eatvio_app/ios/Runner/AppDelegate.swift

import AVFAudio
import CallKit
import Flutter
import PushKit
import UIKit
import UserNotifications
import WebRTC
import YandexLoginSDK
import flutter_callkit_incoming
import flutter_foreground_task

@main
@objc class AppDelegate: FlutterAppDelegate, PKPushRegistryDelegate, CallkitIncomingAppDelegate {
  private var voipRegistry: PKPushRegistry?
  private var voipDiagnosticsChannel: FlutterMethodChannel?
  private let voipDiagnosticsStorageKey = "EatvioVoipDiagnostics"
  private let pendingAcceptedVoipCallKey = "EatvioPendingAcceptedVoipCall"
  private let voipDiagnosticsChannelName = "com.eatvioapp/voip_diagnostics"
  private let callAudioSessionChannelName = "com.eatvioapp/call_audio_session"
  private let appUrlScheme = "eatvio"
  /// CallKit is only the ringing UI. After accept the in-app call continues,
  /// so the audio session must be handed back to WebRTC when CallKit deactivates.
  private var resumeAudioAfterCallKitEnds = false
  /// The push handler and the Flutter channel touch this map on different
  /// queues. The push writes the id before CallKit has the call, so the
  /// in-app path can see it and not report the same call again.
  private var reservedIncomingCallIds: [String: Date] = [:]
  private let incomingCallClaimLock = NSLock()
  private let incomingCallClaimTtl: TimeInterval = 90
  private let voipPushQueue = DispatchQueue(label: "com.eatvioapp.voip")
  private var voipCallReporterStorage: VoipCallReporter?
  private var audioRestartGeneration = 0

  private var voipCallReporter: VoipCallReporter {
    if let voipCallReporterStorage {
      return voipCallReporterStorage
    }
    let reporter = VoipCallReporter()
    voipCallReporterStorage = reporter
    return reporter
  }

  override func application(
    _ application: UIApplication,
    didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
  ) -> Bool {
    GeneratedPluginRegistrant.register(with: self)
    SwiftFlutterForegroundTaskPlugin.setPluginRegistrantCallback { registry in
      GeneratedPluginRegistrant.register(with: registry)
    }

    // Not the main queue. Flutter startup blocks main, and PushKit aborts the
    // process if this push is not reported before that returns.
    voipRegistry = PKPushRegistry(queue: voipPushQueue)
    voipRegistry?.delegate = self
    voipRegistry?.desiredPushTypes = [PKPushType.voIP]
    configureWebRTCAudioSession()

    if #available(iOS 10.0, *) {
      UNUserNotificationCenter.current().delegate = self
    }

    let launched = super.application(application, didFinishLaunchingWithOptions: launchOptions)

    // WebRTC must not activate the session itself. CallKit and the in-app
    // call both own AVAudioSession, and a second activation drops the mic.
    let rtcSession = RTCAudioSession.sharedInstance()
    rtcSession.useManualAudio = true
    rtcSession.isAudioEnabled = false

    registerCallChannels(from: window?.rootViewController as? FlutterViewController)

    return launched
  }

  func registerCallChannels(from controller: FlutterViewController?) {
    guard voipDiagnosticsChannel == nil else { return }
    let flutterController = controller ?? flutterViewControllerFromScenes()
    guard let flutterController else { return }

    let channel = FlutterMethodChannel(
      name: voipDiagnosticsChannelName,
      binaryMessenger: flutterController.binaryMessenger
    )
    voipDiagnosticsChannel = channel
    channel.setMethodCallHandler { [weak self] call, result in
      guard let self else {
        result(nil)
        return
      }
      switch call.method {
      case "drainVoipDiagnostics":
        result(self.drainVoipDiagnostics())
      case "drainPendingAcceptedVoipCall":
        result(self.drainPendingAcceptedVoipCall())
      case "isIncomingCallClaimed":
        result(self.isIncomingCallClaimed(self.incomingCallId(from: call.arguments)))
      case "reserveIncomingCall":
        result(self.reserveIncomingCall(self.incomingCallId(from: call.arguments)))
      default:
        result(FlutterMethodNotImplemented)
      }
    }

