using System;
using System.Collections.Generic;
using System.Linq;
using Microsoft.AspNetCore.StaticFiles;

namespace MyPortal.Logic.Helpers
{
    internal class MimeTypeHelper
    {
        private static readonly Lazy<IDictionary<string, string>> Mappings =
            new Lazy<IDictionary<string, string>>(BuildMappings);

        private static IDictionary<string, string> BuildMappings()
        {
            var genericTypes = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
            {
                #region Big freaking list of mime types

                // combination of values from Windows 7 Registry and 
                // from C:\Windows\System32\inetsrv\config\applicationHost.config
                // some added, including .7z and .dat
                //
                // Some added based on http://www.iana.org/assignments/media-types/media-types.xhtml
                // which lists mime types, but not extensions
                //
                { ".323", "text/h323" },
                { ".3g2", "video/3gpp2" },
                { ".3gp", "video/3gpp" },
                { ".3gp2", "video/3gpp2" },
                { ".3gpp", "video/3gpp" },
                { ".7z", "application/x-7z-compressed" },
                { ".aa", "audio/audible" },
                { ".AAC", "audio/aac" },
                { ".aaf", "application/octet-stream" },
                { ".aax", "audio/vnd.audible.aax" },
                { ".ac3", "audio/ac3" },
                { ".aca", "application/octet-stream" },
                { ".accda", "application/msaccess.addin" },
                { ".accdb", "application/msaccess" },
                { ".accdc", "application/msaccess.cab" },
                { ".accde", "application/msaccess" },
                { ".accdr", "application/msaccess.runtime" },
                { ".accdt", "application/msaccess" },
                { ".accdw", "application/msaccess.webapplication" },
                { ".accft", "application/msaccess.ftemplate" },
                { ".acx", "application/internet-property-stream" },
                { ".AddIn", "text/xml" },
                { ".ade", "application/msaccess" },
                { ".adobebridge", "application/x-bridge-url" },
                { ".adp", "application/msaccess" },
                { ".ADT", "audio/vnd.dlna.adts" },
                { ".ADTS", "audio/aac" },
                { ".afm", "application/octet-stream" },
                { ".ai", "application/postscript" },
                { ".aif", "audio/aiff" },
                { ".aifc", "audio/aiff" },
                { ".aiff", "audio/aiff" },
                { ".air", "application/vnd.adobe.air-application-installer-package+zip" },
                { ".amc", "application/mpeg" },
                { ".anx", "application/annodex" },
                { ".apk", "application/vnd.android.package-archive" },
                { ".application", "application/x-ms-application" },
                { ".art", "image/x-jg" },
                { ".asa", "application/xml" },
                { ".asax", "application/xml" },
                { ".ascx", "application/xml" },
                { ".asd", "application/octet-stream" },
                { ".asf", "video/x-ms-asf" },
                { ".ashx", "application/xml" },
                { ".asi", "application/octet-stream" },
                { ".asm", "text/plain" },
                { ".asmx", "application/xml" },
                { ".aspx", "application/xml" },
                { ".asr", "video/x-ms-asf" },
                { ".asx", "video/x-ms-asf" },
                { ".atom", "application/atom+xml" },
                { ".au", "audio/basic" },
                { ".avi", "video/x-msvideo" },
                { ".axa", "audio/annodex" },
                { ".axs", "application/olescript" },
                { ".axv", "video/annodex" },
                { ".bas", "text/plain" },
                { ".bcpio", "application/x-bcpio" },
                { ".bin", "application/octet-stream" },
                { ".bmp", "image/bmp" },
                { ".c", "text/plain" },
                { ".cab", "application/octet-stream" },
                { ".caf", "audio/x-caf" },
                { ".calx", "application/vnd.ms-office.calx" },
                { ".cat", "application/vnd.ms-pki.seccat" },
                { ".cc", "text/plain" },
                { ".cd", "text/plain" },
                { ".cdda", "audio/aiff" },
                { ".cdf", "application/x-cdf" },
                { ".cer", "application/x-x509-ca-cert" },
                { ".cfg", "text/plain" },
                { ".chm", "application/octet-stream" },
                { ".class", "application/x-java-applet" },
                { ".clp", "application/x-msclip" },
                { ".cmd", "text/plain" },
