a Hebrew Date picker package in Flutter: single and range date selections

Question

I have implemented a working Hebrew Date Picker package (link on pub.dev) in Flutter that supports both single date and date range selection.

Here's what the date picker looks like in action:

Single date selection mode

Single date selection mode

[Date range selection mode4

Date range selection mode

Key features:

• Single date and date range selection.
• Support for Hebrew calendar displays.
• The user can customize the theme.
• Handling of Jewish leap years.
• Utilizes kosher_dart for Hebrew date calculations.

Question

While I'm open to all feedback, I'm particularly interested in improving:

1. The overall structure and organization of the code
2. Efficiency of date calculations, especially with kosher_dart
3. Handling of Jewish calendar specifics (like leap years)

Code

Core implementation

Here's the core implementation (not runnable):

// Base class for shared functionality
abstract class HebrewDatePickerBase extends StatefulWidget {
 final DateTime firstDate;
 final DateTime lastDate;
 final bool hebrewFormat;
 final HebrewDatePickerTheme? theme;
 HebrewDatePickerBase({
 Key? key,
 required this.firstDate,
 required this.lastDate,
 this.hebrewFormat = true,
 this.theme,
 }) : super(key: key);
 @override
 HebrewDatePickerBaseState createState();
}
abstract class HebrewDatePickerBaseState<T extends HebrewDatePickerBase> extends State<T> {
 // ... [other properties]
 String _getHebrewMonthName(int month) {
 // ... [implementation]
 }
 JewishDate _getMonthFromPageIndex(int index) {
 // ... [implementation]
 }
 // ... [other key methods]
}
class MaterialHebrewDatePicker extends HebrewDatePickerBase {
 // ... [constructor and properties]
 @override
 _MaterialHebrewDatePickerState createState() => _MaterialHebrewDatePickerState();
}
class _MaterialHebrewDatePickerState extends HebrewDatePickerBaseState<MaterialHebrewDatePicker> {
 late JewishDate _selectedDate;
 @override
 Widget build(BuildContext context) {
 // ... [condensed build method, focusing on structure]
 }
 Widget _buildMonthView(BuildContext context, int pageIndex) {
 // ... [implementation, as this is a key part of the date picker functionality]
 }
 // ... [other key methods specific to single date selection]
}

Complete code

And here's the implementation of the above code as a almost complete runnable snippet:

