core.js

'use strict';
const Token = require('token-types');
const strtok3 = require('strtok3/lib/core');
const {
	stringToBytes,
	tarHeaderChecksumMatches,
	uint32SyncSafeToken,
	uint8ArrayUtf8ByteString
} = require('./util');
const supported = require('./supported');

const minimumBytes = 4100; // A fair amount of file-types are detectable within this range

async function fromStream(stream) {
	const tokenizer = await strtok3.fromStream(stream);
	try {
		return await fromTokenizer(tokenizer);
	} finally {
		await tokenizer.close();
	}
}

async function fromBuffer(input) {
	if (!(input instanceof Uint8Array || input instanceof ArrayBuffer || Buffer.isBuffer(input))) {
		throw new TypeError(`Expected the \`input\` argument to be of type \`Uint8Array\` or \`Buffer\` or \`ArrayBuffer\`, got \`${typeof input}\``);
	}

	const buffer = input instanceof Buffer ? input : Buffer.from(input);

	if (!(buffer && buffer.length > 1)) {
		return;
	}

	const tokenizer = strtok3.fromBuffer(buffer);
	return fromTokenizer(tokenizer);
}

function _check(buffer, headers, options) {
	options = {
		offset: 0,
		...options
	};

	for (const [index, header] of headers.entries()) {
		// If a bitmask is set
		if (options.mask) {
			// If header doesn't equal `buf` with bits masked off
			if (header !== (options.mask[index] & buffer[index + options.offset])) {
				return false;
			}
		} else if (header !== buffer[index + options.offset]) {
			return false;
		}
	}

	return true;
}

async function _checkSequence(sequence, tokenizer, ignoreBytes) {
	const buffer = Buffer.alloc(minimumBytes);
	await tokenizer.ignore(ignoreBytes);

	await tokenizer.peekBuffer(buffer, {mayBeLess: true});

	return buffer.includes(Buffer.from(sequence));
}

async function fromTokenizer(tokenizer) {
	try {
		return _fromTokenizer(tokenizer);
	} catch (error) {
		if (!(error instanceof strtok3.EndOfStreamError)) {
			throw error;
		}
	}
}

async function _fromTokenizer(tokenizer) {
	let buffer = Buffer.alloc(minimumBytes);
	const bytesRead = 12;
	const check = (header, options) => _check(buffer, header, options);
	const checkString = (header, options) => check(stringToBytes(header), options);
	const checkSequence = (sequence, ignoreBytes) => _checkSequence(sequence, tokenizer, ignoreBytes);

	// Keep reading until EOF if the file size is unknown.
	if (!tokenizer.fileInfo.size) {
		tokenizer.fileInfo.size = Number.MAX_SAFE_INTEGER;
	}

	await tokenizer.peekBuffer(buffer, {length: bytesRead, mayBeLess: true});

	// -- 2-byte signatures --

	if (check([0x42, 0x4D])) {
		return {
			ext: 'bmp',
			mime: 'image/bmp'
		};
	}

	if (check([0x0B, 0x77])) {
		return {
			ext: 'ac3',
			mime: 'audio/vnd.dolby.dd-raw'
		};
	}

	if (check([0x78, 0x01])) {
		return {
			ext: 'dmg',
			mime: 'application/x-apple-diskimage'
		};
	}

	if (check([0x4D, 0x5A])) {
		return {
			ext: 'exe',
			mime: 'application/x-msdownload'
		};
	}

	if (check([0x25, 0x21])) {
		await tokenizer.peekBuffer(buffer, {length: 24, mayBeLess: true});

		if (checkString('PS-Adobe-', {offset: 2}) &&
			checkString(' EPSF-', {offset: 14})) {
			return {
				ext: 'eps',
				mime: 'application/eps'
			};
		}

		return {
			ext: 'ps',
			mime: 'application/postscript'
		};
	}

	if (
		check([0x1F, 0xA0]) ||
		check([0x1F, 0x9D])
	) {
		return {
			ext: 'Z',
			mime: 'application/x-compress'
		};
	}

	// -- 3-byte signatures --

	if (check([0xFF, 0xD8, 0xFF])) {
		return {
			ext: 'jpg',
			mime: 'image/jpeg'
		};
	}

	if (check([0x49, 0x49, 0xBC])) {
		return {
			ext: 'jxr',
			mime: 'image/vnd.ms-photo'
		};
	}

	if (check([0x1F, 0x8B, 0x8])) {
		return {
			ext: 'gz',
			mime: 'application/gzip'
		};
	}

	if (check([0x42, 0x5A, 0x68])) {
		return {
			ext: 'bz2',
			mime: 'application/x-bzip2'
		};
	}

	if (checkString('ID3')) {
		await tokenizer.ignore(6); // Skip ID3 header until the header size
		const id3HeaderLen = await tokenizer.readToken(uint32SyncSafeToken);
		if (tokenizer.position + id3HeaderLen > tokenizer.fileInfo.size) {
			// Guess file type based on ID3 header for backward compatibility
			return {
				ext: 'mp3',
				mime: 'audio/mpeg'
			};
		}

		await tokenizer.ignore(id3HeaderLen);
		return fromTokenizer(tokenizer); // Skip ID3 header, recursion
	}

