    // MARK: - Device enumeration (works pre-connect)

    public func listDevices(_ kind: VoiceCatDeviceKind) -> [Device] {
        var native = vc_device_list()
        _ = vc_list_devices(handle, kind.cValue, &native)
        return Marshaling.devices(&native)
    }

    // MARK: - Moderation

    @discardableResult
    public func kickUser(_ userId: UInt32, reason: String? = nil) -> VoiceCatResult {
        VoiceCatResult(vc_kick_user(handle, userId, reason))
    }

    @discardableResult
    public func banUser(_ userId: UInt32, reason: String? = nil,
                        expiresUnixMs: UInt64 = 0) -> VoiceCatResult {
        VoiceCatResult(vc_ban_user(handle, userId, reason, expiresUnixMs))
    }

    @discardableResult
    public func setPermission(_ userId: UInt32, perms: Permissions) -> VoiceCatResult {
        var native = vc_permissions()
        native.can_create_temp_channel = perms.canCreateTempChannel ? 1 : 0
        native.can_kick = perms.canKick ? 1 : 0
        native.can_ban = perms.canBan ? 1 : 0
        native.can_move_users = perms.canMoveUsers ? 1 : 0
        native.can_admin_accounts = perms.canAdminAccounts ? 1 : 0
        native.is_admin = perms.isAdmin ? 1 : 0
        return VoiceCatResult(vc_set_permission(handle, userId, &native))
    }

    @discardableResult
    public func setServerMute(_ userId: UInt32, muted: Bool, deafened: Bool) -> VoiceCatResult {
        VoiceCatResult(vc_set_server_mute(handle, userId, muted ? 1 : 0, deafened ? 1 : 0))
    }

    @discardableResult
    public func moveUser(_ userId: UInt32, toChannel channelId: UInt32) -> VoiceCatResult {
        VoiceCatResult(vc_move_user(handle, userId, channelId))
    }

    // MARK: - Channel admin

    @discardableResult
    public func createChannel(_ info: ChannelEdit) -> VoiceCatResult {
        var native = vc_channel_info()
        Self.populateChannelInfo(&native, from: info)
        defer { Self.freeChannelInfoStrings(&native) }
        return VoiceCatResult(vc_create_channel(handle, &native))
    }

    @discardableResult
    public func editChannel(_ info: ChannelEdit) -> VoiceCatResult {
        var native = vc_channel_info()
        Self.populateChannelInfo(&native, from: info)
        defer { Self.freeChannelInfoStrings(&native) }
        return VoiceCatResult(vc_edit_channel(handle, &native))
    }

    @discardableResult
    public func deleteChannel(_ channelId: UInt32) -> VoiceCatResult {
        VoiceCatResult(vc_delete_channel(handle, channelId))
    }

    // MARK: - Account admin

    @discardableResult
    public func createAccount(_ username: String, password: String) -> VoiceCatResult {
        VoiceCatResult(vc_create_account(handle, username, password))
    }

    @discardableResult
    public func resetPassword(_ username: String, newPassword: String) -> VoiceCatResult {
        VoiceCatResult(vc_reset_password(handle, username, newPassword))
    }

    @discardableResult
    public func deleteAccount(_ username: String) -> VoiceCatResult {
        VoiceCatResult(vc_delete_account(handle, username))
    }

    /// Request the account list — result arrives as a `.accountList` event, then call
    /// `listAccounts()` to pull the cached list.
    @discardableResult
    public func requestAccountList() -> VoiceCatResult {
        VoiceCatResult(vc_list_accounts(handle))
    }

    public func listAccounts() -> [Account] {
        var native = vc_account_list()
        _ = vc_get_account_list(handle, &native)
        return Marshaling.accounts(&native)
    }

    public func getPermissions() -> Permissions {
        var native = vc_permissions()
        _ = vc_get_permissions(handle, &native)
        return Marshaling.permissions(native)
    }
}

// MARK: - Helpers for vc_channel_info / vc_audio_config construction

extension VoiceCatClient {
    /// Populate a `vc_channel_info` from a Swift `ChannelEdit`. The string fields
    /// (`name`/`topic`/`password`) are strdup'd — the caller MUST call
    /// `freeChannelInfoStrings(_:)` after the C call returns (the core copies what it needs
    /// during the call, so the temporary buffers can be freed via `defer`).
    internal static func populateChannelInfo(_ native: inout vc_channel_info, from info: ChannelEdit) {
        native.id = info.id
        native.parent_id = info.parentId
        native.name = UnsafePointer(strdup(info.name))
        native.topic = UnsafePointer(strdup(info.topic))
        native.password_protected = info.passwordProtected ? 1 : 0
        native.password = (info.passwordProtected && !(info.password?.isEmpty ?? true))
            ? UnsafePointer(strdup(info.password!)) : nil
        native.max_users = info.maxUsers
        native.sort_order = info.sortOrder
        native.audio = info.audio.toNative()
    }

    /// Free the strdup'd string fields of a `vc_channel_info` populated by
    /// `populateChannelInfo`. Call this in a `defer` after the C call.
    internal static func freeChannelInfoStrings(_ native: inout vc_channel_info) {
        if let p = native.name { free(UnsafeMutablePointer(mutating: p)); native.name = nil }
        if let p = native.topic { free(UnsafeMutablePointer(mutating: p)); native.topic = nil }
        if let p = native.password { free(UnsafeMutablePointer(mutating: p)); native.password = nil }
    }
}

extension AudioConfig {
    /// Convert to a native `vc_audio_config`.
    internal func toNative() -> vc_audio_config {
        var n = vc_audio_config()
        n.codec = codec
        n.mode = stereo ? 1 : 0
        n.sample_rate = sampleRate
        n.bitrate_bps = bitrateBps
        n.frame_ms = frameMs
        n.application = application
        n.fec = fec ? 1 : 0
        n.expected_packet_loss = expectedPacketLoss
        n.dtx = dtx ? 1 : 0
        n.complexity = complexity
        n.dred = dred ? 1 : 0
        return n
    }
}