import 'package:flutter/material.dart';
import 'package:kosher_dart/kosher_dart.dart';
import 'theme.dart';
// Base class for shared functionality
abstract class HebrewDatePickerBase extends StatefulWidget {
 final DateTime firstDate;
 final DateTime lastDate;
 final bool hebrewFormat;
 final HebrewDatePickerTheme? theme;
 HebrewDatePickerBase({
 Key? key,
 required this.firstDate,
 required this.lastDate,
 this.hebrewFormat = true,
 this.theme,
 }) : super(key: key);
 @override
 HebrewDatePickerBaseState createState();
}
abstract class HebrewDatePickerBaseState<T extends HebrewDatePickerBase>
 extends State<T> {
 late JewishDate _displayedMonth;
 late HebrewDateFormatter _formatter;
 late PageController _pageController;
 late int _currentPage;
 late int _totalMonths;
 @override
 void initState() {
 super.initState();
 _displayedMonth = JewishDate.fromDateTime(widget.firstDate);
 _formatter = HebrewDateFormatter()..hebrewFormat = widget.hebrewFormat;
 _totalMonths = _monthsBetween(JewishDate.fromDateTime(widget.firstDate),
 JewishDate.fromDateTime(widget.lastDate));
 _currentPage = 0;
 _pageController = PageController(initialPage: _currentPage);
 }
 int _monthsBetween(JewishDate start, JewishDate end) {
 int months = 0;
 JewishDate current = JewishDate()
 ..setJewishDate(start.getJewishYear(), start.getJewishMonth(), 1);
 while (current.compareTo(end) <= 0) {
 months++;
 current.forward(Calendar.MONTH, 1);
 }
 return months - 1;
 }
 JewishDate _getMonthFromPageIndex(int index) {
 JewishDate date = JewishDate.fromDateTime(widget.firstDate);
 if (index > 0) {
 date.forward(Calendar.MONTH, index);
 } else {
 // Go back to the first day of the month, there is no backward method
 for (int i = 0; i > index; i--) {
 date.back();
 }
 }
 return date;
 }
 void _onPageChanged(int page) {
 setState(() {
 _currentPage = page;
 _displayedMonth = _getMonthFromPageIndex(_currentPage);
 });
 }
 void _showPreviousMonth() {
 if (_currentPage > 0) {
 _pageController.previousPage(
 duration: const Duration(milliseconds: 300),
 curve: Curves.easeInOut,
 );
 }
 }
 void _showNextMonth() {
 if (_currentPage < _totalMonths - 1) {
 _pageController.nextPage(
 duration: const Duration(milliseconds: 300),
 curve: Curves.easeInOut,
 );
 }
 }
 String _getHebrewMonthName(int month) {
 List<String> months = widget.hebrewFormat
 ? [
 'ניסן',
 'אייר',
 'סיון',
 'תמוז',
 'אב',
 'אלול',
 'תשרי',
 'חשון',
 'כסלו',
 'טבת',
 'שבט',
 'אדר'
 ]
 : [
 'Nisan',
 'Iyyar',
 'Sivan',
 'Tammuz',
 'Av',
 'Elul',
 'Tishrei',
 'Heshvan',
 'Kislev',
 'Tevet',
 'Shevat',
 'Adar'
 ];
 if (_displayedMonth.isJewishLeapYear()) {
 if (month == JewishDate.ADAR) {
 return widget.hebrewFormat ? 'אדר א' : 'Adar I';
 } else if (month == JewishDate.ADAR_II) {
 return widget.hebrewFormat ? 'אדר ב' : 'Adar II';
 }
 }
 // Adjust the month index for leap years
 int adjustedMonth = month;
 // Jewish leap years have Adar I and Adar II
 // JewishDate.ADAR == 12, JewishDate.ADAR_II == 13
 if (_displayedMonth.isJewishLeapYear() && month > JewishDate.ADAR) {
 adjustedMonth--;
 }
 // Ensure the index is within bounds
 int index = (adjustedMonth - 1) % 12;
 return months[index];
 }
 Widget _buildMonthSelector(HebrewDatePickerTheme theme) {
 return Container(
 padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 12),