	// Musepack, SV7
	if (checkString('MP+')) {
		return {
			ext: 'mpc',
			mime: 'audio/x-musepack'
		};
	}

	if (
		(buffer[0] === 0x43 || buffer[0] === 0x46) &&
		check([0x57, 0x53], {offset: 1})
	) {
		return {
			ext: 'swf',
			mime: 'application/x-shockwave-flash'
		};
	}

	// -- 4-byte signatures --

	if (check([0x47, 0x49, 0x46])) {
		return {
			ext: 'gif',
			mime: 'image/gif'
		};
	}

	if (checkString('FLIF')) {
		return {
			ext: 'flif',
			mime: 'image/flif'
		};
	}

	if (checkString('8BPS')) {
		return {
			ext: 'psd',
			mime: 'image/vnd.adobe.photoshop'
		};
	}

	if (checkString('WEBP', {offset: 8})) {
		return {
			ext: 'webp',
			mime: 'image/webp'
		};
	}

	// Musepack, SV8
	if (checkString('MPCK')) {
		return {
			ext: 'mpc',
			mime: 'audio/x-musepack'
		};
	}

	if (checkString('FORM')) {
		return {
			ext: 'aif',
			mime: 'audio/aiff'
		};
	}

	if (checkString('icns', {offset: 0})) {
		return {
			ext: 'icns',
			mime: 'image/icns'
		};
	}

	// Zip-based file formats
	// Need to be before the `zip` check
	if (check([0x50, 0x4B, 0x3, 0x4])) { // Local file header signature
		try {
			while (tokenizer.position + 30 < tokenizer.fileInfo.size) {
				await tokenizer.readBuffer(buffer, {length: 30});

				// https://en.wikipedia.org/wiki/Zip_(file_format)#File_headers
				const zipHeader = {
					compressedSize: buffer.readUInt32LE(18),
					uncompressedSize: buffer.readUInt32LE(22),
					filenameLength: buffer.readUInt16LE(26),
					extraFieldLength: buffer.readUInt16LE(28)
				};

				zipHeader.filename = await tokenizer.readToken(new Token.StringType(zipHeader.filenameLength, 'utf-8'));
				await tokenizer.ignore(zipHeader.extraFieldLength);

				// Assumes signed `.xpi` from addons.mozilla.org
				if (zipHeader.filename === 'META-INF/mozilla.rsa') {
					return {
						ext: 'xpi',
						mime: 'application/x-xpinstall'
					};
				}

				if (zipHeader.filename.endsWith('.rels') || zipHeader.filename.endsWith('.xml')) {
					const type = zipHeader.filename.split('/')[0];
					switch (type) {
						case '_rels':
							break;
						case 'word':
							return {
								ext: 'docx',
								mime: 'application/vnd.openxmlformats-officedocument.wordprocessingml.document'
							};
						case 'ppt':
							return {
								ext: 'pptx',
								mime: 'application/vnd.openxmlformats-officedocument.presentationml.presentation'
							};
						case 'xl':
							return {
								ext: 'xlsx',
								mime: 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet'
							};
						default:
							break;
					}
				}

				if (zipHeader.filename.startsWith('xl/')) {
					return {
						ext: 'xlsx',
						mime: 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet'
					};
				}

				// The docx, xlsx and pptx file types extend the Office Open XML file format:
				// https://en.wikipedia.org/wiki/Office_Open_XML_file_formats
				// We look for:
				// - one entry named '[Content_Types].xml' or '_rels/.rels',
				// - one entry indicating specific type of file.
				// MS Office, OpenOffice and LibreOffice may put the parts in different order, so the check should not rely on it.
				if (zipHeader.filename === 'mimetype' && zipHeader.compressedSize === zipHeader.uncompressedSize) {
					const mimeType = await tokenizer.readToken(new Token.StringType(zipHeader.compressedSize, 'utf-8'));

					switch (mimeType) {
						case 'application/epub+zip':
							return {
								ext: 'epub',
								mime: 'application/epub+zip'
							};
						case 'application/vnd.oasis.opendocument.text':
							return {
								ext: 'odt',
								mime: 'application/vnd.oasis.opendocument.text'
							};
						case 'application/vnd.oasis.opendocument.spreadsheet':
							return {
								ext: 'ods',
								mime: 'application/vnd.oasis.opendocument.spreadsheet'
							};
						case 'application/vnd.oasis.opendocument.presentation':
							return {
								ext: 'odp',
								mime: 'application/vnd.oasis.opendocument.presentation'
							};
						default:
					}
				}