    let callAudioChannel = FlutterMethodChannel(
      name: callAudioSessionChannelName,
      binaryMessenger: flutterController.binaryMessenger
    )
    callAudioChannel.setMethodCallHandler { [weak self] call, result in
      guard let self else {
        result(nil)
        return
      }
      switch call.method {
      case "activate":
        self.activateInAppCallAudioSession()
        result(nil)
      case "restart":
        self.restartInAppCallAudioUnit()
        result(nil)
      case "deactivate":
        self.deactivateInAppCallAudioSession()
        result(nil)
      default:
        result(FlutterMethodNotImplemented)
      }
    }
  }

  private func flutterViewControllerFromScenes() -> FlutterViewController? {
    for scene in UIApplication.shared.connectedScenes {
      guard let windowScene = scene as? UIWindowScene else { continue }
      for sceneWindow in windowScene.windows {
        if let controller = sceneWindow.rootViewController as? FlutterViewController {
          return controller
        }
      }
    }
    return nil
  }

  @available(iOS 8.0, *)
  override func application(
    _ application: UIApplication,
    continue userActivity: NSUserActivity,
    restorationHandler: @escaping ([UIUserActivityRestoring]?) -> Void
  ) -> Bool {
    if YXLSdk.shared.processUserActivity(userActivity) {
      return true
    }
    return super.application(
      application,
      continue: userActivity,
      restorationHandler: restorationHandler
    )
  }

  override public func application(
    _ app: UIApplication,
    open url: URL,
    options: [UIApplication.OpenURLOptionsKey: Any] = [:]
  ) -> Bool {
    handleOpenURL(
      url,
      sourceApplication: options[UIApplication.OpenURLOptionsKey.sourceApplication] as? String
    )
  }

  @discardableResult
  func handleOpenURL(_ url: URL, sourceApplication: String?) -> Bool {
    if url.scheme == appUrlScheme {
      let components = URLComponents(url: url, resolvingAgainstBaseURL: false)
      let queryItems = components?.queryItems ?? []
      let conversationUuid = queryItems.first { $0.name == "conversationUuid" }?.value?
        .trimmingCharacters(in: .whitespacesAndNewlines) ?? ""
      let callKitId = queryItems.first { $0.name == "callKitId" }?.value?
        .trimmingCharacters(in: .whitespacesAndNewlines)
      recordVoipDiagnostic(
        "accepted_call_url_opened",
        data: [
          "callKitId": callKitId ?? "",
          "hasCallKitId": callKitId != nil,
          "conversationUuid": conversationUuid,
          "url": url.absoluteString,
        ]
      )
      if let callKitId, !callKitId.isEmpty, !conversationUuid.isEmpty {
        voipDiagnosticsChannel?.invokeMethod(
          "acceptedVoipCall",
          arguments: [
            "id": callKitId,
            "handle": conversationUuid,
            "extra": [
              "conversationUuid": conversationUuid
            ],
          ]
        )
      }
      return true
    }

    return YXLSdk.shared.handleOpen(
      url,
      sourceApplication: sourceApplication
    )
  }

  /// Same derivation as [VideoCallKitId.iosUuid]: one CallKit UUID per message,
  /// so the next call in this chat is not rejected as a duplicate UUID.
  private func derivedCallKitId(conversationUuid: String, messageId: UInt64?) -> String? {
    guard let messageId, messageId > 0 else { return nil }
    let pattern =
      #"^([0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-)[0-9a-fA-F]{12}$"#
    guard let regex = try? NSRegularExpression(pattern: pattern) else { return nil }
    let range = NSRange(conversationUuid.startIndex..., in: conversationUuid)
    guard let match = regex.firstMatch(in: conversationUuid, range: range),
      let prefixRange = Range(match.range(at: 1), in: conversationUuid)
    else { return nil }
    let suffix = String(format: "%012llx", messageId)
    guard suffix.count == 12 else { return nil }
    return (String(conversationUuid[prefixRange]) + suffix).lowercased()
  }

  private func voipMessageId(_ value: Any?) -> UInt64? {
    if let number = value as? NSNumber {
      let parsed = number.uint64Value
      return parsed > 0 ? parsed : nil
    }
    if let text = value as? String {
      let trimmed = text.trimmingCharacters(in: .whitespacesAndNewlines)
      guard let parsed = UInt64(trimmed), parsed > 0 else { return nil }
      return parsed
    }
    return nil
  }

  private func conversationUuid(fromActionUrl actionUrl: String?) -> String? {
    guard
      let actionUrl = actionUrl,
      let components = URLComponents(string: actionUrl)
    else {
      return nil
    }