 child: Row(
 mainAxisAlignment: MainAxisAlignment.spaceBetween,
 children: [
 Text(
 '${_getHebrewMonthName(_displayedMonth.getJewishMonth())} ${widget.hebrewFormat ? _formatter.formatHebrewNumber(_displayedMonth.getJewishYear()) : _displayedMonth.getJewishYear()}',
 style: theme.bodyTextStyle.copyWith(
 fontWeight: FontWeight.bold,
 color: theme.primaryColor,
 ),
 ),
 Row(
 mainAxisSize: MainAxisSize.min,
 children: [
 IconButton(
 padding: EdgeInsets.zero,
 icon: const Icon(Icons.chevron_left),
 onPressed: _showPreviousMonth,
 color: theme.primaryColor,
 ),
 IconButton(
 padding: EdgeInsets.zero,
 icon: const Icon(Icons.chevron_right),
 onPressed: _showNextMonth,
 color: theme.primaryColor,
 ),
 ],
 ),
 ],
 ),
 );
 }
 Widget _buildWeekdayHeader(HebrewDatePickerTheme theme) {
 final weekdays = widget.hebrewFormat
 ? ['א', 'ב', 'ג', 'ד', 'ה', 'ו', 'ש']
 : ['S', 'M', 'T', 'W', 'T', 'F', 'S'];
 return Padding(
 padding: const EdgeInsets.symmetric(vertical: 10),
 child: Row(
 mainAxisAlignment: MainAxisAlignment.spaceAround,
 children: weekdays
 .map((day) => Text(day,
 style: theme.weekdayTextStyle.copyWith(
 color: theme.onSurfaceColor.withOpacity(0.6),
 )))
 .toList(),
 ),
 );
 }
 Widget _buildCalendar(HebrewDatePickerTheme theme,
 Widget Function(BuildContext, int) monthViewBuilder) {
 return Container(
 color: theme.surfaceColor,
 child: Column(
 children: [
 _buildMonthSelector(theme),
 _buildWeekdayHeader(theme),
 AspectRatio(
 aspectRatio: 1,
 child: PageView.builder(
 controller: _pageController,
 onPageChanged: _onPageChanged,
 itemBuilder: monthViewBuilder,
 itemCount: _totalMonths,
 ),
 ),
 ],
 ),
 );
 }
 HebrewDatePickerTheme _getMergedTheme() {
 const defaultTheme = HebrewDatePickerTheme();
 return HebrewDatePickerTheme(
 primaryColor: widget.theme?.primaryColor ?? defaultTheme.primaryColor,
 onPrimaryColor:
 widget.theme?.onPrimaryColor ?? defaultTheme.onPrimaryColor,
 surfaceColor: widget.theme?.surfaceColor ?? defaultTheme.surfaceColor,
 onSurfaceColor:
 widget.theme?.onSurfaceColor ?? defaultTheme.onSurfaceColor,
 disabledColor: widget.theme?.disabledColor ?? defaultTheme.disabledColor,
 selectedColor: widget.theme?.selectedColor ?? defaultTheme.selectedColor,
 todayColor: widget.theme?.todayColor ?? defaultTheme.todayColor,
 headerTextStyle:
 widget.theme?.headerTextStyle ?? defaultTheme.headerTextStyle,
 bodyTextStyle: widget.theme?.bodyTextStyle ?? defaultTheme.bodyTextStyle,
 weekdayTextStyle:
 widget.theme?.weekdayTextStyle ?? defaultTheme.weekdayTextStyle,
 );
 }
}
class MaterialHebrewDatePicker extends HebrewDatePickerBase {
 final DateTime initialDate;
 final ValueChanged<DateTime> onDateChange;
 final ValueChanged<DateTime> onConfirmDate;
 MaterialHebrewDatePicker({
 Key? key,
 required this.initialDate,
 required DateTime firstDate,
 required DateTime lastDate,
 required this.onDateChange,
 required this.onConfirmDate,
 bool hebrewFormat = true,
 HebrewDatePickerTheme? theme,
 }) : super(
 key: key,
 firstDate: firstDate,
 lastDate: lastDate,
 hebrewFormat: hebrewFormat,
 theme: theme);
 @override
 _MaterialHebrewDatePickerState createState() =>
 _MaterialHebrewDatePickerState();
}
class _MaterialHebrewDatePickerState
 extends HebrewDatePickerBaseState<MaterialHebrewDatePicker> {
