Core/Toolbox/IO/GetMimeTypeTrait.php
public function getMimeType($filename): string
    {
        // there's a bug that doesn't properly detect
        // the mime type of css files
        // https://bugs.php.net/bug.php?id=53035
        // so the following is used, instead
        // src: http://www.freeformatter.com/mime-types-list.html#mime-types-list
        $mime_types = [
            "3dml" => "text/vnd.in3d.3dml",
            "3g2" => "video/3gpp2",
            "3gp" => "video/3gpp",
            "7z" => "application/x-7z-compressed",
            "aab" => "application/x-authorware-bin",
            "aac" => "audio/x-aac",
            "aam" => "application/x-authorware-map",
            "aas" => "application/x-authorware-seg",
            "abw" => "application/x-abiword",
            "ac" => "application/pkix-attr-cert",
            "acc" => "application/vnd.americandynamics.acc",
            "ace" => "application/x-ace-compressed",
            "acu" => "application/vnd.acucobol",
            "adp" => "audio/adpcm",
            "aep" => "application/vnd.audiograph",
            "afp" => "application/vnd.ibm.modcap",
            "ahead" => "application/vnd.ahead.space",
            "ai" => "application/postscript",
            "aif" => "audio/x-aiff",
            "air" => "application/vnd.adobe.air-application-installer-package+zip",
            "ait" => "application/vnd.dvb.ait",
            "ami" => "application/vnd.amiga.ami",
            "apk" => "application/vnd.android.package-archive",
            "application" => "application/x-ms-application",
            "apr" => "application/vnd.lotus-approach",
            "asf" => "video/x-ms-asf",
            "aso" => "application/vnd.accpac.simply.aso",
            "atc" => "application/vnd.acucorp",
            "atom" => "application/atom+xml",
            "atomcat" => "application/atomcat+xml",
            "atomsvc" => "application/atomsvc+xml",
            "atx" => "application/vnd.antix.game-component",
            "au" => "audio/basic",
            "avi" => "video/x-msvideo",
            "aw" => "application/applixware",
            "azf" => "application/vnd.airzip.filesecure.azf",
            "azs" => "application/vnd.airzip.filesecure.azs",
            "azw" => "application/vnd.amazon.ebook",
            "bcpio" => "application/x-bcpio",
            "bdf" => "application/x-font-bdf",
            "bdm" => "application/vnd.syncml.dm+wbxml",
            "bed" => "application/vnd.realvnc.bed",
            "bh2" => "application/vnd.fujitsu.oasysprs",
            "bin" => "application/octet-stream",
            "bmi" => "application/vnd.bmi",
            "bmp" => "image/bmp",
            "box" => "application/vnd.previewsystems.box",
            "btif" => "image/prs.btif",
            "bz" => "application/x-bzip",
            "bz2" => "application/x-bzip2",
            "c" => "text/x-c",
            "c11amc" => "application/vnd.cluetrust.cartomobile-config",
            "c11amz" => "application/vnd.cluetrust.cartomobile-config-pkg",
            "c4g" => "application/vnd.clonk.c4group",
            "cab" => "application/vnd.ms-cab-compressed",
            "car" => "application/vnd.curl.car",
            "cat" => "application/vnd.ms-pki.seccat",
            "ccxml" => "application/ccxml+xml,",
            "cdbcmsg" => "application/vnd.contact.cmsg",
            "cdkey" => "application/vnd.mediastation.cdkey",
            "cdmia" => "application/cdmi-capability",
            "cdmic" => "application/cdmi-container",
            "cdmid" => "application/cdmi-domain",
            "cdmio" => "application/cdmi-object",
            "cdmiq" => "application/cdmi-queue",
            "cdx" => "chemical/x-cdx",
            "cdxml" => "application/vnd.chemdraw+xml",
            "cdy" => "application/vnd.cinderella",
            "cer" => "application/pkix-cert",
            "cgm" => "image/cgm",
            "chat" => "application/x-chat",
            "chm" => "application/vnd.ms-htmlhelp",
            "chrt" => "application/vnd.kde.kchart",
            "cif" => "chemical/x-cif",
            "cii" => "application/vnd.anser-web-certificate-issue-initiation",
            "cil" => "application/vnd.ms-artgalry",
            "cla" => "application/vnd.claymore",
            "class" => "application/java-vm",
            "clkk" => "application/vnd.crick.clicker.keyboard",
            "clkp" => "application/vnd.crick.clicker.palette",
            "clkt" => "application/vnd.crick.clicker.template",
            "clkw" => "application/vnd.crick.clicker.wordbank",
            "clkx" => "application/vnd.crick.clicker",
            "clp" => "application/x-msclip",
            "cmc" => "application/vnd.cosmocaller",
            "cmdf" => "chemical/x-cmdf",
            "cml" => "chemical/x-cml",
            "cmp" => "application/vnd.yellowriver-custom-menu",
            "cmx" => "image/x-cmx",
            "cod" => "application/vnd.rim.cod",
            "cpio" => "application/x-cpio",
            "cpt" => "application/mac-compactpro",
            "crd" => "application/x-mscardfile",
            "crl" => "application/pkix-crl",
            "cryptonote" => "application/vnd.rig.cryptonote",
            "csh" => "application/x-csh",
            "csml" => "chemical/x-csml",
            "csp" => "application/vnd.commonspace",
            "css" => "text/css",
            "csv" => "text/csv",
            "cu" => "application/cu-seeme",
            "curl" => "text/vnd.curl",
            "cww" => "application/prs.cww",
            "dae" => "model/vnd.collada+xml",
            "daf" => "application/vnd.mobius.daf",
            "davmount" => "application/davmount+xml",
            "dcurl" => "text/vnd.curl.dcurl",
            "dd2" => "application/vnd.oma.dd2+xml",
            "ddd" => "application/vnd.fujixerox.ddd",
            "deb" => "application/x-debian-package",
            "der" => "application/x-x509-ca-cert",
            "dfac" => "application/vnd.dreamfactory",
            "dir" => "application/x-director",
            "dis" => "application/vnd.mobius.dis",
            "djvu" => "image/vnd.djvu",
            "dna" => "application/vnd.dna",
            "doc" => "application/msword",
            "docm" => "application/vnd.ms-word.document.macroenabled.12",
            "docx" => "application/vnd.openxmlformats-officedocument.wordprocessingml.document",
            "dotm" => "application/vnd.ms-word.template.macroenabled.12",
            "dotx" => "application/vnd.openxmlformats-officedocument.wordprocessingml.template",
            "dp" => "application/vnd.osgi.dp",
            "dpg" => "application/vnd.dpgraph",
            "dra" => "audio/vnd.dra",
            "dsc" => "text/prs.lines.tag",
            "dssc" => "application/dssc+der",
            "dtb" => "application/x-dtbook+xml",
            "dtd" => "application/xml-dtd",
            "dts" => "audio/vnd.dts",
            "dtshd" => "audio/vnd.dts.hd",
            "dvi" => "application/x-dvi",
            "dwf" => "model/vnd.dwf",
            "dwg" => "image/vnd.dwg",
            "dxf" => "image/vnd.dxf",
            "dxp" => "application/vnd.spotfire.dxp",
            "ecelp4800" => "audio/vnd.nuera.ecelp4800",
            "ecelp7470" => "audio/vnd.nuera.ecelp7470",
            "ecelp9600" => "audio/vnd.nuera.ecelp9600",
            "edm" => "application/vnd.novadigm.edm",
            "edx" => "application/vnd.novadigm.edx",
            "efif" => "application/vnd.picsel",
            "ei6" => "application/vnd.pg.osasli",
            "eml" => "message/rfc822",
            "emma" => "application/emma+xml",
            "eol" => "audio/vnd.digital-winds",
            "eot" => "application/vnd.ms-fontobject",
            "epub" => "application/epub+zip",
            "es" => "application/ecmascript",
            "es3" => "application/vnd.eszigno3+xml",
            "esf" => "application/vnd.epson.esf",
            "etx" => "text/x-setext",
            "exe" => "application/x-msdownload",
            "exi" => "application/exi",
            "ext" => "application/vnd.novadigm.ext",
            "ez2" => "application/vnd.ezpix-album",
            "ez3" => "application/vnd.ezpix-package",
            "f" => "text/x-fortran",
            "f4v" => "video/x-f4v",
            "fbs" => "image/vnd.fastbidsheet",
            "fcs" => "application/vnd.isac.fcs",
            "fdf" => "application/vnd.fdf",
            "fe_launch" => "application/vnd.denovo.fcselayout-link",
            "fg5" => "application/vnd.fujitsu.oasysgp",
