Europa/Nuvolari/app/test/features/map/map_style_test.dart

import 'dart:convert';
import 'dart:io';

import 'package:flutter_test/flutter_test.dart';
import 'package:nuvolari/core/region/region_config.dart';
import 'package:nuvolari/features/map/map_style.dart';

void main() {
  late RegionConfig region;

  setUpAll(() {
    region = RegionConfig.parse(
      File('assets/regions/piemonte.json').readAsStringSync(),
    );
  });

  group('MapStyle.buildFallbackStyle', () {
    late Map<String, Object?> style;

    setUp(() {
      style = jsonDecode(
        MapStyle.buildFallbackStyle(region),
      ) as Map<String, Object?>;
    });

    test('is a valid MapLibre style document', () {
      expect(style['version'], 8);
      expect(style['sources'], isA<Map<String, Object?>>());
      expect(style['layers'], isA<List<Object?>>());
    });

    // The whole point of the fallback is that it works with no network at all,
    // so a style that referenced a tile server would defeat it.
    test('references no network sources', () {
      final encoded = jsonEncode(style);

      expect(encoded, isNot(contains('http://')));
      expect(encoded, isNot(contains('https://')));

      final sources = style['sources']! as Map<String, Object?>;
      for (final source in sources.values) {
        expect((source! as Map<String, Object?>)['type'], 'geojson');
      }
    });

    test('draws the region extent as a closed ring', () {
      final source =
          (style['sources']! as Map<String, Object?>)['region-extent']!
              as Map<String, Object?>;
      final geometry =
          (source['data']! as Map<String, Object?>)['geometry']!
              as Map<String, Object?>;
      final ring =
          (geometry['coordinates']! as List<Object?>).first! as List<Object?>;

      expect(geometry['type'], 'Polygon');
      // Five points: four corners plus the repeated first point that closes it.
      expect(ring, hasLength(5));
      expect(ring.first, equals(ring.last));
    });

    test('the ring matches the region bounding box', () {
      final source =
          (style['sources']! as Map<String, Object?>)['region-extent']!
              as Map<String, Object?>;
      final geometry =
          (source['data']! as Map<String, Object?>)['geometry']!
              as Map<String, Object?>;
      final ring =
          (geometry['coordinates']! as List<Object?>).first! as List<Object?>;

      final longitudes = <double>[];
      final latitudes = <double>[];
      for (final point in ring) {
        final pair = point! as List<Object?>;
        longitudes.add((pair[0]! as num).toDouble());
        latitudes.add((pair[1]! as num).toDouble());
      }

      expect(longitudes.reduce((a, b) => a < b ? a : b), region.bounds.west);
      expect(longitudes.reduce((a, b) => a > b ? a : b), region.bounds.east);
      expect(latitudes.reduce((a, b) => a < b ? a : b), region.bounds.south);
      expect(latitudes.reduce((a, b) => a > b ? a : b), region.bounds.north);
    });

    test('has a background layer beneath the region layers', () {
      final layers = (style['layers']! as List<Object?>)
          .map((layer) => (layer! as Map<String, Object?>)['id'])
          .toList();

      expect(layers.first, 'background');
      expect(layers, contains('region-extent-fill'));
      expect(layers, contains('region-extent-outline'));
    });
  });

  group('MapStyle.forRegion', () {
    // The test process is built without --dart-define, so MAP_STYLE_URL is
    // empty and the fallback is what must come back.
    test('falls back when no style URL is configured', () {
      final style = MapStyle.forRegion(region);

      expect(style.kind, BaseMapKind.offlineFallback);
      expect(style.styleString, startsWith('{'));
    });

    // Crediting OpenStreetMap while showing a style that contains no OSM data
    // would be a false attribution, so the fallback owes nothing.
    test('the fallback claims no base map attribution', () {
      expect(MapStyle.forRegion(region).attributionIds, isEmpty);
    });

    test('a configured base map owes the OpenStreetMap credit', () {
      const configured = MapStyle(
        kind: BaseMapKind.configured,
        styleString: 'https://example.invalid/style.json',
      );

      expect(configured.attributionIds, contains('osm'));
    });
  });
}