 late JewishDate _selectedDate;
 @override
 void initState() {
 super.initState();
 _selectedDate = JewishDate.fromDateTime(widget.initialDate);
 }
 @override
 Widget build(BuildContext context) {
 final theme = _getMergedTheme();
 final screenSize = MediaQuery.of(context).size;
 final isSmallScreen = screenSize.width < 360;
 return LayoutBuilder(
 builder: (context, constraints) {
 final maxWidth = isSmallScreen ? screenSize.width * 0.95 : 360.0;
 final maxHeight = isSmallScreen ? screenSize.height * 0.9 : 640.0;
 return Center(
 child: ConstrainedBox(
 constraints: BoxConstraints(
 maxWidth: maxWidth,
 maxHeight: maxHeight,
 ),
 child: Directionality(
 textDirection: TextDirection.rtl,
 child: Dialog(
 elevation: 0,
 shape: RoundedRectangleBorder(
 borderRadius: BorderRadius.circular(28)),
 child: Column(
 mainAxisSize: MainAxisSize.min,
 children: [
 _buildHeader(theme),
 Flexible(
 child: SingleChildScrollView(
 child: _buildCalendar(theme, _buildMonthView),
 ),
 ),
 _buildActions(theme),
 ],
 ),
 ),
 ),
 ),
 );
 },
 );
 }
 Widget _buildHeader(HebrewDatePickerTheme theme) {
 return Container(
 width: double.infinity,
 padding: const EdgeInsets.all(24),
 decoration: BoxDecoration(
 color: theme.primaryColor,
 borderRadius: const BorderRadius.vertical(top: Radius.circular(28)),
 ),
 child: Column(
 children: [
 Text(
 widget.hebrewFormat ? 'בחר תאריך' : 'Select Date',
 style: theme.headerTextStyle.copyWith(
 color: theme.onPrimaryColor,
 ),
 ),
 const SizedBox(height: 10),
 Text(
 _formatFullDate(_selectedDate),
 style: theme.bodyTextStyle.copyWith(
 color: theme.onPrimaryColor,
 fontWeight: FontWeight.bold,
 ),
 ),
 ],
 ),
 );
 }
 Widget _buildMonthView(BuildContext context, int pageIndex) {
 final theme = _getMergedTheme();
 final monthDate = _getMonthFromPageIndex(pageIndex);
 final daysInMonth = monthDate.getDaysInJewishMonth();
 final firstDayOfMonth = JewishDate()
 ..setJewishDate(monthDate.getJewishYear(), monthDate.getJewishMonth(), 1);
 final firstWeekday = firstDayOfMonth.getDayOfWeek();
 return GridView.builder(
 shrinkWrap: true,
 physics: const NeverScrollableScrollPhysics(),
 gridDelegate: const SliverGridDelegateWithFixedCrossAxisCount(
 crossAxisCount: 7,
 childAspectRatio: 1,
 ),
 itemCount: 42, // 6 rows * 7 days
 itemBuilder: (context, index) {
 final int day = index - firstWeekday + 2;
 if (day < 1 || day > daysInMonth) return Container();
 final currentDate = JewishDate()
 ..setJewishDate(
 monthDate.getJewishYear(), monthDate.getJewishMonth(), day);
 final isSelected = currentDate.compareTo(_selectedDate) == 0;
 final isDisabled = currentDate
 .compareTo(JewishDate.fromDateTime(widget.firstDate)) <
 0 ||
 currentDate.compareTo(JewishDate.fromDateTime(widget.lastDate)) > 0;
 return LayoutBuilder(
 builder: (context, constraints) {
 final size = constraints.maxWidth / 7;
 return InkWell(
 onTap: isDisabled ? null : () => _selectDate(currentDate),
 child: Padding(
 padding: EdgeInsets.all(1),
 child: Container(
 margin: EdgeInsets.all(1),
 decoration: BoxDecoration(
 shape: BoxShape.circle,
 color: isSelected ? theme.selectedColor : null,
 ),
 child: Center(
 child: Text(
 widget.hebrewFormat
 ? _formatter.formatHebrewNumber(day)
 : day.toString(),
 style: theme.bodyTextStyle.copyWith(
 color: isSelected
