Add custom value formatter to deal better with minimal default values

Author: theEvilReaper

lib/util/formatter/min_value_fomatter.dart

@@ -0,0 +1,45 @@
+import 'package:flutter/services.dart';
+
+class MinValueFormatter extends TextInputFormatter {
+  final int min;
+
+  MinValueFormatter(this.min);
+
+  @override
+  TextEditingValue formatEditUpdate(
+      TextEditingValue oldValue,
+      TextEditingValue newValue,
+      ) {
+    var text = newValue.text;
+    var selectionIndex = newValue.selection.end; // keep track of cursor
+
+    if (text.isEmpty) {
+      text = min.toString();
+      selectionIndex = text.length;
+    } else {
+      // Strip leading zeros (but not a single "0")
+      if (text.length > 1 && text.startsWith('0')) {
+        final withoutLeadingZeros = int.parse(text).toString();
+        // Adjust cursor position by how many zeros we cut
+        selectionIndex -= (text.length - withoutLeadingZeros.length);
+        text = withoutLeadingZeros;
+      }
+
+      // Enforce min
+      final parsed = int.tryParse(text);
+      if (parsed == null || parsed < min) {
+        text = min.toString();
+        selectionIndex = text.length;
+      }
+    }
+
+    // Clamp selection to valid range
+    selectionIndex = selectionIndex.clamp(0, text.length);
+
+    return TextEditingValue(
+      text: text,
+      selection: TextSelection.collapsed(offset: selectionIndex),
+      composing: TextRange.empty,
+    );
+  }
+}