update feature NumberToWords

README.md

@@ -89,28 +89,16 @@ words.convertWordsToNumberString(); // '3212' as String
 - #### Converting Persian numbers to word - [source](https://github.com/persian-tools/dart-persian-tools/blob/master/lib/src/core/number_to_words/number_to_words.dart)
 
 ```dart
-final stringDigit = '257,433';
 final intDigit = -128;
 
-/// use [numberToWordsString] method to convert [stringDigit] to persian
-
-numberToWordsString(stringDigit); // 'دویست و پنجاه و هفت هزار و چهارصد و سی و سه'
-
-/// [numberToWordsString] also has an optional parameter
-/// by default [ordinal] is [false], [true] makes the output an ordinal word
-
-numberToWordsString(stringDigit, ordinal: true); // 'دویست و پنجاه و هفت هزار و چهارصد و سی و سوم'
-
-/// use [numberToWordsInt] method to convert [intDigit] to persian
+/// use [numberToWords] method to convert [intDigit] to persian
 numberToWords(intDigit); // 'منفی صد و بیست و هشت'
 
-/// [numberToWordsInt] also has an optional parameter
+/// [numberToWords] also has an optional parameter
 /// by default [ordinal] is [false], [true] makes the output an ordinal word
 numberToWords(intDigit, ordinal: true); // 'منفی صد و بیست و هشتم'
 
-/// you can simply use extension methods on int or String objects
-stringDigit.convertNumToWords(); // 'دویست و پنجاه و هفت هزار و چهارصد و سی و سه'
-
+/// you can simply use extension methods on int objects
 intDigit.convertNumToWords(); // 'منفی صد و بیست و هشت'
 ```
 

example/example_number_to_words.dart

@@ -1,28 +1,15 @@
 import 'package:persian_tools/persian_tools.dart';
 
 void main() {
-  final stringDigit = '257,433';
   final intDigit = -128;
 
-  /// use [numberToWordsString] method to convert [stringDigit] to persian
-  print(numberToWordsString(
-      stringDigit)); // 'دویست و پنجاه و هفت هزار و چهارصد و سی و سه'
-
-  /// [numberToWordsString] also has an optional parameter
-  /// by default [ordinal] is [false], [true] makes the output an ordinal word
-  print(numberToWordsString(stringDigit,
-      ordinal: true)); // 'دویست و پنجاه و هفت هزار و چهارصد و سی و سوم'
-
-  /// use [numberToWordsInt] method to convert [intDigit] to persian
+  /// use [numberToWords] method to convert [intDigit] to persian
   print(numberToWords(intDigit)); // 'منفی صد و بیست و هشت'
 
-  /// [numberToWordsInt] also has an optional parameter
+  /// [numberToWords] also has an optional parameter
   /// by default [ordinal] is [false], [true] makes the output an ordinal word
   print(numberToWords(intDigit, ordinal: true)); // 'منفی صد و بیست و هشتم'
 
   /// you can simply use extension methods on int or String objects
-  print(stringDigit
-      .convertNumToWords()); // 'دویست و پنجاه و هفت هزار و چهارصد و سی و سه'
-
   print(intDigit.convertNumToWords()); // 'منفی صد و بیست و هشت'
 }

lib/src/constants/number_to_words/constants.dart

@@ -1,13 +1,11 @@
-const base = 1000;
+const errorMessage =
+    'PersianTools: numberToWords - the number must be a safe integer less than 16 digits';
 
 const zeroFa = 'صفر';
 
-const endsWithAnd = ' و ';
-
-const scale = ['', 'هزار', 'میلیون', 'میلیارد'];
+const andFa = ' و ';
 
 const numberToWord = {
-  0: '',
   1: 'یک',
   2: 'دو',
   3: 'سه',
@@ -44,4 +42,9 @@ const numberToWord = {
   700: 'هفتصد',
   800: 'هشتصد',
   900: 'نهصد',
+  1000: 'هزار',
+  1000000: 'میلیون',
+  1000000000: 'میلیارد',
+  1000000000000: 'تریلیون',
+  1000000000000000: 'کوآدریلیون',
 };

lib/src/core/number_to_words/number_to_words.dart

@@ -2,81 +2,88 @@ import 'package:persian_tools/persian_tools.dart';
 import 'package:persian_tools/src/constants/number_to_words/constants.dart';
 import 'package:persian_tools/src/internal_methods.dart';
 
-/// Gets an [int] with 3 or less digits as input and converts it to persian
-String _numToWord(int number) {
-  var unit = 100;
-  var result = '';
-
-  while (unit > 0) {
-    if ((number / unit).floor() * unit != 0) {
-      if (numberToWord.containsKey(number)) {
-        result += numberToWord[number]!;
-        break;
-      } else {
-        result += '${numberToWord[(number / unit).floor() * unit]} و ';
-        number %= unit;
-      }
-    }
-    unit = (unit / 10).floor();
-  }
-  return result;
+/// Gets an [int] as input and checks if it's a negative number
+bool _isNegative(int number) {
+  return number < 0;
 }
 
