handling invalid settings

Author: wasabeef

bin/flutter_gen_command.dart

@@ -1,7 +1,7 @@
 import 'dart:io';
 
 import 'package:args/args.dart';
-import 'package:flutter_gen/flutter_generator.dart';
+import 'package:flutter_gen/src/flutter_generator.dart';
 import 'package:flutter_gen/src/utils/cast.dart';
 
 void main(List<String> args) {

build.yaml

@@ -6,7 +6,7 @@ targets:
 
 builders:
   flutter_gen:
-    import: "package:flutter_gen/flutter_generator.dart"
+    import: "package:flutter_gen/build.dart"
     builder_factories: [ "build" ]
     build_extensions: { "$lib$": [ ".gen.dart" ] }
     auto_apply: dependents

lib/build.dart

@@ -0,0 +1,20 @@
+import 'dart:io';
+
+import 'package:build/build.dart';
+
+import 'src/flutter_generator.dart';
+
+Builder build(BuilderOptions options) {
+  Future(() async {
+    await FlutterGenerator(File('pubspec.yaml')).build();
+  });
+  return EmptyBuilder();
+}
+
+class EmptyBuilder extends Builder {
+  @override
+  Future<void> build(BuildStep buildStep) async {}
+
+  @override
+  Map<String, List<String>> get buildExtensions => {};
+}

lib/flutter_generator.dart

@@ -0,0 +1,83 @@
+import 'dart:io';
+
+import 'package:dart_style/dart_style.dart';
+import 'package:path/path.dart';
+
+import 'generators/assets_generator.dart';
+import 'generators/colors_generator.dart';
+import 'generators/fonts_generator.dart';
+import 'settings/config.dart';
+import 'utils/error.dart';
+import 'utils/file.dart';
+
+class FlutterGenerator {
+  const FlutterGenerator(this.pubspecFile);
+
+  final File pubspecFile;
+
+  Future<void> build() async {
+    final config = Config(pubspecFile);
+    try {
+      await config.load();
+    } on FormatException catch (e) {
+      stderr.writeln(e.message);
+      return;
+    } on FileSystemException catch (e) {
+      stderr.writeln(e.message);
+      return;
+    }
+
+    var output = Config.defaultOutput;
+    var lineLength = Config.defaultLineLength;
+
+    if (config.hasFlutterGen) {
+      output = config.flutterGen.output;
+      lineLength = config.flutterGen.lineLength;
+      final formatter = DartFormatter(pageWidth: lineLength, lineEnding: '\n');
+
+      if (config.flutterGen.hasColors) {
+        try {
+          final generated =
+              generateColors(pubspecFile, formatter, config.flutterGen.colors);
+          final colors = File(normalize(
+              join(pubspecFile.parent.path, output, 'colors.gen.dart')));
+          writeAsString(generated, file: colors);
+          print('Generated: ${colors.absolute.path}');
+        } on InvalidSettingsException catch (e) {
+          stderr.writeln(e.message);
+        }
+      }
+    }
+
+    if (config.hasFlutter) {
+      final formatter = DartFormatter(pageWidth: lineLength, lineEnding: '\n');
+
+      if (config.flutter.hasAssets) {
+        try {
+          final generated = generateAssets(
+              pubspecFile, formatter, config.flutterGen, config.flutter.assets);
+          final assets = File(normalize(
+              join(pubspecFile.parent.path, output, 'assets.gen.dart')));
+          writeAsString(generated, file: assets);
+          print('Generated: ${assets.absolute.path}');
+        } on InvalidSettingsException catch (e) {
+          stderr.writeln(e.message);
+        }
+      }
+
+      if (config.flutter.hasFonts) {
+        try {
+          final generated = generateFonts(formatter, config.flutter.fonts);
+          final fonts = File(normalize(
+              join(pubspecFile.parent.path, output, 'fonts.gen.dart')));
+          writeAsString(generated, file: fonts);
+          print('Generated: ${fonts.absolute.path}');
+        } on InvalidSettingsException catch (e) {
+          stderr.writeln(e.message);
+        }
+      }
+    }
+
+    print('FlutterGen finished.');
+  }
+}

lib/src/flutter_generator.dart

@@ -8,14 +8,17 @@ import '../settings/asset_type.dart';
 import '../settings/flutter.dart';
 import '../settings/flutter_gen.dart';
 import '../utils/camel_case.dart';
+import '../utils/error.dart';
 import 'generator_helper.dart';
 import 'integrations/integration.dart';
 import 'integrations/svg_integration.dart';
 
 String generateAssets(File pubspecFile, DartFormatter formatter,
     FlutterGen flutterGen, FlutterAssets assets) {
-  assert(assets != null && assets.hasAssets,
-      throw 'The value of "flutter/assets:" is incorrect.');
+  if (assets == null || !assets.hasAssets) {
+    throw InvalidSettingsException(
+        'The value of "flutter/assets:" is incorrect.');
+  }
 
   final importsBuffer = StringBuffer();
   final classesBuffer = StringBuffer();

lib/src/generators/assets_generator.dart

@@ -9,14 +9,15 @@ import '../settings/color_path.dart';
 import '../settings/flutter_gen.dart';
 import '../utils/camel_case.dart';
 import '../utils/color.dart';
+import '../utils/error.dart';
 import 'generator_helper.dart';
 
 String generateColors(
     File pubspecFile, DartFormatter formatter, FlutterGenColors colors) {
-  assert(
-      colors != null, throw 'The value of "flutter_gen/colors:" is incorrect.');
-  assert(colors.hasInputs,
-      throw 'The value of "flutter_gen/colors/inputs:" is incorrect.');
+  if (colors == null || !colors.hasInputs) {
+    throw InvalidSettingsException(
+        'The value of "flutter_gen/colors:" is incorrect.');
+  }
 
   final buffer = StringBuffer();
   buffer.writeln(header);

lib/src/generators/colors_generator.dart

@@ -5,11 +5,14 @@ import 'package:yaml/yaml.dart';
 import '../settings/flutter.dart';
 import '../utils/camel_case.dart';
 import '../utils/cast.dart';
+import '../utils/error.dart';
 import 'generator_helper.dart';
 
 String generateFonts(DartFormatter formatter, FlutterFonts fonts) {
-  assert(fonts != null && fonts.hasFonts,
-      throw 'The value of "flutter/fonts:" is incorrect.');
+  if (fonts == null || !fonts.hasFonts) {
+    throw InvalidSettingsException(
+        'The value of "flutter/fonts:" is incorrect.');
+  }
 
   final buffer = StringBuffer();
   buffer.writeln(header);

lib/src/generators/fonts_generator.dart

@@ -0,0 +1,5 @@
+class InvalidSettingsException implements Exception {
+  const InvalidSettingsException(this.message);
+
+  final String message;
+}

lib/src/utils/error.dart

@@ -2,7 +2,7 @@
 import 'dart:io';
 
 import 'package:dart_style/dart_style.dart';
-import 'package:flutter_gen/flutter_generator.dart';
+import 'package:flutter_gen/src/flutter_generator.dart';
 import 'package:flutter_gen/src/generators/assets_generator.dart';
 import 'package:flutter_gen/src/generators/colors_generator.dart';
 import 'package:flutter_gen/src/generators/fonts_generator.dart';