// 日历 BLoC — 管理日历视图状态，通过 JournalRepository 加载数据

import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:nuanji_app/data/models/journal_entry.dart';
import 'package:nuanji_app/data/repositories/journal_repository.dart';

// ===== Events =====

sealed class CalendarEvent {
  const CalendarEvent();
}

/// 切换到指定月份
final class CalendarMonthChanged extends CalendarEvent {
  final DateTime month;
  const CalendarMonthChanged(this.month);
}

/// 选择某一天
final class CalendarDaySelected extends CalendarEvent {
  final DateTime day;
  const CalendarDaySelected(this.day);
}

/// 切换视图模式
final class CalendarViewModeChanged extends CalendarEvent {
  final CalendarViewMode mode;
  const CalendarViewModeChanged(this.mode);
}

// ===== State =====

/// 日历视图模式
enum CalendarViewMode { month, week, timeline }

/// 日历状态
sealed class CalendarState {
  const CalendarState();
}

final class CalendarInitial extends CalendarState {
  const CalendarInitial();
}

/// 日历已加载
final class CalendarLoaded extends CalendarState {
  final DateTime focusedMonth;
  final DateTime selectedDay;
  final Map<DateTime, List<JournalEntry>> journalsByDate;
  final List<JournalEntry> selectedDayJournals;
  final CalendarViewMode viewMode;
  final bool isLoading;

  const CalendarLoaded({
    required this.focusedMonth,
    required this.selectedDay,
    required this.journalsByDate,
    required this.selectedDayJournals,
    this.viewMode = CalendarViewMode.month,
    this.isLoading = false,
  });

  CalendarLoaded copyWith({
    DateTime? focusedMonth,
    DateTime? selectedDay,
    Map<DateTime, List<JournalEntry>>? journalsByDate,
    List<JournalEntry>? selectedDayJournals,
    CalendarViewMode? viewMode,
    bool? isLoading,
  }) =>
      CalendarLoaded(
        focusedMonth: focusedMonth ?? this.focusedMonth,
        selectedDay: selectedDay ?? this.selectedDay,
        journalsByDate: journalsByDate ?? this.journalsByDate,
        selectedDayJournals: selectedDayJournals ?? this.selectedDayJournals,
        viewMode: viewMode ?? this.viewMode,
        isLoading: isLoading ?? this.isLoading,
      );
}

final class CalendarError extends CalendarState {
  final String message;
  const CalendarError(this.message);
}

// ===== BLoC =====

class CalendarBloc extends Bloc<CalendarEvent, CalendarState> {
  final JournalRepository _journalRepo;

  CalendarBloc({required JournalRepository journalRepository})
      : _journalRepo = journalRepository,
        super(const CalendarInitial()) {
    on<CalendarMonthChanged>(_onMonthChanged);
    on<CalendarDaySelected>(_onDaySelected);
    on<CalendarViewModeChanged>(_onViewModeChanged);
  }

  Future<void> _onMonthChanged(
    CalendarMonthChanged event,
    Emitter<CalendarState> emit,
  ) async {
    final currentState = state is CalendarLoaded ? state as CalendarLoaded : null;

    emit(CalendarLoaded(
      focusedMonth: event.month,
      selectedDay: event.month,
      journalsByDate: currentState?.journalsByDate ?? {},
      selectedDayJournals: [],
      viewMode: currentState?.viewMode ?? CalendarViewMode.month,
      isLoading: true,
    ));

    try {
      // 加载当月日记
      final startOfMonth = DateTime(event.month.year, event.month.month, 1);
      final endOfMonth = DateTime(event.month.year, event.month.month + 1, 0);

      final journals = await _journalRepo.getJournals(
        dateFrom: startOfMonth,
        dateTo: endOfMonth,
      );

      // 按日期索引
      final byDate = <DateTime, List<JournalEntry>>{};
      for (final journal in journals) {
        final key = DateTime(journal.date.year, journal.date.month, journal.date.day);
        byDate.putIfAbsent(key, () => []).add(journal);
      }

      if (state is CalendarLoaded) {
        final current = state as CalendarLoaded;
        emit(current.copyWith(
          journalsByDate: byDate,
          isLoading: false,
        ));
      }
    } catch (e) {
      if (state is CalendarLoaded) {
        emit((state as CalendarLoaded).copyWith(isLoading: false));
      }
    }
  }

  void _onDaySelected(
    CalendarDaySelected event,
    Emitter<CalendarState> emit,
  ) {
    if (state is! CalendarLoaded) return;
    final current = state as CalendarLoaded;

    final dayKey = DateTime(event.day.year, event.day.month, event.day.day);
    final dayJournals = current.journalsByDate[dayKey] ?? [];

    emit(current.copyWith(
      selectedDay: event.day,
      selectedDayJournals: dayJournals,
    ));
  }

  void _onViewModeChanged(
    CalendarViewModeChanged event,
    Emitter<CalendarState> emit,
  ) {
    if (state is! CalendarLoaded) return;
    emit((state as CalendarLoaded).copyWith(viewMode: event.mode));
  }
}