 ? theme.onPrimaryColor
 : isDisabled
 ? theme.disabledColor
 : theme.onSurfaceColor,
 fontWeight:
 isSelected ? FontWeight.bold : FontWeight.normal,
 fontSize: size * 2.2,
 ),
 ),
 ),
 ),
 ),
 );
 },
 );
 },
 );
 }
 Widget _buildActions(HebrewDatePickerTheme theme) {
 return Container(
 padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
 child: Row(
 mainAxisAlignment: MainAxisAlignment.end,
 children: [
 TextButton(
 onPressed: () => Navigator.of(context).pop(),
 child: Text(widget.hebrewFormat ? 'ביטול' : 'Cancel'),
 style: TextButton.styleFrom(
 foregroundColor: theme.primaryColor,
 ),
 ),
 const SizedBox(width: 8),
 ElevatedButton(
 onPressed: _confirmDate,
 child: Text(widget.hebrewFormat ? 'אישור' : 'Confirm'),
 style: ElevatedButton.styleFrom(
 foregroundColor: theme.onPrimaryColor,
 backgroundColor: theme.primaryColor,
 ),
 ),
 ],
 ),
 );
 }
 void _selectDate(JewishDate currentDate) {
 setState(() {
 _selectedDate = currentDate;
 });
 widget.onDateChange(currentDate.getGregorianCalendar());
 }
 void _confirmDate() {
 widget.onConfirmDate(_selectedDate.getGregorianCalendar());
 Navigator.of(context).pop();
 }
 String _formatFullDate(JewishDate date) {
 final dayOfWeek = _getHebrewDayOfWeek(date.getDayOfWeek());
 final day = widget.hebrewFormat
 ? _formatter.formatHebrewNumber(date.getJewishDayOfMonth())
 : date.getJewishDayOfMonth().toString();
 final month = _getHebrewMonthName(date.getJewishMonth());
 final year = widget.hebrewFormat
 ? _formatter.formatHebrewNumber(date.getJewishYear())
 : date.getJewishYear().toString();
 return '$dayOfWeek, $day $month $year';
 }
 String _getHebrewDayOfWeek(int day) {
 final days = widget.hebrewFormat
 ? ['ראשון', 'שני', 'שלישי', 'רביעי', 'חמישי', 'שישי', 'שבת']
 : [
 'Sunday',
 'Monday',
 'Tuesday',
 'Wednesday',
 'Thursday',
 'Friday',
 'Saturday'
 ];
 return days[day - 1];
 }
}
class HebrewDateRangePicker extends HebrewDatePickerBase {
 final DateTime? initialStartDate;
 final DateTime? initialEndDate;
 final ValueChanged<DateTimeRange?> onDateRangeChanged;
 HebrewDateRangePicker({
 Key? key,
 this.initialStartDate,
 this.initialEndDate,
 required DateTime firstDate,
 required DateTime lastDate,
 required this.onDateRangeChanged,
 bool hebrewFormat = true,
 HebrewDatePickerTheme? theme,
 }) : super(
 key: key,
 firstDate: firstDate,
 lastDate: lastDate,
 hebrewFormat: hebrewFormat,
 theme: theme);
 @override
 _HebrewDateRangePickerState createState() => _HebrewDateRangePickerState();
}
class _HebrewDateRangePickerState
 extends HebrewDatePickerBaseState<HebrewDateRangePicker> {
 late JewishDate _startDate;
 late JewishDate _endDate;
 bool _isSelectingEndDate = false;
 bool _hasSelection = false;
 @override
 void initState() {
 super.initState();
 _startDate = JewishDate.fromDateTime(widget.firstDate);
 _endDate = JewishDate.fromDateTime(widget.firstDate);
 }
 @override
 Widget build(BuildContext context) {
 final theme = _getMergedTheme();
 final screenSize = MediaQuery.of(context).size;
 final isSmallScreen = screenSize.width < 360;
 return LayoutBuilder(
 builder: (context, constraints) {
 final maxWidth = isSmallScreen ? screenSize.width * 0.95 : 360.0;
 final maxHeight = isSmallScreen ? screenSize.height * 0.9 : 640.0;
 return Center(
 child: ConstrainedBox(