    let queryItems = components.queryItems ?? []
    for key: String in ["uuid", "conversationUuid", "conversation_uuid"] {
      if let value = queryItems.first(where: { $0.name == key })?.value,
        !value.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty
      {
        return value.trimmingCharacters(in: .whitespacesAndNewlines)
      }
    }

    let segments = components.path.split(separator: "/").map(String.init)
    for index in segments.indices where segments[index] == "video-call" {
      let nextIndex = segments.index(after: index)
      if segments.indices.contains(nextIndex), !segments[nextIndex].isEmpty {
        return segments[nextIndex]
      }
    }

    return nil
  }

  private func conversationUuid(fromCall call: Call) -> String? {
    let extra = call.data.extra as? [String: Any] ?? [:]
    for key in ["conversationUuid", "conversation_uuid", "conversation_id", "chat_uuid", "uuid"] {
      if let value = extra[key] as? String {
        let trimmed = value.trimmingCharacters(in: .whitespacesAndNewlines)
        if !trimmed.isEmpty {
          return trimmed
        }
      }
    }

    let handle = call.data.handle.trimmingCharacters(in: .whitespacesAndNewlines)
    if !handle.isEmpty {
      return handle
    }

    return nil
  }

  private func storePendingAcceptedCall(_ call: Call) {
    let payload = sanitizedDiagnosticValue(call.data.toJSON()) as? [String: Any] ?? [:]
    UserDefaults.standard.set(payload, forKey: pendingAcceptedVoipCallKey)
  }

  private func drainPendingAcceptedVoipCall() -> [String: Any]? {
    let defaults = UserDefaults.standard
    guard let payload = defaults.dictionary(forKey: pendingAcceptedVoipCallKey) else {
      return nil
    }
    defaults.removeObject(forKey: pendingAcceptedVoipCallKey)
    return payload
  }

  private func bringAppToForeground() {
    DispatchQueue.main.async {
      for scene in UIApplication.shared.connectedScenes {
        guard let windowScene = scene as? UIWindowScene else { continue }
        for window in windowScene.windows {
          window.makeKeyAndVisible()
        }
      }
      self.window?.makeKeyAndVisible()
    }
  }

  private func openAppForAcceptedCall(_ call: Call) {
    guard let conversationUuid = conversationUuid(fromCall: call), !conversationUuid.isEmpty else {
      recordVoipDiagnostic(
        "accepted_call_missing_conversation_uuid",
        data: ["callKitId": call.data.uuid]
      )
      return
    }

    var components = URLComponents()
    components.scheme = appUrlScheme
    components.host = "video-call"
    components.queryItems = [
      URLQueryItem(name: "callKitId", value: call.data.uuid),
      URLQueryItem(name: "conversationUuid", value: conversationUuid)
    ]

    guard let url = components.url else {
      recordVoipDiagnostic(
        "accepted_call_url_build_failed",
        data: [
          "callKitId": call.data.uuid,
          "conversationUuid": conversationUuid,
        ]
      )
      return
    }

    recordVoipDiagnostic(
      "accepted_call_open_app_requested",
      data: [
        "callKitId": call.data.uuid,
        "conversationUuid": conversationUuid,
        "url": url.absoluteString,
        "appState": UIApplication.shared.applicationState.rawValue,
      ]
    )

    bringAppToForeground()

    UIApplication.shared.open(url, options: [:]) { [weak self] success in
      self?.recordVoipDiagnostic(
        success ? "accepted_call_open_app_succeeded" : "accepted_call_open_app_failed",
        data: [
          "callKitId": call.data.uuid,
          "conversationUuid": conversationUuid,
          "url": url.absoluteString,
        ]
      )
    }
  }

  private func sanitizedDiagnosticValue(_ value: Any?) -> Any {
    guard let value = value else {
      return ""
    }
    if let string = value as? String {
      return string
    }
    if let number = value as? NSNumber {
      return number
    }
    if let bool = value as? Bool {
      return bool
    }
    if let dictionary = value as? [AnyHashable: Any] {
      return dictionary.reduce(into: [String: Any]()) { result, entry in
        result[String(describing: entry.key)] = sanitizedDiagnosticValue(entry.value)
      }
    }
    if let array = value as? [Any] {
      return array.map { sanitizedDiagnosticValue($0) }
    }
    return String(describing: value)
  }

