firebase-ios-sdk/FirebaseAuth/Sources/Swift/Auth/AuthComponent.swift

// Copyright 2023 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

import FirebaseAppCheckInterop
import FirebaseCore
import FirebaseCoreExtension
import Foundation

@available(iOS 13, tvOS 13, macOS 10.15, macCatalyst 13, watchOS 7, *)
@objc(FIRAuthProvider) protocol AuthProvider {
  @objc func auth() -> Auth
}

@available(iOS 13, tvOS 13, macOS 10.15, macCatalyst 13, watchOS 7, *)
@objc(FIRAuthComponent)
class AuthComponent: NSObject, Library, AuthProvider, ComponentLifecycleMaintainer {
  // MARK: - Private Variables

  /// The app associated with all Auth instances in this container.
  /// This is `unowned` instead of `weak` so it can be used without unwrapping in `auth()`
  private unowned let app: FirebaseApp

  /// A map of active instances, grouped by app. Keys are FirebaseApp names and values are arrays
  /// containing all instances of Auth associated with the given app.
  private var instances: [String: Auth] = [:]

  /// Lock to manage access to the instances array to avoid race conditions.
  private var instancesLock: os_unfair_lock = .init()

  // MARK: - Initializers

  required init(app: FirebaseApp) {
    self.app = app
  }

  // MARK: - Library conformance

  static func componentsToRegister() -> [Component] {
    let appCheckInterop = Dependency(with: AppCheckInterop.self, isRequired: false)
    return [Component(AuthProvider.self,
                      instantiationTiming: .alwaysEager,
                      dependencies: [appCheckInterop]) { container, isCacheable in
        guard let app = container.app else { return nil }
        isCacheable.pointee = true
        let newComponent = AuthComponent(app: app)
        // Set up instances early enough so User on keychain will be decoded.
        newComponent.auth()
        return newComponent
      }]
  }

  // MARK: - AuthProvider conformance

  @discardableResult func auth() -> Auth {
    os_unfair_lock_lock(&instancesLock)

    // Unlock before the function returns.
    defer { os_unfair_lock_unlock(&instancesLock) }

    if let instance = instances[app.name] {
      return instance
    }
    let newInstance = FirebaseAuth.Auth(app: app)
    instances[app.name] = newInstance
    return newInstance
  }

  // MARK: - ComponentLifecycleMaintainer conformance

  func appWillBeDeleted(_ app: FirebaseApp) {
    kAuthGlobalWorkQueue.async {
      // This doesn't stop any request already issued, see b/27704535

      if let keychainServiceName = Auth.keychainServiceName(forAppName: app.name) {
        Auth.deleteKeychainServiceNameForAppName(app.name)
        let keychain = AuthKeychainServices(service: keychainServiceName)
        let userKey = "\(app.name)_firebase_user"
        try? keychain.removeData(forKey: userKey)
      }
      DispatchQueue.main.async {
        // TODO(ObjC): Move over to fire an event instead, once ready.
        NotificationCenter.default.post(name: Auth.authStateDidChangeNotification, object: nil)
      }
    }
  }
}