Formatting and dart analyze fixes

LICENSE

@@ -1,3 +1,5 @@
+Copyright 2023 Nathan Anderson
+
 BSD 3-Clause License
 
 Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

example/lib/main.dart

@@ -68,7 +68,7 @@ class _MyHomePageState extends State<MyHomePage> {
         child: Column(
           mainAxisAlignment: MainAxisAlignment.center,
           children: <Widget>[
-            Text(
+            const Text(
               'Enter your card details below:',
             ),
             CardTextField(

lib/card_details.dart

@@ -1,5 +1,10 @@
 import 'package:flutter/foundation.dart';
 
+/// Class encapsulating the card's data
+/// as well as validation of the data.
+///
+/// `CardDetails.validState == ValidState.ok`
+/// when fields are filled and validated as correct.
 class CardDetails {
   CardDetails({
     required dynamic cardNumber,
@@ -11,10 +16,13 @@ class CardDetails {
     checkIsValid();
   }
 
+  /// Sets every field to null, a default
+  /// `CardDetails` when nothing has been entered.
   factory CardDetails.blank() {
     return CardDetails(cardNumber: null, securityCode: null, expirationString: null, postalCode: null);
   }
 
+  /// Returns the CardNumber as a `String` with the spaces removed.
   String? get cardNumber => _cardNumber?.replaceAll(' ', '');
 
   set cardNumber(String? num) => _cardNumber = num;
@@ -29,22 +37,35 @@ class CardDetails {
   int _lastCheckHash = 0;
   CardProvider? provider;
 
+  /// Checks the validity of the `CardDetails` and returns the result.
   ValidState get validState {
     checkIsValid();
     return _validState;
   }
 
+  // TODO rename to be more clear
+  /// Returns true if `_cardNumber` is null, or
+  /// if the _cardNumber matches the detected `provider`'s
+  /// card lenght, defaulting to 16.
   bool get cardNumberFilled =>
       _cardNumber == null ? false : (provider?.cardLength ?? 16) == _cardNumber!.replaceAll(' ', '').length;
 
+  /// Returns true if all details are complete and valid
+  /// otherwise, return false.
   bool get isComplete {
     checkIsValid();
     return _complete;
   }
 
-  int get minInnLength => 1;
+  /// The maximum length of the INN (identifier)
+  /// of a card provider.
   int get maxINNLength => 4;
 
+  /// Validates each field of the `CardDetails` object in entry order,
+  /// namely _cardNumber -> expirationString -> securityCode -> postalCode
+  ///
+  /// If all fields are filled out and valid, `CardDetails.isComplete == true`
+  /// and `CardDetails.validState == ValidState.ok`.
   void checkIsValid() {
     try {
       int currentHash = hash;
@@ -65,7 +86,7 @@ class CardDetails {
             (i) => int.parse(i),
           )
           .toList();
-      if (!luhnAlgorithmCheck(nums)) {
+      if (!_luhnAlgorithmCheck(nums)) {
         _complete = false;
         _validState = ValidState.invalidCard;
         return;
@@ -130,16 +151,21 @@ class CardDetails {
     }
   }
 
+  /// Provides a hash of the CardDetails object
+  /// Hashes `_cardNumber`, `expirationString`,
+  /// `securityCode`, and `postalCode`.
   int get hash {
     return Object.hash(_cardNumber, expirationString, securityCode, postalCode);
   }
 
+  /// Iterates over the list `_providers`, detecting which
+  /// provider the current `_cardNumber` falls under.
   void detectCardProvider() {
     bool found = false;
     if (_cardNumber == null) {
       return;
     }
-    for (var cardPvd in providers) {
+    for (var cardPvd in _providers) {
       if (cardPvd.innValidNums != null) {
         // trim card number to correct length
         String trimmedNum = _cardNumber!;
@@ -180,8 +206,36 @@ class CardDetails {
   String toString() {
     return 'Number: "$_cardNumber" - Exp: "$expirationString" CVC: $securityCode Zip: "$postalCode"';
   }
+
+  /// https://en.wikipedia.org/wiki/Luhn_algorithm
+  /// The Luhn algorithm is used in industry to check
+  /// for valid credit / debit card numbers
+  ///
+  /// The algorithm adds together all the numbers, every
+  /// other number is doubled, then the sum is checked to
+  /// see if it is a multiple of 10.
+  /// https://en.wikipedia.org/wiki/Luhn_algorithm
+  bool _luhnAlgorithmCheck(List<int> digits) {
+    int sum = 0;
+    bool isSecond = false;
+    for (int i = digits.length - 1; i >= 0; i--) {
+      int d = digits[i];
+      if (isSecond) {
+        d *= 2;
+
+        if (d > 9) {
+          d -= 9;
+        }
+      }
+
+      sum += d;
+      isSecond = !isSecond;
+    }
+    return (sum % 10) == 0;
+  }
 }
 