                { ".cmx", "image/x-cmx" },
                { ".cnf", "text/plain" },
                { ".cod", "image/cis-cod" },
                { ".config", "application/xml" },
                { ".contact", "text/x-ms-contact" },
                { ".coverage", "application/xml" },
                { ".cpio", "application/x-cpio" },
                { ".cpp", "text/plain" },
                { ".crd", "application/x-mscardfile" },
                { ".crl", "application/pkix-crl" },
                { ".crt", "application/x-x509-ca-cert" },
                { ".cs", "text/plain" },
                { ".csdproj", "text/plain" },
                { ".csh", "application/x-csh" },
                { ".csproj", "text/plain" },
                { ".css", "text/css" },
                { ".csv", "text/csv" },
                { ".cur", "application/octet-stream" },
                { ".cxx", "text/plain" },
                { ".dat", "application/octet-stream" },
                { ".datasource", "application/xml" },
                { ".dbproj", "text/plain" },
                { ".dcr", "application/x-director" },
                { ".def", "text/plain" },
                { ".deploy", "application/octet-stream" },
                { ".der", "application/x-x509-ca-cert" },
                { ".dgml", "application/xml" },
                { ".dib", "image/bmp" },
                { ".dif", "video/x-dv" },
                { ".dir", "application/x-director" },
                { ".disco", "text/xml" },
                { ".divx", "video/divx" },
                { ".dll", "application/x-msdownload" },
                { ".dll.config", "text/xml" },
                { ".dlm", "text/dlm" },
                { ".doc", "application/msword" },
                { ".docm", "application/vnd.ms-word.document.macroEnabled.12" },
                { ".docx", "application/vnd.openxmlformats-officedocument.wordprocessingml.document" },
                { ".dot", "application/msword" },
                { ".dotm", "application/vnd.ms-word.template.macroEnabled.12" },
                { ".dotx", "application/vnd.openxmlformats-officedocument.wordprocessingml.template" },
                { ".dsp", "application/octet-stream" },
                { ".dsw", "text/plain" },
                { ".dtd", "text/xml" },
                { ".dtsConfig", "text/xml" },
                { ".dv", "video/x-dv" },
                { ".dvi", "application/x-dvi" },
                { ".dwf", "drawing/x-dwf" },
                { ".dwg", "application/acad" },
                { ".dwp", "application/octet-stream" },
                { ".dxf", "application/x-dxf" },
                { ".dxr", "application/x-director" },
                { ".eml", "message/rfc822" },
                { ".emf", "image/emf" },
                { ".emz", "application/octet-stream" },
                { ".eot", "application/vnd.ms-fontobject" },
                { ".eps", "application/postscript" },
                { ".es", "application/ecmascript" },
                { ".etl", "application/etl" },
                { ".etx", "text/x-setext" },
                { ".evy", "application/envoy" },
                { ".exe", "application/vnd.microsoft.portable-executable" },
                { ".exe.config", "text/xml" },
                { ".f4v", "video/mp4" },
                { ".fdf", "application/vnd.fdf" },
                { ".fif", "application/fractals" },
                { ".filters", "application/xml" },
                { ".fla", "application/octet-stream" },
                { ".flac", "audio/flac" },
                { ".flr", "x-world/x-vrml" },
                { ".flv", "video/x-flv" },
                { ".fsscript", "application/fsharp-script" },
                { ".fsx", "application/fsharp-script" },
                { ".generictest", "application/xml" },
                { ".gif", "image/gif" },
                { ".gpx", "application/gpx+xml" },
                { ".group", "text/x-ms-group" },
                { ".gsm", "audio/x-gsm" },
                { ".gtar", "application/x-gtar" },
                { ".gz", "application/x-gzip" },
                { ".h", "text/plain" },
                { ".hdf", "application/x-hdf" },
                { ".hdml", "text/x-hdml" },
                { ".hhc", "application/x-oleobject" },
                { ".hhk", "application/octet-stream" },
                { ".hhp", "application/octet-stream" },
                { ".hlp", "application/winhlp" },
                { ".hpp", "text/plain" },
                { ".hqx", "application/mac-binhex40" },
                { ".hta", "application/hta" },
                { ".htc", "text/x-component" },
                { ".htm", "text/html" },
                { ".html", "text/html" },
                { ".htt", "text/webviewhtml" },