				// Try to find next header manually when current one is corrupted
				if (zipHeader.compressedSize === 0) {
					let nextHeaderIndex = -1;

					while (nextHeaderIndex < 0 && (tokenizer.position < tokenizer.fileInfo.size)) {
						await tokenizer.peekBuffer(buffer, {mayBeLess: true});

						nextHeaderIndex = buffer.indexOf('504B0304', 0, 'hex');
						// Move position to the next header if found, skip the whole buffer otherwise
						await tokenizer.ignore(nextHeaderIndex >= 0 ? nextHeaderIndex : buffer.length);
					}
				} else {
					await tokenizer.ignore(zipHeader.compressedSize);
				}
			}
		} catch (error) {
			if (!(error instanceof strtok3.EndOfStreamError)) {
				throw error;
			}
		}

		return {
			ext: 'zip',
			mime: 'application/zip'
		};
	}

	if (checkString('OggS')) {
		// This is an OGG container
		await tokenizer.ignore(28);
		const type = Buffer.alloc(8);
		await tokenizer.readBuffer(type);

		// Needs to be before `ogg` check
		if (_check(type, [0x4F, 0x70, 0x75, 0x73, 0x48, 0x65, 0x61, 0x64])) {
			return {
				ext: 'opus',
				mime: 'audio/opus'
			};
		}

		// If ' theora' in header.
		if (_check(type, [0x80, 0x74, 0x68, 0x65, 0x6F, 0x72, 0x61])) {
			return {
				ext: 'ogv',
				mime: 'video/ogg'
			};
		}

		// If '\x01video' in header.
		if (_check(type, [0x01, 0x76, 0x69, 0x64, 0x65, 0x6F, 0x00])) {
			return {
				ext: 'ogm',
				mime: 'video/ogg'
			};
		}

		// If ' FLAC' in header  https://xiph.org/flac/faq.html
		if (_check(type, [0x7F, 0x46, 0x4C, 0x41, 0x43])) {
			return {
				ext: 'oga',
				mime: 'audio/ogg'
			};
		}

		// 'Speex  ' in header https://en.wikipedia.org/wiki/Speex
		if (_check(type, [0x53, 0x70, 0x65, 0x65, 0x78, 0x20, 0x20])) {
			return {
				ext: 'spx',
				mime: 'audio/ogg'
			};
		}

		// If '\x01vorbis' in header
		if (_check(type, [0x01, 0x76, 0x6F, 0x72, 0x62, 0x69, 0x73])) {
			return {
				ext: 'ogg',
				mime: 'audio/ogg'
			};
		}

		// Default OGG container https://www.iana.org/assignments/media-types/application/ogg
		return {
			ext: 'ogx',
			mime: 'application/ogg'
		};
	}

	if (
		check([0x50, 0x4B]) &&
		(buffer[2] === 0x3 || buffer[2] === 0x5 || buffer[2] === 0x7) &&
		(buffer[3] === 0x4 || buffer[3] === 0x6 || buffer[3] === 0x8)
	) {
		return {
			ext: 'zip',
			mime: 'application/zip'
		};
	}

	//

	// File Type Box (https://en.wikipedia.org/wiki/ISO_base_media_file_format)
	// It's not required to be first, but it's recommended to be. Almost all ISO base media files start with `ftyp` box.
	// `ftyp` box must contain a brand major identifier, which must consist of ISO 8859-1 printable characters.
	// Here we check for 8859-1 printable characters (for simplicity, it's a mask which also catches one non-printable character).
	if (
		checkString('ftyp', {offset: 4}) &&
		(buffer[8] & 0x60) !== 0x00 // Brand major, first character ASCII?
	) {
		// They all can have MIME `video/mp4` except `application/mp4` special-case which is hard to detect.
		// For some cases, we're specific, everything else falls to `video/mp4` with `mp4` extension.
		const brandMajor = uint8ArrayUtf8ByteString(buffer, 8, 12).replace('\0', ' ').trim();
		switch (brandMajor) {
			case 'avif':
				return {ext: 'avif', mime: 'image/avif'};
			case 'mif1':
				return {ext: 'heic', mime: 'image/heif'};
			case 'msf1':
				return {ext: 'heic', mime: 'image/heif-sequence'};
			case 'heic':
			case 'heix':
				return {ext: 'heic', mime: 'image/heic'};
			case 'hevc':
			case 'hevx':
				return {ext: 'heic', mime: 'image/heic-sequence'};
			case 'qt':
				return {ext: 'mov', mime: 'video/quicktime'};
			case 'M4V':
			case 'M4VH':
			case 'M4VP':
				return {ext: 'm4v', mime: 'video/x-m4v'};
			case 'M4P':
				return {ext: 'm4p', mime: 'video/mp4'};
			case 'M4B':
				return {ext: 'm4b', mime: 'audio/mp4'};
			case 'M4A':
				return {ext: 'm4a', mime: 'audio/x-m4a'};
			case 'F4V':
				return {ext: 'f4v', mime: 'video/mp4'};
			case 'F4P':
				return {ext: 'f4p', mime: 'video/mp4'};
			case 'F4A':
				return {ext: 'f4a', mime: 'audio/mp4'};
			case 'F4B':
				return {ext: 'f4b', mime: 'audio/mp4'};
			case 'crx':
				return {ext: 'cr3', mime: 'image/x-canon-cr3'};
			default:
				if (brandMajor.startsWith('3g')) {
					if (brandMajor.startsWith('3g2')) {
						return {ext: '3g2', mime: 'video/3gpp2'};
					}