  private func recordVoipDiagnostic(_ name: String, data: [String: Any]) {
    let defaults = UserDefaults.standard
    var events = defaults.array(forKey: voipDiagnosticsStorageKey) as? [[String: Any]] ?? []
    var event: [String: Any] = [
      "name": name,
      "timestamp": ISO8601DateFormatter().string(from: Date()),
      "appState": UIApplication.shared.applicationState.rawValue,
    ]
    event["data"] = sanitizedDiagnosticValue(data)
    events.append(event)
    if events.count > 20 {
      events = Array(events.suffix(20))
    }
    defaults.set(events, forKey: voipDiagnosticsStorageKey)
    DispatchQueue.main.async { [weak self] in
      self?.voipDiagnosticsChannel?.invokeMethod("voipDiagnosticsUpdated", arguments: nil)
    }
  }

  private func drainVoipDiagnostics() -> [[String: Any]] {
    let defaults = UserDefaults.standard
    let events = defaults.array(forKey: voipDiagnosticsStorageKey) as? [[String: Any]] ?? []
    defaults.removeObject(forKey: voipDiagnosticsStorageKey)
    return events
  }

  private func isEndedVideoCallMarker(_ marker: String) -> Bool {
    if marker == "video_call_ended" || marker == "video_call_end" {
      return true
    }
    return marker.contains("video_call")
      && (marker.contains("ended") || marker.hasSuffix("_end") || marker.hasSuffix("_cancel"))
  }

  private func incomingCallId(from arguments: Any?) -> String {
    let raw: String?
    if let id = arguments as? String {
      raw = id
    } else if let map = arguments as? [String: Any] {
      raw = map["id"] as? String
    } else {
      raw = nil
    }
    return raw?.trimmingCharacters(in: .whitespacesAndNewlines).lowercased() ?? ""
  }

  /// Caller must hold `incomingCallClaimLock`.
  private func pruneIncomingCallClaims(now: Date = Date()) {
    reservedIncomingCallIds = reservedIncomingCallIds.filter {
      now.timeIntervalSince($0.value) < incomingCallClaimTtl
    }
  }

  private func activeIncomingCallIds() -> Set<String> {
    let calls = SwiftFlutterCallkitIncomingPlugin.sharedInstance?.activeCalls() ?? []
    return Set(calls.compactMap { ($0["id"] as? String)?.lowercased() })
  }

  private func isIncomingCallClaimed(_ id: String) -> Bool {
    let normalized = id.lowercased()
    guard !normalized.isEmpty else { return false }
    let reserved = incomingCallClaimLock.withLock { () -> Bool in
      pruneIncomingCallClaims()
      return reservedIncomingCallIds[normalized] != nil
    }
    if reserved {
      return true
    }
    return activeIncomingCallIds().contains(normalized)
  }

  /// Returns false when this id is already reserved. The VoIP push still
  /// reports the call; this only stops the in-app path from reporting it too.
  private func reserveIncomingCall(_ id: String) -> Bool {
    let normalized = id.lowercased()
    guard !normalized.isEmpty else { return false }
    return incomingCallClaimLock.withLock {
      pruneIncomingCallClaims()
      if reservedIncomingCallIds[normalized] != nil {
        return false
      }
      reservedIncomingCallIds[normalized] = Date()
      return true
    }
  }

  private func releaseIncomingCallClaim(_ id: String) {
    incomingCallClaimLock.withLock {
      _ = reservedIncomingCallIds.removeValue(forKey: id.lowercased())
    }
  }

  /// An ended VoIP push has no message id, so its CallKit id is the
  /// conversation uuid, not the ringing call. End that conversation only.
  /// The first endCall while the push flag is set closes the call this push
  /// just reported; the next ones close the call that is actually ringing.
  private func endCallsForEndedPush(reportedId: String, conversationUuid: String) {
    guard let plugin = SwiftFlutterCallkitIncomingPlugin.sharedInstance else {
      releaseIncomingCallClaim(reportedId)
      return
    }
    let conversation = conversationUuid.trimmingCharacters(in: .whitespacesAndNewlines)
    var ids: [String] = []
    func append(_ id: String) {
      let normalized = id.trimmingCharacters(in: .whitespacesAndNewlines)
      guard !normalized.isEmpty else { return }
      if ids.contains(where: { $0.caseInsensitiveCompare(normalized) == .orderedSame }) {
        return
      }
      ids.append(normalized)
    }
    append(reportedId)
    for call in plugin.activeCalls() {
      let callId = (call["id"] as? String) ?? ""
      let handle = (call["handle"] as? String) ?? ""
      let extraUuid = extraConversationUuid(call["extra"])
      let sameId = callId.caseInsensitiveCompare(reportedId) == .orderedSame
      let sameConversation = !conversation.isEmpty && (
        handle.caseInsensitiveCompare(conversation) == .orderedSame
        || extraUuid.caseInsensitiveCompare(conversation) == .orderedSame
      )
      if sameId || sameConversation {
        append(callId)
      }
    }
    for id in ids {
      let endData = flutter_callkit_incoming.Data(
        id: id,
        nameCaller: "Итвио",
        handle: conversation,
        type: 1
      )
      plugin.endCall(endData)
      releaseIncomingCallClaim(id)
    }
  }

