/BlogEngine/DotNetSlave.BusinessLogic/Web/HttpHandlers/FileHandler.cs

namespace BlogEngine.Core.Web.HttpHandlers

{

    using System;

    using System.IO;

    using System.Web;

    using BlogEngine.Core.Providers;



    /// <summary>

    /// The FileHandler serves all files that is uploaded from

    ///     the admin pages except for images.

    /// </summary>

    /// <remarks>

    /// By using a HttpHandler to serve files, it is very easy

    ///     to add the capability to stop bandwidth leeching or

    ///     to create a statistics analysis feature upon it.

    /// </remarks>

    public class FileHandler : IHttpHandler

    {

        #region Events



        /// <summary>

        ///     Occurs when the requested file does not exist;

        /// </summary>

        public static event EventHandler<EventArgs> BadRequest;



        /// <summary>

        ///     Occurs when a file is served;

        /// </summary>

        public static event EventHandler<EventArgs> Served;



        /// <summary>

        ///     Occurs when the requested file does not exist;

        /// </summary>

        public static event EventHandler<EventArgs> Serving;



        #endregion



        #region Properties



        /// <summary>

        ///     Gets a value indicating whether another request can use the <see cref = "T:System.Web.IHttpHandler"></see> instance.

        /// </summary>

        /// <value></value>

        /// <returns>true if the <see cref = "T:System.Web.IHttpHandler"></see> instance is reusable; otherwise, false.</returns>

        public bool IsReusable

        {

            get

            {

                return false;

            }

        }



        #endregion



        #region Implemented Interfaces



        #region IHttpHandler



        /// <summary>

        /// Enables processing of HTTP Web requests by a custom HttpHandler that 

        ///     implements the <see cref="T:System.Web.IHttpHandler"></see> interface.

        /// </summary>

        /// <param name="context">

        /// An <see cref="T:System.Web.HttpContext"></see> 

        ///     object that provides references to the intrinsic server objects 

        ///     (for example, Request, Response, Session, and Server) used to service HTTP requests.

        /// </param>

        public void ProcessRequest(HttpContext context)

        {

            if (!string.IsNullOrEmpty(context.Request.QueryString["file"]))

            {

                var fileName = context.Request.QueryString["file"];

                OnServing(fileName);

                fileName = !fileName.StartsWith("/") ? string.Format("/{0}", fileName) : fileName;

                try

                {



                    var file = BlogService.GetFile(string.Format("{0}files{1}",Blog.CurrentInstance.StorageLocation, fileName));

                    if (file != null)

                    {

                        context.Response.AppendHeader("Content-Disposition", string.Format("inline; filename=\"{0}\"", file.Name));

                        SetContentType(context, file.Name);

                        if (Utils.SetConditionalGetHeaders(file.DateCreated.ToUniversalTime()))

                            return;



                        context.Response.BinaryWrite(file.FileContents);

                        OnServed(fileName);

                    }

                    else

                    {

                        OnBadRequest(fileName);

                        context.Response.Redirect(string.Format("{0}error404.aspx", Utils.AbsoluteWebRoot));

                    }

                }

                catch (Exception)

                {

                    OnBadRequest(fileName);

                    context.Response.Redirect(string.Format("{0}error404.aspx", Utils.AbsoluteWebRoot));

                }

            }

        }



        #endregion



        #endregion



        #region Methods



        /// <summary>

        /// Called when [bad request].

        /// </summary>

        /// <param name="file">The file name.</param>

        private static void OnBadRequest(string file)

        {

            if (BadRequest != null)

            {

                BadRequest(file, EventArgs.Empty);

            }

        }



        /// <summary>

        /// Called when [served].

        /// </summary>

        /// <param name="file">The file name.</param>

        private static void OnServed(string file)

        {

            if (Served != null)

            {

                Served(file, EventArgs.Empty);

            }

        }



        /// <summary>

        /// Called when [serving].

        /// </summary>

        /// <param name="file">The file name.</param>

        private static void OnServing(string file)

        {

            if (Serving != null)

            {

                Serving(file, EventArgs.Empty);

            }

        }



        /// <summary>

        /// Sets the content type depending on the filename's extension.

        /// </summary>

        /// <param name="context">

        /// The context.

        /// </param>

        /// <param name="fileName">

        /// The file Name.

        /// </param>

        private static void SetContentType(HttpContext context, string fileName)

        {

            context.Response.AddHeader(

                "Content-Type", fileName.EndsWith(".pdf") ? "application/pdf" : "application/octet-stream");

        }



        #endregion

    }

}