/*
 * (c) Copyright Ascensio System SIA 2010-2015
 *
 * This program is a free software product. You can redistribute it and/or 
 * modify it under the terms of the GNU Affero General Public License (AGPL) 
 * version 3 as published by the Free Software Foundation. In accordance with 
 * Section 7(a) of the GNU AGPL its Section 15 shall be amended to the effect 
 * that Ascensio System SIA expressly excludes the warranty of non-infringement
 * of any third-party rights.
 *
 * This program is distributed WITHOUT ANY WARRANTY; without even the implied 
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR  PURPOSE. For 
 * details, see the GNU AGPL at: http://www.gnu.org/licenses/agpl-3.0.html
 *
 * You can contact Ascensio System SIA at Lubanas st. 125a-25, Riga, Latvia,
 * EU, LV-1021.
 *
 * The  interactive user interfaces in modified source and object code versions
 * of the Program must display Appropriate Legal Notices, as required under 
 * Section 5 of the GNU AGPL version 3.
 *
 * Pursuant to Section 7(b) of the License you must retain the original Product
 * logo when distributing the program. Pursuant to Section 7(e) we decline to
 * grant you any rights under trademark law for use of our trademarks.
 *
 * All the Product's GUI elements, including illustrations and icon sets, as
 * well as technical writing content are licensed under the terms of the
 * Creative Commons Attribution-ShareAlike 4.0 International. See the License
 * terms at http://creativecommons.org/licenses/by-sa/4.0/legalcode
 *
 */
 using System;
using System.Net;
using System.Configuration;
using System.Web;
using System.IO;
using System.Text;

using FileConverterUtils2;

using log4net;

namespace DocService
{
public class ResourceService : IHttpAsyncHandler
{
    private readonly ILog _log = LogManager.GetLogger(typeof(ResourceService));
    
    public IAsyncResult BeginProcessRequest(HttpContext context, AsyncCallback cb, Object extraData)
    {
        bool bStartAsync = false;
        try
        {
            _log.Info("Starting process request...");
            _log.Info(context.Request.QueryString.ToString());
            
            Storage oStorage = new Storage();
            ITaskResultInterface oTaskResult = TaskResult.NewTaskResult();
            string sPathOriginal = context.Request.QueryString["path"];
            string sPath = null;
            if (null != sPathOriginal)
            {
                sPath = sPathOriginal.Replace("../", "").Replace("..\\", "");
                if (sPathOriginal != sPath)
                {
                    _log.Error("Possible XSS attack:" + sPathOriginal);
                }
            }

            string sOutputFilename = context.Request.QueryString["filename"];

            string sDeletePathOriginal = context.Request.QueryString["deletepath"];
            string sDeletePath = null;
            if (null != sDeletePathOriginal)
            {
                sDeletePath = sDeletePathOriginal.Replace("../", "").Replace("..\\", "");
                if (sDeletePathOriginal != sDeletePath)
                {
                    _log.Error("Possible XSS attack:" + sDeletePathOriginal);
                }
            }

            string sNoCache = context.Request.QueryString["nocache"];
            if (string.IsNullOrEmpty(sOutputFilename))
            {
                if (null != sPath)
                {
                    int nIndex1 = sPath.LastIndexOf('/');
                    int nIndex2 = sPath.LastIndexOf('\\');
                    if (-1 != nIndex1 || -1 != nIndex2)
                    {
                        int nIndex = Math.Max(nIndex1, nIndex2);
                        sOutputFilename = sPath.Substring(nIndex + 1);
                    }
                    else
                        sOutputFilename = "resource";
                }
            }
               
            context.Response.Clear();

            context.Response.Cache.SetCacheability(HttpCacheability.Public);
            context.Response.ContentType = Utils.GetMimeType(sOutputFilename);
            string contentDisposition = Utils.GetContentDisposition(context.Request.UserAgent, context.Request.Browser.Browser, context.Request.Browser.Version, sOutputFilename);
            context.Response.AppendHeader("Content-Disposition", contentDisposition);
            if (null != sPath)
            {
                TransportClass oTransportClass = new TransportClass(context, cb, oStorage, oTaskResult, sPath, sDeletePath);
                oStorage.GetFileInfoBegin(sPath, GetFileInfoCallback, oTransportClass);
                bStartAsync = true;
            }
            else
                context.Response.StatusCode = (int)HttpStatusCode.NotFound;
                