					return {ext: '3gp', mime: 'video/3gpp'};
				}

				return {ext: 'mp4', mime: 'video/mp4'};
		}
	}

	if (checkString('MThd')) {
		return {
			ext: 'mid',
			mime: 'audio/midi'
		};
	}

	if (
		checkString('wOFF') &&
		(
			check([0x00, 0x01, 0x00, 0x00], {offset: 4}) ||
			checkString('OTTO', {offset: 4})
		)
	) {
		return {
			ext: 'woff',
			mime: 'font/woff'
		};
	}

	if (
		checkString('wOF2') &&
		(
			check([0x00, 0x01, 0x00, 0x00], {offset: 4}) ||
			checkString('OTTO', {offset: 4})
		)
	) {
		return {
			ext: 'woff2',
			mime: 'font/woff2'
		};
	}

	if (check([0xD4, 0xC3, 0xB2, 0xA1]) || check([0xA1, 0xB2, 0xC3, 0xD4])) {
		return {
			ext: 'pcap',
			mime: 'application/vnd.tcpdump.pcap'
		};
	}

	// Sony DSD Stream File (DSF)
	if (checkString('DSD ')) {
		return {
			ext: 'dsf',
			mime: 'audio/x-dsf' // Non-standard
		};
	}

	if (checkString('LZIP')) {
		return {
			ext: 'lz',
			mime: 'application/x-lzip'
		};
	}

	if (checkString('fLaC')) {
		return {
			ext: 'flac',
			mime: 'audio/x-flac'
		};
	}

	if (check([0x42, 0x50, 0x47, 0xFB])) {
		return {
			ext: 'bpg',
			mime: 'image/bpg'
		};
	}

	if (checkString('wvpk')) {
		return {
			ext: 'wv',
			mime: 'audio/wavpack'
		};
	}

	if (checkString('%PDF')) {
		// Check if this is an Adobe Illustrator file
		const isAiFile = await checkSequence('Adobe Illustrator', 1350);
		if (isAiFile) {
			return {
				ext: 'ai',
				mime: 'application/postscript'
			};
		}

		// Assume this is just a normal PDF
		return {
			ext: 'pdf',
			mime: 'application/pdf'
		};
	}

	if (check([0x00, 0x61, 0x73, 0x6D])) {
		return {
			ext: 'wasm',
			mime: 'application/wasm'
		};
	}

	// TIFF, little-endian type
	if (check([0x49, 0x49, 0x2A, 0x0])) {
		if (checkString('CR', {offset: 8})) {
			return {
				ext: 'cr2',
				mime: 'image/x-canon-cr2'
			};
		}

		if (check([0x1C, 0x00, 0xFE, 0x00], {offset: 8}) || check([0x1F, 0x00, 0x0B, 0x00], {offset: 8})) {
			return {
				ext: 'nef',
				mime: 'image/x-nikon-nef'
			};
		}

		if (
			check([0x08, 0x00, 0x00, 0x00], {offset: 4}) &&
			(check([0x2D, 0x00, 0xFE, 0x00], {offset: 8}) ||
				check([0x27, 0x00, 0xFE, 0x00], {offset: 8}))
		) {
			return {
				ext: 'dng',
				mime: 'image/x-adobe-dng'
			};
		}

		buffer = Buffer.alloc(24);
		await tokenizer.peekBuffer(buffer);
		if (
			(check([0x10, 0xFB, 0x86, 0x01], {offset: 4}) || check([0x08, 0x00, 0x00, 0x00], {offset: 4})) &&
			// This pattern differentiates ARW from other TIFF-ish file types:
			check([0x00, 0xFE, 0x00, 0x04, 0x00, 0x01, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x03, 0x01], {offset: 9})
		) {
			return {
				ext: 'arw',
				mime: 'image/x-sony-arw'
			};
		}

		return {
			ext: 'tif',
			mime: 'image/tiff'
		};
	}

	// TIFF, big-endian type
	if (check([0x4D, 0x4D, 0x0, 0x2A])) {
		return {
			ext: 'tif',
			mime: 'image/tiff'
		};
	}

	if (checkString('MAC ')) {
		return {
			ext: 'ape',
			mime: 'audio/ape'
		};
	}

	// https://github.com/threatstack/libmagic/blob/master/magic/Magdir/matroska
	if (check([0x1A, 0x45, 0xDF, 0xA3])) { // Root element: EBML
		async function readField() {
			const msb = await tokenizer.peekNumber(Token.UINT8);
			let mask = 0x80;
			let ic = 0; // 0 = A, 1 = B, 2 = C, 3 = D

			while ((msb & mask) === 0) {
				++ic;
				mask >>= 1;
			}

			const id = Buffer.alloc(ic + 1);
			await tokenizer.readBuffer(id);
			return id;
		}

		async function readElement() {
			const id = await readField();
			const lenField = await readField();
			lenField[0] ^= 0x80 >> (lenField.length - 1);
			const nrLen = Math.min(6, lenField.length); // JavaScript can max read 6 bytes integer
			return {
				id: id.readUIntBE(0, id.length),
				len: lenField.readUIntBE(lenField.length - nrLen, nrLen)
			};
		}

