import Flutter
import Security
import UIKit

@main
@objc class AppDelegate: FlutterAppDelegate {
  override func application(
    _ application: UIApplication,
    didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
  ) -> Bool {
    GeneratedPluginRegistrant.register(with: self)
    registerDurableAuthStorageChannel()
    registerMobileContextChannel()
    return super.application(application, didFinishLaunchingWithOptions: launchOptions)
  }

  private func registerMobileContextChannel() {
    guard let controller = window?.rootViewController as? FlutterViewController else {
      return
    }
    let channel = FlutterMethodChannel(
      name: "com.org.yumiparty/mobile_context",
      binaryMessenger: controller.binaryMessenger
    )
    channel.setMethodCallHandler { call, result in
      switch call.method {
      case "getTimeZoneIdentifier":
        result(TimeZone.current.identifier)
      default:
        result(FlutterMethodNotImplemented)
      }
    }
  }

  private func registerDurableAuthStorageChannel() {
    guard let controller = window?.rootViewController as? FlutterViewController else {
      return
    }
    let channel = FlutterMethodChannel(
      name: "com.org.yumiparty/durable_auth_storage",
      binaryMessenger: controller.binaryMessenger
    )
    channel.setMethodCallHandler { [weak self] call, result in
      guard
        let self,
        let args = call.arguments as? [String: Any],
        let key = args["key"] as? String
      else {
        result(FlutterError(code: "bad_args", message: "Missing key", details: nil))
        return
      }

      switch call.method {
      case "write":
        guard let value = args["value"] as? String else {
          result(FlutterError(code: "bad_args", message: "Missing value", details: nil))
          return
        }
        self.writeKeychainValue(value, key: key)
        result(nil)
      case "read":
        result(self.readKeychainValue(key: key))
      case "delete":
        self.deleteKeychainValue(key: key)
        result(nil)
      default:
        result(FlutterMethodNotImplemented)
      }
    }
  }

  private func keychainQuery(key: String) -> [String: Any] {
    [
      kSecClass as String: kSecClassGenericPassword,
      kSecAttrService as String: "com.org.yumiparty.durable_auth_storage",
      kSecAttrAccount as String: key
    ]
  }

  private func writeKeychainValue(_ value: String, key: String) {
    deleteKeychainValue(key: key)
    guard let data = value.data(using: .utf8) else {
      return
    }
    var query = keychainQuery(key: key)
    query[kSecValueData as String] = data
    query[kSecAttrAccessible as String] = kSecAttrAccessibleAfterFirstUnlock
    SecItemAdd(query as CFDictionary, nil)
  }

  private func readKeychainValue(key: String) -> String? {
    var query = keychainQuery(key: key)
    query[kSecReturnData as String] = true
    query[kSecMatchLimit as String] = kSecMatchLimitOne

    var result: AnyObject?
    let status = SecItemCopyMatching(query as CFDictionary, &result)
    guard
      status == errSecSuccess,
      let data = result as? Data
    else {
      return nil
    }
    return String(data: data, encoding: .utf8)
  }

  private func deleteKeychainValue(key: String) {
    SecItemDelete(keychainQuery(key: key) as CFDictionary)
  }
}