import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:maplibre_gl/maplibre_gl.dart';

import '../../core/config/env.dart';
import '../../core/region/region_config.dart';
import '../../core/region/region_repository.dart';
import '../../l10n/app_localizations.dart';
import 'attribution_bar.dart';
import 'map_style.dart';

/// The radar map.
///
/// Milestone 2 renders the base map, frames it on the region and keeps the
/// attribution visible. The radar image layers and the timeline arrive in
/// milestone 3.
class RadarMapScreen extends ConsumerWidget {
  const RadarMapScreen({super.key});

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final l10n = AppLocalizations.of(context);
    final region = ref.watch(regionConfigProvider);

    return Scaffold(
      appBar: AppBar(title: Text(l10n.appTitle)),
      body: switch (region) {
        AsyncData(:final value) => _MapWithAttribution(region: value),
        AsyncError(:final error) => Center(
          child: Padding(
            padding: const EdgeInsets.all(24),
            child: Text('${l10n.dataUnavailable}\n$error'),
          ),
        ),
        _ => Center(child: Text(l10n.loading)),
      },
    );
  }
}

class _MapWithAttribution extends StatelessWidget {
  const _MapWithAttribution({required this.region});

  final RegionConfig region;

  @override
  Widget build(BuildContext context) {
    final l10n = AppLocalizations.of(context);
    final style = MapStyle.forRegion(region);

    return Column(
      children: [
        if (Env.isDemoMode)
          MaterialBanner(
            content: Text(l10n.demoModeBanner),
            actions: const [SizedBox.shrink()],
          ),
        Expanded(
          child: _RegionMap(region: region, style: style),
        ),
        // Outside the map rather than floating over it, so the credit can never
        // be occluded by a map control. SafeArea keeps it clear of the system
        // gesture bar as well — a credit sitting behind the navigation pill is
        // a credit that is not being displayed.
        SafeArea(
          top: false,
          child: AttributionBar(
            region: region,
            activeSourceIds: style.attributionIds,
            showBaseMapNotice: style.kind == BaseMapKind.offlineFallback,
          ),
        ),
      ],
    );
  }
}

class _RegionMap extends StatelessWidget {
  const _RegionMap({required this.region, required this.style});

  final RegionConfig region;
  final MapStyle style;

  /// Frames the whole region once the map is ready.
  ///
  /// The configured initial zoom is only a starting point: a single zoom number
  /// cannot fit the region on both a small phone and a tablet, and on a 411dp
  /// screen zoom 7.2 puts the viewport entirely inside the region, so the user
  /// sees a flat expanse with no coastline, border or outline to orient by.
  /// Fitting the bounds works on every screen size.
  Future<void> _frameRegion(MapLibreMapController controller) async {
    final bounds = region.bounds;
    await controller.moveCamera(
      CameraUpdate.newLatLngBounds(
        LatLngBounds(
          southwest: LatLng(bounds.south, bounds.west),
          northeast: LatLng(bounds.north, bounds.east),
        ),
        left: 16,
        top: 16,
        right: 16,
        bottom: 16,
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    final center = region.map.center;
    final zoom = region.map.zoom;
    final bounds = region.bounds;

    return MapLibreMap(
      styleString: style.styleString,
      onMapCreated: _frameRegion,
      initialCameraPosition: CameraPosition(
        target: LatLng(center.latitude, center.longitude),
        zoom: zoom.initial,
      ),
      minMaxZoomPreference: MinMaxZoomPreference(zoom.min, zoom.max),
      // Panning is confined to the region: this app has data for Piedmont and
      // nowhere else, so letting the user drift away would only ever show an
      // empty map.
      cameraTargetBounds: CameraTargetBounds(
        LatLngBounds(
          southwest: LatLng(bounds.south, bounds.west),
          northeast: LatLng(bounds.north, bounds.east),
        ),
      ),
      // Kept enabled on top of our own attribution bar: some tile providers
      // require the plugin's own attribution control, and a duplicated credit
      // is harmless where a missing one is a licence breach.
      attributionButtonPosition: AttributionButtonPosition.bottomRight,
      compassEnabled: false,
      rotateGesturesEnabled: false,
      tiltGesturesEnabled: false,
      myLocationEnabled: false,
    );
  }
}