		async function readChildren(level, children) {
			while (children > 0) {
				const e = await readElement();
				if (e.id === 0x4282) {
					return tokenizer.readToken(new Token.StringType(e.len, 'utf-8')); // Return DocType
				}

				await tokenizer.ignore(e.len); // ignore payload
				--children;
			}
		}

		const re = await readElement();
		const docType = await readChildren(1, re.len);

		switch (docType) {
			case 'webm':
				return {
					ext: 'webm',
					mime: 'video/webm'
				};

			case 'matroska':
				return {
					ext: 'mkv',
					mime: 'video/x-matroska'
				};

			default:
				return;
		}
	}

	// RIFF file format which might be AVI, WAV, QCP, etc
	if (check([0x52, 0x49, 0x46, 0x46])) {
		if (check([0x41, 0x56, 0x49], {offset: 8})) {
			return {
				ext: 'avi',
				mime: 'video/vnd.avi'
			};
		}

		if (check([0x57, 0x41, 0x56, 0x45], {offset: 8})) {
			return {
				ext: 'wav',
				mime: 'audio/vnd.wave'
			};
		}

		// QLCM, QCP file
		if (check([0x51, 0x4C, 0x43, 0x4D], {offset: 8})) {
			return {
				ext: 'qcp',
				mime: 'audio/qcelp'
			};
		}
	}

	if (checkString('SQLi')) {
		return {
			ext: 'sqlite',
			mime: 'application/x-sqlite3'
		};
	}

	if (check([0x4E, 0x45, 0x53, 0x1A])) {
		return {
			ext: 'nes',
			mime: 'application/x-nintendo-nes-rom'
		};
	}

	if (checkString('Cr24')) {
		return {
			ext: 'crx',
			mime: 'application/x-google-chrome-extension'
		};
	}

	if (
		checkString('MSCF') ||
		checkString('ISc(')
	) {
		return {
			ext: 'cab',
			mime: 'application/vnd.ms-cab-compressed'
		};
	}

	if (check([0xED, 0xAB, 0xEE, 0xDB])) {
		return {
			ext: 'rpm',
			mime: 'application/x-rpm'
		};
	}

	if (check([0xC5, 0xD0, 0xD3, 0xC6])) {
		return {
			ext: 'eps',
			mime: 'application/eps'
		};
	}

	// -- 5-byte signatures --

	if (check([0x4F, 0x54, 0x54, 0x4F, 0x00])) {
		return {
			ext: 'otf',
			mime: 'font/otf'
		};
	}

	if (checkString('#!AMR')) {
		return {
			ext: 'amr',
			mime: 'audio/amr'
		};
	}

	if (checkString('{\\rtf')) {
		return {
			ext: 'rtf',
			mime: 'application/rtf'
		};
	}

	if (check([0x46, 0x4C, 0x56, 0x01])) {
		return {
			ext: 'flv',
			mime: 'video/x-flv'
		};
	}

	if (checkString('IMPM')) {
		return {
			ext: 'it',
			mime: 'audio/x-it'
		};
	}

	if (
		checkString('-lh0-', {offset: 2}) ||
		checkString('-lh1-', {offset: 2}) ||
		checkString('-lh2-', {offset: 2}) ||
		checkString('-lh3-', {offset: 2}) ||
		checkString('-lh4-', {offset: 2}) ||
		checkString('-lh5-', {offset: 2}) ||
		checkString('-lh6-', {offset: 2}) ||
		checkString('-lh7-', {offset: 2}) ||
		checkString('-lzs-', {offset: 2}) ||
		checkString('-lz4-', {offset: 2}) ||
		checkString('-lz5-', {offset: 2}) ||
		checkString('-lhd-', {offset: 2})
	) {
		return {
			ext: 'lzh',
			mime: 'application/x-lzh-compressed'
		};
	}

	// MPEG program stream (PS or MPEG-PS)
	if (check([0x00, 0x00, 0x01, 0xBA])) {
		//  MPEG-PS, MPEG-1 Part 1
		if (check([0x21], {offset: 4, mask: [0xF1]})) {
			return {
				ext: 'mpg', // May also be .ps, .mpeg
				mime: 'video/MP1S'
			};
		}

		// MPEG-PS, MPEG-2 Part 1
		if (check([0x44], {offset: 4, mask: [0xC4]})) {
			return {
				ext: 'mpg', // May also be .mpg, .m2p, .vob or .sub
				mime: 'video/MP2P'
			};
		}
	}

	// -- 6-byte signatures --

	if (check([0xFD, 0x37, 0x7A, 0x58, 0x5A, 0x00])) {
		return {
			ext: 'xz',
			mime: 'application/x-xz'
		};
	}

	if (checkString('<?xml ')) {
		return {
			ext: 'xml',
			mime: 'application/xml'
		};
	}

	if (checkString('BEGIN:')) {
		return {
			ext: 'ics',
			mime: 'text/calendar'
		};
	}

	if (check([0x37, 0x7A, 0xBC, 0xAF, 0x27, 0x1C])) {
		return {
			ext: '7z',
			mime: 'application/x-7z-compressed'
		};
	}

	if (
		check([0x52, 0x61, 0x72, 0x21, 0x1A, 0x7]) &&
		(buffer[6] === 0x0 || buffer[6] === 0x1)
	) {
		return {
			ext: 'rar',
			mime: 'application/x-rar-compressed'
		};
	}

