import Flutter
import UIKit

@main
@objc class AppDelegate: FlutterAppDelegate, FlutterImplicitEngineDelegate {
  override func application(
    _ application: UIApplication,
    didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
  ) -> Bool {
    // 后台会话启动即重建：App 被系统在后台拉起（Dart 引擎未起）时，
    // delegate 回调即可入总线缓存（终态落盘，引擎 onListen 后重放）。
    UploadPlugin.shared.ensureSession()
    return super.application(application, didFinishLaunchingWithOptions: launchOptions)
  }

  func didInitializeImplicitFlutterEngine(_ engineBridge: FlutterImplicitEngineBridge) {
    GeneratedPluginRegistrant.register(with: engineBridge.pluginRegistry)
    // 上传桥接（P3 Task 8）：MethodChannel 命令 + EventChannel 事件流
    // （通道/协议与 Android UploadPlugin 一致，Dart 侧同一 NativeTransport）。
    UploadPlugin.register(with: engineBridge.applicationRegistrar.messenger())
  }

  /// 系统完成后台会话事件投递前的拉起回调：暂存 completionHandler，
  /// 供 urlSessionDidFinishEvents 消费（否则 App 被系统挂起惩罚）。
  override func application(
    _ application: UIApplication,
    handleEventsForBackgroundURLSession identifier: String,
    completionHandler: @escaping () -> Void
  ) {
    super.application(
      application, handleEventsForBackgroundURLSession: identifier,
      completionHandler: completionHandler)
    if identifier == UploadBridge.sessionIdentifier {
      UploadPlugin.shared.ensureSession()
      UploadPlugin.shared.storeBackgroundCompletionHandler(completionHandler)
    }
  }
}