import 'dart:math';

import 'package:cyberhybridhub_server/question_source_preferences.dart';
import 'package:test/test.dart';

void main() {
  group('QuestionSourcePreferences.effectiveMix', () {
    test('matches client-style normalization for enabled sources', () {
      final List<ResolvedQuestionSourcePreference> prefs =
          QuestionSourcePreferences.mergeStored(<Map<String, dynamic>>[
        <String, dynamic>{'id': 'market_history', 'enabled': true, 'ratio': 70},
        <String, dynamic>{'id': 'spelling', 'enabled': true, 'ratio': 30},
      ]);

      final Map<String, int> mix = QuestionSourcePreferences.effectiveMix(prefs);

      expect(mix['market_history'], 70);
      expect(mix['spelling'], 30);
    });

    test('excludes disabled sources', () {
      final List<ResolvedQuestionSourcePreference> prefs =
          QuestionSourcePreferences.mergeStored(<Map<String, dynamic>>[
        <String, dynamic>{'id': 'market_history', 'enabled': true, 'ratio': 50},
        <String, dynamic>{'id': 'spelling', 'enabled': false, 'ratio': 50},
      ]);

      final Map<String, int> mix = QuestionSourcePreferences.effectiveMix(prefs);

      expect(mix.keys, <String>{'market_history'});
      expect(mix['market_history'], 100);
    });
  });

  group('_sourceTryOrder (via dispatcher selection)', () {
    test('weighted random favors configured ratio over many rolls', () {
      final List<ResolvedQuestionSourcePreference> prefs =
          QuestionSourcePreferences.mergeStored(<Map<String, dynamic>>[
        <String, dynamic>{'id': 'market_history', 'enabled': true, 'ratio': 90},
        <String, dynamic>{'id': 'spelling', 'enabled': true, 'ratio': 10},
      ]);

      final Random random = Random(42);
      var marketFirst = 0;
      for (var i = 0; i < 200; i++) {
        final List<String> order = _sourceTryOrderForTest(prefs, random);
        if (order.first == 'market_history') {
          marketFirst++;
        }
      }

      expect(marketFirst, greaterThan(140));
    });

    test('only enabled source is always first', () {
      final List<ResolvedQuestionSourcePreference> prefs =
          QuestionSourcePreferences.mergeStored(<Map<String, dynamic>>[
        <String, dynamic>{'id': 'market_history', 'enabled': false, 'ratio': 0},
        <String, dynamic>{'id': 'spelling', 'enabled': true, 'ratio': 100},
      ]);

      final List<String> order =
          _sourceTryOrderForTest(prefs, Random(1));

      expect(order, <String>['spelling']);
    });
  });
}

/// Mirrors [QuestionDispatcher._sourceTryOrder] for deterministic unit tests.
List<String> _sourceTryOrderForTest(
  List<ResolvedQuestionSourcePreference> prefs,
  Random random,
) {
  final List<ResolvedQuestionSourcePreference> enabled = prefs
      .where(
        (ResolvedQuestionSourcePreference s) => s.enabled && !s.comingSoon,
      )
      .toList(growable: false);
  if (enabled.isEmpty) {
    return <String>[];
  }

  final int totalWeight = enabled.fold<int>(
    0,
    (int sum, ResolvedQuestionSourcePreference s) => sum + s.ratio,
  );
  if (totalWeight <= 0) {
    final List<String> ids =
        enabled.map((ResolvedQuestionSourcePreference s) => s.id).toList();
    ids.shuffle(random);
    return ids;
  }

  var roll = random.nextInt(totalWeight);
  String? primary;
  for (final ResolvedQuestionSourcePreference source in enabled) {
    roll -= source.ratio;
    if (roll < 0) {
      primary = source.id;
      break;
    }
  }
  primary ??= enabled.first.id;

  final List<ResolvedQuestionSourcePreference> rest = enabled
      .where((ResolvedQuestionSourcePreference s) => s.id != primary)
      .toList()
    ..sort(
      (
        ResolvedQuestionSourcePreference a,
        ResolvedQuestionSourcePreference b,
      ) =>
          b.ratio.compareTo(a.ratio),
    );

  return <String>[
    primary,
    ...rest.map((ResolvedQuestionSourcePreference s) => s.id),
  ];
}