tools/widget_explorer/packages/widget_explorer_core/lib/src/widget_specs.dart

// Copyright 2017 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'package:analyzer/dart/constant/value.dart';
import 'package:analyzer/dart/element/element.dart';

import 'utils.dart';

/// A class describing the specifications of a custom flutter widget.
class WidgetSpecs implements Comparable<WidgetSpecs> {
  /// Creates a new instance of [WidgetSpecs] class with the given parameters.
  WidgetSpecs({
    this.packageName,
    this.name,
    this.path,
    this.pathFromFuchsiaRoot,
    this.doc,
    this.exampleWidth,
    this.exampleHeight,
    this.hasSizeParam,
    this.classElement,
  });

  /// Name of the package in which this widget is defined.
  final String packageName;

  /// Name of the widget.
  final String name;

  /// Relative path of the dart file (under `lib`) where this widget is defined.
  final String path;

  /// Relative path of this file under the fuchsia root.
  final String pathFromFuchsiaRoot;

  /// Contents of the document comments associated with the widget.
  final String doc;

  /// Example width to be used as the initial width.
  final double exampleWidth;

  /// Example height to be used as the initial height.
  final double exampleHeight;

  /// Indicates whether the widget has a parameter annotated with `@sizeParam`,
  /// whih implies that this widget's width and height values should always be
  /// the same.
  final bool hasSizeParam;

  /// The [ClassElement] corresponding to this widget.
  final ClassElement classElement;

  /// Gets the default [ConstructorElement] of this widget.
  ConstructorElement get constructor => classElement?.constructors?.firstWhere(
        (ConstructorElement constructor) => constructor.isDefaultConstructor,
        orElse: () => null,
      );

  /// Gets the example value specified for the given parameter.
  dynamic getExampleValue(ParameterElement param) {
    ElementAnnotation annotation = getExampleValueAnnotation(param);
    if (annotation == null) {
      return null;
    }

    DartObject valueObj = annotation.computeConstantValue().getField('value');

    // TODO(youngseokyoon): handle more types.
    switch (param.type.name) {
      case 'int':
        return valueObj.toIntValue();
      case 'bool':
        return valueObj.toBoolValue();
      case 'double':
        return valueObj.toDoubleValue();
      case 'String':
        return valueObj.toStringValue();
      default:
        return null;
    }
  }

  /// Gets the `ExampleValue` annotation associated with the given
  /// [ParameterElement].
  ElementAnnotation getExampleValueAnnotation(ParameterElement param) {
    return getAnnotationWithName(param, 'ExampleValue');
  }

  /// Gets the config key specified for the given parameter.
  String getConfigKey(ParameterElement param) {
    ElementAnnotation annotation = getConfigKeyAnnotation(param);
    if (annotation == null) {
      return null;
    }

    DartObject keyObj = annotation.computeConstantValue().getField('key');
    return keyObj?.toStringValue();
  }

  /// Gets the `ConfigKey` annotation associated with the given
  /// [ParameterElement].
  ElementAnnotation getConfigKeyAnnotation(ParameterElement param) {
    return getAnnotationWithName(param, 'ConfigKey');
  }

  @override
  int compareTo(WidgetSpecs other) {
    return name.compareTo(other.name);
  }

  @override
  String toString() => '''WidgetSpecs: $name

$doc''';
}