Combres - WebForm & MVC Client-side Resource Combine Library

#region License
// Copyright 2009 Buu Nguyen (http://www.buunguyen.net/blog)
// 
// Licensed under the Apache License, Version 2.0 (the "License"); 
// you may not use this file except in compliance with the License. 
// You may obtain a copy of the License at 
// 
// http://www.apache.org/licenses/LICENSE-2.0 
// 
// Unless required by applicable law or agreed to in writing, software 
// distributed under the License is distributed on an "AS IS" BASIS, 
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
// See the License for the specific language governing permissions and 
// limitations under the License.
// 
// The latest version of this file can be found at http://combres.codeplex.com
#endregion

using System.Web;
using System.Web.Mvc;
using System.Web.Routing;

namespace Combres
{
    /// <summary>
    /// Utility class providing extension methods for ASP.NET and ASP.NET MVC applications to
    /// work with the library.
    /// </summary>
    public static class WebExtensions
    {
        private const string UrlPattern = "{0}/{1}/{2}";

        /// <summary>
        /// Retrieves the URL of the Combres engine as registered in XML data file.
        /// </summary>
        /// <param name="routes">The actual argument is typically <code>RouteTable.Routes</code></param>
        /// <returns>The URL of the Combres engine as registered in XML data file</returns>
        public static string GetCombresUrl(this RouteCollection routes)
        {
            return Settings.Url.ResolveUrl();
        }

        /// <summary>
        /// Registers the combiner route to the <code>routes</code> collection.
        /// Invoke this in <code>Application_Start</code>.
        /// </summary>
        /// <param name="routes">The actual argument is typically <code>RouteTable.Routes</code></param>
        /// <param name="name">The route name</param>
        public static void AddCombresRoute(this RouteCollection routes, string name)
        {
            var adjustedUrl = Settings.Url.Substring(2); // Remove the "~/"
            routes.Add(name, new Route(adjustedUrl + "/{name}/{version}",
                new RouteValueDictionary(new { version = string.Empty }),
                new CombresRouteHandler()));
        }

        /// <summary>
        /// See <c>WebExtensions#CombresUrl</c>.
        /// </summary>
        public static string CombresUrl(this HtmlHelper html, string setName)
        {
            return CombresUrl(setName);
        }

        /// <summary>
        /// Generates the URL to the resource combiner for the specified <paramref name="setName"/>.
        /// </summary>
        /// <example>
        /// <![CDATA[<script type="text/javascript" src="<%= Html.CombresUrl("siteJsSet") %>"></script>]]>    
        /// </example>
        /// <param name="setName">The name of the resource set to be linked to</param>
        /// <returns>The URL to the reousrce combiner for the specified <paramref name="setName"/></returns>
        public static string CombresUrl(string setName)
        {
            var settings = Settings;
            var set = GetResourceSet(setName);
            var fullUrl = string.Format(UrlPattern, settings.Url, set.Name, set.Version);
            return fullUrl.ResolveUrl();
        }
        
        /// <summary>
        /// See <c>WebExtensions#CombresLink</c>.
        /// </summary>
        public static string CombresLink(this HtmlHelper html, string setName)
        {
            return CombresLink(setName);
        }

        /// <summary>
        /// Generates the link to the resource combiner for the specified 
        /// <paramref name="setName"/>.  If the set is a JavaScript set, 
        /// <![CDATA[<script type="text/javascript" src=...></script>]]> is returned.  
        /// If the set is a CSS set, <![CDATA[<link rel="stylesheet" type="text/css" href=... />]]> 
        /// is returned.
        /// </summary>
        /// <example>
        /// <![CDATA[<%= Html.CombresLink("bootstrapJs")%>]]>    
        /// </example>
        /// <param name="setName">The name of the resource set to be linked to</param>
        /// <returns>The link to the resource combiner for the specified <paramref name="setName"/></returns>
        public static string CombresLink(string setName)
        {
            var set = GetResourceSet(setName);
            string optimizerUrl = set.Type == ResourceType.JS ?
                "<script type=\"text/javascript\" src=\"{0}\"></script>" :
                "<link rel=\"stylesheet\" type=\"text/css\" href=\"{0}\" />";
            return string.Format(optimizerUrl, CombresUrl(set.Name));
        }

        private static ResourceSet GetResourceSet(string setName)
        {
            var set = Settings[setName];
            if (set == null)
                throw new ResourceSetNotFoundException("Set " + setName + " does not exist");
            return set;
        }

        private static Settings Settings
        {
            get
            {
                return Configuration.GetSettings(HttpContext.Current);
            }
        }
    }
}