	// -- 7-byte signatures --

	if (checkString('BLENDER')) {
		return {
			ext: 'blend',
			mime: 'application/x-blender'
		};
	}

	if (checkString('!<arch>')) {
		await tokenizer.ignore(8);
		const str = await tokenizer.readToken(new Token.StringType(13, 'ascii'));
		if (str === 'debian-binary') {
			return {
				ext: 'deb',
				mime: 'application/x-deb'
			};
		}

		return {
			ext: 'ar',
			mime: 'application/x-unix-archive'
		};
	}

	// -- 8-byte signatures --

	if (check([0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A])) {
		// APNG format (https://wiki.mozilla.org/APNG_Specification)
		// 1. Find the first IDAT (image data) chunk (49 44 41 54)
		// 2. Check if there is an "acTL" chunk before the IDAT one (61 63 54 4C)

		// Offset calculated as follows:
		// - 8 bytes: PNG signature
		// - 4 (length) + 4 (chunk type) + 13 (chunk data) + 4 (CRC): IHDR chunk

		await tokenizer.ignore(8); // ignore PNG signature

		async function readChunkHeader() {
			return {
				length: await tokenizer.readToken(Token.INT32_BE),
				type: await tokenizer.readToken(new Token.StringType(4, 'binary'))
			};
		}

		do {
			const chunk = await readChunkHeader();
			switch (chunk.type) {
				case 'IDAT':
					return {
						ext: 'png',
						mime: 'image/png'
					};
				case 'acTL':
					return {
						ext: 'apng',
						mime: 'image/apng'
					};
				default:
					await tokenizer.ignore(chunk.length + 4); // Ignore chunk-data + CRC
			}
		} while (tokenizer.position < tokenizer.fileInfo.size);

		return {
			ext: 'png',
			mime: 'image/png'
		};
	}

	if (check([0x41, 0x52, 0x52, 0x4F, 0x57, 0x31, 0x00, 0x00])) {
		return {
			ext: 'arrow',
			mime: 'application/x-apache-arrow'
		};
	}

	if (check([0x67, 0x6C, 0x54, 0x46, 0x02, 0x00, 0x00, 0x00])) {
		return {
			ext: 'glb',
			mime: 'model/gltf-binary'
		};
	}

	// `mov` format variants
	if (
		check([0x66, 0x72, 0x65, 0x65], {offset: 4}) || // `free`
		check([0x6D, 0x64, 0x61, 0x74], {offset: 4}) || // `mdat` MJPEG
		check([0x6D, 0x6F, 0x6F, 0x76], {offset: 4}) || // `moov`
		check([0x77, 0x69, 0x64, 0x65], {offset: 4}) // `wide`
	) {
		return {
			ext: 'mov',
			mime: 'video/quicktime'
		};
	}

	// -- 9-byte signatures --

	if (check([0x49, 0x49, 0x52, 0x4F, 0x08, 0x00, 0x00, 0x00, 0x18])) {
		return {
			ext: 'orf',
			mime: 'image/x-olympus-orf'
		};
	}

	// -- 12-byte signatures --

	if (check([0x49, 0x49, 0x55, 0x00, 0x18, 0x00, 0x00, 0x00, 0x88, 0xE7, 0x74, 0xD8])) {
		return {
			ext: 'rw2',
			mime: 'image/x-panasonic-rw2'
		};
	}

	// ASF_Header_Object first 80 bytes
	if (check([0x30, 0x26, 0xB2, 0x75, 0x8E, 0x66, 0xCF, 0x11, 0xA6, 0xD9])) {
		async function readHeader() {
			const guid = Buffer.alloc(16);
			await tokenizer.readBuffer(guid);
			return {
				id: guid,
				size: await tokenizer.readToken(Token.UINT64_LE)
			};
		}

		await tokenizer.ignore(30);
		// Search for header should be in first 1KB of file.
		while (tokenizer.position + 24 < tokenizer.fileInfo.size) {
			const header = await readHeader();
			let payload = header.size - 24;
			if (_check(header.id, [0x91, 0x07, 0xDC, 0xB7, 0xB7, 0xA9, 0xCF, 0x11, 0x8E, 0xE6, 0x00, 0xC0, 0x0C, 0x20, 0x53, 0x65])) {
				// Sync on Stream-Properties-Object (B7DC0791-A9B7-11CF-8EE6-00C00C205365)
				const typeId = Buffer.alloc(16);
				payload -= await tokenizer.readBuffer(typeId);

				if (_check(typeId, [0x40, 0x9E, 0x69, 0xF8, 0x4D, 0x5B, 0xCF, 0x11, 0xA8, 0xFD, 0x00, 0x80, 0x5F, 0x5C, 0x44, 0x2B])) {
					// Found audio:
					return {
						ext: 'wma',
						mime: 'audio/x-ms-wma'
					};
				}