  private func activeCallId(forConversation conversationUuid: String) -> String? {
    let conversation = conversationUuid.trimmingCharacters(in: .whitespacesAndNewlines)
    guard !conversation.isEmpty else { return nil }
    let calls = SwiftFlutterCallkitIncomingPlugin.sharedInstance?.activeCalls() ?? []
    for call in calls {
      let callId = (call["id"] as? String) ?? ""
      guard !callId.isEmpty else { continue }
      let handle = (call["handle"] as? String) ?? ""
      let extraUuid = extraConversationUuid(call["extra"])
      if handle.caseInsensitiveCompare(conversation) == .orderedSame
        || extraUuid.caseInsensitiveCompare(conversation) == .orderedSame
      {
        return callId
      }
    }
    return nil
  }

  private func extraConversationUuid(_ extra: Any?) -> String {
    let map: [String: Any]
    if let typed = extra as? [String: Any] {
      map = typed
    } else if let object = extra as? NSDictionary {
      var converted: [String: Any] = [:]
      for (key, value) in object {
        if let key = key as? String {
          converted[key] = value
        }
      }
      map = converted
    } else {
      return ""
    }
    for key in ["conversationUuid", "conversation_uuid"] {
      if let value = map[key] as? String {
        let trimmed = value.trimmingCharacters(in: .whitespacesAndNewlines)
        if !trimmed.isEmpty {
          return trimmed
        }
      }
    }
    return ""
  }

  func pushRegistry(
    _ registry: PKPushRegistry,
    didUpdate credentials: PKPushCredentials,
    for type: PKPushType
  ) {
    let deviceToken = credentials.token.map { String(format: "%02x", $0) }.joined()
    DispatchQueue.main.async {
      SwiftFlutterCallkitIncomingPlugin.sharedInstance?.setDevicePushTokenVoIP(deviceToken)
    }
  }

  func pushRegistry(_ registry: PKPushRegistry, didInvalidatePushTokenFor type: PKPushType) {
    DispatchQueue.main.async {
      SwiftFlutterCallkitIncomingPlugin.sharedInstance?.setDevicePushTokenVoIP("")
    }
  }

  func pushRegistry(
    _ registry: PKPushRegistry,
    didReceiveIncomingPushWith payload: PKPushPayload,
    for type: PKPushType,
    completion: @escaping () -> Void
  ) {
    guard type == .voIP else {
      completion()
      return
    }

    let dict = payload.dictionaryPayload
    let pushMarkers = [
      dict["type"] as? String,
      dict["notification_type"] as? String,
      dict["event"] as? String,
      dict["action"] as? String,
      dict["push_type"] as? String,
      dict["call_type"] as? String,
    ]
      .compactMap { $0?.lowercased().replacingOccurrences(of: "-", with: "_") }

    let isEndedPush = pushMarkers.contains(where: { self.isEndedVideoCallMarker($0) })
    if isEndedPush {
      recordVoipDiagnostic(
        "voip_end_or_cancel_received",
        data: [
          "markers": pushMarkers,
          "payload": dict,
        ]
      )
    }

