Months of the Year using InheritedNotifier

main.dart

import 'package:flutter/material.dart';

void main() {
  runApp(const MyApp());
}

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

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      home: Scaffold(
        body: Center(
          child: CalendarWidget(
            selectedDate: DateTime.now(),
          ),
        ),
      ),
    );
  }
}

class CalendarWidget extends StatelessWidget {
  const CalendarWidget({super.key, required this.selectedDate});

  final DateTime selectedDate;

  @override
  Widget build(BuildContext context) {
    final initialMonth = MonthsOfTheYear.values[selectedDate.month - 1];
    // Initialize the ValueNotifier with the default month
    return CalendarProvider(
      notifier: ValueNotifier<MonthsOfTheYear>(initialMonth),
      child: Scaffold(
        appBar: AppBar(title: Text('Calendar')),
        body: Center(
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.center,
            mainAxisSize: MainAxisSize.min,
            children: [
              MonthNavigation(),
              // A child context is needed to access the provider
              // can be a extracted widget or a builder
              Builder(
                builder: (context) => Text(
                  'Selected Month: ${CalendarProvider.of(context).name}',
                  style: TextStyle(fontSize: 20),
                ),
              )
            ],
          ),
        ),
      ),
    );
  }
}

class MonthNavigation extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Row(
      mainAxisSize: MainAxisSize.min,
      spacing: 20,
      children: [
        IconButton.filled(
          icon: Icon(Icons.arrow_left),
          color: Colors.red,
          onPressed: () {
            final currentMonth = CalendarProvider.of(context);
            final newMonth = MonthsOfTheYear.values[
                (currentMonth.index - 1 + MonthsOfTheYear.values.length) %
                    MonthsOfTheYear.values.length];
            CalendarProvider.updateMonth(context, newMonth);
          },
        ),
        IconButton.filledTonal(
          icon: Icon(Icons.arrow_right),
          color: Colors.red,
          onPressed: () {
            final currentMonth = CalendarProvider.of(context);
            final newMonth = MonthsOfTheYear.values[
                (currentMonth.index + 1) % MonthsOfTheYear.values.length];
            CalendarProvider.updateMonth(context, newMonth);
          },
        ),
      ],
    );
  }
}

// Define your enum for the months
enum MonthsOfTheYear {
  january,
  february,
  march,
  april,
  may,
  june,
  july,
  august,
  september,
  october,
  november,
  december;
}

// Create the InheritedNotifier to hold the selected month
class CalendarProvider
    extends InheritedNotifier<ValueNotifier<MonthsOfTheYear>> {
  const CalendarProvider({
    Key? key,
    required ValueNotifier<MonthsOfTheYear> notifier,
    required Widget child,
  }) : super(key: key, notifier: notifier, child: child);

  // Helper method to access the current month
  static MonthsOfTheYear of(BuildContext context) {
    final widget =
        context.dependOnInheritedWidgetOfExactType<CalendarProvider>();
    assert(widget != null, 'No CalendarProvider found in context');
    return widget!.notifier!.value;
  }

  // Helper method to update the current month
  static void updateMonth(BuildContext context, MonthsOfTheYear newMonth) {
    final widget =
        context.dependOnInheritedWidgetOfExactType<CalendarProvider>();
    assert(widget != null, 'No CalendarProvider found in context');
    widget!.notifier!.value = newMonth;
  }
}