        }
        catch(Exception e)
        {
            context.Response.StatusCode = (int)HttpStatusCode.BadRequest;
            
            _log.Error(context.Request.QueryString.ToString());
            _log.Error("Exeption catched in BeginProcessRequest:", e);
        }
        TransportClass oTempTransportClass = new TransportClass(context, cb, null, null, null, null);
        if (false == bStartAsync)
            cb(new AsyncOperationData(oTempTransportClass));
        return new AsyncOperationData(oTempTransportClass);
    }
    public void EndProcessRequest(IAsyncResult result)
    {
        return;
    }
    private void GetFileInfoCallback(IAsyncResult result)
    {
        TransportClass oTransportClass = result.AsyncState as TransportClass;
        HttpContext context = oTransportClass.m_oContext;
        bool bStartAsync = false;
        try
        {
            string sPath = oTransportClass.m_sPath;
            Storage oStorage = oTransportClass.m_oStorage;
            StorageFileInfo oStorageFileInfo;
            if (ErrorTypes.NoError == oStorage.GetFileInfoEnd(result, out oStorageFileInfo) && null != oStorageFileInfo)
            {
                string sETag = oStorageFileInfo.m_oLastModify.Ticks.ToString("x");
                DateTime oLastModified = oStorageFileInfo.m_oLastModify;

                DateTime oDateTimeUtcNow = DateTime.UtcNow;
                _log.InfoFormat("oLastModified = {0}", oLastModified);
                _log.InfoFormat("oDateTimeUtcNow = {0}", oDateTimeUtcNow);

                if (oLastModified.CompareTo(oDateTimeUtcNow) > 0)
                {
                    _log.DebugFormat("LastModifiedTimeStamp changed from {0} to {1}", oLastModified, oDateTimeUtcNow);
                    oLastModified = oDateTimeUtcNow;
                }

                string sRequestIfModifiedSince = context.Request.Headers["If-Modified-Since"];
                string sRequestETag = context.Request.Headers["If-None-Match"];
                bool bNoModify = false;
                if (false == string.IsNullOrEmpty(sRequestETag) || false == string.IsNullOrEmpty(sRequestIfModifiedSince))
                {
                    bool bRequestETag = true;
                    if (false == string.IsNullOrEmpty(sRequestETag) && sRequestETag != sETag)
                        bRequestETag = false;
                    bool bRequestIfModifiedSince = true;
                    if (false == string.IsNullOrEmpty(sRequestIfModifiedSince))
                    {
                        try
                        {
                            DateTime oRequestIfModifiedSince = DateTime.ParseExact(sRequestIfModifiedSince, "R", System.Globalization.CultureInfo.InvariantCulture);
                            if ((oRequestIfModifiedSince - oLastModified).TotalSeconds > 1)
                                bRequestIfModifiedSince = false;
                        }
                        catch
                        {
                            bRequestIfModifiedSince = false;
                        }
                    }
                    if (bRequestETag && bRequestIfModifiedSince)
                    {
                        context.Response.StatusCode = (int)HttpStatusCode.NotModified;
                        bNoModify = true;
                    }
                }
                if (false == bNoModify)
                {
                    context.Response.Cache.SetETag(sETag);

                    context.Response.Cache.SetLastModified(oLastModified.ToLocalTime());
                    
                    oStorage.ReadFileBegin(sPath, context.Response.OutputStream, ReadFileCallback, oTransportClass);
                    bStartAsync = true;
                }
            }
            else
                context.Response.StatusCode = (int)HttpStatusCode.NotFound;
        }
        catch (Exception e)
        {
            _log.Error("Exception catched in GetFileInfoCallback:", e);

            context.Response.StatusCode = (int)HttpStatusCode.BadRequest;
        }
        if (!bStartAsync)
            oTransportClass.m_oCallback(new AsyncOperationData(oTransportClass)); 
    }
    private void ReadFileCallback(IAsyncResult result)
    {
        SendResponse(result);
        DeletePath(result);
    }