            "fh" => "image/x-freehand",
            "fig" => "application/x-xfig",
            "fli" => "video/x-fli",
            "flo" => "application/vnd.micrografx.flo",
            "flv" => "video/x-flv",
            "flw" => "application/vnd.kde.kivio",
            "flx" => "text/vnd.fmi.flexstor",
            "fly" => "text/vnd.fly",
            "fm" => "application/vnd.framemaker",
            "fnc" => "application/vnd.frogans.fnc",
            "fpx" => "image/vnd.fpx",
            "fsc" => "application/vnd.fsc.weblaunch",
            "fst" => "image/vnd.fst",
            "ftc" => "application/vnd.fluxtime.clip",
            "fti" => "application/vnd.anser-web-funds-transfer-initiation",
            "fvt" => "video/vnd.fvt",
            "fxp" => "application/vnd.adobe.fxp",
            "fzs" => "application/vnd.fuzzysheet",
            "g2w" => "application/vnd.geoplan",
            "g3" => "image/g3fax",
            "g3w" => "application/vnd.geospace",
            "gac" => "application/vnd.groove-account",
            "gdl" => "model/vnd.gdl",
            "geo" => "application/vnd.dynageo",
            "gex" => "application/vnd.geometry-explorer",
            "ggb" => "application/vnd.geogebra.file",
            "ggt" => "application/vnd.geogebra.tool",
            "ghf" => "application/vnd.groove-help",
            "gif" => "image/gif",
            "gim" => "application/vnd.groove-identity-message",
            "gmx" => "application/vnd.gmx",
            "gnumeric" => "application/x-gnumeric",
            "gph" => "application/vnd.flographit",
            "gqf" => "application/vnd.grafeq",
            "gram" => "application/srgs",
            "grv" => "application/vnd.groove-injector",
            "grxml" => "application/srgs+xml",
            "gsf" => "application/x-font-ghostscript",
            "gtar" => "application/x-gtar",
            "gtm" => "application/vnd.groove-tool-message",
            "gtw" => "model/vnd.gtw",
            "gv" => "text/vnd.graphviz",
            "gxt" => "application/vnd.geonext",
            "h261" => "video/h261",
            "h263" => "video/h263",
            "h264" => "video/h264",
            "hal" => "application/vnd.hal+xml",
            "hbci" => "application/vnd.hbci",
            "hdf" => "application/x-hdf",
            "hlp" => "application/winhlp",
            "hpgl" => "application/vnd.hp-hpgl",
            "hpid" => "application/vnd.hp-hpid",
            "hps" => "application/vnd.hp-hps",
            "hqx" => "application/mac-binhex40",
            "htke" => "application/vnd.kenameaapp",
            "html" => "text/html",
            "hvd" => "application/vnd.yamaha.hv-dic",
            "hvp" => "application/vnd.yamaha.hv-voice",
            "hvs" => "application/vnd.yamaha.hv-script",
            "i2g" => "application/vnd.intergeo",
            "icc" => "application/vnd.iccprofile",
            "ice" => "x-conference/x-cooltalk",
            "ico" => "image/x-icon",
            "ics" => "text/calendar",
            "ief" => "image/ief",
            "ifm" => "application/vnd.shana.informed.formdata",
            "igl" => "application/vnd.igloader",
            "igm" => "application/vnd.insors.igm",
            "igs" => "model/iges",
            "igx" => "application/vnd.micrografx.igx",
            "iif" => "application/vnd.shana.informed.interchange",
            "imp" => "application/vnd.accpac.simply.imp",
            "ims" => "application/vnd.ms-ims",
            "ipfix" => "application/ipfix",
            "ipk" => "application/vnd.shana.informed.package",
            "irm" => "application/vnd.ibm.rights-management",
            "irp" => "application/vnd.irepository.package+xml",
            "itp" => "application/vnd.shana.informed.formtemplate",
            "ivp" => "application/vnd.immervision-ivp",
            "ivu" => "application/vnd.immervision-ivu",
            "jad" => "text/vnd.sun.j2me.app-descriptor",
            "jam" => "application/vnd.jam",
            "jar" => "application/java-archive",
            "java" => "text/x-java-source,java",
            "jisp" => "application/vnd.jisp",
            "jlt" => "application/vnd.hp-jlyt",
            "jnlp" => "application/x-java-jnlp-file",
            "joda" => "application/vnd.joost.joda-archive",
            "jpeg" => "image/jpeg",
            "jpg" => "image/jpeg",
            "jpgv" => "video/jpeg",
            "jpm" => "video/jpm",
            "js" => "application/javascript",
            "json" => "application/json",
            "karbon" => "application/vnd.kde.karbon",
            "kfo" => "application/vnd.kde.kformula",
            "kia" => "application/vnd.kidspiration",
            "kml" => "application/vnd.google-earth.kml+xml",
            "kmz" => "application/vnd.google-earth.kmz",
            "kne" => "application/vnd.kinar",
            "kon" => "application/vnd.kde.kontour",
            "kpr" => "application/vnd.kde.kpresenter",
            "ksp" => "application/vnd.kde.kspread",
            "ktx" => "image/ktx",
            "ktz" => "application/vnd.kahootz",
            "kwd" => "application/vnd.kde.kword",
            "lasxml" => "application/vnd.las.las+xml",
            "latex" => "application/x-latex",
            "lbd" => "application/vnd.llamagraphics.life-balance.desktop",
            "lbe" => "application/vnd.llamagraphics.life-balance.exchange+xml",
            "les" => "application/vnd.hhe.lesson-player",
            "link66" => "application/vnd.route66.link66+xml",
            "lrm" => "application/vnd.ms-lrm",
            "ltf" => "application/vnd.frogans.ltf",
            "lvp" => "audio/vnd.lucent.voice",
            "lwp" => "application/vnd.lotus-wordpro",
            "m21" => "application/mp21",
            "m3u" => "audio/x-mpegurl",
            "m3u8" => "application/vnd.apple.mpegurl",
            "m4v" => "video/x-m4v",
            "ma" => "application/mathematica",
            "mads" => "application/mads+xml",
            "mag" => "application/vnd.ecowin.chart",
            "map" => "application/json",
            "mathml" => "application/mathml+xml",
            "mbk" => "application/vnd.mobius.mbk",
            "mbox" => "application/mbox",
            "mc1" => "application/vnd.medcalcdata",
            "mcd" => "application/vnd.mcd",
            "mcurl" => "text/vnd.curl.mcurl",
            "md" => "text/x-markdown", // http://bit.ly/1Kc5nUB
            "mdb" => "application/x-msaccess",
            "mdi" => "image/vnd.ms-modi",
            "meta4" => "application/metalink4+xml",
            "mets" => "application/mets+xml",
            "mfm" => "application/vnd.mfmp",
            "mgp" => "application/vnd.osgeo.mapguide.package",
            "mgz" => "application/vnd.proteus.magazine",
            "mid" => "audio/midi",
            "mif" => "application/vnd.mif",
            "mj2" => "video/mj2",
            "mlp" => "application/vnd.dolby.mlp",
            "mmd" => "application/vnd.chipnuts.karaoke-mmd",
            "mmf" => "application/vnd.smaf",
            "mmr" => "image/vnd.fujixerox.edmics-mmr",
            "mny" => "application/x-msmoney",
            "mods" => "application/mods+xml",
            "movie" => "video/x-sgi-movie",
            "mp1" => "audio/mpeg",
            "mp2" => "audio/mpeg",
            "mp3" => "audio/mpeg",
            "mp4" => "video/mp4",
            "mp4a" => "audio/mp4",
            "mpc" => "application/vnd.mophun.certificate",
            "mpeg" => "video/mpeg",
            "mpga" => "audio/mpeg",
            "mpkg" => "application/vnd.apple.installer+xml",
            "mpm" => "application/vnd.blueice.multipass",
            "mpn" => "application/vnd.mophun.application",
            "mpp" => "application/vnd.ms-project",
            "mpy" => "application/vnd.ibm.minipay",
            "mqy" => "application/vnd.mobius.mqy",
            "mrc" => "application/marc",
            "mrcx" => "application/marcxml+xml",
            "mscml" => "application/mediaservercontrol+xml",
            "mseq" => "application/vnd.mseq",
            "msf" => "application/vnd.epson.msf",
            "msh" => "model/mesh",
            "msl" => "application/vnd.mobius.msl",
            "msty" => "application/vnd.muvee.style",
            "mts" => "model/vnd.mts",
            "mus" => "application/vnd.musician",
            "musicxml" => "application/vnd.recordare.musicxml+xml",
            "mvb" => "application/x-msmediaview",
            "mwf" => "application/vnd.mfer",
            "mxf" => "application/mxf",