    let rawNameCaller = (dict["nameCaller"] as? String)
      ?? (dict["counterpartName"] as? String)
      ?? (dict["counterpart_name"] as? String)
      ?? (dict["caller_name"] as? String)
      ?? (dict["callerName"] as? String)
      ?? (dict["caller"] as? String)
      ?? ""
    let nameCaller = rawNameCaller.trimmingCharacters(in: .whitespacesAndNewlines).isEmpty
      ? "Итвио"
      : rawNameCaller.trimmingCharacters(in: .whitespacesAndNewlines)
    let conversationUuid = (dict["conversation_uuid"] as? String)
      ?? (dict["conversationUuid"] as? String)
      ?? (dict["conversation_id"] as? String)
      ?? (dict["chat_uuid"] as? String)
      ?? (dict["uuid"] as? String)
      ?? conversationUuid(fromActionUrl: dict["action_url"] as? String)
      ?? (dict["handle"] as? String)
      ?? ""
    let trimmedConversationUuid = conversationUuid.trimmingCharacters(in: .whitespacesAndNewlines)
    let parsedMessageId = voipMessageId(dict["message_id"])
    let id: String
    let callKitIdSourceName: String
    if isEndedPush, let existing = activeCallId(forConversation: trimmedConversationUuid) {
      id = existing
      callKitIdSourceName = "active_conversation"
    } else if let derived = derivedCallKitId(
      conversationUuid: trimmedConversationUuid,
      messageId: parsedMessageId
    ) {
      id = derived
      callKitIdSourceName = "conversation_and_message"
    } else if UUID(uuidString: trimmedConversationUuid) != nil {
      id = trimmedConversationUuid.lowercased()
      callKitIdSourceName = "conversation"
    } else {
      id = UUID().uuidString.lowercased()
      callKitIdSourceName = "generated"
    }
    let isVideo = (dict["isVideo"] as? Bool)
      ?? (dict["is_video"] as? Bool)
      ?? true

    var extra: [String: Any] = [:]
    if !trimmedConversationUuid.isEmpty {
      extra["conversationUuid"] = trimmedConversationUuid
    }
    if let avatar = dict["caller_avatar"] as? String ?? dict["avatar"] as? String
      ?? dict["avatarUrl"] as? String
      ?? dict["avatar_url"] as? String
      ?? dict["counterpartAvatarUrl"] as? String
      ?? dict["counterpart_avatar_url"] as? String
    {
      extra["counterpartAvatarUrl"] = avatar
    }
    if let messageId = dict["message_id"] as? String {
      extra["messageId"] = messageId
    }
    if let roomName = dict["room_name"] as? String {
      extra["roomName"] = roomName
    }
    if let localName = dict["localParticipantName"] as? String
      ?? dict["local_participant_name"] as? String
    {
      extra["localParticipantName"] = localName
    }
    if let counterpartName = dict["counterpartName"] as? String {
      extra["counterpartName"] = counterpartName
    } else if let counterpartName = dict["counterpart_name"] as? String {
      extra["counterpartName"] = counterpartName
    } else if !nameCaller.isEmpty {
      extra["counterpartName"] = nameCaller
    }
    // Closing this report looks like a user decline. Dart must not tell the
    // backend, or the server sends another ended VoIP and the other phone
    // shows it as a new incoming call.
    if isEndedPush {
      extra["endedPush"] = true
    }

    let data = flutter_callkit_incoming.Data(
      id: id,
      nameCaller: nameCaller,
      handle: trimmedConversationUuid.isEmpty ? nameCaller : trimmedConversationUuid,
      type: isVideo ? 1 : 0
    )
    data.duration = 45000
    data.extra = extra as NSDictionary
    // The plugin activates AVAudioSession itself on answer and again 1.2s
    // later. That drops the ringing UI and leaves one side silent. CallKit
    // and WebRTC own the session instead.
    data.configureAudioSession = false
    data.audioSessionActive = false
    data.audioSessionMode = "videoChat"
    // Do not set ringtonePath. The plugin stores that string as the ringtone
    // file name. "system_ringtone_default" is not in the app, so CallKit ends
    // the call at once and PushKit delivers the same push again.
    // Remember the id so the in-app socket path does not report it again.
    // The push itself must still be reported, or iOS kills the process.
    _ = reserveIncomingCall(id)

    NSLog(
      "[EatvioVoIP] report incoming call id=\(id) conversation=\(conversationUuid) state=\(UIApplication.shared.applicationState.rawValue) markers=\(pushMarkers.joined(separator: ",")) payload=\(dict)"
    )
    recordVoipDiagnostic(
      "voip_incoming_received",
      data: [
        "callKitId": id,
        "callKitIdSource": callKitIdSourceName,
        "conversationUuid": conversationUuid,
        "nameCaller": nameCaller,
        "isVideo": isVideo,
        "markers": pushMarkers,
        "payload": dict,
      ]
    )

    reportVoipPushToCallKit(
      data,
      callKitId: id,
      callKitIdSourceName: callKitIdSourceName,
      conversationUuid: conversationUuid,
      endAfterReport: isEndedPush,
      completion: completion
    )
  }

