recurrence_kit 0.2.0

A standalone recurrence rule system with data models, computation engine, and picker UI widget.

example/lib/main.dart

import 'dart:convert';

import 'package:flutter/material.dart';
import 'package:intl/intl.dart';
import 'package:recurrence_kit/recurrence_kit.dart';

void main() => runApp(const RecurrenceKitExample());

class RecurrenceKitExample extends StatelessWidget {
  const RecurrenceKitExample({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'recurrence_kit example',
      theme: ThemeData(
        colorSchemeSeed: const Color(0xFF5B6ABF),
        useMaterial3: true,
      ),
      home: const ExampleScreen(),
    );
  }
}

// ── Theme configurations ─────────────────────────────────────────────────────

const _lightTheme = RecurrencePickerTheme();

const _darkTheme = RecurrencePickerTheme(
  textColor: Color(0xFFE0E0E0),
  secondaryTextColor: Color(0xFF9E9E9E),
  accentColor: Color(0xFF81C784),
  borderColor: Color(0xFF616161),
);

// ── Main screen ──────────────────────────────────────────────────────────────

class ExampleScreen extends StatefulWidget {
  const ExampleScreen({super.key});

  @override
  State<ExampleScreen> createState() => _ExampleScreenState();
}

class _ExampleScreenState extends State<ExampleScreen> {
  final DateTime _startDate = DateTime.now();
  bool _useDarkTheme = false;

  late RecurrenceRule _rule = RecurrenceRule(
    pattern: Weekly(weekdays: [_startDate.weekday]),
    end: const NeverEnds(),
  );

  // Derived display values, recomputed in _updateRule() rather than in
  // build().
  List<DateTime> _upcoming = [];
  DateTime? _lastOccurrence;
  String _jsonString = '';

  RecurrencePickerTheme get _pickerTheme =>
      _useDarkTheme ? _darkTheme : _lightTheme;

  @override
  void initState() {
    super.initState();
    _recompute();
  }

  void _updateRule(RecurrenceRule updated) {
    setState(() {
      _rule = updated;
      _recompute();
    });
  }

  /// Recomputes the derived display values from the current [_rule]. The
  /// rule and the start date are all the engine needs; an after-N end is
  /// interpreted directly.
  void _recompute() {
    _upcoming = RecurrenceEngine.nextOccurrences(
      _rule,
      _startDate,
      _startDate,
      count: 5,
    );
    _lastOccurrence = RecurrenceEngine.lastOccurrence(_rule, _startDate);
    _jsonString = const JsonEncoder.withIndent('  ').convert(_rule.toJson());
  }

  /// [_upcoming] is queried from the start date, so an empty list means the
  /// schedule has no occurrences; a non-empty schedule without a last
  /// occurrence is unbounded.
  String get _endSummary {
    if (_upcoming.isEmpty) return 'No occurrences.';
    final last = _lastOccurrence;
    if (last != null) return 'Ends ${DateFormat.yMMMEd().format(last)}.';
    return 'Never ends.';
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('recurrence_kit'),
        actions: [
          Tooltip(
            message: 'Toggle picker theme',
            child: IconButton(
              icon: Icon(_useDarkTheme ? Icons.light_mode : Icons.dark_mode),
              onPressed: () => setState(() => _useDarkTheme = !_useDarkTheme),
            ),
          ),
        ],
      ),
      body: ListView(
        padding: const EdgeInsets.all(16),
        children: [
          // ── Picker section ──
          _SectionCard(
            title: 'RecurrencePicker',
            backgroundColor: _useDarkTheme ? const Color(0xFF2C2C2C) : null,
            child: RecurrencePicker(
              rule: _rule,
              onChanged: _updateRule,
              startDate: _startDate,
              theme: _pickerTheme,
            ),
          ),
          const SizedBox(height: 16),

          // ── Display text section ──
          _SectionCard(
            title: 'RecurrenceRule.displayText',
            child: Text(
              _rule.displayText,
              style: Theme.of(context).textTheme.titleMedium,
            ),
          ),
          const SizedBox(height: 16),

          // ── Next occurrences section ──
          _SectionCard(
            title: 'Next occurrences',
            subtitle:
                'Up to 5 shown, starting from today. '
                'If today is an occurrence, it appears as the first entry.',
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                if (_upcoming.isEmpty)
                  Text(
                    'No upcoming occurrences.',
                    style: TextStyle(
                      color: Theme.of(context).colorScheme.outline,
                      fontStyle: FontStyle.italic,
                    ),
                  )
                else
                  for (var i = 0; i < _upcoming.length; i++)
                    Padding(
                      padding: const EdgeInsets.symmetric(vertical: 2),
                      child: Text(
                        '${i + 1}. ${DateFormat.yMMMEd().format(_upcoming[i])}',
                        style: Theme.of(context).textTheme.bodyMedium,
                      ),
                    ),
                const SizedBox(height: 8),
                Text(
                  _endSummary,
                  style: Theme.of(context).textTheme.bodySmall?.copyWith(
                    color: Theme.of(context).colorScheme.outline,
                  ),
                ),
              ],
            ),
          ),
          const SizedBox(height: 16),

          // ── JSON section ──
          _SectionCard(
            title: 'RecurrenceRule.toJson()',
            child: Container(
              width: double.infinity,
              padding: const EdgeInsets.all(12),
              decoration: BoxDecoration(
                color: Theme.of(context).colorScheme.surfaceContainerHighest,
                borderRadius: BorderRadius.circular(8),
              ),
              child: SelectableText(
                _jsonString,
                style: TextStyle(
                  fontFamily: 'monospace',
                  fontSize: 12,
                  color: Theme.of(context).colorScheme.onSurfaceVariant,
                ),
              ),
            ),
          ),
          const SizedBox(height: 32),
        ],
      ),
    );
  }
}

// ── Reusable card wrapper ────────────────────────────────────────────────────

class _SectionCard extends StatelessWidget {
  const _SectionCard({
    required this.title,
    required this.child,
    this.subtitle,
    this.backgroundColor,
  });

  final String title;
  final String? subtitle;
  final Widget child;
  final Color? backgroundColor;

  @override
  Widget build(BuildContext context) {
    return Card(
      color: backgroundColor,
      child: Padding(
        padding: const EdgeInsets.all(16),
        child: Column(
          crossAxisAlignment: CrossAxisAlignment.start,
          children: [
            Text(
              title,
              style: Theme.of(context).textTheme.labelLarge?.copyWith(
                color: Theme.of(context).colorScheme.primary,
              ),
            ),
            if (subtitle != null) ...[
              const SizedBox(height: 2),
              Text(
                subtitle!,
                style: Theme.of(context).textTheme.bodySmall?.copyWith(
                  color: Theme.of(context).colorScheme.outline,
                ),
              ),
            ],
            const SizedBox(height: 12),
            child,
          ],
        ),
      ),
    );
  }
}