using System;
using System.Collections;
using System.Collections.Generic;


namespace Netron.Diagramming.Core {
  /// <summary>
  /// This is a wrapper around the <see cref="Stack"/> which communicates Push and Pop events
  /// </summary>
  /// <typeparam name="T"></typeparam>
  public class StackBase<T> {
    #region Fields
    /// <summary>
    /// the internal stack based on the .Net <see cref="Stack"/> implementation
    /// </summary>
    private Stack<T> InnerStack;
    #endregion

    #region Events
    /// <summary>
    /// Occurs when an item is pushed onto the stack
    /// </summary>
    public event EventHandler<CollectionEventArgs<T>> OnItemPushed;
    /// <summary>
    /// Occurs when an item is popped from the stack
    /// </summary>
    public event EventHandler<CollectionEventArgs<T>> OnItemPopped;
    #endregion;

    #region Constructor
    /// <summary>
    /// Initializes a new instance of the <see cref="T:StackBase&lt;T&gt;"/> class.
    /// </summary>
    public StackBase() {
      InnerStack = new Stack<T>();
    }
    #endregion

    #region Methods

    /// <summary>
    /// Gets the number of elements in the stack
    /// </summary>
    /// <value>The count.</value>
    public int Count {
      get { return InnerStack.Count; }
    }


    /// <summary>
    /// Pushes the specified item.
    /// </summary>
    /// <param name="item">A parameter of the generics Type T</param>
    public void Push(T item) {

      this.InnerStack.Push(item);
      RaiseOnItemPushed(item);

    }

    /// <summary>
    /// Pops the next item from the stack
    /// </summary>
    /// <returns></returns>
    public T Pop() {
      T item =
       InnerStack.Pop();
      RaiseOnItemPopped(item);
      return item;
    }

    /// <summary>
    /// Peeks the next item in the stack
    /// </summary>
    /// <returns></returns>
    public T Peek() {
      return InnerStack.Peek();
    }


    /// <summary>
    /// Converts the stack to an array.
    /// </summary>
    /// <returns></returns>
    public T[] ToArray() {
      return InnerStack.ToArray();
    }


    /// <summary>
    /// Raises the <see cref="OnItemPushed"/>.
    /// </summary>
    /// <param name="item">A parameter of the generics Type T</param>
    private void RaiseOnItemPushed(T item) {
      EventHandler<CollectionEventArgs<T>> handler = OnItemPushed;
      handler(this, new CollectionEventArgs<T>(item));
    }

    /// <summary>
    /// Raises the on OnItemPopped event.
    /// </summary>
    /// <param name="item">A parameter of the generics Type T</param>
    private void RaiseOnItemPopped(T item) {
      EventHandler<CollectionEventArgs<T>> handler = OnItemPopped;
      handler(this, new CollectionEventArgs<T>(item));
    }


    #endregion

  }
}