feat: handle package name for fonts (#567)

## What does this change?

Fixes #357 🎯

Parse `package_parameter_enabled` for the fonts property and add a
`package` accessor to the generated font class.

## Example

```dart
class MyFonts {
  MyFonts._();

  static const String package = 'design_system';

  /// Font family: Arial Black
  static const String arialBlack = 'packages/$package/Arial Black';

  /// Font family: Calibri
  static const String calibri = 'packages/$package/Calibri';
}
```

## Type of change

- [x] New feature (non-breaking change which adds functionality)
- [x] This change requires a documentation update

Author: TesteurManiak

README.md

@@ -470,6 +470,31 @@ flutter:
 
 These configurations will generate **`fonts.gen.dart`** under the **`lib/gen/`** directory by default.
 
+#### Generate for packages
+
+If you want to generate fonts for a package,
+use `package_parameter_enabled` under `flutter_gen > fonts > outputs`.
+
+```yaml
+flutter_gen:
+  fonts:
+    outputs:
+      package_parameter_enabled: true # <- Add this line.
+```
+
+This would add the package constant to the generated class. For example:
+
+```dart
+class Fonts {
+  Fonts._();
+
+  static const String package = 'test';
+
+  static const String raleway = 'packages/$package/Raleway';
+  static const String robotoMono = 'packages/$package/RobotoMono';
+}
+```
+
 #### Usage Example
 
 ```dart

packages/core/lib/flutter_generator.dart

@@ -70,8 +70,10 @@ class FlutterGenerator {
     }
 
     if (flutterGen.fonts.enabled && flutter.fonts.isNotEmpty) {
-      final generated =
-          generateFonts(formatter, flutter.fonts, flutterGen.fonts);
+      final generated = generateFonts(
+        FontsGenConfig.fromConfig(config),
+        formatter,
+      );
       final fontsPath =
           normalize(join(pubspecFile.parent.path, output, fontsName));
       writer(generated, fontsPath);

packages/core/lib/generators/fonts_generator.dart

@@ -3,15 +3,40 @@
 import 'package:dart_style/dart_style.dart';
 import 'package:dartx/dartx.dart';
 import 'package:flutter_gen_core/generators/generator_helper.dart';
+import 'package:flutter_gen_core/settings/config.dart';
 import 'package:flutter_gen_core/settings/pubspec.dart';
 import 'package:flutter_gen_core/utils/error.dart';
 import 'package:flutter_gen_core/utils/string.dart';
 
+class FontsGenConfig {
+  FontsGenConfig._(
+    this._packageName,
+    this.flutterGen,
+    this.fonts,
+  );
+
+  factory FontsGenConfig.fromConfig(Config config) {
+    return FontsGenConfig._(
+      config.pubspec.packageName,
+      config.pubspec.flutterGen,
+      config.pubspec.flutter.fonts,
+    );
+  }
+
+  final String _packageName;
+  final FlutterGen flutterGen;
+  final List<FlutterFonts> fonts;
+
+  String get packageParameterLiteral =>
+      flutterGen.fonts.outputs.packageParameterEnabled ? _packageName : '';
+}
+
 String generateFonts(
+  FontsGenConfig config,
   DartFormatter formatter,
-  List<FlutterFonts> fonts,
-  FlutterGenFonts fontsConfig,
 ) {
+  final fonts = config.fonts;
+  final fontsConfig = config.flutterGen.fonts;
   if (fonts.isEmpty) {
     throw InvalidSettingsException(
         'The value of "flutter/fonts:" is incorrect.');
@@ -25,9 +50,16 @@ String generateFonts(
   buffer.writeln('$className._();');
   buffer.writeln();
 
+  final isPackage = config.packageParameterLiteral.isNotEmpty;
+  if (isPackage) {
+    buffer.writeln("static const String package = '${config._packageName}';");
+    buffer.writeln();
+  }
+
   fonts.map((element) => element.family).distinct().sorted().forEach((family) {
+    final keyName = isPackage ? 'packages/\$package/$family' : family;
     buffer.writeln("""/// Font family: $family
-    static const String ${family.camelCase()} = '$family';""");
+    static const String ${family.camelCase()} = '$keyName';""");
   });
 
   buffer.writeln('}');

packages/core/lib/settings/pubspec.dart

@@ -149,7 +149,7 @@ class FlutterGenFonts {
   final bool enabled;
 
   @JsonKey(name: 'outputs', required: true)
-  final FlutterGenElementOutputs outputs;
+  final FlutterGenElementFontsOutputs outputs;
 
   factory FlutterGenFonts.fromJson(Map json) => _$FlutterGenFontsFromJson(json);
 }
@@ -229,3 +229,17 @@ class FlutterGenElementAssetsOutputs extends FlutterGenElementOutputs {
   factory FlutterGenElementAssetsOutputs.fromJson(Map json) =>
       _$FlutterGenElementAssetsOutputsFromJson(json);
 }
+
+@JsonSerializable()
+class FlutterGenElementFontsOutputs extends FlutterGenElementOutputs {
+  FlutterGenElementFontsOutputs({
+    required super.className,
+    required this.packageParameterEnabled,
+  });
+
+  @JsonKey(name: 'package_parameter_enabled', defaultValue: false)
+  final bool packageParameterEnabled;
+
+  factory FlutterGenElementFontsOutputs.fromJson(Map json) =>
+      _$FlutterGenElementFontsOutputsFromJson(json);
+}

packages/core/lib/settings/pubspec.g.dart

@@ -26,8 +26,7 @@ void main() {
           pageWidth: config.pubspec.flutterGen.lineLength, lineEnding: '\n');
 
       expect(() {
-        return generateFonts(formatter, config.pubspec.flutter.fonts,
-            config.pubspec.flutterGen.fonts);
+        return generateFonts(FontsGenConfig.fromConfig(config), formatter);
       }, throwsA(isA<InvalidSettingsException>()));
     });
 
@@ -40,5 +39,15 @@ void main() {
 
       await expectedFontsGen(pubspec, generated, fact);
     });
+
+    test('Package parameter enabled', () async {
+      const pubspec = 'test_resources/pubspec_fonts_package_parameter.yaml';
+      const fact =
+          'test_resources/actual_data/fonts_package_parameter.gen.dart';
+      const generated =
+          'test_resources/lib/gen/fonts_package_parameter.gen.dart';
+
+      await expectedFontsGen(pubspec, generated, fact);
+    });
   });
 }

packages/core/test/fonts_gen_test.dart

@@ -121,9 +121,8 @@ Future<List<String>> runFontsGen(
   );
 
   final actual = generateFonts(
+    FontsGenConfig.fromConfig(config),
     formatter,
-    config.pubspec.flutter.fonts,
-    config.pubspec.flutterGen.fonts,
   );
   final expected = formatter.format(
     File(fact).readAsStringSync().replaceAll('\r\n', '\n'),

packages/core/test/gen_test_helper.dart

@@ -0,0 +1,17 @@
+name: test
+
+flutter_gen:
+  output: lib/gen/ # Optional (default: lib/gen/)
+  line_length: 80 # Optional (default: 80)
+
+  fonts:
+    outputs:
+      package_parameter_enabled: true
+
+flutter:
+  fonts:
+    - family: Raleway
+      fonts:
+        - asset: assets/fonts/Raleway-Regular.ttf
+        - asset: assets/fonts/Raleway-Italic.ttf
+          style: italic