deflock-app/lib/screens/home_screen.dart

import 'package:flutter/material.dart';
import 'package:provider/provider.dart';
import 'package:latlong2/latlong.dart';

import '../app_state.dart';
import '../widgets/map_view.dart';
import 'package:flutter_map/flutter_map.dart';
import '../services/offline_area_service.dart';
import '../widgets/add_camera_sheet.dart';

class HomeScreen extends StatefulWidget {
  const HomeScreen({super.key});

  @override
  State<HomeScreen> createState() => _HomeScreenState();
}

class _HomeScreenState extends State<HomeScreen> {
  final GlobalKey<ScaffoldState> _scaffoldKey = GlobalKey<ScaffoldState>();
  final MapController _mapController = MapController();
  bool _followMe = true;

  void _openAddCameraSheet() {
    final appState = context.read<AppState>();
    appState.startAddSession();
    final session = appState.session!;          // guaranteed non‑null now

    _scaffoldKey.currentState!.showBottomSheet(
      (ctx) => AddCameraSheet(session: session),
    );
  }

  @override
  Widget build(BuildContext context) {
    final appState = context.watch<AppState>();

    return Scaffold(
      key: _scaffoldKey,
      appBar: AppBar(
        title: const Text('Flock Map'),
        actions: [
          IconButton(
            tooltip: _followMe ? 'Disable follow‑me' : 'Enable follow‑me',
            icon: Icon(_followMe ? Icons.gps_fixed : Icons.gps_off),
            onPressed: () => setState(() => _followMe = !_followMe),
          ),
          IconButton(
            icon: const Icon(Icons.settings),
            onPressed: () => Navigator.pushNamed(context, '/settings'),
          ),
        ],
      ),
      body: MapView(
        controller: _mapController,
        followMe: _followMe,
        onUserGesture: () {
          if (_followMe) setState(() => _followMe = false);
        },
      ),
      floatingActionButton: appState.session == null
          ? Column(
              mainAxisSize: MainAxisSize.min,
              crossAxisAlignment: CrossAxisAlignment.end,
              children: [
                FloatingActionButton.extended(
                  onPressed: _openAddCameraSheet,
                  icon: const Icon(Icons.add_location_alt),
                  label: const Text('Tag Camera'),
                  heroTag: 'tag_camera_fab',
                ),
                const SizedBox(height: 12),
                FloatingActionButton.extended(
                  onPressed: () => showDialog(
                    context: context,
                    builder: (ctx) => DownloadAreaDialog(controller: _mapController),
                  ),
                  icon: const Icon(Icons.download_for_offline),
                  label: const Text('Download'),
                  heroTag: 'download_fab',
                ),
              ],
            )
          : null,
      floatingActionButtonLocation: FloatingActionButtonLocation.endFloat,
    );
  }
}

// --- Download area dialog ---
class DownloadAreaDialog extends StatefulWidget {
  final MapController controller;
  const DownloadAreaDialog({super.key, required this.controller});

  @override
  State<DownloadAreaDialog> createState() => _DownloadAreaDialogState();
}

class _DownloadAreaDialogState extends State<DownloadAreaDialog> {
  double _zoom = 15;
  int? _minZoom;
  int? _tileCount;
  double? _mbEstimate;

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addPostFrameCallback((_) => _recomputeEstimates());
  }

