YUI Compressor for .net Handler

YuiCompressor.ashx

<%@ WebHandler Language="C#" Class="YuiCompressor" %>

// Requirements: 
// bin/Yahoo.Yui.Compressor.dll (See the project on codeplex)
// bin/EcmaScript.NET.dll
// bin/EcmaScript.NET.dll
// bin/Iesi.Collections.dll
//
// How to use this, in your templates or HTML:
//
// For CSS:
// <link rel="stylesheet" type="text/css" href="/YuiCompressor.ashx?css=reset,style" />
//
// For JS:
// <script type="text/javascript" src="/YuiCompressor.ashx?js=main,someotherscript"></script>

using System;
using System.Collections.Generic;
using System.Web;
using Yahoo.Yui.Compressor;

public class YuiCompressor : IHttpHandler
{
	public const char DELIMITER = ',';
	public const bool ENABLEHTTPCOMPRESSION = true;
	public TimeSpan CacheDuration = TimeSpan.FromDays(1);
	
	public class ContentTypes
	{
		public const string CSS = "text/css";
		public const string JS = "application/x-javascript";
		public const string ERROR = "text/plain";
	}
	
	public class Folders
	{
		// customize these to your site's paths
		public const string CSS = "~/styles/";
		public const string JS = "~/scripts/";
	}
	
	public class Extensions
	{
		public const string CSS = ".css";
		public const string JS = ".js";
	}
	
	public void ProcessRequest(HttpContext context)
	{
		context.Response.ContentEncoding = System.Text.Encoding.Default;
		
		context.Response.Cache.SetExpires(DateTime.Now.Add(CacheDuration));
		context.Response.Cache.SetMaxAge(CacheDuration);
		context.Response.Cache.SetCacheability(HttpCacheability.Private);
		
		string cssFiles = context.Request.QueryString["css"];
		string jsFiles = context.Request.QueryString["js"];
		string fileName = context.Request.QueryString["f"];
		
		if (! string.IsNullOrEmpty(cssFiles))
		{
			// A list of CSS files has been passed in, write each file's contents to the response object
			context.Response.ContentType = ContentTypes.CSS;
			foreach (string cssFile in cssFiles.Split(DELIMITER))
			{
				WriteCompressedFile(context, cssFile + Extensions.CSS, Folders.CSS);
			}
		} 
		else if (! string.IsNullOrEmpty(jsFiles)) 
		{
			// A list of JS files has been passed in, write each file's contents to the response object
			context.Response.ContentType = ContentTypes.JS;
			foreach (string jsFile in jsFiles.Split(DELIMITER))
			{
				WriteCompressedFile(context, jsFile + Extensions.JS, Folders.JS);
			}
		}
		else if (! string.IsNullOrEmpty(fileName))
		{
			// A specific file has been passed in, write that file's contents to the response object
			if (fileName.EndsWith(Extensions.JS))
			{
				context.Response.ContentType = ContentTypes.JS;
				WriteCompressedFile(context, fileName, Folders.JS);
			}
			else if (fileName.EndsWith(Extensions.CSS))
			{
				context.Response.ContentType = ContentTypes.CSS;
				WriteCompressedFile(context, fileName, Folders.CSS);
			}
			else
			{
				// 500?
				//Throw New System.IO.FileNotFoundException("The file specified isn't an allowed type.", fileName)
				context.Response.ContentType = ContentTypes.ERROR;
			}
		}
		else
		{
			// 404?
			//Throw New System.IO.FileNotFoundException("A filename hasn't been specified.")
			context.Response.ContentType = ContentTypes.ERROR;
			context.Response.Write(Environment.NewLine);
		}
		
		// compress output if enabled
		if (ENABLEHTTPCOMPRESSION) 
		{
			string encodingsAccepted = context.Request.Headers["Accept-Encoding"];
			if (! string.IsNullOrEmpty(encodingsAccepted))
			{
				encodingsAccepted = encodingsAccepted.ToLowerInvariant();
				if (encodingsAccepted.Contains("deflate")) 
				{
					context.Response.AppendHeader("Content-Encoding", "deflate");
					context.Response.Filter = new System.IO.Compression.DeflateStream(context.Response.Filter, System.IO.Compression.CompressionMode.Compress);
				}
				else if (encodingsAccepted.Contains("gzip")) 
				{
					context.Response.AppendHeader("Content-Encoding", "gzip");
					context.Response.Filter = new System.IO.Compression.GZipStream(context.Response.Filter, System.IO.Compression.CompressionMode.Compress);
				}
			}
		}
	}
	
	public bool IsReusable
	{
		get
		{
			return false;
		}
	}
	
	public void WriteCompressedFile(HttpContext context, string fileName, string folder) 
	{
		// Add each file's compressed contents to the cache as it is read with a file dependency on itself
		if (context.Cache[fileName] == null)
		{
			string filePath = HttpContext.Current.Server.MapPath(folder + fileName);
			string output = string.Empty;
			try
			{
                JavaScriptCompressor javascriptCompressor = new JavaScriptCompressor();
                CssCompressor cssCompressor = new CssCompressor();
				output = System.IO.File.ReadAllText(filePath);
				if (folder == Folders.JS)
				{
                    output = javascriptCompressor.Compress(output) + Environment.NewLine;
				}
				else
				{
                    output = cssCompressor.Compress(output) + Environment.NewLine;
				}
				context.Response.Write(output);
				context.Cache.Insert(fileName, output, new System.Web.Caching.CacheDependency(filePath));
			}
			catch (System.IO.FileNotFoundException)
			{
				// throw 404?
			}
		}
		else
		{
			context.Response.Write((string) context.Cache[fileName]);
		}
	}
}