            "mxl" => "application/vnd.recordare.musicxml",
            "mxml" => "application/xv+xml",
            "mxs" => "application/vnd.triscape.mxs",
            "mxu" => "video/vnd.mpegurl",
            "n3" => "text/n3",
            "nbp" => "application/vnd.wolfram.player",
            "nc" => "application/x-netcdf",
            "ncx" => "application/x-dtbncx+xml",
            "n-gage" => "application/vnd.nokia.n-gage.symbian.install",
            "ngdat" => "application/vnd.nokia.n-gage.data",
            "nlu" => "application/vnd.neurolanguage.nlu",
            "nml" => "application/vnd.enliven",
            "nnd" => "application/vnd.noblenet-directory",
            "nns" => "application/vnd.noblenet-sealer",
            "nnw" => "application/vnd.noblenet-web",
            "npx" => "image/vnd.net-fpx",
            "nsf" => "application/vnd.lotus-notes",
            "oa2" => "application/vnd.fujitsu.oasys2",
            "oa3" => "application/vnd.fujitsu.oasys3",
            "oas" => "application/vnd.fujitsu.oasys",
            "obd" => "application/x-msbinder",
            "oda" => "application/oda",
            "odb" => "application/vnd.oasis.opendocument.database",
            "odc" => "application/vnd.oasis.opendocument.chart",
            "odf" => "application/vnd.oasis.opendocument.formula",
            "odft" => "application/vnd.oasis.opendocument.formula-template",
            "odg" => "application/vnd.oasis.opendocument.graphics",
            "odi" => "application/vnd.oasis.opendocument.image",
            "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",
            "ogv" => "video/ogg",
            "ogx" => "application/ogg",
            "onetoc" => "application/onenote",
            "opf" => "application/oebps-package+xml",
            "org" => "application/vnd.lotus-organizer",
            "osf" => "application/vnd.yamaha.openscoreformat",
            "osfpvg" => "application/vnd.yamaha.openscoreformat.osfpvg+xml",
            "otc" => "application/vnd.oasis.opendocument.chart-template",
            "otf" => "application/x-font-otf",
            "otg" => "application/vnd.oasis.opendocument.graphics-template",
            "oth" => "application/vnd.oasis.opendocument.text-web",
            "oti" => "application/vnd.oasis.opendocument.image-template",
            "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",
            "p" => "text/x-pascal",
            "p10" => "application/pkcs10",
            "p12" => "application/x-pkcs12",
            "p7b" => "application/x-pkcs7-certificates",
            "p7m" => "application/pkcs7-mime",
            "p7r" => "application/x-pkcs7-certreqresp",
            "p7s" => "application/pkcs7-signature",
            "p8" => "application/pkcs8",
            "par" => "text/plain-bas",
            "paw" => "application/vnd.pawaafile",
            "pbd" => "application/vnd.powerbuilder6",
            "pbm" => "image/x-portable-bitmap",
            "pcf" => "application/x-font-pcf",
            "pcl" => "application/vnd.hp-pcl",
            "pclxl" => "application/vnd.hp-pclxl",
            "pcurl" => "application/vnd.curl.pcurl",
            "pcx" => "image/x-pcx",
            "pdb" => "application/vnd.palm",
            "pdf" => "application/pdf",
            "pfa" => "application/x-font-type1",
            "pfr" => "application/font-tdpfr",
            "pgm" => "image/x-portable-graymap",
            "pgn" => "application/x-chess-pgn",
            "pgp" => "application/pgp-signature",
            "pic" => "image/x-pict",
            "pki" => "application/pkixcmp",
            "pkipath" => "application/pkix-pkipath",
            "plb" => "application/vnd.3gpp.pic-bw-large",
            "plc" => "application/vnd.mobius.plc",
            "plf" => "application/vnd.pocketlearn",
            "pls" => "application/pls+xml",
            "pml" => "application/vnd.ctc-posml",
            "png" => "image/png",
            "pnm" => "image/x-portable-anymap",
            "portpkg" => "application/vnd.macports.portpkg",
            "potm" => "application/vnd.ms-powerpoint.template.macroenabled.12",
            "potx" => "application/vnd.openxmlformats-officedocument.presentationml.template",
            "ppam" => "application/vnd.ms-powerpoint.addin.macroenabled.12",
            "ppd" => "application/vnd.cups-ppd",
            "ppm" => "image/x-portable-pixmap",
            "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",
            "prc" => "application/x-mobipocket-ebook",
            "pre" => "application/vnd.lotus-freelance",
            "prf" => "application/pics-rules",
            "psb" => "application/vnd.3gpp.pic-bw-small",
            "psd" => "image/vnd.adobe.photoshop",
            "psf" => "application/x-font-linux-psf",
            "pskcxml" => "application/pskc+xml",
            "ptid" => "application/vnd.pvi.ptid1",
            "pub" => "application/x-mspublisher",
            "pvb" => "application/vnd.3gpp.pic-bw-var",
            "pwn" => "application/vnd.3m.post-it-notes",
            "pya" => "audio/vnd.ms-playready.media.pya",
            "pyv" => "video/vnd.ms-playready.media.pyv",
            "qam" => "application/vnd.epson.quickanime",
            "qbo" => "application/vnd.intu.qbo",
            "qfx" => "application/vnd.intu.qfx",
            "qps" => "application/vnd.publishare-delta-tree",
            "qt" => "video/quicktime",
            "qxd" => "application/vnd.quark.quarkxpress",
            "ram" => "audio/x-pn-realaudio",
            "rar" => "application/x-rar-compressed",
            "ras" => "image/x-cmu-raster",
            "rcprofile" => "application/vnd.ipunplugged.rcprofile",
            "rdf" => "application/rdf+xml",
            "rdz" => "application/vnd.data-vision.rdz",
            "rep" => "application/vnd.businessobjects",
            "res" => "application/x-dtbresource+xml",
            "rgb" => "image/x-rgb",
            "rif" => "application/reginfo+xml",
            "rip" => "audio/vnd.rip",
            "rl" => "application/resource-lists+xml",
            "rlc" => "image/vnd.fujixerox.edmics-rlc",
            "rld" => "application/resource-lists-diff+xml",
            "rm" => "application/vnd.rn-realmedia",
            "rmp" => "audio/x-pn-realaudio-plugin",
            "rms" => "application/vnd.jcp.javame.midlet-rms",
            "rnc" => "application/relax-ng-compact-syntax",
            "rp9" => "application/vnd.cloanto.rp9",
            "rpss" => "application/vnd.nokia.radio-presets",
            "rpst" => "application/vnd.nokia.radio-preset",
            "rq" => "application/sparql-query",
            "rs" => "application/rls-services+xml",
            "rsd" => "application/rsd+xml",
            "rss" => "application/rss+xml",
            "rtf" => "application/rtf",
            "rtx" => "text/richtext",
            "s" => "text/x-asm",
            "saf" => "application/vnd.yamaha.smaf-audio",
            "sbml" => "application/sbml+xml",
            "sc" => "application/vnd.ibm.secure-container",
            "scd" => "application/x-msschedule",
            "scm" => "application/vnd.lotus-screencam",
            "scq" => "application/scvp-cv-request",
            "scs" => "application/scvp-cv-response",
            "scurl" => "text/vnd.curl.scurl",
            "sda" => "application/vnd.stardivision.draw",
            "sdc" => "application/vnd.stardivision.calc",
            "sdd" => "application/vnd.stardivision.impress",
            "sdkm" => "application/vnd.solent.sdkm+xml",
            "sdp" => "application/sdp",
            "sdw" => "application/vnd.stardivision.writer",
            "see" => "application/vnd.seemail",
            "seed" => "application/vnd.fdsn.seed",
            "sema" => "application/vnd.sema",
            "semd" => "application/vnd.semd",
            "semf" => "application/vnd.semf",
            "ser" => "application/java-serialized-object",
            "setpay" => "application/set-payment-initiation",
            "setreg" => "application/set-registration-initiation",
            "sfd-hdstx" => "application/vnd.hydrostatix.sof-data",
            "sfs" => "application/vnd.spotfire.sfs",
            "sgl" => "application/vnd.stardivision.writer-global",
            "sgml" => "text/sgml",
            "sh" => "application/x-sh",
            "shar" => "application/x-shar",
            "shf" => "application/shf+xml",
            "sis" => "application/vnd.symbian.install",
            "sit" => "application/x-stuffit",
            "sitx" => "application/x-stuffitx",