                { ".hxa", "application/xml" },
                { ".hxc", "application/xml" },
                { ".hxd", "application/octet-stream" },
                { ".hxe", "application/xml" },
                { ".hxf", "application/xml" },
                { ".hxh", "application/octet-stream" },
                { ".hxi", "application/octet-stream" },
                { ".hxk", "application/xml" },
                { ".hxq", "application/octet-stream" },
                { ".hxr", "application/octet-stream" },
                { ".hxs", "application/octet-stream" },
                { ".hxt", "text/html" },
                { ".hxv", "application/xml" },
                { ".hxw", "application/octet-stream" },
                { ".hxx", "text/plain" },
                { ".i", "text/plain" },
                { ".ical", "text/calendar" },
                { ".icalendar", "text/calendar" },
                { ".ico", "image/x-icon" },
                { ".ics", "text/calendar" },
                { ".idl", "text/plain" },
                { ".ief", "image/ief" },
                { ".ifb", "text/calendar" },
                { ".iii", "application/x-iphone" },
                { ".inc", "text/plain" },
                { ".inf", "application/octet-stream" },
                { ".ini", "text/plain" },
                { ".inl", "text/plain" },
                { ".ins", "application/x-internet-signup" },
                { ".ipa", "application/x-itunes-ipa" },
                { ".ipg", "application/x-itunes-ipg" },
                { ".ipproj", "text/plain" },
                { ".ipsw", "application/x-itunes-ipsw" },
                { ".iqy", "text/x-ms-iqy" },
                { ".isp", "application/x-internet-signup" },
                { ".isma", "application/octet-stream" },
                { ".ismv", "application/octet-stream" },
                { ".ite", "application/x-itunes-ite" },
                { ".itlp", "application/x-itunes-itlp" },
                { ".itms", "application/x-itunes-itms" },
                { ".itpc", "application/x-itunes-itpc" },
                { ".IVF", "video/x-ivf" },
                { ".jar", "application/java-archive" },
                { ".java", "application/octet-stream" },
                { ".jck", "application/liquidmotion" },
                { ".jcz", "application/liquidmotion" },
                { ".jfif", "image/pjpeg" },
                { ".jnlp", "application/x-java-jnlp-file" },
                { ".jpb", "application/octet-stream" },
                { ".jpe", "image/jpeg" },
                { ".jpeg", "image/jpeg" },
                { ".jpg", "image/jpeg" },
                { ".js", "application/javascript" },
                { ".json", "application/json" },
                { ".jsx", "text/jscript" },
                { ".jsxbin", "text/plain" },
                { ".latex", "application/x-latex" },
                { ".library-ms", "application/windows-library+xml" },
                { ".lit", "application/x-ms-reader" },
                { ".loadtest", "application/xml" },
                { ".lpk", "application/octet-stream" },
                { ".lsf", "video/x-la-asf" },
                { ".lst", "text/plain" },
                { ".lsx", "video/x-la-asf" },
                { ".lzh", "application/octet-stream" },
                { ".m13", "application/x-msmediaview" },
                { ".m14", "application/x-msmediaview" },
                { ".m1v", "video/mpeg" },
                { ".m2t", "video/vnd.dlna.mpeg-tts" },
                { ".m2ts", "video/vnd.dlna.mpeg-tts" },
                { ".m2v", "video/mpeg" },
                { ".m3u", "audio/x-mpegurl" },
                { ".m3u8", "audio/x-mpegurl" },
                { ".m4a", "audio/m4a" },
                { ".m4b", "audio/m4b" },
                { ".m4p", "audio/m4p" },
                { ".m4r", "audio/x-m4r" },
                { ".m4v", "video/x-m4v" },
                { ".mac", "image/x-macpaint" },
                { ".mak", "text/plain" },
                { ".man", "application/x-troff-man" },
                { ".manifest", "application/x-ms-manifest" },
                { ".map", "text/plain" },
                { ".master", "application/xml" },
                { ".mbox", "application/mbox" },
                { ".mda", "application/msaccess" },
                { ".mdb", "application/x-msaccess" },
                { ".mde", "application/msaccess" },
                { ".mdp", "application/octet-stream" },
                { ".me", "application/x-troff-me" },
                { ".mfp", "application/x-shockwave-flash" },
                { ".mht", "message/rfc822" },
                { ".mhtml", "message/rfc822" },
                { ".mid", "audio/mid" },
                { ".midi", "audio/mid" },
