import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:table_calendar/table_calendar.dart';

import '../../data/models/calendar_event.dart';
import '../../providers/calendar_provider.dart';
import 'event_form_sheet.dart';

class CalendarScreen extends ConsumerWidget {
  const CalendarScreen({super.key});

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final calAsync = ref.watch(calendarProvider);
    final notifier = ref.read(calendarProvider.notifier);

    return Scaffold(
      appBar: AppBar(title: const Text('Calendar')),
      body: calAsync.when(
        loading: () => const Center(child: CircularProgressIndicator()),
        error: (e, _) => Center(
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: [
              const Text('Could not load calendar.'),
              const SizedBox(height: 12),
              FilledButton.tonal(
                onPressed: () => ref.invalidate(calendarProvider),
                child: const Text('Retry'),
              ),
            ],
          ),
        ),
        data: (cal) => Column(
          children: [
            TableCalendar<CalendarEvent>(
              firstDay: DateTime(2020),
              lastDay: DateTime(2030),
              focusedDay: cal.focusedMonth,
              selectedDayPredicate: (day) => isSameDay(day, cal.selectedDay),
              eventLoader: (day) =>
                  cal.eventsByDay[dateOnly(day)] ?? [],
              calendarFormat: CalendarFormat.month,
              headerStyle: const HeaderStyle(
                formatButtonVisible: false,
                titleCentered: true,
              ),
              calendarStyle: CalendarStyle(
                selectedDecoration: BoxDecoration(
                  color: Theme.of(context).colorScheme.primary,
                  shape: BoxShape.circle,
                ),
                todayDecoration: BoxDecoration(
                  color: Theme.of(context)
                      .colorScheme
                      .primary
                      .withValues(alpha: 0.3),
                  shape: BoxShape.circle,
                ),
                markerDecoration: BoxDecoration(
                  color: Theme.of(context).colorScheme.secondary,
                  shape: BoxShape.circle,
                ),
              ),
              onDaySelected: (selected, _) => notifier.selectDay(selected),
              onPageChanged: (focused) => notifier.loadMonth(focused),
            ),
            const Divider(height: 1),
            Expanded(
              child: RefreshIndicator(
                onRefresh: () => ref.read(calendarProvider.notifier).refresh(),
                child: _AgendaList(
                  events:
                      cal.eventsByDay[dateOnly(cal.selectedDay)] ?? [],
                  notifier: notifier,
                ),
              ),
            ),
          ],
        ),
      ),
      floatingActionButton: calAsync.hasValue
          ? FloatingActionButton(
              onPressed: () => showModalBottomSheet(
                context: context,
                isScrollControlled: true,
                useSafeArea: true,
                builder: (_) => EventFormSheet(
                  event: null,
                  initialDate: calAsync.value!.selectedDay,
                  notifier: notifier,
                ),
              ),
              child: const Icon(Icons.add),
            )
          : null,
    );
  }
}

// ── Agenda list ───────────────────────────────────────────────────────────────

class _AgendaList extends StatelessWidget {
  final List<CalendarEvent> events;
  final CalendarNotifier notifier;

  const _AgendaList({required this.events, required this.notifier});

  @override
  Widget build(BuildContext context) {
    if (events.isEmpty) {
      return ListView(
        children: const [
          SizedBox(height: 80),
          Center(child: Text('No events')),
        ],
      );
    }
    return ListView.builder(
      padding: const EdgeInsets.symmetric(vertical: 8),
      itemCount: events.length,
      itemBuilder: (_, i) =>
          _EventTile(event: events[i], notifier: notifier),
    );
  }
}

// ── Event tile ────────────────────────────────────────────────────────────────

class _EventTile extends StatelessWidget {
  final CalendarEvent event;
  final CalendarNotifier notifier;

  const _EventTile({required this.event, required this.notifier});

  Color _dotColor(BuildContext context) {
    if (event.color.isEmpty) return Theme.of(context).colorScheme.primary;
    try {
      return Color(int.parse(event.color.replaceFirst('#', '0xFF')));
    } catch (_) {
      return Theme.of(context).colorScheme.primary;
    }
  }

  String _timeLabel() {
    if (event.allDay) return 'All day';
    final h = event.startDt.hour.toString().padLeft(2, '0');
    final m = event.startDt.minute.toString().padLeft(2, '0');
    return '$h:$m';
  }

  @override
  Widget build(BuildContext context) {
    return ListTile(
      leading: CircleAvatar(
        radius: 6,
        backgroundColor: _dotColor(context),
      ),
      title: Text(event.title),
      subtitle: Text(_timeLabel()),
      onTap: () => showModalBottomSheet(
        context: context,
        isScrollControlled: true,
        useSafeArea: true,
        builder: (_) => EventFormSheet(
          event: event,
          initialDate: null,
          notifier: notifier,
        ),
      ),
    );
  }
}