import 'dart:async';

import 'package:flutter_test/flutter_test.dart';
import 'package:glp1_companion/core/platform/notification_service.dart';
import 'package:glp1_companion/features/medication/domain/entities/dose_entry.dart';
import 'package:glp1_companion/features/medication/domain/entities/injection_site.dart';
import 'package:glp1_companion/features/medication/domain/repositories/medication_repository.dart';
import 'package:glp1_companion/features/medication/domain/value_objects/glp1_compound.dart';
import 'package:glp1_companion/features/medication/presentation/controllers/medication_controller.dart';

/// In-memory [IMedicationRepository] that broadcasts every mutation.
class _FakeMedicationRepository implements IMedicationRepository {
  final List<DoseEntry> entries = [];
  final StreamController<List<DoseEntry>> _changes =
      StreamController<List<DoseEntry>>.broadcast(sync: true);
  int _nextId = 1;
  bool failNextSave = false;

  void seed(List<DoseEntry> seeded) {
    entries.addAll(seeded);
    _emit();
  }

  void _emit() => _changes.add(List.unmodifiable(entries));

  @override
  Stream<List<DoseEntry>> watchDoseEntries({int limit = 500}) => _changes.stream;

  @override
  Future<List<DoseEntry>> getDoseEntries({int limit = 500}) async =>
      List.unmodifiable(entries);

  @override
  Future<DoseEntry> saveDoseEntry(DoseEntry entry) async {
    if (failNextSave) {
      failNextSave = false;
      throw StateError('write failed');
    }
    final stored = DoseEntry(
      id: entry.id ?? _nextId++,
      compoundName: entry.compoundName,
      doseMg: entry.doseMg,
      administeredAt: entry.administeredAt,
      scheduledAt: entry.scheduledAt,
      injectionSite: entry.injectionSite,
      notes: entry.notes,
    );
    final index = entries.indexWhere((e) => e.id == stored.id);
    if (index == -1) {
      entries.insert(0, stored);
    } else {
      entries[index] = stored;
    }
    _emit();
    return stored;
  }

  @override
  Future<void> deleteDoseEntry(int id) async {
    entries.removeWhere((entry) => entry.id == id);
    _emit();
  }

  @override
  Future<DoseEntry?> getLatestAdministeredDose() async =>
      entries.isEmpty ? null : entries.first;

  Future<void> close() => _changes.close();
}

/// Records scheduling calls instead of touching platform channels.
class _RecordingNotificationService implements INotificationService {
  final List<DateTime> scheduledTimes = [];
  int permissionRequests = 0;

  @override
  Future<void> initialize() async {}

  @override
  Future<bool> requestPermissions() async {
    permissionRequests++;
    return true;
  }

  @override
  Future<bool> scheduleDoseReminder({
    required DateTime scheduledAt,
    required String title,
    required String body,
    int id = kDoseReminderNotificationId,
    String? payload,
  }) async {
    scheduledTimes.add(scheduledAt);
    return true;
  }

  @override
  Future<void> cancelReminder(int id) async {}

  @override
  Future<void> cancelAllReminders() async {}
}

DoseEntry _dose({
  int? id,
  String compound = 'Semaglutide',
  double doseMg = 1,
  required DateTime administeredAt,
  InjectionSite? site,
}) =>
    DoseEntry(
      id: id,
      compoundName: compound,
      doseMg: doseMg,
      administeredAt: administeredAt,
      injectionSite: site,
    );

void main() {
  late _FakeMedicationRepository repository;
  late _RecordingNotificationService notifications;

  setUp(() {
    repository = _FakeMedicationRepository();
    notifications = _RecordingNotificationService();
  });

  tearDown(() => repository.close());