 constraints: BoxConstraints(
 maxWidth: maxWidth,
 maxHeight: maxHeight,
 ),
 child: Directionality(
 textDirection: TextDirection.rtl,
 child: Dialog(
 shape: RoundedRectangleBorder(
 borderRadius: BorderRadius.circular(28),
 ),
 child: Column(
 mainAxisSize: MainAxisSize.min,
 children: [
 _buildHeader(theme),
 Flexible(
 child: _buildCalendar(theme, _buildMonthView),
 ),
 _buildFooter(theme),
 ],
 ),
 ),
 ),
 ),
 );
 },
 );
 }
 Widget _buildHeader(HebrewDatePickerTheme theme) {
 return Container(
 padding: const EdgeInsets.all(16),
 color: theme.primaryColor,
 child: Column(
 children: [
 Text(
 widget.hebrewFormat ? 'בחר טווח תאריכים' : 'Select Date Range',
 style: theme.headerTextStyle,
 ),
 const SizedBox(height: 8),
 Row(
 mainAxisAlignment: MainAxisAlignment.spaceBetween,
 children: [
 Column(
 crossAxisAlignment: CrossAxisAlignment.start,
 children: [
 Text(widget.hebrewFormat ? 'מתאריך' : 'Start Date'),
 Text(_hasSelection ? _formatDate(_startDate) : '-'),
 ],
 ),
 Column(
 crossAxisAlignment: CrossAxisAlignment.end,
 children: [
 Text(widget.hebrewFormat ? 'עד תאריך' : 'End Date'),
 Text(_hasSelection && !_isSelectingEndDate
 ? _formatDate(_endDate)
 : '-'),
 ],
 ),
 ],
 ),
 ],
 ),
 );
 }
 Widget _buildMonthView(BuildContext context, int pageIndex) {
 final theme = _getMergedTheme();
 final monthDate = _getMonthFromPageIndex(pageIndex);
 final daysInMonth = monthDate.getDaysInJewishMonth();
 final firstDayOfMonth = JewishDate()
 ..setJewishDate(monthDate.getJewishYear(), monthDate.getJewishMonth(), 1);
 final firstWeekday = firstDayOfMonth.getDayOfWeek();
 final today = JewishDate.fromDateTime(DateTime.now());
 return GridView.builder(
 gridDelegate: const SliverGridDelegateWithFixedCrossAxisCount(
 crossAxisCount: 7,
 childAspectRatio: 1,
 ),
 itemCount: 42,
 itemBuilder: (context, index) {
 final int day = index - firstWeekday + 2;
 if (day < 1 || day > daysInMonth) return Container();
 final currentDate = JewishDate()
 ..setJewishDate(
 monthDate.getJewishYear(), monthDate.getJewishMonth(), day);
 final isSelected = _isDateInRange(currentDate);
 final isDisabled = _isDateDisabled(currentDate);
 final isToday = currentDate.compareTo(today) == 0;
 return LayoutBuilder(
 builder: (context, constraints) {
 final size = constraints.maxWidth / 7;
 return InkWell(
 onTap: isDisabled ? null : () => _selectDate(currentDate),
 child: Padding(
 padding: EdgeInsets.all(size * 0.05),
 child: Container(
 margin: EdgeInsets.all(size * 0.01),
 decoration: BoxDecoration(
 color: isSelected
 ? theme.primaryColor
 : isToday
 ? theme.todayColor.withOpacity(0.3)
 : null,
 borderRadius: BorderRadius.circular(20),
 border: isToday
 ? Border.all(color: theme.todayColor, width: 2)
 : null,
 ),
 child: Center(
 child: Text(
 widget.hebrewFormat
 ? _formatter.formatHebrewNumber(day)
 : day.toString(),
 style: theme.bodyTextStyle.copyWith(
 color: isSelected
 ? theme.onPrimaryColor
 : isDisabled
 ? theme.onSurfaceColor.withOpacity(0.38)
 : isToday
 ? theme.todayColor
 : theme.onSurfaceColor,
 fontWeight:
 isToday ? FontWeight.bold : FontWeight.normal,
 fontSize: size * 2.2,
 ),
 ),
 ),
 ),
 ),
 );
 },
 );
 },
 );
 }
 Widget _buildFooter(HebrewDatePickerTheme theme) {
 return Container(
 padding: const EdgeInsets.symmetric(horizontal: 16, vertical: 8),
