import ActivityKit
import Flutter
import UIKit

// ─────────────────────────────────────────────────────────────────────────────
// Live Activity attributes.
//
// This MUST stay byte-for-byte compatible with InvoiceBatchAttributes in
// MusadaqLiveActivity/MusadaqLiveActivityBundle.swift. ActivityKit matches the
// app's activity to the widget's UI by attributes type name and shape, and the
// two targets compile separately, so the declaration is intentionally duplicated
// rather than shared. Change one, change the other.
// ─────────────────────────────────────────────────────────────────────────────
struct InvoiceBatchAttributes: ActivityAttributes {
  public struct ContentState: Codable, Hashable {
    var current: Int
    var total: Int
    var isDone: Bool
    var failed: Int = 0
    var statusText: String = ""
  }

  var companyName: String
}

@main
@objc class AppDelegate: FlutterAppDelegate {

  /// The Live Activity currently on screen, if any.
  private var currentActivity: Any?

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

    if let controller = window?.rootViewController as? FlutterViewController {
      registerLiveActivityChannel(with: controller.binaryMessenger)
    }

    return super.application(application, didFinishLaunchingWithOptions: launchOptions)
  }

  // MARK: - Flutter channel

  private func registerLiveActivityChannel(with messenger: FlutterBinaryMessenger) {
    let channel = FlutterMethodChannel(
      name: "com.musadaq.liveactivity",
      binaryMessenger: messenger
    )

    channel.setMethodCallHandler { [weak self] call, result in
      guard let self else {
        result(nil)
        return
      }

      let args = call.arguments as? [String: Any] ?? [:]

      switch call.method {
      case "start":
        self.startActivity(args: args, result: result)
      case "update":
        self.updateActivity(args: args, result: result)
      case "end":
        self.endActivity(args: args, result: result)
      case "isSupported":
        result(self.areActivitiesEnabled())
      default:
        result(FlutterMethodNotImplemented)
      }
    }
  }

  // MARK: - ActivityKit

  private func areActivitiesEnabled() -> Bool {
    if #available(iOS 16.2, *) {
      return ActivityAuthorizationInfo().areActivitiesEnabled
    }
    return false
  }

  /// Starts a Live Activity and returns its ActivityKit push token (hex) so the
  /// server can update it remotely while the app is closed.
  private func startActivity(args: [String: Any], result: @escaping FlutterResult) {
    guard #available(iOS 16.2, *) else {
      result(nil)
      return
    }

    guard ActivityAuthorizationInfo().areActivitiesEnabled else {
      // The user disabled Live Activities for this app. Not an error.
      result(nil)
      return
    }

    // Never stack activities: replace any previous one.
    endCurrentActivityImmediately()

    let companyName = args["companyName"] as? String ?? ""
    let total = args["total"] as? Int ?? 1
    let current = args["current"] as? Int ?? 0

    let attributes = InvoiceBatchAttributes(companyName: companyName)
    let state = InvoiceBatchAttributes.ContentState(
      current: current,
      total: max(total, 1),
      isDone: false,
      failed: 0,
      statusText: "جارٍ الرفع"
    )

    do {
      let activity = try Activity<InvoiceBatchAttributes>.request(
        attributes: attributes,
        content: .init(state: state, staleDate: Date().addingTimeInterval(30 * 60)),
        pushType: .token
      )
      self.currentActivity = activity

      // The push token arrives asynchronously, so hand the result back from the
      // first token update rather than blocking here.
      var didReturn = false
      let lock = NSLock()

      Task {
        for await tokenData in activity.pushTokenUpdates {
          let token = tokenData.map { String(format: "%02x", $0) }.joined()
          lock.lock()
          let shouldReturn = !didReturn
          didReturn = true
          lock.unlock()

          if shouldReturn {
            DispatchQueue.main.async { result(token) }
          } else {
            // Token rotated mid-activity: tell Flutter so it can re-register.
            DispatchQueue.main.async {
              if let controller = self.window?.rootViewController as? FlutterViewController {
                FlutterMethodChannel(
                  name: "com.musadaq.liveactivity",
                  binaryMessenger: controller.binaryMessenger
                ).invokeMethod("onPushTokenChanged", arguments: token)
              }
            }
          }
        }
      }

      // Don't leave Flutter awaiting forever if no token ever arrives.
      DispatchQueue.main.asyncAfter(deadline: .now() + 5) {
        lock.lock()
        let shouldReturn = !didReturn
        didReturn = true
        lock.unlock()
        if shouldReturn { result(nil) }
      }
    } catch {
      NSLog("[LiveActivity] request failed: \(error.localizedDescription)")
      result(FlutterError(
        code: "START_FAILED",
        message: error.localizedDescription,
        details: nil
      ))
    }
  }

  private func updateActivity(args: [String: Any], result: @escaping FlutterResult) {
    guard #available(iOS 16.2, *),
          let activity = currentActivity as? Activity<InvoiceBatchAttributes> else {
      result(nil)
      return
    }

    let current = args["current"] as? Int ?? 0
    let total = max(args["total"] as? Int ?? 1, 1)
    let failed = args["failed"] as? Int ?? 0
    let isDone = args["isDone"] as? Bool ?? false
    let statusText = args["statusText"] as? String ?? ""

    let state = InvoiceBatchAttributes.ContentState(
      current: current,
      total: total,
      isDone: isDone,
      failed: failed,
      statusText: statusText
    )

    Task {
      await activity.update(.init(state: state, staleDate: Date().addingTimeInterval(30 * 60)))
      DispatchQueue.main.async { result(nil) }
    }
  }

  private func endActivity(args: [String: Any], result: @escaping FlutterResult) {
    guard #available(iOS 16.2, *),
          let activity = currentActivity as? Activity<InvoiceBatchAttributes> else {
      currentActivity = nil
      result(nil)
      return
    }

    let finalText = args["finalText"] as? String ?? "اكتمل"
    let finalState = InvoiceBatchAttributes.ContentState(
      current: activity.content.state.total,
      total: activity.content.state.total,
      isDone: true,
      failed: activity.content.state.failed,
      statusText: finalText
    )

    currentActivity = nil

    Task {
      // Leave the finished state visible briefly instead of vanishing instantly.
      await activity.end(
        .init(state: finalState, staleDate: nil),
        dismissalPolicy: .after(Date().addingTimeInterval(10))
      )
      DispatchQueue.main.async { result(nil) }
    }
  }

  private func endCurrentActivityImmediately() {
    guard #available(iOS 16.2, *),
          let activity = currentActivity as? Activity<InvoiceBatchAttributes> else {
      return
    }
    currentActivity = nil
    Task { await activity.end(nil, dismissalPolicy: .immediate) }
  }
}