  void _recomputeEstimates() {
    var bounds = widget.controller.camera.visibleBounds;
    // If the visible area is nearly zero, nudge the bounds for estimation
    const double epsilon = 0.0002;
    final latSpan = (bounds.north - bounds.south).abs();
    final lngSpan = (bounds.east - bounds.west).abs();
    if (latSpan < epsilon && lngSpan < epsilon) {
      bounds = LatLngBounds(
        LatLng(bounds.southWest.latitude - epsilon, bounds.southWest.longitude - epsilon),
        LatLng(bounds.northEast.latitude + epsilon, bounds.northEast.longitude + epsilon)
      );
    } else if (latSpan < epsilon) {
      bounds = LatLngBounds(
        LatLng(bounds.southWest.latitude - epsilon, bounds.southWest.longitude),
        LatLng(bounds.northEast.latitude + epsilon, bounds.northEast.longitude)
      );
    } else if (lngSpan < epsilon) {
      bounds = LatLngBounds(
        LatLng(bounds.southWest.latitude, bounds.southWest.longitude - epsilon),
        LatLng(bounds.northEast.latitude, bounds.northEast.longitude + epsilon)
      );
    }
    final minZoom = OfflineAreaService().findDynamicMinZoom(bounds);
    final maxZoom = _zoom.toInt();
    final nTiles = OfflineAreaService().computeTileList(bounds, minZoom, maxZoom).length;
    const kbPerTile = 6.5; // Empirically ~6.5kB average for OSM tiles at z=1-19
    final totalMb = (nTiles * kbPerTile) / 1024.0;
    setState(() {
      _minZoom = minZoom;
      _tileCount = nTiles;
      _mbEstimate = totalMb;
    });
  }

  @override
  Widget build(BuildContext context) {
    final bounds = widget.controller.camera.visibleBounds;
    final maxZoom = _zoom.toInt();
    // We recompute estimates when the zoom slider changes
    return AlertDialog(
      title: Row(
        children: const [
          Icon(Icons.download_for_offline),
          SizedBox(width: 10),
          Text("Download Map Area"),
        ],
      ),
      content: SizedBox(
        width: 350,
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            Row(
              mainAxisAlignment: MainAxisAlignment.spaceBetween,
              children: [
                const Text('Max zoom level'),
                Text('Z${_zoom.toStringAsFixed(0)}'),
              ],
            ),
            Slider(
              min: 12,
              max: 19,
              divisions: 7,
              label: 'Z${_zoom.toStringAsFixed(0)}',
              value: _zoom,
              onChanged: (v) {
                setState(() => _zoom = v);
                WidgetsBinding.instance.addPostFrameCallback((_) => _recomputeEstimates());
              },
            ),
            const SizedBox(height: 8),
            Row(
              mainAxisAlignment: MainAxisAlignment.spaceBetween,
              children: [
                const Text('Storage estimate:'),
                Text(_mbEstimate == null
                    ? '…'
                    : '${_tileCount} tiles, ${_mbEstimate!.toStringAsFixed(1)} MB'),
              ],
            ),
            if (_minZoom != null)
              Row(
                mainAxisAlignment: MainAxisAlignment.spaceBetween,
                children: [
                  const Text('Min zoom:'),
                  Text('Z$_minZoom'),
                ],
              )
          ],
        ),
      ),
      actions: [
        TextButton(
          onPressed: () => Navigator.pop(context),
          child: const Text('Cancel'),
        ),
        ElevatedButton(
          onPressed: () async {
            try {
              final id = DateTime.now().toIso8601String().replaceAll(':', '-');
              final appDocDir = await OfflineAreaService().getOfflineAreaDir();
              final dir = "${appDocDir.path}/$id";
              // Fire and forget: don't await download, so dialog closes immediately
              // ignore: unawaited_futures
              OfflineAreaService().downloadArea(
                id: id,
                bounds: bounds,
                minZoom: _minZoom ?? 12,
                maxZoom: maxZoom,
                directory: dir,
                onProgress: (progress) {},
                onComplete: (status) {},
              );
              Navigator.pop(context);
              ScaffoldMessenger.of(context).showSnackBar(
                const SnackBar(
                  content: Text('Download started!'),
                ),
              );
            } catch (e) {
              Navigator.pop(context);
              ScaffoldMessenger.of(context).showSnackBar(
                SnackBar(
                  content: Text('Failed to start download: $e'),
                ),
              );
            }
          },
          child: const Text('Download'),
        ),
      ],
    );
  }
}