// Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
// This code is distributed under MIT license (for details please see \doc\license.txt)

using System;

namespace ICSharpCode.Editor
{
	/// <summary>
	/// Describes a change of the document text.
	/// This class is thread-safe.
	/// </summary>
	[Serializable]
	public class TextChangeEventArgs : EventArgs
	{
		readonly int offset;
		readonly string removedText;
		readonly string insertedText;
		
		/// <summary>
		/// The offset at which the change occurs.
		/// </summary>
		public int Offset {
			get { return offset; }
		}
		
		/// <summary>
		/// The text that was inserted.
		/// </summary>
		public string RemovedText {
			get { return removedText; }
		}
		
		/// <summary>
		/// The number of characters removed.
		/// </summary>
		public int RemovalLength {
			get { return removedText.Length; }
		}
		
		/// <summary>
		/// The text that was inserted.
		/// </summary>
		public string InsertedText {
			get { return insertedText; }
		}
		
		/// <summary>
		/// The number of characters inserted.
		/// </summary>
		public int InsertionLength {
			get { return insertedText.Length; }
		}
		
		/// <summary>
		/// Creates a new TextChangeEventArgs object.
		/// </summary>
		public TextChangeEventArgs(int offset, string removedText, string insertedText)
		{
			this.offset = offset;
			this.removedText = removedText ?? string.Empty;
			this.insertedText = insertedText ?? string.Empty;
		}
	}
}