 child: Row(
 mainAxisAlignment: MainAxisAlignment.end,
 children: [
 TextButton(
 onPressed: () => Navigator.of(context).pop(),
 child: Text(widget.hebrewFormat ? 'ביטול' : 'Cancel'),
 style: TextButton.styleFrom(
 foregroundColor: theme.primaryColor,
 ),
 ),
 const SizedBox(width: 8),
 ElevatedButton(
 onPressed: _hasSelection ? _confirmDateRange : null,
 child: Text(widget.hebrewFormat ? 'אישור' : 'Confirm'),
 style: ElevatedButton.styleFrom(
 foregroundColor: theme.onPrimaryColor,
 backgroundColor: theme.primaryColor,
 ),
 ),
 ],
 ),
 );
 }
 void _selectDate(JewishDate date) {
 setState(() {
 if (!_hasSelection) {
 _startDate = date;
 _endDate = date;
 _hasSelection = true;
 _isSelectingEndDate = true;
 } else if (_isSelectingEndDate) {
 if (date.compareTo(_startDate) < 0) {
 _endDate = _startDate;
 _startDate = date;
 } else {
 _endDate = date;
 }
 _isSelectingEndDate = false;
 } else {
 _startDate = date;
 _endDate = date;
 _isSelectingEndDate = true;
 }
 });
 }
 bool _isDateInRange(JewishDate date) {
 if (!_hasSelection) return false;
 if (!_isSelectingEndDate && _startDate.compareTo(_endDate) == 0) {
 return date.compareTo(_startDate) == 0;
 }
 return (date.compareTo(_startDate) >= 0 && date.compareTo(_endDate) <= 0);
 }
 bool _isDateDisabled(JewishDate date) {
 return date.compareTo(JewishDate.fromDateTime(widget.firstDate)) < 0 ||
 date.compareTo(JewishDate.fromDateTime(widget.lastDate)) > 0;
 }
 void _confirmDateRange() {
 final selectedRange = DateTimeRange(
 start: _startDate.getGregorianCalendar(),
 end: _endDate.getGregorianCalendar(),
 );
 Navigator.of(context).pop(selectedRange);
 }
 String _formatDate(JewishDate date) {
 final day = _formatter.formatHebrewNumber(date.getJewishDayOfMonth());
 final month = _getHebrewMonthName(date.getJewishMonth());
 final year = widget.hebrewFormat
 ? _formatter.formatHebrewNumber(date.getJewishYear())
 : date.getJewishYear().toString();
 return '$day $month $year';
 }
}
// Helper functions
Future<void> showMaterialHebrewDatePicker({
 required BuildContext context,
 DateTime? initialDate,
 required DateTime firstDate,
 required DateTime lastDate,
 bool hebrewFormat = true,
 required ValueChanged<DateTime> onDateChange,
 required ValueChanged<DateTime> onConfirmDate,
 HebrewDatePickerTheme? theme,
}) async {
 return showDialog<void>(
 context: context,
 builder: (BuildContext context) {
 return MaterialHebrewDatePicker(
 initialDate: initialDate ?? DateTime.now(),
 firstDate: firstDate,
 lastDate: lastDate,
 onDateChange: onDateChange,
 onConfirmDate: onConfirmDate,
 hebrewFormat: hebrewFormat,
 theme: theme,
 );
 },
 );
}
Future<DateTimeRange?> showMaterialHebrewDateRangePicker({
 required BuildContext context,
 DateTime? initialStartDate,
 DateTime? initialEndDate,
 required DateTime firstDate,
 required DateTime lastDate,
 bool hebrewFormat = true,
 HebrewDatePickerTheme? theme,
}) async {
 return showDialog<DateTimeRange>(
 context: context,
 builder: (BuildContext context) {
 return HebrewDateRangePicker(
 initialStartDate: initialStartDate,
 initialEndDate: initialEndDate,
 firstDate: firstDate,
 lastDate: lastDate,
 hebrewFormat: hebrewFormat,
 onDateRangeChanged: (DateTimeRange? range) {
 Navigator.of(context).pop(range);
 },
 theme: theme,
 );
 },
 );
}

