import 'dart:math';
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:geolocator/geolocator.dart';
import 'package:google_maps_flutter/google_maps_flutter.dart';
import 'package:permission_handler/permission_handler.dart';

class ServiceLocationsRadiusScreen extends StatefulWidget {
  final LatLng? initialPosition;
  final ValueListenable<double>? radiusKmListenable;

  const ServiceLocationsRadiusScreen({
    Key? key,
    this.initialPosition,
    this.radiusKmListenable,
  }) : super(key: key);

  @override
  State<ServiceLocationsRadiusScreen> createState() =>
      _ServiceLocationsRadiusScreenState();
}

class _ServiceLocationsRadiusScreenState
    extends State<ServiceLocationsRadiusScreen> {
  GoogleMapController? _controller;
  LatLng? _currentPosition;
  LatLng? _circleCenter;
  bool _isMapReady = false;
  Set<Circle> _circles = {};

  final double _fallbackRadiusMeters = 10000; // 10 km
  final LatLng _indiaCenter = const LatLng(20.5937, 78.9629);

  @override
  void initState() {
    super.initState();
    if (widget.initialPosition == null) {
      _checkLocationPermissionAndGetCurrentPosition();
    } else {
      _circleCenter = widget.initialPosition;
    }

    widget.radiusKmListenable?.addListener(_onRadiusChangedFromParent);
  }

  @override
  void dispose() {
    widget.radiusKmListenable?.removeListener(_onRadiusChangedFromParent);
    super.dispose();
  }

  // 🔹 When radius changes in parent
  void _onRadiusChangedFromParent() {
    final km =
        widget.radiusKmListenable?.value ?? (_fallbackRadiusMeters / 1000.0);
    final meters = km * 1000.0;
    final center = _circleCenter ?? _currentPosition ?? _indiaCenter;
    _addRadiusCircle(center, radiusInMeters: meters);
  }

  // 🔹 Get current location
  Future<void> _checkLocationPermissionAndGetCurrentPosition() async {
    var status = await Permission.location.status;
    if (!status.isGranted) {
      status = await Permission.location.request();
      if (!status.isGranted) return;
    }

    bool serviceEnabled = await Geolocator.isLocationServiceEnabled();
    if (!serviceEnabled) return;

    final position = await Geolocator.getCurrentPosition();
    setState(() {
      _currentPosition = LatLng(position.latitude, position.longitude);
    });
  }

  // 🔹 Add / update the circle
  void _addRadiusCircle(LatLng center, {double? radiusInMeters}) async {
    final meters = radiusInMeters ??
        (widget.radiusKmListenable?.value ?? (_fallbackRadiusMeters / 1000.0)) *
            1000.0;

    setState(() {
      _circleCenter = center;
      _circles = {
        Circle(
          circleId: const CircleId("radius_circle"),
          center: center,
          radius: meters,
          fillColor: Colors.blue.withOpacity(0.2),
          strokeColor: Colors.blueAccent,
          strokeWidth: 2,
        ),
      };
    });

    // 👇 adjust zoom so full circle is visible even in small container
    if (_controller != null) {
      final zoom = _getZoomLevelForSmallMap(meters);
      await _controller!.animateCamera(
        CameraUpdate.newCameraPosition(
          CameraPosition(target: center, zoom: zoom),
        ),
      );
    }
  }

  // 🔹 Calculate zoom for small map container (200–300 px)
  double _getZoomLevelForSmallMap(double radiusMeters) {
    // Adjust constant here if map size differs
    final scale = radiusMeters / 200; // Smaller scale for small map
    double zoomLevel = 16 - log(scale) / log(2);
    if (zoomLevel > 18) zoomLevel = 18;
    if (zoomLevel < 4) zoomLevel = 4;
    return zoomLevel;
  }

  @override
  Widget build(BuildContext context) {
    final LatLng target =
        widget.initialPosition ?? _currentPosition ?? _indiaCenter;

    final initialCameraPosition = CameraPosition(
      target: target,
      zoom: 12,
    );

    return GoogleMap(
      initialCameraPosition: initialCameraPosition,
      mapType: MapType.normal,
      circles: _circles,
      zoomControlsEnabled: false,
      myLocationEnabled: false,
      myLocationButtonEnabled: false,
      onMapCreated: (controller) async {
        _controller = controller;
        _isMapReady = true;

        await Future.delayed(const Duration(milliseconds: 500));
        final center = widget.initialPosition ?? _currentPosition ?? _indiaCenter;
        final km = widget.radiusKmListenable?.value ?? 10;
        _addRadiusCircle(center, radiusInMeters: km * 1000.0);
      },
    );
  }
}