            "skp" => "application/vnd.koan",
            "sldm" => "application/vnd.ms-powerpoint.slide.macroenabled.12",
            "sldx" => "application/vnd.openxmlformats-officedocument.presentationml.slide",
            "slt" => "application/vnd.epson.salt",
            "sm" => "application/vnd.stepmania.stepchart",
            "smf" => "application/vnd.stardivision.math",
            "smi" => "application/smil+xml",
            "snf" => "application/x-font-snf",
            "spf" => "application/vnd.yamaha.smaf-phrase",
            "spl" => "application/x-futuresplash",
            "spot" => "text/vnd.in3d.spot",
            "spp" => "application/scvp-vp-response",
            "spq" => "application/scvp-vp-request",
            "src" => "application/x-wais-source",
            "sru" => "application/sru+xml",
            "srx" => "application/sparql-results+xml",
            "sse" => "application/vnd.kodak-descriptor",
            "ssf" => "application/vnd.epson.ssf",
            "ssml" => "application/ssml+xml",
            "st" => "application/vnd.sailingtracker.track",
            "stc" => "application/vnd.sun.xml.calc.template",
            "std" => "application/vnd.sun.xml.draw.template",
            "stf" => "application/vnd.wt.stf",
            "sti" => "application/vnd.sun.xml.impress.template",
            "stk" => "application/hyperstudio",
            "stl" => "application/vnd.ms-pki.stl",
            "str" => "application/vnd.pg.format",
            "stw" => "application/vnd.sun.xml.writer.template",
            "sub" => "image/vnd.dvb.subtitle",
            "sus" => "application/vnd.sus-calendar",
            "sv4cpio" => "application/x-sv4cpio",
            "sv4crc" => "application/x-sv4crc",
            "svc" => "application/vnd.dvb.service",
            "svd" => "application/vnd.svd",
            "svg" => "image/svg+xml",
            "swf" => "application/x-shockwave-flash",
            "swi" => "application/vnd.aristanetworks.swi",
            "sxc" => "application/vnd.sun.xml.calc",
            "sxd" => "application/vnd.sun.xml.draw",
            "sxg" => "application/vnd.sun.xml.writer.global",
            "sxi" => "application/vnd.sun.xml.impress",
            "sxm" => "application/vnd.sun.xml.math",
            "sxw" => "application/vnd.sun.xml.writer",
            "t" => "text/troff",
            "tao" => "application/vnd.tao.intent-module-archive",
            "tar" => "application/x-tar",
            "tcap" => "application/vnd.3gpp2.tcap",
            "tcl" => "application/x-tcl",
            "teacher" => "application/vnd.smart.teacher",
            "tei" => "application/tei+xml",
            "tex" => "application/x-tex",
            "texinfo" => "application/x-texinfo",
            "tfi" => "application/thraud+xml",
            "tfm" => "application/x-tex-tfm",
            "thmx" => "application/vnd.ms-officetheme",
            "tiff" => "image/tiff",
            "tmo" => "application/vnd.tmobile-livetv",
            "torrent" => "application/x-bittorrent",
            "tpl" => "application/vnd.groove-tool-template",
            "tpt" => "application/vnd.trid.tpt",
            "tra" => "application/vnd.trueapp",
            "trm" => "application/x-msterminal",
            "tsd" => "application/timestamped-data",
            "tsv" => "text/tab-separated-values",
            "ttf" => "application/x-font-ttf",
            "ttl" => "text/turtle",
            "twd" => "application/vnd.simtech-mindmapper",
            "txd" => "application/vnd.genomatix.tuxedo",
            "txf" => "application/vnd.mobius.txf",
            "txt" => "text/plain",
            "ufd" => "application/vnd.ufdl",
            "umj" => "application/vnd.umajin",
            "unityweb" => "application/vnd.unity",
            "uoml" => "application/vnd.uoml+xml",
            "uri" => "text/uri-list",
            "ustar" => "application/x-ustar",
            "utz" => "application/vnd.uiq.theme",
            "uu" => "text/x-uuencode",
            "uva" => "audio/vnd.dece.audio",
            "uvh" => "video/vnd.dece.hd",
            "uvi" => "image/vnd.dece.graphic",
            "uvm" => "video/vnd.dece.mobile",
            "uvp" => "video/vnd.dece.pd",
            "uvs" => "video/vnd.dece.sd",
            "uvu" => "video/vnd.uvvu.mp4",
            "uvv" => "video/vnd.dece.video",
            "vcd" => "application/x-cdlink",
            "vcf" => "text/x-vcard",
            "vcg" => "application/vnd.groove-vcard",
            "vcs" => "text/x-vcalendar",
            "vcx" => "application/vnd.vcx",
            "vis" => "application/vnd.visionary",
            "viv" => "video/vnd.vivo",
            "vsd" => "application/vnd.visio",
            "vsf" => "application/vnd.vsf",
            "vtu" => "model/vnd.vtu",
            "vxml" => "application/voicexml+xml",
            "wad" => "application/x-doom",
            "wav" => "audio/x-wav",
            "wax" => "audio/x-ms-wax",
            "wbmp" => "image/vnd.wap.wbmp",
            "wbs" => "application/vnd.criticaltools.wbs+xml",
            "wbxml" => "application/vnd.wap.wbxml",
            "weba" => "audio/webm",
            "webm" => "video/webm",
            "webp" => "image/webp",
            "wg" => "application/vnd.pmi.widget",
            "wgt" => "application/widget",
            "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",
            "wmv" => "video/x-ms-wmv",
            "wmx" => "video/x-ms-wmx",
            "wmz" => "application/x-ms-wmz",
            "woff" => "application/x-font-woff",
            "woff2" => "application/font-woff2",
            "wpd" => "application/vnd.wordperfect",
            "wpl" => "application/vnd.ms-wpl",
            "wps" => "application/vnd.ms-works",
            "wqd" => "application/vnd.wqd",
            "wri" => "application/x-mswrite",
            "wrl" => "model/vrml",
            "wsdl" => "application/wsdl+xml",
            "wspolicy" => "application/wspolicy+xml",
            "wtb" => "application/vnd.webturbo",
            "wvx" => "video/x-ms-wvx",
            "x3d" => "application/vnd.hzn-3d-crossword",
            "xap" => "application/x-silverlight-app",
            "xar" => "application/vnd.xara",
            "xbap" => "application/x-ms-xbap",
            "xbd" => "application/vnd.fujixerox.docuworks.binder",
            "xbm" => "image/x-xbitmap",
            "xdf" => "application/xcap-diff+xml",
            "xdm" => "application/vnd.syncml.dm+xml",
            "xdp" => "application/vnd.adobe.xdp+xml",
            "xdssc" => "application/dssc+xml",
            "xdw" => "application/vnd.fujixerox.docuworks",
            "xenc" => "application/xenc+xml",
            "xer" => "application/patch-ops-error+xml",
            "xfdf" => "application/vnd.adobe.xfdf",
            "xfdl" => "application/vnd.xfdl",
            "xhtml" => "application/xhtml+xml",
            "xif" => "image/vnd.xiff",
            "xlam" => "application/vnd.ms-excel.addin.macroenabled.12",
            "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",
            "xltm" => "application/vnd.ms-excel.template.macroenabled.12",
            "xltx" => "application/vnd.openxmlformats-officedocument.spreadsheetml.template",
            "xml" => "application/xml",
            "xo" => "application/vnd.olpc-sugar",
            "xop" => "application/xop+xml",
            "xpi" => "application/x-xpinstall",
            "xpm" => "image/x-xpixmap",
            "xpr" => "application/vnd.is-xpr",
            "xps" => "application/vnd.ms-xpsdocument",
            "xpw" => "application/vnd.intercon.formnet",
            "xslt" => "application/xslt+xml",
            "xsm" => "application/vnd.syncml+xml",
            "xspf" => "application/xspf+xml",
            "xul" => "application/vnd.mozilla.xul+xml",
            "xwd" => "image/x-xwindowdump",
            "xyz" => "chemical/x-xyz",
            "yaml" => "text/yaml",
            "yang" => "application/yang",
            "yin" => "application/yin+xml",
            "zaz" => "application/vnd.zzazz.deck+xml",
            "zip" => "application/zip",
            "zir" => "application/vnd.zul",
            "zmm" => "application/vnd.handheld-entertainment+xml"
        ];

        $extension = strtolower(pathinfo($filename, PATHINFO_EXTENSION));

        return $mime_types[$extension] ?? 'unknown';
    }
public function getMimeType($filename): string
    {
        // there's a bug that doesn't properly detect
        // the mime type of css files
        // https://bugs.php.net/bug.php?id=53035
