Initial

lib/utils/frequency_input_formatter.dart

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+import 'package:flutter/services.dart';
+
+class FrequencyInputFormatter extends TextInputFormatter {
+  static const int maxDigits = 5;
+
+  @override
+  TextEditingValue formatEditUpdate(
+      TextEditingValue oldValue, TextEditingValue newValue) {
+    String digitsOnly = newValue.text.replaceAll(RegExp(r'[^0-9]'), '');
+
+    if (digitsOnly.length > maxDigits) {
+      return oldValue;
+    }
+
+    String formatted = digitsOnly;
+    if (digitsOnly.length > 3) {
+      formatted = '${digitsOnly.substring(0, 3)}.${digitsOnly.substring(3)}';
+    }
+
+    if (formatted.endsWith('.') && digitsOnly.length <= 3) {
+      formatted = formatted.substring(0, formatted.length - 1);
+    }
+
+    return TextEditingValue(
+      text: formatted,
+      selection: TextSelection.collapsed(offset: formatted.length),
+    );
+  }
+}