                { ".mix", "application/octet-stream" },
                { ".mk", "text/plain" },
                { ".mk3d", "video/x-matroska-3d" },
                { ".mka", "audio/x-matroska" },
                { ".mkv", "video/x-matroska" },
                { ".mmf", "application/x-smaf" },
                { ".mno", "text/xml" },
                { ".mny", "application/x-msmoney" },
                { ".mod", "video/mpeg" },
                { ".mov", "video/quicktime" },
                { ".movie", "video/x-sgi-movie" },
                { ".mp2", "video/mpeg" },
                { ".mp2v", "video/mpeg" },
                { ".mp3", "audio/mpeg" },
                { ".mp4", "video/mp4" },
                { ".mp4v", "video/mp4" },
                { ".mpa", "video/mpeg" },
                { ".mpe", "video/mpeg" },
                { ".mpeg", "video/mpeg" },
                { ".mpf", "application/vnd.ms-mediapackage" },
                { ".mpg", "video/mpeg" },
                { ".mpp", "application/vnd.ms-project" },
                { ".mpv2", "video/mpeg" },
                { ".mqv", "video/quicktime" },
                { ".ms", "application/x-troff-ms" },
                { ".msg", "application/vnd.ms-outlook" },
                { ".msi", "application/octet-stream" },
                { ".mso", "application/octet-stream" },
                { ".mts", "video/vnd.dlna.mpeg-tts" },
                { ".mtx", "application/xml" },
                { ".mvb", "application/x-msmediaview" },
                { ".mvc", "application/x-miva-compiled" },
                { ".mxf", "application/mxf" },
                { ".mxp", "application/x-mmxp" },
                { ".nc", "application/x-netcdf" },
                { ".nsc", "video/x-ms-asf" },
                { ".nws", "message/rfc822" },
                { ".ocx", "application/octet-stream" },
                { ".oda", "application/oda" },
                { ".odb", "application/vnd.oasis.opendocument.database" },
                { ".odc", "application/vnd.oasis.opendocument.chart" },
                { ".odf", "application/vnd.oasis.opendocument.formula" },
                { ".odg", "application/vnd.oasis.opendocument.graphics" },
                { ".odh", "text/plain" },
                { ".odi", "application/vnd.oasis.opendocument.image" },
                { ".odl", "text/plain" },
                { ".odm", "application/vnd.oasis.opendocument.text-master" },
                { ".odp", "application/vnd.oasis.opendocument.presentation" },
                { ".ods", "application/vnd.oasis.opendocument.spreadsheet" },
                { ".odt", "application/vnd.oasis.opendocument.text" },
                { ".oga", "audio/ogg" },
                { ".ogg", "audio/ogg" },
                { ".ogv", "video/ogg" },
                { ".ogx", "application/ogg" },
                { ".one", "application/onenote" },
                { ".onea", "application/onenote" },
                { ".onepkg", "application/onenote" },
                { ".onetmp", "application/onenote" },
                { ".onetoc", "application/onenote" },
                { ".onetoc2", "application/onenote" },
                { ".opus", "audio/ogg" },
                { ".orderedtest", "application/xml" },
                { ".osdx", "application/opensearchdescription+xml" },
                { ".otf", "application/font-sfnt" },
                { ".otg", "application/vnd.oasis.opendocument.graphics-template" },
                { ".oth", "application/vnd.oasis.opendocument.text-web" },
                { ".otp", "application/vnd.oasis.opendocument.presentation-template" },
                { ".ots", "application/vnd.oasis.opendocument.spreadsheet-template" },
                { ".ott", "application/vnd.oasis.opendocument.text-template" },
                { ".oxt", "application/vnd.openofficeorg.extension" },
                { ".p10", "application/pkcs10" },
                { ".p12", "application/x-pkcs12" },
                { ".p7b", "application/x-pkcs7-certificates" },
                { ".p7c", "application/pkcs7-mime" },
                { ".p7m", "application/pkcs7-mime" },
                { ".p7r", "application/x-pkcs7-certreqresp" },
                { ".p7s", "application/pkcs7-signature" },
                { ".pbm", "image/x-portable-bitmap" },
                { ".pcast", "application/x-podcast" },
                { ".pct", "image/pict" },
                { ".pcx", "application/octet-stream" },
                { ".pcz", "application/octet-stream" },
                { ".pdf", "application/pdf" },
                { ".pfb", "application/octet-stream" },
                { ".pfm", "application/octet-stream" },
                { ".pfx", "application/x-pkcs12" },
                { ".pgm", "image/x-portable-graymap" },
