ImageResizer.Plugins.AzureCDN

using System;
using System.Collections.Generic;
using System.Text;
using ImageResizer.Configuration;
using System.Text.RegularExpressions;
using System.Collections.Specialized;
using System.Web;
using ImageResizer.Util;

namespace ImageResizer.Plugins.AzureCDN {
    /// <summary>
    /// Allows querystrings to be expressed with '/' or ';' instead of '?', allow the querystring to survive the AzureCDN guillotine.
    /// Since IIS can't stand '&' symbols in the path, you have to replace both '?' and '&' with ';'
    /// Later I hope to include control adapters to automate the process.
    /// </summary>
    public class AzureCDNPlugin : IPlugin {

        public AzureCDNPlugin() { }

        Config c;

        protected string redirectThrough = null;
        protected bool redirectPermanent = false;
        public IPlugin Install(Configuration.Config c) {
            this.c = c;
            c.Plugins.add_plugin(this);
            c.Pipeline.PostAuthorizeRequestStart += Pipeline_PostAuthorizeRequestStart;
            c.Pipeline.RewriteDefaults += Pipeline_RewriteDefaults;
            redirectThrough = c.get("azurecdn.redirectthrough", null);
            redirectPermanent = c.get("azurecdn.permanentRedirect", false);
            return this;
        }

        void Pipeline_PostAuthorizeRequestStart(System.Web.IHttpModule sender, System.Web.HttpContext context) {
            if (redirectThrough != null && c.Pipeline.ModifiedQueryString.Count > 0) {
                //It wasn't a AzureCDN URL - it had a normal querystring
                context.Items[c.Pipeline.ModifiedPathKey + ".hadquery"] = true;
            }
        }

        void Pipeline_RewriteDefaults(System.Web.IHttpModule sender, System.Web.HttpContext context, IUrlEventArgs e) {
            ///Handle redirectThrough behavior
            if (redirectThrough != null && context.Items[c.Pipeline.ModifiedPathKey + ".hadquery"] != null) {
                //It had a querystring originally - which means the request didn't come from AzureCDN, it came directly from the browser. Perform a redirect, rewriting the querystring appropriately
                string finalPath = redirectThrough + e.VirtualPath + PathUtils.BuildQueryString(e.QueryString, true);

                //Redirect according to setting
                context.Response.Redirect(finalPath, !redirectPermanent);
                if (redirectPermanent) {
                    context.Response.StatusCode = 301;
                    context.Response.End();
                }
            }

        }

        public bool Uninstall(Configuration.Config c) {
            c.Plugins.remove_plugin(this);
            c.Pipeline.RewriteDefaults -= Pipeline_RewriteDefaults;
            c.Pipeline.PostAuthorizeRequestStart -= Pipeline_PostAuthorizeRequestStart;
            return true;
        }
    }
}