/// Copyright (c) Microsoft Corporation.  All rights reserved.

using System;
using System.Collections.Generic;
using System.Drawing;
using System.IO;
using System.Windows.Forms;
using Microsoft.VisualStudio;

namespace Microsoft.VisualStudio.Project
{
	public class ImageHandler : IDisposable
	{
		private ImageList imageList;
		private List<IntPtr> iconHandles;
		private static volatile object Mutex;
		private bool isDisposed;

		/// <summary>
		/// Initializes the <see cref="RDTListener"/> class.
		/// </summary>
		[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Performance", "CA1810:InitializeReferenceTypeStaticFieldsInline")]
		static ImageHandler()
		{
			Mutex = new object();
		}

		/// <summary>
		/// Builds an empty ImageHandler object.
		/// </summary>
		public ImageHandler()
		{
		}

		/// <summary>
		/// Builds an ImageHandler object from a Stream providing the bitmap that
		/// stores the images for the image list.
		/// </summary>
		public ImageHandler(Stream resourceStream)
		{
			if(null == resourceStream)
			{
				throw new ArgumentNullException("resourceStream");
			}
			imageList = Utilities.GetImageList(resourceStream);
		}

		/// <summary>
		/// Builds an ImageHandler object from an ImageList object.
		/// </summary>
		public ImageHandler(ImageList list)
		{
			if(null == list)
			{
				throw new ArgumentNullException("list");
			}
			imageList = list;
		}

		/// <summary>
		/// Closes the ImageHandler object freeing its resources.
		/// </summary>
		public void Close()
		{
			if(null != iconHandles)
			{
				foreach(IntPtr hnd in iconHandles)
				{
					if(hnd != IntPtr.Zero)
					{
						NativeMethods.DestroyIcon(hnd);
					}
				}
				iconHandles = null;
			}

			if(null != imageList)
			{
				imageList.Dispose();
				imageList = null;
			}
		}

		/// <summary>
		/// Add an image to the ImageHandler.
		/// </summary>
		/// <param name="image">the image object to be added.</param>
		public void AddImage(Image image)
		{
			if(null == image)
			{
				throw new ArgumentNullException("image");
			}
			if(null == imageList)
			{
				imageList = new ImageList();
			}
			imageList.Images.Add(image);
			if(null != iconHandles)
			{
				iconHandles.Add(IntPtr.Zero);
			}
		}

		/// <summary>
		/// Get or set the ImageList object for this ImageHandler.
		/// </summary>
		public ImageList ImageList
		{
			get { return imageList; }
			set
			{
				Close();
				imageList = value;
			}
		}

		/// <summary>
		/// Returns the handle to an icon build from the image of index
		/// iconIndex in the image list.
		/// </summary>
		public IntPtr GetIconHandle(int iconIndex)
		{
			// Verify that the object is in a consistent state.
			if((null == imageList))
			{
				throw new InvalidOperationException();
			}
			// Make sure that the list of handles is initialized.
			if(null == iconHandles)
			{
				InitHandlesList();
			}

			// Verify that the index is inside the expected range.
			if((iconIndex < 0) || (iconIndex >= iconHandles.Count))
			{
				throw new ArgumentOutOfRangeException("iconIndex");
			}

			// Check if the icon is in the cache.
			if(IntPtr.Zero == iconHandles[iconIndex])
			{
				Bitmap bitmap = imageList.Images[iconIndex] as Bitmap;
				// If the image is not a bitmap, then we can not build the icon,
				// so we have to return a null handle.
				if(null == bitmap)
				{
					return IntPtr.Zero;
				}

				iconHandles[iconIndex] = bitmap.GetHicon();
			}

			return iconHandles[iconIndex];
		}

		private void InitHandlesList()
		{
			iconHandles = new List<IntPtr>(imageList.Images.Count);
			for(int i = 0; i < imageList.Images.Count; ++i)
			{
				iconHandles.Add(IntPtr.Zero);
			}
		}

		#region IDisposable Members

		/// <summary>
		/// Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.
		/// </summary>
		public void Dispose()
		{
			this.Dispose(true);
			GC.SuppressFinalize(this);
		}
		#endregion

		private void Dispose(bool disposing)
		{
			if(!this.isDisposed)
			{
				lock(Mutex)
				{
					if(disposing)
					{
						this.imageList.Dispose();
					}

					this.isDisposed = true;
				}
			}
		}
	}
}