+/// Enum of validation states a `CardDetails` object can have.
 enum ValidState {
   ok,
   error,
@@ -198,6 +252,7 @@ enum ValidState {
   invalidZip,
 }
 
+/// Enum of supported U.S. Card Providers
 enum CardProviderID {
   americanExpress,
   dinersClub,
@@ -207,6 +262,9 @@ enum CardProviderID {
   visa,
 }
 
+/// Encapsulates criteria for Card Providers in the U.S.
+/// Used by `CardDetails.detectCardProvider()` to determine
+/// a card's Provider.
 class CardProvider {
   CardProviderID id;
   List<int>? innValidNums;
@@ -228,6 +286,9 @@ class CardProvider {
   }
 }
 
+/// Object for `CardProvider` to determine valid number ranges.
+/// A loose wrapper on a tuple, that provides assertion of
+/// valid inputs and the `isWithin()` helper function.
 class Range {
   int high;
   int low;
@@ -236,12 +297,19 @@ class Range {
     assert(low <= high);
   }
 
+  /// Returns bool whether or not `val` is between `low` and `high`.
+  /// The range includes the `val`, so
+  /// ```dart
+  /// Range(low: 1, high: 3).isWithin(3);
+  /// ```
+  /// would return true.
   bool isWithin(int val) {
     return low <= val && val <= high;
   }
 }
 
-List<CardProvider> providers = [
+/// List of CardProviders for US-based Credit / Debit Cards.
+List<CardProvider> _providers = [
   CardProvider(
     id: CardProviderID.americanExpress,
     cardLength: 15,
@@ -280,29 +348,3 @@ List<CardProvider> providers = [
     innValidNums: [4],
   )
 ];
-
-// https://en.wikipedia.org/wiki/Luhn_algorithm
-// The Luhn algorithm is used in industry to check
-// for valid credit / debit card numbers
-//
-// The algorithm adds together all the numbers, every
-// other number is doubled, then the sum is checked to
-// see if it is a multiple of 10.
-bool luhnAlgorithmCheck(List<int> digits) {
-  int sum = 0;
-  bool isSecond = false;
-  for (int i = digits.length - 1; i >= 0; i--) {
-    int d = digits[i];
-    if (isSecond) {
-      d *= 2;
-
-      if (d > 9) {
-        d -= 9;
-      }
-    }
-
-    sum += d;
-    isSecond = !isSecond;
-  }
-  return (sum % 10) == 0;
-}

lib/card_provider_icon.dart

@@ -2,6 +2,10 @@ import 'card_details.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_svg/flutter_svg.dart';
 
+/// Widget that provides the various supported card provider's
+/// icons, as well as a default and error card icon.
+///
+/// To see a list of supported card providers, see `CardDetails.provider`.
 class CardProviderIcon extends StatefulWidget {
   const CardProviderIcon({required this.cardDetails, super.key});
 
@@ -77,6 +81,7 @@ class _CardProviderIconState extends State<CardProviderIcon> {
     );
   }
 
+  /// Helper function to create the SVG icons provided a `CardProviderID`.
   Widget createCardSvg(CardProviderID id) {
     return SvgPicture.string(
       key: Key('${id.name}-card'),

lib/stripe_native_card_field.dart

@@ -6,8 +6,18 @@ import 'card_provider_icon.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 
+/// Enum to track each step of the card detail
+/// entry process.
 enum CardEntryStep { number, exp, cvc, postal }
 