-/// Checks current [input] for negative [value] and deploying converting process
-String _convert(int number, bool ordinal) {
-  var result = <String>[];
-
-  final isNegative = number < 0;
-  number = isNegative ? number * -1 : number;
-
-  while (number > 0) {
-    result.add(_numToWord(number % base));
-    number = (number / base).floor();
-  }
-  if (result.length > 4) return '';
-
-  for (var i = 0; i < result.length; i++) {
-    if (result[i] != '' && i != 0) result[i] += ' ${scale[i]} و ';
-  }
-  result = result.reversed.toList();
-
-  var words = result.join('');
-
-  if (words.endsWith(endsWithAnd)) {
-    words = words.substring(0, (words.length - 3));
-  }
+/// Returns error message for [input] with more than 16 digits
+String _numberIsNotValidError() {
+  return errorMessage;
+}
 
-  words = trim(isNegative ? 'منفی $words' : words);
+/// Gets an [int] as input and if exists, returns persian word
+String _getWord(int number) {
+  return numberToWord[number] ?? '';
+}
 
-  if (ordinal) words = addOrdinalSuffix(words);
+/// Gets an [String] input and add negative persian prefix to it
+String _addNegativeSuffix(String number) {
+  return 'منفی $number';
+}
 
-  return words;
+/// Gets an [int] as input and returns [unitName] for numbers over 1000
+/// [_getUnitName] parameter is calculated by subtracting current [map] key
+/// from [separated] length multiplied by 3
+String _getUnitName(int numberOfZeros) {
+  return numberOfZeros == 0
+      ? ''
+      : numberToWord[int.parse('1${"0" * numberOfZeros}')]!;
 }
 
-/// Returns Persian word of the given number in String. Number can contain commas.
-/// You can determine returned string has ordinal suffix or not by `ordinal` flag.
-String? numberToWordsString(String number, {bool ordinal = false}) {
-  if (number.isEmpty) return null;
-  if (number == '0') return zeroFa;
+/// Gets an [int] with 3 or less digits as input and converts it to persian
+/// [num] between 1 & 19,except for 10, are converted directly like other
+/// numbers that divisible by 10
+/// For other numbers, the remainder of dividing by 10 would be passed to
+/// [_transformToWord]
+String _transformToWord(int number) {
+  if (number == 0) return '';
+  if (number <= 19 && number != 10) return _getWord(number);
+
+  final residual = number <= 99 ? number % 10 : number % 100;
+  return residual == 0
+      ? _getWord(number)
+      : '${_getWord(number - residual)} و ${_transformToWord(residual)}';
+}
 
-  return _convert(removeCommas(number).toInt(), ordinal);
+/// Transform [input] to string, breaks the number into three digit
+/// parts, assign the string to [separated], get each part's [unitName]
+/// and [transformedVal] inside [map] function of [numberArr]. each separated
+/// part is handled in [map]. After [map] function, [where] function checks
+/// the result created by [map] and ignores the empty items.
+/// Finally [toList] combines and returns the result of the parts as a [String]
+String _performer(int number) {
+  if (number <= 999) return _transformToWord(number);
+  final separated = addCommas(number.toString()).split(',');
+  final numberArr = separated
+      .asMap()
+      .entries
+      .map((e) {
+    final transformedVal = _transformToWord(int.parse(e.value, radix: 10));
+    final unitName = _getUnitName((separated.length - (e.key + 1)) * 3);
+    return transformedVal.isNotEmpty ? '$transformedVal $unitName' : '';
+  })
+      .where((element) => element.length > 1)
+      .toList();
+  return trim(numberArr.join(andFa));
 }
 
 /// Returns Persian word of the given number in int You can determine
 /// returned string has ordinal suffix or not by `ordinal` flag.
+/// The current [input] is passed to [_performer] as positive integer
+/// If [input] is negative, prefix would be added to [_performer] result
+/// If `ordinal` is true, suffix would be added to the result of [tmpResult]
 String numberToWords(int number, {bool ordinal = false}) {
   if (number == 0) return zeroFa;
-  return _convert(number, ordinal);
-}
-
-/// [String] Extension wrapper to convert number to Persian word on String object
-extension NumberToPersianWordsString on String {
-  String? convertNumToWords({bool ordinal = false}) =>
-      numberToWordsString(this, ordinal: ordinal);
+  if (number.toString().length > 16) return _numberIsNotValidError();
+  final _tmpResult = _isNegative(number)
+      ? _addNegativeSuffix(_performer(number.abs()))
+      : _performer(number);
+  return ordinal ? addOrdinalSuffix(_tmpResult) : _tmpResult;
 }
 
 /// [int] Extension wrapper to convert number to Persian word on int object
 extension NumberToPersianWordsInt on int {
-  String? convertNumToWords({bool ordinal = false}) =>
+  String convertNumToWords({bool ordinal = false}) =>
       numberToWords(this, ordinal: ordinal);
 }