				if (_check(typeId, [0xC0, 0xEF, 0x19, 0xBC, 0x4D, 0x5B, 0xCF, 0x11, 0xA8, 0xFD, 0x00, 0x80, 0x5F, 0x5C, 0x44, 0x2B])) {
					// Found video:
					return {
						ext: 'wmv',
						mime: 'video/x-ms-asf'
					};
				}

				break;
			}

			await tokenizer.ignore(payload);
		}

		// Default to ASF generic extension
		return {
			ext: 'asf',
			mime: 'application/vnd.ms-asf'
		};
	}

	if (check([0xAB, 0x4B, 0x54, 0x58, 0x20, 0x31, 0x31, 0xBB, 0x0D, 0x0A, 0x1A, 0x0A])) {
		return {
			ext: 'ktx',
			mime: 'image/ktx'
		};
	}

	if ((check([0x7E, 0x10, 0x04]) || check([0x7E, 0x18, 0x04])) && check([0x30, 0x4D, 0x49, 0x45], {offset: 4})) {
		return {
			ext: 'mie',
			mime: 'application/x-mie'
		};
	}

	if (check([0x27, 0x0A, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00], {offset: 2})) {
		return {
			ext: 'shp',
			mime: 'application/x-esri-shape'
		};
	}

	if (check([0x00, 0x00, 0x00, 0x0C, 0x6A, 0x50, 0x20, 0x20, 0x0D, 0x0A, 0x87, 0x0A])) {
		// JPEG-2000 family

		await tokenizer.ignore(20);
		const type = await tokenizer.readToken(new Token.StringType(4, 'ascii'));
		switch (type) {
			case 'jp2 ':
				return {
					ext: 'jp2',
					mime: 'image/jp2'
				};
			case 'jpx ':
				return {
					ext: 'jpx',
					mime: 'image/jpx'
				};
			case 'jpm ':
				return {
					ext: 'jpm',
					mime: 'image/jpm'
				};
			case 'mjp2':
				return {
					ext: 'mj2',
					mime: 'image/mj2'
				};
			default:
				return;
		}
	}

	// -- Unsafe signatures --

	if (
		check([0x0, 0x0, 0x1, 0xBA]) ||
		check([0x0, 0x0, 0x1, 0xB3])
	) {
		return {
			ext: 'mpg',
			mime: 'video/mpeg'
		};
	}

	if (check([0x00, 0x01, 0x00, 0x00, 0x00])) {
		return {
			ext: 'ttf',
			mime: 'font/ttf'
		};
	}

	if (check([0x00, 0x00, 0x01, 0x00])) {
		return {
			ext: 'ico',
			mime: 'image/x-icon'
		};
	}

	if (check([0x00, 0x00, 0x02, 0x00])) {
		return {
			ext: 'cur',
			mime: 'image/x-icon'
		};
	}

	// Increase sample size from 12 to 256.
	await tokenizer.peekBuffer(buffer, {length: Math.min(256, tokenizer.fileInfo.size), mayBeLess: true});

	// `raf` is here just to keep all the raw image detectors together.
	if (checkString('FUJIFILMCCD-RAW')) {
		return {
			ext: 'raf',
			mime: 'image/x-fujifilm-raf'
		};
	}

	if (checkString('Extended Module:')) {
		return {
			ext: 'xm',
			mime: 'audio/x-xm'
		};
	}

	if (checkString('Creative Voice File')) {
		return {
			ext: 'voc',
			mime: 'audio/x-voc'
		};
	}

	if (
		check([0x30, 0x30, 0x30, 0x30, 0x30, 0x30], {offset: 148, mask: [0xF8, 0xF8, 0xF8, 0xF8, 0xF8, 0xF8]}) && // Valid tar checksum
		tarHeaderChecksumMatches(buffer)
	) {
		return {
			ext: 'tar',
			mime: 'application/x-tar'
		};
	}

	if (check([0xD0, 0xCF, 0x11, 0xE0, 0xA1, 0xB1, 0x1A, 0xE1, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x3E])) {
		return {
			ext: 'msi',
			mime: 'application/x-msi'
		};
	}

	if (check([0x06, 0x0E, 0x2B, 0x34, 0x02, 0x05, 0x01, 0x01, 0x0D, 0x01, 0x02, 0x01, 0x01, 0x02])) {
		return {
			ext: 'mxf',
			mime: 'application/mxf'
		};
	}

	if (checkString('SCRM', {offset: 44})) {
		return {
			ext: 's3m',
			mime: 'audio/x-s3m'
		};
	}

	if (check([0x47], {offset: 4}) && (check([0x47], {offset: 192}) || check([0x47], {offset: 196}))) {
		return {
			ext: 'mts',
			mime: 'video/mp2t'
		};
	}

	if (check([0x42, 0x4F, 0x4F, 0x4B, 0x4D, 0x4F, 0x42, 0x49], {offset: 60})) {
		return {
			ext: 'mobi',
			mime: 'application/x-mobipocket-ebook'
		};
	}

