import 'package:flutter_test/flutter_test.dart';
import 'package:marianum_mobile/api/marianumconnect/queries/parent_letters/parent_letter_models.dart';
import 'package:marianum_mobile/state/app/modules/parent_letters/bloc/parent_letters_state.dart';
import 'package:marianum_mobile/state/app/modules/parent_letters/parent_letters_logic.dart';

ParentLetterSummary _letter(
  String id, {
  bool read = true,
  List<String> childIds = const ['c1'],
}) => ParentLetterSummary(
  id: id,
  sentAt: DateTime(2026, 9, 20),
  read: read,
  childIds: childIds,
);

void main() {
  test('firstPageState takes over list and counters', () {
    final state = firstPageState(
      ParentLetterListResponse(
        items: [_letter('a')],
        hasMore: true,
        unreadCount: 2,
        openCount: 1,
      ),
    );
    expect(state.letters.single.id, 'a');
    expect(state.hasMore, isTrue);
    expect(state.unreadCount, 2);
    expect(state.openCount, 1);
  });

  test('appendOlderPage appends without duplicating known letters', () {
    final state = ParentLettersState(
      letters: [_letter('a'), _letter('b')],
      hasMore: true,
    );
    final next = appendOlderPage(
      state,
      ParentLetterListResponse(items: [_letter('b'), _letter('c')]),
    );
    expect(next.letters.map((l) => l.id), ['a', 'b', 'c']);
    expect(next.hasMore, isFalse);
  });

  group('withLetterRead', () {
    final state = ParentLettersState(
      letters: [_letter('a', read: false), _letter('b')],
      unreadCount: 1,
    );

    test('marks the letter and lowers the counter', () {
      final next = withLetterRead(state, 'a');
      expect(next.letters.first.read, isTrue);
      expect(next.unreadCount, 0);
    });

    test('returns the same state for read or unknown letters', () {
      expect(identical(withLetterRead(state, 'b'), state), isTrue);
      expect(identical(withLetterRead(state, 'x'), state), isTrue);
    });

    test('never drops the counter below zero', () {
      final drifted = state.copyWith(unreadCount: 0);
      expect(withLetterRead(drifted, 'a').unreadCount, 0);
    });
  });

  group('withSummary', () {
    final open = _letter('b').copyWith(status: ParentLetterStatus.open);
    final state = ParentLettersState(
      letters: [_letter('a'), open],
      openCount: 3,
    );

    test('replaces the letter in place and lowers the open counter', () {
      final next = withSummary(
        state,
        open.copyWith(status: ParentLetterStatus.done),
      );
      expect(next.letters.map((l) => l.id), ['a', 'b']);
      expect(next.letters.last.status, ParentLetterStatus.done);
      expect(next.openCount, 2);
    });

    test('keeps the counter while the letter stays open', () {
      expect(withSummary(state, open.copyWith(read: false)).openCount, 3);
    });

    test('ignores letters the inbox does not hold', () {
      expect(identical(withSummary(state, _letter('x')), state), isTrue);
    });
  });

  test('filterLettersByChild keeps letters that concern the child', () {
    final letters = [
      _letter('a', childIds: ['c1']),
      _letter('b', childIds: ['c2']),
      _letter('c', childIds: ['c1', 'c2']),
    ];
    expect(filterLettersByChild(letters, null), letters);
    expect(filterLettersByChild(letters, 'c2').map((l) => l.id), ['b', 'c']);
  });
}