  /// PushKit kills the app unless every VoIP push is reported to CallKit and
  /// its completion handler runs. Both happen here, including an "ended" push.
  private func reportVoipPushToCallKit(
    _ data: flutter_callkit_incoming.Data,
    callKitId: String,
    callKitIdSourceName: String,
    conversationUuid: String,
    endAfterReport: Bool,
    completion: @escaping () -> Void
  ) {
    let gate = VoipPushCompletion(completion)
    let finish = { self.voipPushQueue.async { gate.call() } }
    voipPushQueue.asyncAfter(deadline: .now() + 1.5) {
      finish()
    }

    let afterReport = {
      if endAfterReport {
        DispatchQueue.main.async {
          self.endCallsForEndedPush(
            reportedId: callKitId,
            conversationUuid: conversationUuid
          )
        }
      }
      if let plugin = SwiftFlutterCallkitIncomingPlugin.sharedInstance {
        let activeCalls = plugin.activeCalls()
        let activeIds = activeCalls.compactMap { $0["id"] as? String }.joined(separator: ",")
        self.recordVoipDiagnostic(
          "callkit_report_completed",
          data: [
            "callKitId": callKitId,
            "callKitIdSource": callKitIdSourceName,
            "conversationUuid": conversationUuid,
            "activeCallIds": activeIds,
            "activeCallsCount": activeCalls.count,
            "endAfterReport": endAfterReport,
          ]
        )
      }
      finish()
    }

    if let plugin = SwiftFlutterCallkitIncomingPlugin.sharedInstance {
      plugin.showCallkitIncoming(data, fromPushKit: true, completion: afterReport)
      return
    }

    NSLog("[EatvioVoIP] CallKit plugin missing id=\(callKitId)")
    recordVoipDiagnostic(
      "callkit_plugin_missing",
      data: [
        "callKitId": callKitId,
        "conversationUuid": conversationUuid,
      ]
    )
    guard let uuid = UUID(uuidString: data.uuid) else {
      finish()
      return
    }
    voipCallReporter.report(
      uuid: uuid,
      callerName: data.nameCaller,
      hasVideo: data.type > 0
    ) { _ in
      if endAfterReport {
        self.voipCallReporter.provider.reportCall(
          with: uuid,
          endedAt: Date(),
          reason: .remoteEnded
        )
      }
      afterReport()
    }
  }


  func onAccept(_ call: Call, _ action: CXAnswerCallAction) {
    resumeAudioAfterCallKitEnds = true
    prepareCallAudioCategory()
    storePendingAcceptedCall(call)
    recordVoipDiagnostic(
      "callkit_accept_native",
      data: [
        "callKitId": call.data.uuid,
        "conversationUuid": conversationUuid(fromCall: call) ?? "",
        "data": call.data.toJSON(),
      ]
    )
    voipDiagnosticsChannel?.invokeMethod("acceptedVoipCall", arguments: call.data.toJSON())
    DispatchQueue.main.async { [weak self] in
      self?.bringAppToForeground()
      self?.openAppForAcceptedCall(call)
    }
    action.fulfill()
  }

  func onDecline(_ call: Call, _ action: CXEndCallAction) {
    resumeAudioAfterCallKitEnds = false
    audioRestartGeneration += 1
    action.fulfill()
  }

  func onEnd(_ call: Call, _ action: CXEndCallAction) {
    action.fulfill()
  }

  func onTimeOut(_ call: Call) {}

  func didActivateAudioSession(_ audioSession: AVAudioSession) {
    let rtcSession = RTCAudioSession.sharedInstance()
    rtcSession.useManualAudio = true
    rtcSession.audioSessionDidActivate(audioSession)
    applyCallAudioConfiguration(active: false)
    rtcSession.isAudioEnabled = true
  }

  func didDeactivateAudioSession(_ audioSession: AVAudioSession) {
    let rtcSession = RTCAudioSession.sharedInstance()
    rtcSession.audioSessionDidDeactivate(audioSession)
    // The audio unit is stopped, but isAudioEnabled stays true. A later
    // assignment of true is then a no-op and the microphone never restarts.
    rtcSession.isAudioEnabled = false
    guard resumeAudioAfterCallKitEnds else { return }
    DispatchQueue.main.async { [weak self] in
      guard let self, self.resumeAudioAfterCallKitEnds else { return }
      self.restartInAppCallAudioUnit()
    }
  }