+/// A uniform text field for entering card details, based
+/// on the behavior of Stripe's various html elements.
+///
+/// Required `width` and `onCardDetailsComplete`.
+///
+/// If the provided `width < 450.0`, the `CardTextField`
+/// will scroll its content horizontally with the cursor
+/// to compensate.
 class CardTextField extends StatefulWidget {
   const CardTextField(
       {Key? key,
@@ -23,6 +33,8 @@ class CardTextField extends StatefulWidget {
   final BoxDecoration? boxDecoration; // TODO unapplied style
   final BoxDecoration? errorBoxDecoration; // TODO unapplied style
   final double width;
+
+  /// Callback that returns the completed CardDetails object
   final void Function(CardDetails) onCardDetailsComplete;
   final double? height;
 
@@ -30,6 +42,9 @@ class CardTextField extends StatefulWidget {
   State<CardTextField> createState() => CardTextFieldState();
 }
 
+/// State Widget for CardTextField
+/// Should not be used directly, create a
+/// `CardTextField()` instead.
 @visibleForTesting
 class CardTextFieldState extends State<CardTextField> {
   late TextEditingController _cardNumberController;
@@ -361,10 +376,14 @@ class CardTextFieldState extends State<CardTextField> {
     );
   }
 
+  /// Provided a list of `ValidState`, returns whether
+  /// make the text field red
   bool _isRedText(List<ValidState> args) {
     return _showBorderError && args.contains(_cardDetails.validState);
   }
 
+  /// Helper function to change the `_showBorderError` and
+  /// `_validationErrorText`.
   void _setValidationState(String? text) {
     setState(() {
       _validationErrorText = text;
@@ -372,6 +391,8 @@ class CardTextFieldState extends State<CardTextField> {
     });
   }
 
+  /// Calls `validate()` on the form state and resets
+  /// the validation state
   void _validateFields() {
     _validationErrorText = null;
     _formFieldKey.currentState!.validate();
@@ -382,6 +403,8 @@ class CardTextFieldState extends State<CardTextField> {
     return;
   }
 
+  /// Used when `_isWideFormat == false`, scrolls
+  /// the `_horizontalScrollController` to a given offset
   void _scrollRow(CardEntryStep step) {
     const dur = Duration(milliseconds: 150);
     const cur = Curves.easeOut;
@@ -402,6 +425,9 @@ class CardTextFieldState extends State<CardTextField> {
     }
   }
 
+  /// Function that is listening to the `_currentCardEntryStepController`
+  /// StreamController. Manages validation and tracking of the current step
+  /// as well as scrolling the text fields.
   void _onStepChange(CardEntryStep step) {
     if (_currentStep.index < step.index) {
       _validateFields();
@@ -431,6 +457,11 @@ class CardTextFieldState extends State<CardTextField> {
     }
   }
 
+  /// Function that is listening to the keyboard events.
+  ///
+  /// This provides the functionality of hitting backspace
+  /// and the focus changing between fields when the current
+  /// entry step is empty.
   void _backspaceTransitionListener(RawKeyEvent value) {
     if (!value.isKeyPressed(LogicalKeyboardKey.backspace)) {
       return;
@@ -461,6 +492,8 @@ class CardTextFieldState extends State<CardTextField> {
   }
 }
 
+/// Formatter that adds the appropriate space ' ' characters
+/// to make the card number display cleanly.
 class CardNumberInputFormatter implements TextInputFormatter {
   @override
   TextEditingValue formatEditUpdate(TextEditingValue oldValue, TextEditingValue newValue) {
@@ -482,6 +515,8 @@ class CardNumberInputFormatter implements TextInputFormatter {
   }
 }
 
+/// Formatter that adds a backslash '/' character in between
+/// the month and the year for the expiration date.
 class CardExpirationFormatter implements TextInputFormatter {
   @override
   TextEditingValue formatEditUpdate(TextEditingValue oldValue, TextEditingValue newValue) {
@@ -494,11 +529,6 @@ class CardExpirationFormatter implements TextInputFormatter {
       }
     }
     if (cardExp.length == 2 && oldValue.text.length == 3) return newValue;
-    // Auto delete the slash on backspace
-    // if (cardExp.length == 3 && oldValue.text.length == 4 && cardExp[2] == '/') {
-    //   return newValue.copyWith(
-    //       text: cardExp.substring(0, 2), selection: TextSelection.collapsed(offset: cardExp.length - 1));
-    // }
 
     cardExp = cardExp.replaceAll('/', '');
     StringBuffer buffer = StringBuffer();