                { ".pic", "image/pict" },
                { ".pict", "image/pict" },
                { ".pkgdef", "text/plain" },
                { ".pkgundef", "text/plain" },
                { ".pko", "application/vnd.ms-pki.pko" },
                { ".pls", "audio/scpls" },
                { ".pma", "application/x-perfmon" },
                { ".pmc", "application/x-perfmon" },
                { ".pml", "application/x-perfmon" },
                { ".pmr", "application/x-perfmon" },
                { ".pmw", "application/x-perfmon" },
                { ".png", "image/png" },
                { ".pnm", "image/x-portable-anymap" },
                { ".pnt", "image/x-macpaint" },
                { ".pntg", "image/x-macpaint" },
                { ".pnz", "image/png" },
                { ".pot", "application/vnd.ms-powerpoint" },
                { ".potm", "application/vnd.ms-powerpoint.template.macroEnabled.12" },
                { ".potx", "application/vnd.openxmlformats-officedocument.presentationml.template" },
                { ".ppa", "application/vnd.ms-powerpoint" },
                { ".ppam", "application/vnd.ms-powerpoint.addin.macroEnabled.12" },
                { ".ppm", "image/x-portable-pixmap" },
                { ".pps", "application/vnd.ms-powerpoint" },
                { ".ppsm", "application/vnd.ms-powerpoint.slideshow.macroEnabled.12" },
                { ".ppsx", "application/vnd.openxmlformats-officedocument.presentationml.slideshow" },
                { ".ppt", "application/vnd.ms-powerpoint" },
                { ".pptm", "application/vnd.ms-powerpoint.presentation.macroEnabled.12" },
                { ".pptx", "application/vnd.openxmlformats-officedocument.presentationml.presentation" },
                { ".prf", "application/pics-rules" },
                { ".prm", "application/octet-stream" },
                { ".prx", "application/octet-stream" },
                { ".ps", "application/postscript" },
                { ".psc1", "application/PowerShell" },
                { ".psd", "application/octet-stream" },
                { ".psess", "application/xml" },
                { ".psm", "application/octet-stream" },
                { ".psp", "application/octet-stream" },
                { ".pst", "application/vnd.ms-outlook" },
                { ".pub", "application/x-mspublisher" },
                { ".pwz", "application/vnd.ms-powerpoint" },
                { ".qht", "text/x-html-insertion" },
                { ".qhtm", "text/x-html-insertion" },
                { ".qt", "video/quicktime" },
                { ".qti", "image/x-quicktime" },
                { ".qtif", "image/x-quicktime" },
                { ".qtl", "application/x-quicktimeplayer" },
                { ".qxd", "application/octet-stream" },
                { ".ra", "audio/x-pn-realaudio" },
                { ".ram", "audio/x-pn-realaudio" },
                { ".rar", "application/x-rar-compressed" },
                { ".ras", "image/x-cmu-raster" },
                { ".rat", "application/rat-file" },
                { ".rc", "text/plain" },
                { ".rc2", "text/plain" },
                { ".rct", "text/plain" },
                { ".rdlc", "application/xml" },
                { ".reg", "text/plain" },
                { ".resx", "application/xml" },
                { ".rf", "image/vnd.rn-realflash" },
                { ".rgb", "image/x-rgb" },
                { ".rgs", "text/plain" },
                { ".rm", "application/vnd.rn-realmedia" },
                { ".rmi", "audio/mid" },
                { ".rmp", "application/vnd.rn-rn_music_package" },
                { ".roff", "application/x-troff" },
                { ".rpm", "audio/x-pn-realaudio-plugin" },
                { ".rqy", "text/x-ms-rqy" },
                { ".rtf", "application/rtf" },
                { ".rtx", "text/richtext" },
                { ".rvt", "application/octet-stream" },
                { ".ruleset", "application/xml" },
                { ".s", "text/plain" },
                { ".safariextz", "application/x-safari-safariextz" },
                { ".scd", "application/x-msschedule" },
                { ".scr", "text/plain" },
                { ".sct", "text/scriptlet" },
                { ".sd2", "audio/x-sd2" },
                { ".sdp", "application/sdp" },
                { ".sea", "application/octet-stream" },
                { ".searchConnector-ms", "application/windows-search-connector+xml" },
                { ".setpay", "application/set-payment-initiation" },
                { ".setreg", "application/set-registration-initiation" },
                { ".settings", "application/xml" },
                { ".sgimb", "application/x-sgimb" },
                { ".sgml", "text/sgml" },
                { ".sh", "application/x-sh" },
