import 'dart:async';
import 'dart:convert';

import 'package:flutter_inappwebview/flutter_inappwebview.dart';
import 'package:geolocator/geolocator.dart';
import 'package:getx_scaffold/getx_scaffold.dart';
import 'package:permission_handler/permission_handler.dart';

class MapController extends GetxController with BaseControllerMixin ,WidgetsBindingObserver{
  @override
  String get builderId => 'map';

  InAppWebViewController? webViewController;
  StreamSubscription<Position>? positionStream;

  // --- 状态标志 ---
  final RxBool isLocationPermissionGranted = false.obs;
  final RxBool isMapReady = false.obs; // 跟踪地图是否加载完成

  Position? _lastKnownPosition;

  @override
  void onInit() {
    super.onInit();
    WidgetsBinding.instance.addObserver(this); // 注册监听
    requestLocationPermission();
  }

  @override
  void onClose() {
    WidgetsBinding.instance.removeObserver(this); // 移除监听
    positionStream?.cancel();
    super.onClose();
  }

  @override
  void didChangeAppLifecycleState(AppLifecycleState state) {
    if (state == AppLifecycleState.resumed) {
      // 回到前台，如果之前有权限且开启过，恢复定位
      if(isLocationPermissionGranted.value) _startLocationTracking();
    } else if (state == AppLifecycleState.paused) {
      // 切到后台，取消定位流
      positionStream?.cancel();
    }
  }

  /// WebView 创建完成时调用
  void onWebViewCreated(InAppWebViewController controller) {
    webViewController = controller;
    // 添加 JS Handler 来监听来自网页的 'mapReady' 事件
    controller.addJavaScriptHandler(
      handlerName: 'mapReady',
      callback: (args) {
        print("Flutter<-JS: Map is ready, starting location tracking.");
        isMapReady.value = true;
        // 地图就绪后，如果已有权限和缓存的定位，则开始定位
        if (isLocationPermissionGranted.value) {
          _startLocationTracking();
        }
      },
    );
  }

  /// 优化后的权限请求函数
  void requestLocationPermission() async {
    bool serviceEnabled = await Geolocator.isLocationServiceEnabled();
    if (!serviceEnabled) {
      showErrorToast('请开启手机的定位服务');
      return;
    }

    var status = await Permission.locationWhenInUse.request();

    switch (status) {
      case PermissionStatus.granted:
        isLocationPermissionGranted.value = true;
        // 权限已获取，如果地图也已就绪，则开始定位
        if (isMapReady.value) {
          _startLocationTracking();
        }
        break;
      case PermissionStatus.denied:
        showErrorToast('需要定位权限才能显示您的位置');
        break;
      case PermissionStatus.permanentlyDenied:
        showErrorToast('定位权限已被永久拒绝，请到设置中手动开启');
        openAppSettings();
        break;
      default:
        showErrorToast('获取定位权限时发生未知错误');
        break;
    }
  }

  /// 开始定位监听 (不再需要 delay)
  void _startLocationTracking() async {
    if (!isLocationPermissionGranted.value ||
        !await Geolocator.isLocationServiceEnabled()) {
      return;
    }

    const LocationSettings locationSettings = LocationSettings(
      accuracy: LocationAccuracy.high,
      distanceFilter: 10,
    );

    // 立即获取一次当前位置，用于快速初始化
    try {
      Position position = await Geolocator.getCurrentPosition();
      _lastKnownPosition = position;
      _syncLocationToMap(position);
    } catch (e) {
      print("Error getting initial position: $e");
    }

    // 持续监听位置变化
    positionStream?.cancel(); // 先取消旧的监听
    positionStream = Geolocator.getPositionStream(locationSettings: locationSettings)
        .listen((Position position) {
          _lastKnownPosition = position;
          _syncLocationToMap(position);
        });
  }

  // 将 Flutter 的定位数据同步给 JS
  void _syncLocationToMap(Position position) {
    if (webViewController == null || !isMapReady.value) return;
    // 只有当 heading 有效且大于 0 时才传给 JS，否则传 null，让 JS 保持上一次的角度
    String headingVal = (position.heading > 0) ? "${position.heading}" : "null";

    webViewController!.evaluateJavascript(
      source:
          "updateMyLocation(${position.latitude}, ${position.longitude}, ${position.heading})",
    );
  }
}