The full implementation can be found on GitHub.

To the best of my knowledge, it works as intended for the basic use cases I've tested.

I'm looking to improve all aspects of this code to make it more robust, efficient, and maintainable.

Any suggestions for improvement would be greatly appreciated!

Answer 1

Here are a few suggestions:

• months is currently a List<String> in _getHebrewMonthName and an int in _monthsBetween. So I would rename the List<String> version of months to month_names. A similar issue occurs with weekdays and days, where I would rename the List<String> versions to weekday_names and long_weekday_names. I find that consistent naming across all code (even different scopes) makes things much easier to reason about. You might even decide to only use day as shorthand for day-of-month and only use weekday as shorthand for day-of-week.
• You will need to generate two arrays in _monthsBetween for each call. Similar issues occur for _getHebrewDayOfWeek and _buildWeekdayHeader. Instead, use constants with appropriate scope:

final List<String> month_names1 = [
 'ניסן',
 'אייר',
 'סיון',
 'תמוז',
 'אב',
 'אלול',
 'תשרי',
 'חשון',
 'כסלו',
 'טבת',
 'שבט',
 'אדר'
];
final List<String> month_names2 = [
 'Nisan',
 'Iyyar',
 'Sivan',
 'Tammuz',
 'Av',
 'Elul',
 'Tishrei',
 'Heshvan',
 'Kislev',
 'Tevet',
 'Shevat',
 'Adar'
];
String _getHebrewMonthName(int month) {
 if (_displayedMonth.isJewishLeapYear()) {
 // same as before ...
 }
 // same as before ...
 int index = (adjustedMonth - 1) % 12;
 
 if (widget.hebrewFormat)
 return month_names1[index];
 return month_names2[index];
}

• I would similarly make two constant arrays for days. I would lengthen the English weekday names to avoid duplicates:

final weekday_names1 = ['א', 'ב', 'ג', 'ד', 'ה', 'ו', 'ש'];
final weekday_names2 = ['Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat'];

• I would also make constant arrays for the longer versions of weekday names:

final long_weekday_names1 = ['ראשון', 'שני', 'שלישי', 'רביעי', 'חמישי', 'שישי', 'שבת'];
final long_weekday_names2 = [
 'Sunday',
 'Monday',
 'Tuesday',
 'Wednesday',
 'Thursday',
 'Friday',
 'Saturday'
];

• The chained ternary : operators are somewhat confusing to me. Similarly, I feel that the extensive nesting / indentation makes braces / parentheses hard to track. For example, I might rewrite _MaterialHebrewDatePickerState.build() as:

Widget build(BuildContext context) {
 final theme = _getMergedTheme();
 final screenSize = MediaQuery.of(context).size;
 final isSmallScreen = screenSize.width < 360;
 final border = RoundedRectangleBorder(BorderRadius.circular(28));
 final builder = (context, constraints) => {
 final maxWidth = isSmallScreen ? screenSize.width * 0.95 : 360.0;
 final maxHeight = isSmallScreen ? screenSize.height * 0.9 : 640.0;
 final monthCalendar = _buildCalendar(theme, _buildMonthView);
 final monthView = Flexible(SingleChildScrollView(monthCalendar));
 final bounds = BoxConstraints(
 maxWidth: maxWidth,
 maxHeight: maxHeight,
 );
 final monthBox = ConstrainedBox(
 constraints: bounds,
 child: Directionality(
 textDirection: TextDirection.rtl,
 child: Dialog(
 elevation: 0,
 shape: border,
 child: Column(
 mainAxisSize: MainAxisSize.min,
 children: [
 _buildHeader(theme),
 monthView 
 _buildActions(theme),
 ],
 ),
 ),
 )
 );
 return Center(monthBox);
 };
 return LayoutBuilder(builder);
}

Overall, good job on making a reproducible example. Hope this helps.