import 'dart:convert';
import 'dart:ui' show Color;

import 'package:flutter_test/flutter_test.dart';
import 'package:nuvolari/data/radar/radar_manifest.dart';

Map<String, Object?> validManifest() => <String, Object?>{
  'region': 'piemonte',
  'product': 'VMI',
  'generatedAt': 1768478400000,
  'bbox': <double>[6.55, 43.95, 9.30, 46.55],
  'crs': 'EPSG:3857',
  'frames': <Object?>[
    <String, Object?>{'ts': 1768478400000, 'url': 'frames/a.png'},
    <String, Object?>{'ts': 1768478700000, 'url': 'frames/b.png'},
  ],
  'legend': <String, Object?>{
    'unit': 'dBZ',
    'stops': <Object?>[
      <String, Object?>{'value': 5, 'color': '#4FA3D1'},
      <String, Object?>{'value': 30, 'color': '#E9D22B'},
    ],
  },
  'attribution': 'Radar-DPC — CC BY-SA',
};

RadarManifest parseWith(void Function(Map<String, Object?> doc) mutate) {
  final doc = validManifest();
  mutate(doc);
  return RadarManifest.fromJson(doc);
}

void main() {
  group('RadarManifest.fromJson', () {
    test('parses a complete manifest', () {
      final manifest = RadarManifest.fromJson(validManifest());

      expect(manifest.regionId, 'piemonte');
      expect(manifest.product, 'VMI');
      expect(manifest.bounds.west, 6.55);
      expect(manifest.frames, hasLength(2));
      expect(manifest.legend.unit, 'dBZ');
      expect(manifest.attribution, contains('Radar-DPC'));
      expect(manifest.generatedAt.isUtc, isTrue);
    });

    test('frame timestamps are UTC', () {
      final manifest = RadarManifest.fromJson(validManifest());

      expect(manifest.frames.first.timestamp.isUtc, isTrue);
      expect(
        manifest.frames.first.timestamp.millisecondsSinceEpoch,
        1768478400000,
      );
    });

    test('sorts frames by timestamp regardless of publication order', () {
      final manifest = parseWith((doc) {
        doc['frames'] = <Object?>[
          <String, Object?>{'ts': 1768478700000, 'url': 'frames/b.png'},
          <String, Object?>{'ts': 1768478400000, 'url': 'frames/a.png'},
        ];
      });

      expect(
        manifest.frames.map((frame) => frame.path),
        orderedEquals(<String>['frames/a.png', 'frames/b.png']),
      );
    });

    // The map overlays each PNG on a lat/lng quad, which only lines up if the
    // image is already in Web Mercator. A different CRS renders visibly skewed
    // with no error, so it has to be caught here.
    test('rejects a manifest that is not in EPSG:3857', () {
      expect(
        () => parseWith((doc) => doc['crs'] = 'EPSG:4326'),
        throwsA(
          isA<FormatException>().having(
            (e) => e.message,
            'message',
            contains('EPSG:3857'),
          ),
        ),
      );
    });

    test('rejects a manifest with no CRS at all', () {
      expect(
        () => parseWith((doc) => doc.remove('crs')),
        throwsFormatException,
      );
    });

    // The frames are a derived product of CC BY-SA data. Publishing them
    // without the credit travelling alongside is a licence breach, so a
    // manifest that omits it must not load.
    test('rejects a manifest with no attribution', () {
      expect(
        () => parseWith((doc) => doc.remove('attribution')),
        throwsFormatException,
      );
      expect(
        () => parseWith((doc) => doc['attribution'] = ''),
        throwsFormatException,
      );
    });

    test('rejects a non-integer timestamp', () {
      expect(
        () => parseWith((doc) {
          doc['frames'] = <Object?>[
            <String, Object?>{'ts': '1768478400000', 'url': 'frames/a.png'},
          ];
        }),
        throwsFormatException,
      );
    });

    test('accepts an empty frame list', () {
      final manifest = parseWith((doc) => doc['frames'] = <Object?>[]);

      expect(manifest.isEmpty, isTrue);
      expect(manifest.newestFrame, isNull);
      expect(manifest.ageAt(DateTime.now()), Duration.zero);
    });
  });

  group('RadarManifest.ageAt', () {
    test('measures from the newest frame', () {
      final manifest = RadarManifest.fromJson(validManifest());
      final now = DateTime.fromMillisecondsSinceEpoch(
        1768478700000 + Duration.millisecondsPerMinute * 12,
        isUtc: true,
      );

      expect(manifest.ageAt(now), const Duration(minutes: 12));
    });

    test('handles a local-time argument', () {
      final manifest = RadarManifest.fromJson(validManifest());
      final now = DateTime.fromMillisecondsSinceEpoch(
        1768478700000 + Duration.millisecondsPerMinute * 5,
      );

      expect(manifest.ageAt(now), const Duration(minutes: 5));
    });
  });

  group('RadarLegend', () {
    late RadarLegend legend;

    setUp(() {
      legend = RadarManifest.fromJson(validManifest()).legend;
    });

    test('parses #RRGGBB as opaque', () {
      expect(legend.stops.first.color, const Color(0xFF4FA3D1));
    });

    test('picks the highest stop at or below the value', () {
      expect(legend.colorFor(5), const Color(0xFF4FA3D1));
      expect(legend.colorFor(29.9), const Color(0xFF4FA3D1));
      expect(legend.colorFor(30), const Color(0xFFE9D22B));
      expect(legend.colorFor(120), const Color(0xFFE9D22B));
    });

    // Below the lowest stop means "no precipitation", which must be transparent
    // rather than the first colour of the ramp — otherwise a dry region renders
    // as light drizzle everywhere.
    test('returns null below the lowest stop', () {
      expect(legend.colorFor(4.9), isNull);
      expect(legend.colorFor(-10), isNull);
      expect(legend.minimumValue, 5);
    });

    test('rejects stops that do not ascend', () {
      expect(
        () => parseWith((doc) {
          doc['legend'] = <String, Object?>{
            'unit': 'dBZ',
            'stops': <Object?>[
              <String, Object?>{'value': 30, 'color': '#E9D22B'},
              <String, Object?>{'value': 5, 'color': '#4FA3D1'},
            ],
          };
        }),
        throwsA(
          isA<FormatException>().having(
            (e) => e.message,
            'message',
            contains('ascend'),
          ),
        ),
      );
    });

    test('rejects an empty stop list', () {
      expect(
        () => parseWith((doc) {
          doc['legend'] = <String, Object?>{
            'unit': 'dBZ',
            'stops': <Object?>[],
          };
        }),
        throwsFormatException,
      );
    });

    test('rejects a malformed colour', () {
      expect(
        () => parseWith((doc) {
          doc['legend'] = <String, Object?>{
            'unit': 'dBZ',
            'stops': <Object?>[
              <String, Object?>{'value': 5, 'color': 'blue'},
            ],
          };
        }),
        throwsFormatException,
      );
    });
  });

  group('RadarManifest.parse', () {
    test('parses JSON text', () {
      expect(RadarManifest.parse(jsonEncode(validManifest())).product, 'VMI');
    });

    test('rejects JSON that is not an object', () {
      expect(() => RadarManifest.parse('[]'), throwsFormatException);
    });
  });
}