  func providerDidReset() {
    resumeAudioAfterCallKitEnds = false
    audioRestartGeneration += 1
  }

  private func configureWebRTCAudioSession() {
    let configuration = callAudioConfiguration()
    RTCAudioSessionConfiguration.setWebRTC(configuration)
  }

  private func prepareCallAudioCategory() {
    applyCallAudioConfiguration(active: false)
  }

  private func activateInAppCallAudioSession() {
    let rtcSession = RTCAudioSession.sharedInstance()
    rtcSession.useManualAudio = true
    applyCallAudioConfiguration(active: true)
    // Starting the audio unit while the configuration lock is held deadlocks
    // the capture thread, so the mic stays silent.
    rtcSession.isAudioEnabled = true
  }

  /// Restarts capture after the previous audio graph has disconnected.
  /// Toggling the unit in the same turn makes voice processing throw.
  private func restartInAppCallAudioUnit() {
    audioRestartGeneration += 1
    let generation = audioRestartGeneration
    let rtcSession = RTCAudioSession.sharedInstance()
    rtcSession.useManualAudio = true
    rtcSession.isAudioEnabled = false
    DispatchQueue.main.asyncAfter(deadline: .now() + 0.25) { [weak self] in
      guard let self, generation == self.audioRestartGeneration else { return }
      self.activateInAppCallAudioSession()
    }
  }

  private func applyCallAudioConfiguration(active: Bool) {
    let rtcSession = RTCAudioSession.sharedInstance()
    rtcSession.lockForConfiguration()
    defer { rtcSession.unlockForConfiguration() }
    do {
      try rtcSession.setConfiguration(callAudioConfiguration(), active: active)
    } catch {
      NSLog("[EatvioVoIP] apply call audio configuration failed: \(error)")
    }
  }

  private func deactivateInAppCallAudioSession() {
    resumeAudioAfterCallKitEnds = false
    audioRestartGeneration += 1
    let rtcSession = RTCAudioSession.sharedInstance()
    rtcSession.isAudioEnabled = false
    rtcSession.lockForConfiguration()
    defer { rtcSession.unlockForConfiguration() }
    do {
      try rtcSession.setActive(false)
    } catch {
      NSLog("[EatvioVoIP] deactivate call audio session failed: \(error)")
    }
  }

  private func callAudioConfiguration() -> RTCAudioSessionConfiguration {
    let configuration = RTCAudioSessionConfiguration.webRTC()
    configuration.category = AVAudioSession.Category.playAndRecord.rawValue
    configuration.categoryOptions = [
      .allowBluetooth,
      .defaultToSpeaker,
    ]
    // videoChat is the speakerphone mode for a video call. voiceChat keeps
    // the input on the receiver, so the mic is silent once audio goes to
    // the loudspeaker.
    configuration.mode = AVAudioSession.Mode.videoChat.rawValue
    // Voice processing rejects 44.1 kHz and throws from AVAudioEngine.
    configuration.sampleRate = 48000
    configuration.ioBufferDuration = 0.02
    configuration.inputNumberOfChannels = 1
    configuration.outputNumberOfChannels = 1
    return configuration
  }
}

/// Reports a VoIP push when the Flutter CallKit plugin is not registered yet.
private final class VoipPushCompletion {
  private var finished = false
  private let completion: () -> Void

  init(_ completion: @escaping () -> Void) {
    self.completion = completion
  }

  func call() {
    if finished { return }
    finished = true
    completion()
  }
}

private final class VoipCallReporter: NSObject, CXProviderDelegate {
  let provider: CXProvider

  override init() {
    let configuration = CXProviderConfiguration(localizedName: "Итвио")
    configuration.supportsVideo = true
    configuration.maximumCallGroups = 1
    configuration.maximumCallsPerCallGroup = 1
    configuration.supportedHandleTypes = [.generic]
    provider = CXProvider(configuration: configuration)
    super.init()
    provider.setDelegate(self, queue: nil)
  }

  func report(
    uuid: UUID,
    callerName: String,
    hasVideo: Bool,
    completion: @escaping (Error?) -> Void
  ) {
    let update = CXCallUpdate()
    update.remoteHandle = CXHandle(type: .generic, value: callerName)
    update.localizedCallerName = callerName
    update.hasVideo = hasVideo
    provider.reportNewIncomingCall(with: uuid, update: update, completion: completion)
  }

  func providerDidReset(_ provider: CXProvider) {}
}