        // so the following is used, instead
        // src: http://www.freeformatter.com/mime-types-list.html#mime-types-list
        $mime_types = [
            "3dml" => "text/vnd.in3d.3dml",
            "3g2" => "video/3gpp2",
            "3gp" => "video/3gpp",
            "7z" => "application/x-7z-compressed",
            "aab" => "application/x-authorware-bin",
            "aac" => "audio/x-aac",
            "aam" => "application/x-authorware-map",
            "aas" => "application/x-authorware-seg",
            "abw" => "application/x-abiword",
            "ac" => "application/pkix-attr-cert",
            "acc" => "application/vnd.americandynamics.acc",
            "ace" => "application/x-ace-compressed",
            "acu" => "application/vnd.acucobol",
            "adp" => "audio/adpcm",
            "aep" => "application/vnd.audiograph",
            "afp" => "application/vnd.ibm.modcap",
            "ahead" => "application/vnd.ahead.space",
            "ai" => "application/postscript",
            "aif" => "audio/x-aiff",
            "air" => "application/vnd.adobe.air-application-installer-package+zip",
            "ait" => "application/vnd.dvb.ait",
            "ami" => "application/vnd.amiga.ami",
            "apk" => "application/vnd.android.package-archive",
            "application" => "application/x-ms-application",
            "apr" => "application/vnd.lotus-approach",
            "asf" => "video/x-ms-asf",
            "aso" => "application/vnd.accpac.simply.aso",
            "atc" => "application/vnd.acucorp",
            "atom" => "application/atom+xml",
            "atomcat" => "application/atomcat+xml",
            "atomsvc" => "application/atomsvc+xml",
            "atx" => "application/vnd.antix.game-component",
            "au" => "audio/basic",
            "avi" => "video/x-msvideo",
            "aw" => "application/applixware",
            "azf" => "application/vnd.airzip.filesecure.azf",
            "azs" => "application/vnd.airzip.filesecure.azs",
            "azw" => "application/vnd.amazon.ebook",
            "bcpio" => "application/x-bcpio",
            "bdf" => "application/x-font-bdf",
            "bdm" => "application/vnd.syncml.dm+wbxml",
            "bed" => "application/vnd.realvnc.bed",
            "bh2" => "application/vnd.fujitsu.oasysprs",
            "bin" => "application/octet-stream",
            "bmi" => "application/vnd.bmi",
            "bmp" => "image/bmp",
            "box" => "application/vnd.previewsystems.box",
            "btif" => "image/prs.btif",
            "bz" => "application/x-bzip",
            "bz2" => "application/x-bzip2",
            "c" => "text/x-c",
            "c11amc" => "application/vnd.cluetrust.cartomobile-config",
            "c11amz" => "application/vnd.cluetrust.cartomobile-config-pkg",
            "c4g" => "application/vnd.clonk.c4group",
            "cab" => "application/vnd.ms-cab-compressed",
            "car" => "application/vnd.curl.car",
            "cat" => "application/vnd.ms-pki.seccat",
            "ccxml" => "application/ccxml+xml,",
            "cdbcmsg" => "application/vnd.contact.cmsg",
            "cdkey" => "application/vnd.mediastation.cdkey",
            "cdmia" => "application/cdmi-capability",
            "cdmic" => "application/cdmi-container",
            "cdmid" => "application/cdmi-domain",
            "cdmio" => "application/cdmi-object",
            "cdmiq" => "application/cdmi-queue",
            "cdx" => "chemical/x-cdx",
            "cdxml" => "application/vnd.chemdraw+xml",
            "cdy" => "application/vnd.cinderella",
            "cer" => "application/pkix-cert",
            "cgm" => "image/cgm",
            "chat" => "application/x-chat",
            "chm" => "application/vnd.ms-htmlhelp",
            "chrt" => "application/vnd.kde.kchart",
            "cif" => "chemical/x-cif",
            "cii" => "application/vnd.anser-web-certificate-issue-initiation",
            "cil" => "application/vnd.ms-artgalry",
            "cla" => "application/vnd.claymore",
            "class" => "application/java-vm",
            "clkk" => "application/vnd.crick.clicker.keyboard",
            "clkp" => "application/vnd.crick.clicker.palette",
            "clkt" => "application/vnd.crick.clicker.template",
            "clkw" => "application/vnd.crick.clicker.wordbank",
            "clkx" => "application/vnd.crick.clicker",
            "clp" => "application/x-msclip",
            "cmc" => "application/vnd.cosmocaller",
            "cmdf" => "chemical/x-cmdf",
            "cml" => "chemical/x-cml",
            "cmp" => "application/vnd.yellowriver-custom-menu",
            "cmx" => "image/x-cmx",
            "cod" => "application/vnd.rim.cod",
            "cpio" => "application/x-cpio",
            "cpt" => "application/mac-compactpro",
            "crd" => "application/x-mscardfile",
            "crl" => "application/pkix-crl",
            "cryptonote" => "application/vnd.rig.cryptonote",
            "csh" => "application/x-csh",
            "csml" => "chemical/x-csml",
            "csp" => "application/vnd.commonspace",
            "css" => "text/css",
            "csv" => "text/csv",
            "cu" => "application/cu-seeme",
            "curl" => "text/vnd.curl",
            "cww" => "application/prs.cww",
            "dae" => "model/vnd.collada+xml",
            "daf" => "application/vnd.mobius.daf",
            "davmount" => "application/davmount+xml",
            "dcurl" => "text/vnd.curl.dcurl",
            "dd2" => "application/vnd.oma.dd2+xml",
            "ddd" => "application/vnd.fujixerox.ddd",
            "deb" => "application/x-debian-package",
            "der" => "application/x-x509-ca-cert",
            "dfac" => "application/vnd.dreamfactory",
            "dir" => "application/x-director",
            "dis" => "application/vnd.mobius.dis",
            "djvu" => "image/vnd.djvu",
            "dna" => "application/vnd.dna",
            "doc" => "application/msword",
            "docm" => "application/vnd.ms-word.document.macroenabled.12",
            "docx" => "application/vnd.openxmlformats-officedocument.wordprocessingml.document",
            "dotm" => "application/vnd.ms-word.template.macroenabled.12",
            "dotx" => "application/vnd.openxmlformats-officedocument.wordprocessingml.template",
            "dp" => "application/vnd.osgi.dp",
            "dpg" => "application/vnd.dpgraph",
            "dra" => "audio/vnd.dra",
            "dsc" => "text/prs.lines.tag",
            "dssc" => "application/dssc+der",
            "dtb" => "application/x-dtbook+xml",
            "dtd" => "application/xml-dtd",
            "dts" => "audio/vnd.dts",
            "dtshd" => "audio/vnd.dts.hd",
            "dvi" => "application/x-dvi",
            "dwf" => "model/vnd.dwf",
            "dwg" => "image/vnd.dwg",
            "dxf" => "image/vnd.dxf",
            "dxp" => "application/vnd.spotfire.dxp",
            "ecelp4800" => "audio/vnd.nuera.ecelp4800",
            "ecelp7470" => "audio/vnd.nuera.ecelp7470",
            "ecelp9600" => "audio/vnd.nuera.ecelp9600",
            "edm" => "application/vnd.novadigm.edm",
            "edx" => "application/vnd.novadigm.edx",
            "efif" => "application/vnd.picsel",
            "ei6" => "application/vnd.pg.osasli",
            "eml" => "message/rfc822",
            "emma" => "application/emma+xml",
            "eol" => "audio/vnd.digital-winds",
            "eot" => "application/vnd.ms-fontobject",
            "epub" => "application/epub+zip",
            "es" => "application/ecmascript",
            "es3" => "application/vnd.eszigno3+xml",
            "esf" => "application/vnd.epson.esf",
            "etx" => "text/x-setext",
            "exe" => "application/x-msdownload",
            "exi" => "application/exi",
            "ext" => "application/vnd.novadigm.ext",
            "ez2" => "application/vnd.ezpix-album",
            "ez3" => "application/vnd.ezpix-package",
            "f" => "text/x-fortran",
            "f4v" => "video/x-f4v",
            "fbs" => "image/vnd.fastbidsheet",
            "fcs" => "application/vnd.isac.fcs",
            "fdf" => "application/vnd.fdf",
            "fe_launch" => "application/vnd.denovo.fcselayout-link",
            "fg5" => "application/vnd.fujitsu.oasysgp",
            "fh" => "image/x-freehand",
            "fig" => "application/x-xfig",
            "fli" => "video/x-fli",
            "flo" => "application/vnd.micrografx.flo",
            "flv" => "video/x-flv",