  MedicationController buildController() {
    final controller = MedicationController(repository, notifications);
    addTearDown(controller.dispose);
    return controller;
  }

  group('MedicationController', () {
    test('starts in a loading state before history arrives', () {
      final controller = buildController();
      expect(controller.state.isLoading, isTrue);
      expect(controller.state.entries, isEmpty);
      expect(controller.state.suggestedSite, InjectionSite.values.first);
    });

    test('loads history, computes serum level, and suggests a rotation site',
        () async {
      final controller = buildController();
      final oneHalfLifeAgo =
          DateTime.now().subtract(Glp1Compound.semaglutide.dosingInterval);

      repository.seed([
        _dose(
          administeredAt: oneHalfLifeAgo,
          site: InjectionSite.abdomenRightUpper,
        ),
      ]);

      expect(controller.state.isLoading, isFalse);
      expect(controller.state.entries, hasLength(1));
      // 1 mg after one semaglutide half-life decays to ~0.5 mg.
      expect(controller.state.serumLevelMg, closeTo(0.5, 0.01));
      expect(
        controller.state.suggestedSite,
        isNot(InjectionSite.abdomenRightUpper),
      );
      expect(
        controller.state.suggestedSite,
        InjectionSite.leastRecentlyUsed({
          InjectionSite.abdomenRightUpper: oneHalfLifeAgo,
        }),
      );
    });

    test('nextDoseDueAt follows the compound dosing interval', () async {
      final controller = buildController();
      final administeredAt = DateTime.now().subtract(const Duration(days: 1));

      repository.seed([
        _dose(
          compound: 'Liraglutide',
          administeredAt: administeredAt,
          site: InjectionSite.thighRightLateral,
        ),
      ]);

      expect(
        controller.state.nextDoseDueAt,
        administeredAt.add(Glp1Compound.liraglutide.dosingInterval),
      );
    });

    test('logInjection persists the entry and schedules the next reminder',
        () async {
      final controller = buildController();
      final administeredAt = DateTime(2026, 10, 16, 8);

      final saved = await controller.logInjection(
        compoundName: 'Tirzepatide',
        doseMg: 2.5,
        site: InjectionSite.thighRightAnterior,
        administeredAt: administeredAt,
      );

      expect(saved, isTrue);
      expect(repository.entries, hasLength(1));
      expect(
        repository.entries.single.injectionSite,
        InjectionSite.thighRightAnterior,
      );
      expect(notifications.permissionRequests, 1);
      expect(notifications.scheduledTimes, [
        administeredAt.add(Glp1Compound.tirzepatide.dosingInterval),
      ]);
    });

    test('rotation moves away from the most recently used quadrant', () async {
      final controller = buildController();

      await controller.logInjection(
        compoundName: 'Semaglutide',
        doseMg: 0.25,
        site: InjectionSite.abdomenRightUpper,
      );

      expect(controller.state.suggestedSite, InjectionSite.abdomenRightLower);
    });

    test('logInjection failure returns false and records the error', () async {
      final controller = buildController();
      repository.failNextSave = true;

      final saved = await controller.logInjection(
        compoundName: 'Semaglutide',
        doseMg: 0.25,
        site: InjectionSite.armLeftTricep,
      );

      expect(saved, isFalse);
      expect(controller.state.error, isA<StateError>());
      expect(notifications.scheduledTimes, isEmpty);
    });

    test('deleteInjection removes an entry from the stream', () async {
      final controller = buildController();
      final stored = await repository.saveDoseEntry(
        _dose(
          administeredAt: DateTime.now(),
          site: InjectionSite.armRightLateral,
        ),
      );

      expect(controller.state.entries, hasLength(1));
      final removed = await controller.deleteInjection(stored.id!);

      expect(removed, isTrue);
      expect(controller.state.entries, isEmpty);
    });

    test('refreshSerumLevel re-evaluates decay at the requested time', () async {
      final controller = buildController();
      final administeredAt =
          DateTime.now().subtract(const Duration(hours: 168));
      repository.seed([
        _dose(doseMg: 2, administeredAt: administeredAt),
      ]);
      final seededLevel = controller.state.serumLevelMg;

      final later = administeredAt.add(const Duration(hours: 336));
      controller.refreshSerumLevel(now: later);

      // Two half-lives after administration: 2 mg -> 0.5 mg, below the
      // freshly seeded estimate.
      expect(controller.state.serumLevelMg, closeTo(0.5, 1e-9));
      expect(controller.state.serumLevelMg, lessThan(seededLevel));
      expect(controller.state.evaluatedAt, later);
    });
  });
}