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

    /// <summary>
    /// connection descriptor
    /// </summary>
    private static ConnectionDescriptor connectionDescriptor;


    #endregion

    #region Properties


    #endregion

    #region Constructor
    /// <summary>
    /// Initializes a new instance of the <see cref="T:ConnectionProvider"/> class.
    /// </summary>
    public ConnectionProvider() {
      connectionDescriptor = new ConnectionDescriptor(this, typeof(ConnectionBase));
    }
    #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(ConnectionBase).IsInstanceOfType(instance)) {
        return connectionDescriptor;
      } else //if nothing found use the base descriptor
        return base.GetTypeDescriptor(objectType, instance);

    }
    #endregion

  }

}