            "flw" => "application/vnd.kde.kivio",
            "flx" => "text/vnd.fmi.flexstor",
            "fly" => "text/vnd.fly",
            "fm" => "application/vnd.framemaker",
            "fnc" => "application/vnd.frogans.fnc",
            "fpx" => "image/vnd.fpx",
            "fsc" => "application/vnd.fsc.weblaunch",
            "fst" => "image/vnd.fst",
            "ftc" => "application/vnd.fluxtime.clip",
            "fti" => "application/vnd.anser-web-funds-transfer-initiation",
            "fvt" => "video/vnd.fvt",
            "fxp" => "application/vnd.adobe.fxp",
            "fzs" => "application/vnd.fuzzysheet",
            "g2w" => "application/vnd.geoplan",
            "g3" => "image/g3fax",
            "g3w" => "application/vnd.geospace",
            "gac" => "application/vnd.groove-account",
            "gdl" => "model/vnd.gdl",
            "geo" => "application/vnd.dynageo",
            "gex" => "application/vnd.geometry-explorer",
            "ggb" => "application/vnd.geogebra.file",
            "ggt" => "application/vnd.geogebra.tool",
            "ghf" => "application/vnd.groove-help",
            "gif" => "image/gif",
            "gim" => "application/vnd.groove-identity-message",
            "gmx" => "application/vnd.gmx",
            "gnumeric" => "application/x-gnumeric",
            "gph" => "application/vnd.flographit",
            "gqf" => "application/vnd.grafeq",
            "gram" => "application/srgs",
            "grv" => "application/vnd.groove-injector",
            "grxml" => "application/srgs+xml",
            "gsf" => "application/x-font-ghostscript",
            "gtar" => "application/x-gtar",
            "gtm" => "application/vnd.groove-tool-message",
            "gtw" => "model/vnd.gtw",
            "gv" => "text/vnd.graphviz",
            "gxt" => "application/vnd.geonext",
            "h261" => "video/h261",
            "h263" => "video/h263",
            "h264" => "video/h264",
            "hal" => "application/vnd.hal+xml",
            "hbci" => "application/vnd.hbci",
            "hdf" => "application/x-hdf",
            "hlp" => "application/winhlp",
            "hpgl" => "application/vnd.hp-hpgl",
            "hpid" => "application/vnd.hp-hpid",
            "hps" => "application/vnd.hp-hps",
            "hqx" => "application/mac-binhex40",
            "htke" => "application/vnd.kenameaapp",
            "html" => "text/html",
            "hvd" => "application/vnd.yamaha.hv-dic",
            "hvp" => "application/vnd.yamaha.hv-voice",
            "hvs" => "application/vnd.yamaha.hv-script",
            "i2g" => "application/vnd.intergeo",
            "icc" => "application/vnd.iccprofile",
            "ice" => "x-conference/x-cooltalk",
            "ico" => "image/x-icon",
            "ics" => "text/calendar",
            "ief" => "image/ief",
            "ifm" => "application/vnd.shana.informed.formdata",
            "igl" => "application/vnd.igloader",
            "igm" => "application/vnd.insors.igm",
            "igs" => "model/iges",
            "igx" => "application/vnd.micrografx.igx",
            "iif" => "application/vnd.shana.informed.interchange",
            "imp" => "application/vnd.accpac.simply.imp",
            "ims" => "application/vnd.ms-ims",
            "ipfix" => "application/ipfix",
            "ipk" => "application/vnd.shana.informed.package",
            "irm" => "application/vnd.ibm.rights-management",
            "irp" => "application/vnd.irepository.package+xml",
            "itp" => "application/vnd.shana.informed.formtemplate",
            "ivp" => "application/vnd.immervision-ivp",
            "ivu" => "application/vnd.immervision-ivu",
            "jad" => "text/vnd.sun.j2me.app-descriptor",
            "jam" => "application/vnd.jam",
            "jar" => "application/java-archive",
            "java" => "text/x-java-source,java",
            "jisp" => "application/vnd.jisp",
            "jlt" => "application/vnd.hp-jlyt",
            "jnlp" => "application/x-java-jnlp-file",
            "joda" => "application/vnd.joost.joda-archive",
            "jpeg" => "image/jpeg",
            "jpg" => "image/jpeg",
            "jpgv" => "video/jpeg",
            "jpm" => "video/jpm",
            "js" => "application/javascript",
            "json" => "application/json",
            "karbon" => "application/vnd.kde.karbon",
            "kfo" => "application/vnd.kde.kformula",
            "kia" => "application/vnd.kidspiration",
            "kml" => "application/vnd.google-earth.kml+xml",
            "kmz" => "application/vnd.google-earth.kmz",
            "kne" => "application/vnd.kinar",
            "kon" => "application/vnd.kde.kontour",
            "kpr" => "application/vnd.kde.kpresenter",
            "ksp" => "application/vnd.kde.kspread",
            "ktx" => "image/ktx",
            "ktz" => "application/vnd.kahootz",
            "kwd" => "application/vnd.kde.kword",
            "lasxml" => "application/vnd.las.las+xml",
            "latex" => "application/x-latex",
            "lbd" => "application/vnd.llamagraphics.life-balance.desktop",
            "lbe" => "application/vnd.llamagraphics.life-balance.exchange+xml",
            "les" => "application/vnd.hhe.lesson-player",
            "link66" => "application/vnd.route66.link66+xml",
            "lrm" => "application/vnd.ms-lrm",
            "ltf" => "application/vnd.frogans.ltf",
            "lvp" => "audio/vnd.lucent.voice",
            "lwp" => "application/vnd.lotus-wordpro",
            "m21" => "application/mp21",
            "m3u" => "audio/x-mpegurl",
            "m3u8" => "application/vnd.apple.mpegurl",
            "m4v" => "video/x-m4v",
            "ma" => "application/mathematica",
            "mads" => "application/mads+xml",
            "mag" => "application/vnd.ecowin.chart",
            "map" => "application/json",
            "mathml" => "application/mathml+xml",
            "mbk" => "application/vnd.mobius.mbk",
            "mbox" => "application/mbox",
            "mc1" => "application/vnd.medcalcdata",
            "mcd" => "application/vnd.mcd",
            "mcurl" => "text/vnd.curl.mcurl",
            "md" => "text/x-markdown", // http://bit.ly/1Kc5nUB
            "mdb" => "application/x-msaccess",
            "mdi" => "image/vnd.ms-modi",
            "meta4" => "application/metalink4+xml",
            "mets" => "application/mets+xml",
            "mfm" => "application/vnd.mfmp",
            "mgp" => "application/vnd.osgeo.mapguide.package",
            "mgz" => "application/vnd.proteus.magazine",
            "mid" => "audio/midi",
            "mif" => "application/vnd.mif",
            "mj2" => "video/mj2",
            "mlp" => "application/vnd.dolby.mlp",
            "mmd" => "application/vnd.chipnuts.karaoke-mmd",
            "mmf" => "application/vnd.smaf",
            "mmr" => "image/vnd.fujixerox.edmics-mmr",
            "mny" => "application/x-msmoney",
            "mods" => "application/mods+xml",
            "movie" => "video/x-sgi-movie",
            "mp1" => "audio/mpeg",
            "mp2" => "audio/mpeg",
            "mp3" => "audio/mpeg",
            "mp4" => "video/mp4",
            "mp4a" => "audio/mp4",
            "mpc" => "application/vnd.mophun.certificate",
            "mpeg" => "video/mpeg",
            "mpga" => "audio/mpeg",
            "mpkg" => "application/vnd.apple.installer+xml",
            "mpm" => "application/vnd.blueice.multipass",
            "mpn" => "application/vnd.mophun.application",
            "mpp" => "application/vnd.ms-project",
            "mpy" => "application/vnd.ibm.minipay",
            "mqy" => "application/vnd.mobius.mqy",
            "mrc" => "application/marc",
            "mrcx" => "application/marcxml+xml",
            "mscml" => "application/mediaservercontrol+xml",
            "mseq" => "application/vnd.mseq",
            "msf" => "application/vnd.epson.msf",
            "msh" => "model/mesh",
            "msl" => "application/vnd.mobius.msl",
            "msty" => "application/vnd.muvee.style",
            "mts" => "model/vnd.mts",
            "mus" => "application/vnd.musician",
            "musicxml" => "application/vnd.recordare.musicxml+xml",
            "mvb" => "application/x-msmediaview",
            "mwf" => "application/vnd.mfer",
            "mxf" => "application/mxf",
            "mxl" => "application/vnd.recordare.musicxml",
            "mxml" => "application/xv+xml",
            "mxs" => "application/vnd.triscape.mxs",
            "mxu" => "video/vnd.mpegurl",
            "n3" => "text/n3",