                { ".shar", "application/x-shar" },
                { ".shtml", "text/html" },
                { ".sit", "application/x-stuffit" },
                { ".sitemap", "application/xml" },
                { ".skin", "application/xml" },
                { ".skp", "application/x-koan" },
                { ".sldm", "application/vnd.ms-powerpoint.slide.macroEnabled.12" },
                { ".sldx", "application/vnd.openxmlformats-officedocument.presentationml.slide" },
                { ".slk", "application/vnd.ms-excel" },
                { ".sln", "text/plain" },
                { ".slupkg-ms", "application/x-ms-license" },
                { ".smd", "audio/x-smd" },
                { ".smi", "application/octet-stream" },
                { ".smx", "audio/x-smd" },
                { ".smz", "audio/x-smd" },
                { ".snd", "audio/basic" },
                { ".snippet", "application/xml" },
                { ".snp", "application/octet-stream" },
                { ".sol", "text/plain" },
                { ".sor", "text/plain" },
                { ".spc", "application/x-pkcs7-certificates" },
                { ".spl", "application/futuresplash" },
                { ".spx", "audio/ogg" },
                { ".src", "application/x-wais-source" },
                { ".srf", "text/plain" },
                { ".SSISDeploymentManifest", "text/xml" },
                { ".ssm", "application/streamingmedia" },
                { ".sst", "application/vnd.ms-pki.certstore" },
                { ".stl", "application/vnd.ms-pki.stl" },
                { ".sv4cpio", "application/x-sv4cpio" },
                { ".sv4crc", "application/x-sv4crc" },
                { ".svc", "application/xml" },
                { ".svg", "image/svg+xml" },
                { ".swf", "application/x-shockwave-flash" },
                { ".step", "application/step" },
                { ".stp", "application/step" },
                { ".t", "application/x-troff" },
                { ".tar", "application/x-tar" },
                { ".tcl", "application/x-tcl" },
                { ".testrunconfig", "application/xml" },
                { ".testsettings", "application/xml" },
                { ".tex", "application/x-tex" },
                { ".texi", "application/x-texinfo" },
                { ".texinfo", "application/x-texinfo" },
                { ".tgz", "application/x-compressed" },
                { ".thmx", "application/vnd.ms-officetheme" },
                { ".thn", "application/octet-stream" },
                { ".tif", "image/tiff" },
                { ".tiff", "image/tiff" },
                { ".tlh", "text/plain" },
                { ".tli", "text/plain" },
                { ".toc", "application/octet-stream" },
                { ".tr", "application/x-troff" },
                { ".trm", "application/x-msterminal" },
                { ".trx", "application/xml" },
                { ".ts", "video/vnd.dlna.mpeg-tts" },
                { ".tsv", "text/tab-separated-values" },
                { ".ttf", "application/font-sfnt" },
                { ".tts", "video/vnd.dlna.mpeg-tts" },
                { ".txt", "text/plain" },
                { ".u32", "application/octet-stream" },
                { ".uls", "text/iuls" },
                { ".user", "text/plain" },
                { ".ustar", "application/x-ustar" },
                { ".vb", "text/plain" },
                { ".vbdproj", "text/plain" },
                { ".vbk", "video/mpeg" },
                { ".vbproj", "text/plain" },
                { ".vbs", "text/vbscript" },
                { ".vcf", "text/x-vcard" },
                { ".vcproj", "application/xml" },
                { ".vcs", "text/plain" },
                { ".vcxproj", "application/xml" },
                { ".vddproj", "text/plain" },
                { ".vdp", "text/plain" },
                { ".vdproj", "text/plain" },
                { ".vdx", "application/vnd.ms-visio.viewer" },
                { ".vml", "text/xml" },
                { ".vscontent", "application/xml" },
                { ".vsct", "text/xml" },
                { ".vsd", "application/vnd.visio" },
                { ".vsi", "application/ms-vsi" },
                { ".vsix", "application/vsix" },
                { ".vsixlangpack", "text/xml" },
                { ".vsixmanifest", "text/xml" },
                { ".vsmdi", "application/xml" },
                { ".vspscc", "text/plain" },
                { ".vss", "application/vnd.visio" },
                { ".vsscc", "text/plain" },
                { ".vssettings", "text/xml" },
                { ".vssscc", "text/plain" },
                { ".vst", "application/vnd.visio" },
                { ".vstemplate", "text/xml" },
                { ".vsto", "application/x-ms-vsto" },