	if (check([0x44, 0x49, 0x43, 0x4D], {offset: 128})) {
		return {
			ext: 'dcm',
			mime: 'application/dicom'
		};
	}

	if (check([0x4C, 0x00, 0x00, 0x00, 0x01, 0x14, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0xC0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x46])) {
		return {
			ext: 'lnk',
			mime: 'application/x.ms.shortcut' // Invented by us
		};
	}

	if (check([0x62, 0x6F, 0x6F, 0x6B, 0x00, 0x00, 0x00, 0x00, 0x6D, 0x61, 0x72, 0x6B, 0x00, 0x00, 0x00, 0x00])) {
		return {
			ext: 'alias',
			mime: 'application/x.apple.alias' // Invented by us
		};
	}

	if (
		check([0x4C, 0x50], {offset: 34}) &&
		(
			check([0x00, 0x00, 0x01], {offset: 8}) ||
			check([0x01, 0x00, 0x02], {offset: 8}) ||
			check([0x02, 0x00, 0x02], {offset: 8})
		)
	) {
		return {
			ext: 'eot',
			mime: 'application/vnd.ms-fontobject'
		};
	}

	// Increase sample size from 256 to 512
	await tokenizer.peekBuffer(buffer, {length: Math.min(512, tokenizer.fileInfo.size), mayBeLess: true});

	if (
		check([0x30, 0x30, 0x30, 0x30, 0x30, 0x30], {offset: 148, mask: [0xF8, 0xF8, 0xF8, 0xF8, 0xF8, 0xF8]}) && // Valid tar checksum
		tarHeaderChecksumMatches(buffer)
	) {
		return {
			ext: 'tar',
			mime: 'application/x-tar'
		};
	}

	if (check([0xFF, 0xFE, 0xFF, 0x0E, 0x53, 0x00, 0x6B, 0x00, 0x65, 0x00, 0x74, 0x00, 0x63, 0x00, 0x68, 0x00, 0x55, 0x00, 0x70, 0x00, 0x20, 0x00, 0x4D, 0x00, 0x6F, 0x00, 0x64, 0x00, 0x65, 0x00, 0x6C, 0x00])) {
		return {
			ext: 'skp',
			mime: 'application/vnd.sketchup.skp'
		};
	}

	if (checkString('-----BEGIN PGP MESSAGE-----')) {
		return {
			ext: 'pgp',
			mime: 'application/pgp-encrypted'
		};
	}

	// Check for MPEG header at different starting offsets
	for (let start = 0; start < 2 && start < (buffer.length - 16); start++) {
		// Check MPEG 1 or 2 Layer 3 header, or 'layer 0' for ADTS (MPEG sync-word 0xFFE)
		if (buffer.length >= start + 2 && check([0xFF, 0xE0], {offset: start, mask: [0xFF, 0xE0]})) {
			if (check([0x10], {offset: start + 1, mask: [0x16]})) {
				// Check for (ADTS) MPEG-2
				if (check([0x08], {offset: start + 1, mask: [0x08]})) {
					return {
						ext: 'aac',
						mime: 'audio/aac'
					};
				}

				// Must be (ADTS) MPEG-4
				return {
					ext: 'aac',
					mime: 'audio/aac'
				};
			}

			// MPEG 1 or 2 Layer 3 header
			// Check for MPEG layer 3
			if (check([0x02], {offset: start + 1, mask: [0x06]})) {
				return {
					ext: 'mp3',
					mime: 'audio/mpeg'
				};
			}

			// Check for MPEG layer 2
			if (check([0x04], {offset: start + 1, mask: [0x06]})) {
				return {
					ext: 'mp2',
					mime: 'audio/mpeg'
				};
			}

			// Check for MPEG layer 1
			if (check([0x06], {offset: start + 1, mask: [0x06]})) {
				return {
					ext: 'mp1',
					mime: 'audio/mpeg'
				};
			}
		}
	}
}

const stream = readableStream => new Promise((resolve, reject) => {
	// Using `eval` to work around issues when bundling with Webpack
	const stream = eval('require')('stream'); // eslint-disable-line no-eval

	readableStream.on('error', reject);
	readableStream.once('readable', async () => {
		// Set up output stream
		const pass = new stream.PassThrough();
		let outputStream;
		if (stream.pipeline) {
			outputStream = stream.pipeline(readableStream, pass, () => {});
		} else {
			outputStream = readableStream.pipe(pass);
		}

		// Read the input stream and detect the filetype
		const chunk = readableStream.read(minimumBytes) || readableStream.read() || Buffer.alloc(0);
		try {
			const fileType = await fromBuffer(chunk);
			pass.fileType = fileType;
		} catch (error) {
			reject(error);
		}

		resolve(outputStream);
	});
});

const fileType = {
	fromStream,
	fromTokenizer,
	fromBuffer,
	stream
};

Object.defineProperty(fileType, 'extensions', {
	get() {
		return new Set(supported.extensions);
	}
});

Object.defineProperty(fileType, 'mimeTypes', {
	get() {
		return new Set(supported.mimeTypes);
	}
});

module.exports = fileType;