    private void DeletePath(IAsyncResult result)
    {
        TransportClass oTransportClass = result.AsyncState as TransportClass;
        try
        {
            if (null != oTransportClass.m_sDeletePath && false == string.IsNullOrEmpty(oTransportClass.m_sDeletePath))
            {
                ITaskResultInterface oTaskResult = oTransportClass.m_oTaskResult;

                string sKey = oTransportClass.m_sDeletePath;

                oTaskResult.RemoveBegin(sKey, RemoveTaskCallback, oTransportClass);
            }
            else
            {
                oTransportClass.m_oCallback(new AsyncOperationData(oTransportClass));
            }
        }
        catch (Exception e)
        {
            _log.Error("Exception catched in DeletePath:", e);
            
            oTransportClass.m_oCallback(new AsyncOperationData(oTransportClass));
        }
    }

    private void SendResponse(IAsyncResult result)
    {
        TransportClass oTransportClass = result.AsyncState as TransportClass;
        HttpContext context = oTransportClass.m_oContext;
        try
        {

            Storage oStorage = oTransportClass.m_oStorage;
            if (null == oStorage)
            {
                throw new NullReferenceException();
            }

            int nReadWriteBytes = 0;
            ErrorTypes eResult = oStorage.ReadFileEnd(result, out nReadWriteBytes);
            if (ErrorTypes.NoError == eResult)
            {
                context.Response.AppendHeader("Content-Length", nReadWriteBytes.ToString());
                context.Response.StatusCode = (int)HttpStatusCode.OK;
            }

        }
        catch (HttpException httpEx)
        {
            _log.Error("HttpException catched in SendResponse:", httpEx);
        }
        catch (Exception e)
        {
            _log.Error("Exception catched in SendResponse:", e);

            context.Response.StatusCode = (int)HttpStatusCode.BadRequest;
        }
        
        try
        {
            if (context.Response.IsClientConnected)
            {
                context.Response.Flush();
            }
        }
        catch (Exception e)
        {
            _log.Error("Exception catched in SendResponse, while response end:", e);
        }
    }
    private void RemoveTaskCallback(IAsyncResult result)
    {
        TransportClass oTransportClass = result.AsyncState as TransportClass;
        try
        {
            ITaskResultInterface oTaskResult = oTransportClass.m_oTaskResult;
            
            if (null != oTaskResult)
                oTaskResult.RemoveEnd(result);
            
            Storage oStorage = oTransportClass.m_oStorage;

            if (null != oStorage)
                oStorage.RemovePathBegin(oTransportClass.m_sDeletePath, RemoveFileCallback, oTransportClass);
        }
        catch(Exception e)
        {
            _log.Error("Exception catched in RemoveTaskCallback:", e);

            oTransportClass.m_oCallback(new AsyncOperationData(oTransportClass));
        }
    }
    private void RemoveFileCallback(IAsyncResult result)
    {
        TransportClass oTransportClass = result.AsyncState as TransportClass;
        HttpContext context = oTransportClass.m_oContext;
        try
        {
            Storage oStorage = oTransportClass.m_oStorage;
            if (null != oStorage)
                oStorage.RemovePathEnd(result);
            oTransportClass.m_oCallback(new AsyncOperationData(oTransportClass));
        }
        catch(Exception e)
        {
            _log.Error("Exception catched in RemoveFileCallback:", e);

            oTransportClass.m_oCallback(new AsyncOperationData(oTransportClass));
        }
    }
    public void ProcessRequest(HttpContext context)
    {
        throw new InvalidOperationException();
    }

    public bool IsReusable
    {
        get
        {
            return false;
        }
    }
    private class TransportClass
    {
        public HttpContext m_oContext;
        public AsyncCallback m_oCallback;
        public Storage m_oStorage;
        public ITaskResultInterface m_oTaskResult;
        public string m_sPath;
        public string m_sDeletePath;
        public TransportClass(HttpContext oContext, AsyncCallback oCallback, Storage oStorage, ITaskResultInterface oTaskResult, string sPath, string sDeletePath)
        {
            m_oContext = oContext;
            m_oCallback = oCallback;
            m_oStorage = oStorage;
            m_oTaskResult = oTaskResult;
            m_sPath = sPath;
            m_sDeletePath = sDeletePath;
        }
    }
}
}