                { ".vsw", "application/vnd.visio" },
                { ".vsx", "application/vnd.visio" },
                { ".vtt", "text/vtt" },
                { ".vtx", "application/vnd.visio" },
                { ".wasm", "application/wasm" },
                { ".wav", "audio/wav" },
                { ".wave", "audio/wav" },
                { ".wax", "audio/x-ms-wax" },
                { ".wbk", "application/msword" },
                { ".wbmp", "image/vnd.wap.wbmp" },
                { ".wcm", "application/vnd.ms-works" },
                { ".wdb", "application/vnd.ms-works" },
                { ".wdp", "image/vnd.ms-photo" },
                { ".webarchive", "application/x-safari-webarchive" },
                { ".webm", "video/webm" },
                { ".webp", "image/webp" }, /* https://en.wikipedia.org/wiki/WebP */
                { ".webtest", "application/xml" },
                { ".wiq", "application/xml" },
                { ".wiz", "application/msword" },
                { ".wks", "application/vnd.ms-works" },
                { ".WLMP", "application/wlmoviemaker" },
                { ".wlpginstall", "application/x-wlpg-detect" },
                { ".wlpginstall3", "application/x-wlpg3-detect" },
                { ".wm", "video/x-ms-wm" },
                { ".wma", "audio/x-ms-wma" },
                { ".wmd", "application/x-ms-wmd" },
                { ".wmf", "application/x-msmetafile" },
                { ".wml", "text/vnd.wap.wml" },
                { ".wmlc", "application/vnd.wap.wmlc" },
                { ".wmls", "text/vnd.wap.wmlscript" },
                { ".wmlsc", "application/vnd.wap.wmlscriptc" },
                { ".wmp", "video/x-ms-wmp" },
                { ".wmv", "video/x-ms-wmv" },
                { ".wmx", "video/x-ms-wmx" },
                { ".wmz", "application/x-ms-wmz" },
                { ".woff", "application/font-woff" },
                { ".woff2", "application/font-woff2" },
                { ".wpl", "application/vnd.ms-wpl" },
                { ".wps", "application/vnd.ms-works" },
                { ".wri", "application/x-mswrite" },
                { ".wrl", "x-world/x-vrml" },
                { ".wrz", "x-world/x-vrml" },
                { ".wsc", "text/scriptlet" },
                { ".wsdl", "text/xml" },
                { ".wvx", "video/x-ms-wvx" },
                { ".x", "application/directx" },
                { ".xaf", "x-world/x-vrml" },
                { ".xaml", "application/xaml+xml" },
                { ".xap", "application/x-silverlight-app" },
                { ".xbap", "application/x-ms-xbap" },
                { ".xbm", "image/x-xbitmap" },
                { ".xdr", "text/plain" },
                { ".xht", "application/xhtml+xml" },
                { ".xhtml", "application/xhtml+xml" },
                { ".xla", "application/vnd.ms-excel" },
                { ".xlam", "application/vnd.ms-excel.addin.macroEnabled.12" },
                { ".xlc", "application/vnd.ms-excel" },
                { ".xld", "application/vnd.ms-excel" },
                { ".xlk", "application/vnd.ms-excel" },
                { ".xll", "application/vnd.ms-excel" },
                { ".xlm", "application/vnd.ms-excel" },
                { ".xls", "application/vnd.ms-excel" },
                { ".xlsb", "application/vnd.ms-excel.sheet.binary.macroEnabled.12" },
                { ".xlsm", "application/vnd.ms-excel.sheet.macroEnabled.12" },
                { ".xlsx", "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet" },
                { ".xlt", "application/vnd.ms-excel" },
                { ".xltm", "application/vnd.ms-excel.template.macroEnabled.12" },
                { ".xltx", "application/vnd.openxmlformats-officedocument.spreadsheetml.template" },
                { ".xlw", "application/vnd.ms-excel" },
                { ".xml", "text/xml" },
                { ".xmp", "application/octet-stream" },
                { ".xmta", "application/xml" },
                { ".xof", "x-world/x-vrml" },
                { ".XOML", "text/plain" },
                { ".xpm", "image/x-xpixmap" },
                { ".xps", "application/vnd.ms-xpsdocument" },
                { ".xrm-ms", "text/xml" },
                { ".xsc", "application/xml" },
                { ".xsd", "text/xml" },
                { ".xsf", "text/xml" },
                { ".xsl", "text/xml" },
                { ".xslt", "text/xml" },
                { ".xsn", "application/octet-stream" },
                { ".xss", "application/xml" },
                { ".xspf", "application/xspf+xml" },
                { ".xtp", "application/octet-stream" },
                { ".xwd", "image/x-xwindowdump" },
                { ".z", "application/x-compress" },
                { ".zip", "application/zip" }

