using System;
using System.Drawing;
using System.Text.RegularExpressions;
using System.IO;

namespace AM
{
	class AMImageResizer
	{

		public static bool ThumbnailCallback()
		{
			return false;
		}



		[STAThread]
		static int Main(string[] args)
		{
			if (args.Length < 1 || args.Length > 9 || args[0] == "/?" || args[0].ToLower() == "/help")
			{
				Console.Write("AMImageResizer version 1.0\n"+
					"This program resizes an image and returns the resulting image size.\n\n"+
					"Usage:\n"+
					"AMImageResizer SourceFile [DestinationFile] [/Resize widthXheight]\n"+
					"[/NoAutoAspect] [/Thumbnail] [/Size]\n\n" +
					"Example: AMImageResizer largeimage.jpg smallimage.jpg /Resize 640x480\n"+
					"This would resize largeimage.jpg to smallimage.jpg with\n"+
					"its width and height being proportional to source width and height\n"+
					"and neither width exceeding 640 or height exceeding 480.\n\n"+
					"If DestinationFile is not specified we save the resized image to\n"+
					"SourceFile.\n\n"+
					"If /Resize widthXheight is not specified we resize the image\n"+
					"to its current size. You may want to use this to reduce an image's\n"+
					"filesize. Both width and height do not need to be specified together.\n"+
					"You could specify just /Resize x100 to make the height 100 and the width\n"+
					"proportional to that. When both width and height are specified the\n"+
					"original aspect ratio is maintained with the smaller of the width or\n"+
					"height being the base measurement for SourceFiles whose proportions\n"+
					"don't match the target width:height ratio (ex. 576x768 when resized\n"+
					"to 100x75 will result in 56x75 size).\n\n"+
					"If /NoAutoAspect is specified we will not automatically adjust\n"+
					"the image dimensions. This switch may only be used if\n"+
					"both width and height are specified.\n\n"+
					"If /Thumbnail is specified the GetThumbnailImage method is used.\n"+
					"This is recommended if you're resizing an image to a small\n"+
					"size (100x75).\n\n"+
					"If /Size is specified we will return the dimensions of SourceFile. We\n"+
					"will not resize the image.\n\n\n"+
					"Copyright 2003 by am.net - http://am.net - help@am.net\n");
				return 0;
			}

			Image srcImage;
			Bitmap destImage;

			bool autoAspectRatio = true;
			bool useBitmap = true;
			bool returnDimensionsOnly = false;
			bool widthHeightSpecified = false;
			string srcFilename  = "";
			string destFilename = "";
			double width  = 0;
			double height = 0;

			for (int i = 0; i <= (args.Length-1); i++)
			{
				switch (args[i].ToLower())
				{
					case "/resize":
						// if resize was specified and there is no argument after it
						// we break. this ensures we use the source width and height
						if (i == (args.Length-1))
						{
							break;
						}

						Match dimensions = Regex.Match(args[i+1],
							"^(?<width>[0-9]*)[Xx](?<height>[0-9]*)$");
						
						if (dimensions.Length == 0)
						{
							Console.Write("Error: Invalid parameter after /Resize");
							return -1;
						}

						// if there was no match for width subexpression, 
						// set width = 0; otherwise width equals the match
						width = (dimensions.Groups["width"].Length == 0) ? 0 : 
							(int)Int32.Parse(dimensions.Groups["width"].Value);

						// if there was no match for the height subexpression, 
						// set height = 0; otherwise height equals the match.
						height = (dimensions.Groups["height"].Length == 0) ? 0 : 
							(int)Int32.Parse(dimensions.Groups["height"].Value);
						
						// Since the arguemnt after /Resize is the dimensions
						// which we've just parsed, we increment i so the next
						// iteration we will be on the argument after the dimensions.
						i++;
						widthHeightSpecified = true;
						break;

					case "/noautoaspect":
						if (width == 0 || height == 0) 
						{
							Console.Write("Error: Both width and height must be specified "+
								"to use /noAutoAspect");
							return -1;
						}
						autoAspectRatio = false;
						break;

					case "/thumbnail":
						useBitmap = false;
						break;

					case "/size":
						returnDimensionsOnly = true;
						break;
					
					default:
						// if srcFilename has not been specified yet, this args
						// is srcFilename. otherwise if destFilename has not been 
						// specified it's destFilename. if both have been specified
						// it's an illegal argument
						if (srcFilename.Length == 0)
						{
							srcFilename = args[i];
						}
						else if (destFilename.Length == 0)
						{
							destFilename = args[i];
						} 
						else 
						{
							Console.Write("Error: Illegal argument: " + args[i]);
							return -1;
						}
						break;
				}
			}


			if (destFilename == "")
				destFilename = srcFilename;

			try
			{
				srcImage = Image.FromFile(srcFilename);
			}
			catch
			{
				Console.Write("Error: Could not open " + args[0]);
				return -1;
			}
			
			if (returnDimensionsOnly)
			{
				Console.Write("{0}x{1}", srcImage.Width, srcImage.Height);
				return 0;
			}

			if (!widthHeightSpecified)
			{
				width = srcImage.Width;
				height = srcImage.Height;
			} 
			else if (autoAspectRatio)
			{

				double widthRatio = srcImage.Width / width;
				double heightRatio = srcImage.Height / height;

				// If only one dimension was specified, scale the image based
				// on that dimension.
				if (width == 0) 
				{
					width = srcImage.Width / heightRatio;
				}
				else if (height == 0)
				{
					height = srcImage.Height / widthRatio;
				}
				else
				{
					// We scale the image so that its dimensions are proportional
					// to the source--and neither scaled dimension is larger then the
					// specified dimensions.
					if (widthRatio > heightRatio) 
					{
						height = srcImage.Height / widthRatio;
					}
					else
					{
						width = srcImage.Width / heightRatio;
					}
				}				
			}


			try
			{
				if (!useBitmap)
				{
					Image.GetThumbnailImageAbort dummyCallBack = 
						new Image.GetThumbnailImageAbort(ThumbnailCallback);
					destImage = (System.Drawing.Bitmap)srcImage.GetThumbnailImage(
						(int)width, (int)height, dummyCallBack, IntPtr.Zero);
				}
				else
				{
					destImage = new Bitmap(srcImage, (int)width, (int)height);
				}
				System.Drawing.Imaging.ImageFormat imageFormat =
					srcImage.RawFormat;
				srcImage.Dispose();

				// We use to use Bitmap.Save to save the image but
				// on AM that wouldn't save the file "in-place". So instead
				// we use File.Create which seems to do this fine.
				//destImage.Save(destFilename, imageFormat);
				// we later discovered this kb article documenting the problem:
			    // http://support.microsoft.com/default.aspx?scid=kb;en-us;312119
				
				FileStream fr = File.Create(destFilename);
				destImage.Save(fr, imageFormat);
				fr.Flush();
				fr.Close();

				destImage.Dispose();
			}
			catch (Exception e)
			{
				Console.Write("Error: Could not create destination image");
				return -1;
			}
			
			Console.Write("{0}x{1}", (int)width, (int)height);
			return 0;
		}

	}
}