part of angel_serialize_generator;

class JsonModelGenerator extends GeneratorForAnnotation<Serializable> {
  final bool autoIdAndDateFields;

  const JsonModelGenerator({this.autoIdAndDateFields: true});

  @override
  Future<String> generateForAnnotatedElement(
      Element element, ConstantReader annotation, BuildStep buildStep) async {
    if (element.kind != ElementKind.CLASS)
      throw 'Only classes can be annotated with a @Serializable() annotation.';

    var ctx = await buildContext(element, annotation, buildStep,
        await buildStep.resolver, true, autoIdAndDateFields != false);

    var lib = new File((b) {
      generateClass(ctx, b);
    });

    var buf = lib.accept(new DartEmitter());
    return buf.toString();
  }

  /// Generate an extended model class.
  void generateClass(BuildContext ctx, FileBuilder file) {
    file.body.add(new Class((clazz) {
      clazz
        ..name = ctx.modelClassNameRecase.pascalCase
        ..extend = new Reference(ctx.originalClassName);

      for (var field in ctx.fields) {
        clazz.fields.add(new Field((b) {
          b
            ..name = field.name
            ..modifier = FieldModifier.final$
            ..annotations
                .add(new Annotation((b) => b.code = new Code('override')))
            ..type = convertTypeReference(field.type);
        }));
      }

      generateConstructor(ctx, clazz, file);
      generateCopyWithMethod(ctx, clazz, file);
    }));
  }

  /// Generate a constructor with named parameters.
  void generateConstructor(
      BuildContext ctx, ClassBuilder clazz, FileBuilder file) {
    clazz.constructors.add(new Constructor((constructor) {
      for (var field in ctx.fields) {
        constructor.optionalParameters.add(new Parameter((b) {
          b
            ..name = field.name
            ..named = true
            ..toThis = true;
        }));
      }
    }));
  }

  /// Generate a `copyWith` method.
  void generateCopyWithMethod(
      BuildContext ctx, ClassBuilder clazz, FileBuilder file) {
    clazz.methods.add(new Method((method) {
      method
        ..name = 'copyWith'
        ..returns = ctx.modelClassType;

      var buf = new StringBuffer('return new ${ctx.modelClassName}(');
      int i = 0;

      // Add named parameters
      for (var field in ctx.fields) {
        method.optionalParameters.add(new Parameter((b) {
          b
            ..name = field.name
            ..named = true
            ..type = convertTypeReference(field.type);
        }));

        if (i++ > 0) buf.write(', ');
        buf.write('${field.name}: ${field.name} ?? this.${field.name}');
      }

      buf.write(');');
      method.body = new Code(buf.toString());
    }));
  }
}