import Flutter
import UIKit
import AVFoundation

private let thumbnailHTTPHeaderFieldsKey = "AVURLAssetHTTPHeaderFieldsKey"

private final class ThumbnailResponseGate {
  private let lock = NSLock()
  private var completed = false

  func send(_ result: @escaping FlutterResult, data: Data?) {
    lock.lock()
    if completed {
      lock.unlock()
      return
    }
    completed = true
    lock.unlock()
    DispatchQueue.main.async {
      result(data)
    }
  }
}

/// Keeps the system LaunchScreen as the only splash. Flutter would otherwise
/// instantiate that storyboard again and the icon appears a second time.
final class RunnerFlutterViewController: FlutterViewController {
  override func loadDefaultSplashScreenView() -> Bool {
    false
  }

  override func viewDidLoad() {
    super.viewDidLoad()
    view.backgroundColor = .black
  }
}

@main
@objc class AppDelegate: FlutterAppDelegate, FlutterImplicitEngineDelegate {
  private let thumbnailQueue = DispatchQueue(
    label: "com.stormg.lumadrama.thumbnail",
    qos: .userInitiated
  )

  override func application(
    _ application: UIApplication,
    didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
  ) -> Bool {
    UIApplication.shared.isIdleTimerDisabled = true
    return super.application(application, didFinishLaunchingWithOptions: launchOptions)
  }

  func didInitializeImplicitFlutterEngine(_ engineBridge: FlutterImplicitEngineBridge) {
    GeneratedPluginRegistrant.register(with: engineBridge.pluginRegistry)
    let channel = FlutterMethodChannel(
      name: "com.stormg.lumadrama/share",
      binaryMessenger: engineBridge.applicationRegistrar.messenger()
    )
    channel.setMethodCallHandler { [weak self] call, result in
      guard call.method == "shareText",
            let arguments = call.arguments as? [String: Any],
            let text = arguments["text"] as? String,
            !text.isEmpty,
            let controller = self?.window?.rootViewController else {
        result(FlutterError(code: "share_unavailable", message: "Share sheet is unavailable", details: nil))
        return
      }
      let activity = UIActivityViewController(activityItems: [text], applicationActivities: nil)
      activity.popoverPresentationController?.sourceView = controller.view
      activity.completionWithItemsHandler = { _, _, _, _ in result(nil) }
      controller.present(activity, animated: true)
    }

    let thumbnailChannel = FlutterMethodChannel(
      name: "com.stormg.lumadrama/thumbnail",
      binaryMessenger: engineBridge.applicationRegistrar.messenger()
    )
    thumbnailChannel.setMethodCallHandler { [weak self] call, result in
      guard call.method == "frame" else {
        result(FlutterMethodNotImplemented)
        return
      }
      guard let self,
            let arguments = call.arguments as? [String: Any],
            let timeNumber = arguments["timeMs"] as? NSNumber else {
        result(nil)
        return
      }
      let localPath = arguments["localPath"] as? String ?? ""
      let remoteUrl = arguments["url"] as? String ?? ""
      let headers = arguments["headers"] as? [String: String] ?? [:]
      let assetUrl: URL?
      if !localPath.isEmpty {
        assetUrl = localPath.hasPrefix("file:")
          ? URL(string: localPath)
          : URL(fileURLWithPath: localPath)
      } else if !remoteUrl.isEmpty {
        assetUrl = URL(string: remoteUrl)
      } else {
        assetUrl = nil
      }
      guard let assetUrl else {
        result(nil)
        return
      }

      let options: [String: Any]? = headers.isEmpty
        ? nil
        : [thumbnailHTTPHeaderFieldsKey: headers]
      let asset = AVURLAsset(url: assetUrl, options: options)
      let generator = AVAssetImageGenerator(asset: asset)
      generator.appliesPreferredTrackTransform = true
      generator.maximumSize = CGSize(width: 240, height: 426)
      generator.requestedTimeToleranceBefore = CMTime(seconds: 0.5, preferredTimescale: 600)
      generator.requestedTimeToleranceAfter = CMTime(seconds: 0.5, preferredTimescale: 600)
      let time = CMTime(value: timeNumber.int64Value, timescale: 1000)
      let gate = ThumbnailResponseGate()

      self.thumbnailQueue.async {
        do {
          let image = try generator.copyCGImage(at: time, actualTime: nil)
          let data = UIImage(cgImage: image).jpegData(compressionQuality: 0.7)
          gate.send(result, data: data)
        } catch {
          gate.send(result, data: nil)
        }
      }
      DispatchQueue.global(qos: .userInitiated).asyncAfter(
        deadline: .now() + 1.5
      ) {
        gate.send(result, data: nil)
      }
    }
  }
}