            "nbp" => "application/vnd.wolfram.player",
            "nc" => "application/x-netcdf",
            "ncx" => "application/x-dtbncx+xml",
            "n-gage" => "application/vnd.nokia.n-gage.symbian.install",
            "ngdat" => "application/vnd.nokia.n-gage.data",
            "nlu" => "application/vnd.neurolanguage.nlu",
            "nml" => "application/vnd.enliven",
            "nnd" => "application/vnd.noblenet-directory",
            "nns" => "application/vnd.noblenet-sealer",
            "nnw" => "application/vnd.noblenet-web",
            "npx" => "image/vnd.net-fpx",
            "nsf" => "application/vnd.lotus-notes",
            "oa2" => "application/vnd.fujitsu.oasys2",
            "oa3" => "application/vnd.fujitsu.oasys3",
            "oas" => "application/vnd.fujitsu.oasys",
            "obd" => "application/x-msbinder",
            "oda" => "application/oda",
            "odb" => "application/vnd.oasis.opendocument.database",
            "odc" => "application/vnd.oasis.opendocument.chart",
            "odf" => "application/vnd.oasis.opendocument.formula",
            "odft" => "application/vnd.oasis.opendocument.formula-template",
            "odg" => "application/vnd.oasis.opendocument.graphics",
            "odi" => "application/vnd.oasis.opendocument.image",
            "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",
            "ogv" => "video/ogg",
            "ogx" => "application/ogg",
            "onetoc" => "application/onenote",
            "opf" => "application/oebps-package+xml",
            "org" => "application/vnd.lotus-organizer",
            "osf" => "application/vnd.yamaha.openscoreformat",
            "osfpvg" => "application/vnd.yamaha.openscoreformat.osfpvg+xml",
            "otc" => "application/vnd.oasis.opendocument.chart-template",
            "otf" => "application/x-font-otf",
            "otg" => "application/vnd.oasis.opendocument.graphics-template",
            "oth" => "application/vnd.oasis.opendocument.text-web",
            "oti" => "application/vnd.oasis.opendocument.image-template",
            "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",
            "p" => "text/x-pascal",
            "p10" => "application/pkcs10",
            "p12" => "application/x-pkcs12",
            "p7b" => "application/x-pkcs7-certificates",
            "p7m" => "application/pkcs7-mime",
            "p7r" => "application/x-pkcs7-certreqresp",
            "p7s" => "application/pkcs7-signature",
            "p8" => "application/pkcs8",
            "par" => "text/plain-bas",
            "paw" => "application/vnd.pawaafile",
            "pbd" => "application/vnd.powerbuilder6",
            "pbm" => "image/x-portable-bitmap",
            "pcf" => "application/x-font-pcf",
            "pcl" => "application/vnd.hp-pcl",
            "pclxl" => "application/vnd.hp-pclxl",
            "pcurl" => "application/vnd.curl.pcurl",
            "pcx" => "image/x-pcx",
            "pdb" => "application/vnd.palm",
            "pdf" => "application/pdf",
            "pfa" => "application/x-font-type1",
            "pfr" => "application/font-tdpfr",
            "pgm" => "image/x-portable-graymap",
            "pgn" => "application/x-chess-pgn",
            "pgp" => "application/pgp-signature",
            "pic" => "image/x-pict",
            "pki" => "application/pkixcmp",
            "pkipath" => "application/pkix-pkipath",
            "plb" => "application/vnd.3gpp.pic-bw-large",
            "plc" => "application/vnd.mobius.plc",
            "plf" => "application/vnd.pocketlearn",
            "pls" => "application/pls+xml",
            "pml" => "application/vnd.ctc-posml",
            "png" => "image/png",
            "pnm" => "image/x-portable-anymap",
            "portpkg" => "application/vnd.macports.portpkg",
            "potm" => "application/vnd.ms-powerpoint.template.macroenabled.12",
            "potx" => "application/vnd.openxmlformats-officedocument.presentationml.template",
            "ppam" => "application/vnd.ms-powerpoint.addin.macroenabled.12",
            "ppd" => "application/vnd.cups-ppd",
            "ppm" => "image/x-portable-pixmap",
            "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",
            "prc" => "application/x-mobipocket-ebook",
            "pre" => "application/vnd.lotus-freelance",
            "prf" => "application/pics-rules",
            "psb" => "application/vnd.3gpp.pic-bw-small",
            "psd" => "image/vnd.adobe.photoshop",
            "psf" => "application/x-font-linux-psf",
            "pskcxml" => "application/pskc+xml",
            "ptid" => "application/vnd.pvi.ptid1",
            "pub" => "application/x-mspublisher",
            "pvb" => "application/vnd.3gpp.pic-bw-var",
            "pwn" => "application/vnd.3m.post-it-notes",
            "pya" => "audio/vnd.ms-playready.media.pya",
            "pyv" => "video/vnd.ms-playready.media.pyv",
            "qam" => "application/vnd.epson.quickanime",
            "qbo" => "application/vnd.intu.qbo",
            "qfx" => "application/vnd.intu.qfx",
            "qps" => "application/vnd.publishare-delta-tree",
            "qt" => "video/quicktime",
            "qxd" => "application/vnd.quark.quarkxpress",
            "ram" => "audio/x-pn-realaudio",
            "rar" => "application/x-rar-compressed",
            "ras" => "image/x-cmu-raster",
            "rcprofile" => "application/vnd.ipunplugged.rcprofile",
            "rdf" => "application/rdf+xml",
            "rdz" => "application/vnd.data-vision.rdz",
            "rep" => "application/vnd.businessobjects",
            "res" => "application/x-dtbresource+xml",
            "rgb" => "image/x-rgb",
            "rif" => "application/reginfo+xml",
            "rip" => "audio/vnd.rip",
            "rl" => "application/resource-lists+xml",
            "rlc" => "image/vnd.fujixerox.edmics-rlc",
            "rld" => "application/resource-lists-diff+xml",
            "rm" => "application/vnd.rn-realmedia",
            "rmp" => "audio/x-pn-realaudio-plugin",
            "rms" => "application/vnd.jcp.javame.midlet-rms",
            "rnc" => "application/relax-ng-compact-syntax",
            "rp9" => "application/vnd.cloanto.rp9",
            "rpss" => "application/vnd.nokia.radio-presets",
            "rpst" => "application/vnd.nokia.radio-preset",
            "rq" => "application/sparql-query",
            "rs" => "application/rls-services+xml",
            "rsd" => "application/rsd+xml",
            "rss" => "application/rss+xml",
            "rtf" => "application/rtf",
            "rtx" => "text/richtext",
            "s" => "text/x-asm",
            "saf" => "application/vnd.yamaha.smaf-audio",
            "sbml" => "application/sbml+xml",
            "sc" => "application/vnd.ibm.secure-container",
            "scd" => "application/x-msschedule",
            "scm" => "application/vnd.lotus-screencam",
            "scq" => "application/scvp-cv-request",
            "scs" => "application/scvp-cv-response",
            "scurl" => "text/vnd.curl.scurl",
            "sda" => "application/vnd.stardivision.draw",
            "sdc" => "application/vnd.stardivision.calc",
            "sdd" => "application/vnd.stardivision.impress",
            "sdkm" => "application/vnd.solent.sdkm+xml",
            "sdp" => "application/sdp",
            "sdw" => "application/vnd.stardivision.writer",
            "see" => "application/vnd.seemail",
            "seed" => "application/vnd.fdsn.seed",
            "sema" => "application/vnd.sema",
            "semd" => "application/vnd.semd",
            "semf" => "application/vnd.semf",
            "ser" => "application/java-serialized-object",
            "setpay" => "application/set-payment-initiation",
            "setreg" => "application/set-registration-initiation",
            "sfd-hdstx" => "application/vnd.hydrostatix.sof-data",
            "sfs" => "application/vnd.spotfire.sfs",
            "sgl" => "application/vnd.stardivision.writer-global",
            "sgml" => "text/sgml",
            "sh" => "application/x-sh",
            "shar" => "application/x-shar",
            "shf" => "application/shf+xml",
            "sis" => "application/vnd.symbian.install",
            "sit" => "application/x-stuffit",
            "sitx" => "application/x-stuffitx",
            "skp" => "application/vnd.koan",
            "sldm" => "application/vnd.ms-powerpoint.slide.macroenabled.12",
            "sldx" => "application/vnd.openxmlformats-officedocument.presentationml.slide",
