using System;
using System.ComponentModel;
namespace Netron.Diagramming.Core {
  /// <summary>
  /// Type descriptor provider for all descendants of the <see cref="ShapeBase"/> classes. 
  /// </summary>
  class ShapeProvider : TypeDescriptionProvider {
    #region Fields

    /// <summary>
    /// simple shape descriptor
    /// </summary>
    private static SimpleShapeBaseDescriptor simpleShapeBaseDescriptor;
    /// <summary>
    /// complex shape descriptor
    /// </summary>
    private static ComplexShapeBaseDescriptor complexShapeBaseDescriptor;


    private static ClassShapeDescriptor classShapeDescriptor;

    #endregion

    #region Properties


    #endregion

    #region Constructor
    public ShapeProvider() {
      simpleShapeBaseDescriptor = new SimpleShapeBaseDescriptor(this, typeof(SimpleShapeBase));
      complexShapeBaseDescriptor = new ComplexShapeBaseDescriptor(this, typeof(ComplexShapeBase));
      classShapeDescriptor = new ClassShapeDescriptor(this, typeof(ClassShape));
    }
    #endregion

    #region Methods
    /// <summary>
    /// Gets a custom type descriptor for the given type and object.
    /// </summary>
    /// <param name="objectType">The type of object for which to retrieve the type descriptor.</param>
    /// <param name="instance">An instance of the type. Can be null if no instance was passed to the <see cref="T:System.ComponentModel.TypeDescriptor"></see>.</param>
    /// <returns>
    /// An <see cref="T:System.ComponentModel.ICustomTypeDescriptor"></see> that can provide metadata for the type.
    /// </returns>
    public override ICustomTypeDescriptor GetTypeDescriptor(Type objectType, object instance) {
      if (typeof(SimpleShapeBase).IsInstanceOfType(instance)) {
        return simpleShapeBaseDescriptor;
      } else if (typeof(ClassShape).IsInstanceOfType(instance)) {
        return classShapeDescriptor;
      } else if (typeof(ComplexShapeBase).IsInstanceOfType(instance)) {
        return complexShapeBaseDescriptor;
      } else //if nothing found use the base descriptor
        return base.GetTypeDescriptor(objectType, instance);

    }
    #endregion

  }
}