                #endregion
            };

            var cache = genericTypes.ToList();

            foreach (var mapping in cache)
            {
                Mappings.Value.TryAdd(mapping.Value, mapping.Key);
            }

            return genericTypes;
        }

        public static string GetMimeType(string extension)
        {
            if (extension == null)
            {
                throw new ArgumentNullException("extension");
            }

            if (!extension.StartsWith("."))
            {
                extension = "." + extension;
            }

            string mime;

            var typeProvider = new FileExtensionContentTypeProvider();

            //return typeProvider.TryGetContentType(extension, out mime) ? mime : "application/octet-stream";

            return Mappings.Value.TryGetValue(extension, out mime) ? mime : "application/octet-stream";
        }

        public static string GetExtension(string mimeType, bool throwErrorIfNotFound = true)
        {
            if (mimeType == null)
            {
                throw new ArgumentNullException("mimeType");
            }

            if (mimeType.StartsWith("."))
            {
                throw new ArgumentException("Requested mime type is not valid: " + mimeType);
            }

            string extension;

            if (Mappings.Value.TryGetValue(mimeType, out extension))
            {
                return extension;
            }

            if (throwErrorIfNotFound)
            {
                throw new ArgumentException("Requested mime type is not registered: " + mimeType);
            }

            return string.Empty;
        }

        public static bool IsWord(string mimeType)
        {
            var wordTypes = new[]
            {
                "application/msword", "application/vnd.ms-word.document.macroEnabled.12",
                "application/vnd.openxmlformats-officedocument.wordprocessingml.document", "application/msword",
                "application/vnd.ms-word.template.macroEnabled.12",
                "application/vnd.openxmlformats-officedocument.wordprocessingml.template"
            };

            return wordTypes.Contains(mimeType);
        }

        public static bool IsExcel(string mimeType)
        {
            var excelTypes = new[]
            {
                "application/vnd.ms-excel", "application/vnd.ms-excel.sheet.binary.macroEnabled.12",
                "application/vnd.ms-excel.sheet.macroEnabled.12",
                "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet", "application/vnd.ms-excel",
                "application/vnd.ms-excel.template.macroEnabled.12",
                "application/vnd.openxmlformats-officedocument.spreadsheetml.template", "application/vnd.ms-excel"
            };

            return excelTypes.Contains(mimeType);
        }

        public static bool IsPowerPoint(string mimeType)
        {
            var pptTypes = new[]
            {
                ""
            };

            return pptTypes.Contains(mimeType);
        }
    }
}