            "slt" => "application/vnd.epson.salt",
            "sm" => "application/vnd.stepmania.stepchart",
            "smf" => "application/vnd.stardivision.math",
            "smi" => "application/smil+xml",
            "snf" => "application/x-font-snf",
            "spf" => "application/vnd.yamaha.smaf-phrase",
            "spl" => "application/x-futuresplash",
            "spot" => "text/vnd.in3d.spot",
            "spp" => "application/scvp-vp-response",
            "spq" => "application/scvp-vp-request",
            "src" => "application/x-wais-source",
            "sru" => "application/sru+xml",
            "srx" => "application/sparql-results+xml",
            "sse" => "application/vnd.kodak-descriptor",
            "ssf" => "application/vnd.epson.ssf",
            "ssml" => "application/ssml+xml",
            "st" => "application/vnd.sailingtracker.track",
            "stc" => "application/vnd.sun.xml.calc.template",
            "std" => "application/vnd.sun.xml.draw.template",
            "stf" => "application/vnd.wt.stf",
            "sti" => "application/vnd.sun.xml.impress.template",
            "stk" => "application/hyperstudio",
            "stl" => "application/vnd.ms-pki.stl",
            "str" => "application/vnd.pg.format",
            "stw" => "application/vnd.sun.xml.writer.template",
            "sub" => "image/vnd.dvb.subtitle",
            "sus" => "application/vnd.sus-calendar",
            "sv4cpio" => "application/x-sv4cpio",
            "sv4crc" => "application/x-sv4crc",
            "svc" => "application/vnd.dvb.service",
            "svd" => "application/vnd.svd",
            "svg" => "image/svg+xml",
            "swf" => "application/x-shockwave-flash",
            "swi" => "application/vnd.aristanetworks.swi",
            "sxc" => "application/vnd.sun.xml.calc",
            "sxd" => "application/vnd.sun.xml.draw",
            "sxg" => "application/vnd.sun.xml.writer.global",
            "sxi" => "application/vnd.sun.xml.impress",
            "sxm" => "application/vnd.sun.xml.math",
            "sxw" => "application/vnd.sun.xml.writer",
            "t" => "text/troff",
            "tao" => "application/vnd.tao.intent-module-archive",
            "tar" => "application/x-tar",
            "tcap" => "application/vnd.3gpp2.tcap",
            "tcl" => "application/x-tcl",
            "teacher" => "application/vnd.smart.teacher",
            "tei" => "application/tei+xml",
            "tex" => "application/x-tex",
            "texinfo" => "application/x-texinfo",
            "tfi" => "application/thraud+xml",
            "tfm" => "application/x-tex-tfm",
            "thmx" => "application/vnd.ms-officetheme",
            "tiff" => "image/tiff",
            "tmo" => "application/vnd.tmobile-livetv",
            "torrent" => "application/x-bittorrent",
            "tpl" => "application/vnd.groove-tool-template",
            "tpt" => "application/vnd.trid.tpt",
            "tra" => "application/vnd.trueapp",
            "trm" => "application/x-msterminal",
            "tsd" => "application/timestamped-data",
            "tsv" => "text/tab-separated-values",
            "ttf" => "application/x-font-ttf",
            "ttl" => "text/turtle",
            "twd" => "application/vnd.simtech-mindmapper",
            "txd" => "application/vnd.genomatix.tuxedo",
            "txf" => "application/vnd.mobius.txf",
            "txt" => "text/plain",
            "ufd" => "application/vnd.ufdl",
            "umj" => "application/vnd.umajin",
            "unityweb" => "application/vnd.unity",
            "uoml" => "application/vnd.uoml+xml",
            "uri" => "text/uri-list",
            "ustar" => "application/x-ustar",
            "utz" => "application/vnd.uiq.theme",
            "uu" => "text/x-uuencode",
            "uva" => "audio/vnd.dece.audio",
            "uvh" => "video/vnd.dece.hd",
            "uvi" => "image/vnd.dece.graphic",
            "uvm" => "video/vnd.dece.mobile",
            "uvp" => "video/vnd.dece.pd",
            "uvs" => "video/vnd.dece.sd",
            "uvu" => "video/vnd.uvvu.mp4",
            "uvv" => "video/vnd.dece.video",
            "vcd" => "application/x-cdlink",
            "vcf" => "text/x-vcard",
            "vcg" => "application/vnd.groove-vcard",
            "vcs" => "text/x-vcalendar",
            "vcx" => "application/vnd.vcx",
            "vis" => "application/vnd.visionary",
            "viv" => "video/vnd.vivo",
            "vsd" => "application/vnd.visio",
            "vsf" => "application/vnd.vsf",
            "vtu" => "model/vnd.vtu",
            "vxml" => "application/voicexml+xml",
            "wad" => "application/x-doom",
            "wav" => "audio/x-wav",
            "wax" => "audio/x-ms-wax",
            "wbmp" => "image/vnd.wap.wbmp",
            "wbs" => "application/vnd.criticaltools.wbs+xml",
            "wbxml" => "application/vnd.wap.wbxml",
            "weba" => "audio/webm",
            "webm" => "video/webm",
            "webp" => "image/webp",
            "wg" => "application/vnd.pmi.widget",
            "wgt" => "application/widget",
            "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",
            "wmv" => "video/x-ms-wmv",
            "wmx" => "video/x-ms-wmx",
            "wmz" => "application/x-ms-wmz",
            "woff" => "application/x-font-woff",
            "woff2" => "application/font-woff2",
            "wpd" => "application/vnd.wordperfect",
            "wpl" => "application/vnd.ms-wpl",
            "wps" => "application/vnd.ms-works",
            "wqd" => "application/vnd.wqd",
            "wri" => "application/x-mswrite",
            "wrl" => "model/vrml",
            "wsdl" => "application/wsdl+xml",
            "wspolicy" => "application/wspolicy+xml",
            "wtb" => "application/vnd.webturbo",
            "wvx" => "video/x-ms-wvx",
            "x3d" => "application/vnd.hzn-3d-crossword",
            "xap" => "application/x-silverlight-app",
            "xar" => "application/vnd.xara",
            "xbap" => "application/x-ms-xbap",
            "xbd" => "application/vnd.fujixerox.docuworks.binder",
            "xbm" => "image/x-xbitmap",
            "xdf" => "application/xcap-diff+xml",
            "xdm" => "application/vnd.syncml.dm+xml",
            "xdp" => "application/vnd.adobe.xdp+xml",
            "xdssc" => "application/dssc+xml",
            "xdw" => "application/vnd.fujixerox.docuworks",
            "xenc" => "application/xenc+xml",
            "xer" => "application/patch-ops-error+xml",
            "xfdf" => "application/vnd.adobe.xfdf",
            "xfdl" => "application/vnd.xfdl",
            "xhtml" => "application/xhtml+xml",
            "xif" => "image/vnd.xiff",
            "xlam" => "application/vnd.ms-excel.addin.macroenabled.12",
            "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",
            "xltm" => "application/vnd.ms-excel.template.macroenabled.12",
            "xltx" => "application/vnd.openxmlformats-officedocument.spreadsheetml.template",
            "xml" => "application/xml",
            "xo" => "application/vnd.olpc-sugar",
            "xop" => "application/xop+xml",
            "xpi" => "application/x-xpinstall",
            "xpm" => "image/x-xpixmap",
            "xpr" => "application/vnd.is-xpr",
            "xps" => "application/vnd.ms-xpsdocument",
            "xpw" => "application/vnd.intercon.formnet",
            "xslt" => "application/xslt+xml",
            "xsm" => "application/vnd.syncml+xml",
            "xspf" => "application/xspf+xml",
            "xul" => "application/vnd.mozilla.xul+xml",
            "xwd" => "image/x-xwindowdump",
            "xyz" => "chemical/x-xyz",
            "yaml" => "text/yaml",
            "yang" => "application/yang",
            "yin" => "application/yin+xml",
            "zaz" => "application/vnd.zzazz.deck+xml",
            "zip" => "application/zip",
            "zir" => "application/vnd.zul",
            "zmm" => "application/vnd.handheld-entertainment+xml"
        ];

        $extension = strtolower(pathinfo($filename, PATHINFO_EXTENSION));

        return $mime_types[$extension] ?? 'unknown';
    }
Returns the mime type of a file by analyzing it's extension

!!! IMPORTANT !!!
This will just match the file extension to a mimetype array.
It does not guarantee that the file is TRULY that of the extension that this function returns.

@see https://gist.github.com/Erutan409/8e774dfb2b343fe78b14 Thanks to Erutan409

@param string $filename

@throws FileException

@return string