utils.js

var UNDEFINED = 'undefined';

var SOF = {
	0xc0: true,
	0xc1: true,
	0xc2: true,
	0xc3: true,
	0xc5: true,
	0xc6: true,
	0xc7: true,
	0xc9: true,
	0xca: true,
	0xcb: true,
	0xcd: true,
	0xce: true,
	0xcf: true
};

var EXTENSION = {
	'ai': 'application/postscript',
	'aif': 'audio/x-aiff',
	'aifc': 'audio/x-aiff',
	'aiff': 'audio/x-aiff',
	'asc': 'text/plain',
	'atom': 'application/atom+xml',
	'au': 'audio/basic',
	'avi': 'video/x-msvideo',
	'bcpio': 'application/x-bcpio',
	'bin': 'application/octet-stream',
	'bmp': 'image/bmp',
	'cdf': 'application/x-netcdf',
	'cgm': 'image/cgm',
	'class': 'application/octet-stream',
	'cpio': 'application/x-cpio',
	'cpt': 'application/mac-compactpro',
	'csh': 'application/x-csh',
	'css': 'text/css',
	'dcr': 'application/x-director',
	'dif': 'video/x-dv',
	'dir': 'application/x-director',
	'djv': 'image/vnd.djvu',
	'djvu': 'image/vnd.djvu',
	'dll': 'application/octet-stream',
	'dmg': 'application/octet-stream',
	'dms': 'application/octet-stream',
	'doc': 'application/msword',
	'dtd': 'application/xml-dtd',
	'dv': 'video/x-dv',
	'dvi': 'application/x-dvi',
	'dxr': 'application/x-director',
	'eps': 'application/postscript',
	'etx': 'text/x-setext',
	'exe': 'application/octet-stream',
	'ez': 'application/andrew-inset',
	'gif': 'image/gif',
	'gram': 'application/srgs',
	'grxml': 'application/srgs+xml',
	'gtar': 'application/x-gtar',
	'hdf': 'application/x-hdf',
	'hqx': 'application/mac-binhex40',
	'htm': 'text/html',
	'html': 'text/html',
	'ice': 'x-conference/x-cooltalk',
	'ico': 'image/x-icon',
	'ics': 'text/calendar',
	'ief': 'image/ief',
	'ifb': 'text/calendar',
	'iges': 'model/iges',
	'igs': 'model/iges',
	'jnlp': 'application/x-java-jnlp-file',
	'jp2': 'image/jp2',
	'jpe': 'image/jpeg',
	'jpeg': 'image/jpeg',
	'jpg': 'image/jpeg',
	'js': 'application/x-javascript',
	'kar': 'audio/midi',
	'latex': 'application/x-latex',
	'lha': 'application/octet-stream',
	'lzh': 'application/octet-stream',
	'm3u': 'audio/x-mpegurl',
	'm4a': 'audio/mp4a-latm',
	'm4b': 'audio/mp4a-latm',
	'm4p': 'audio/mp4a-latm',
	'm4u': 'video/vnd.mpegurl',
	'm4v': 'video/x-m4v',
	'mac': 'image/x-macpaint',
	'man': 'application/x-troff-man',
	'mathml': 'application/mathml+xml',
	'me': 'application/x-troff-me',
	'mesh': 'model/mesh',
	'mid': 'audio/midi',
	'midi': 'audio/midi',
	'mif': 'application/vnd.mif',
	'mov': 'video/quicktime',
	'movie': 'video/x-sgi-movie',
	'mp2': 'audio/mpeg',
	'mp3': 'audio/mpeg',
	'mp4': 'video/mp4',
	'mpe': 'video/mpeg',
	'mpeg': 'video/mpeg',
	'mpg': 'video/mpeg',
	'mpga': 'audio/mpeg',
	'ms': 'application/x-troff-ms',
	'msh': 'model/mesh',
	'mv4': 'video/mv4',
	'mxu': 'video/vnd.mpegurl',
	'nc': 'application/x-netcdf',
	'oda': 'application/oda',
	'ogg': 'application/ogg',
	'pbm': 'image/x-portable-bitmap',
	'pct': 'image/pict',
	'pdb': 'chemical/x-pdb',
	'pdf': 'application/pdf',
	'pgm': 'image/x-portable-graymap',
	'pgn': 'application/x-chess-pgn',
	'pic': 'image/pict',
	'pict': 'image/pict',
	'png': 'image/png',
	'pnm': 'image/x-portable-anymap',
	'pnt': 'image/x-macpaint',
	'pntg': 'image/x-macpaint',
	'ppm': 'image/x-portable-pixmap',
	'ppt': 'application/vnd.ms-powerpoint',
	'ps': 'application/postscript',
	'qt': 'video/quicktime',
	'qti': 'image/x-quicktime',
	'qtif': 'image/x-quicktime',
	'ra': 'audio/x-pn-realaudio',
	'ram': 'audio/x-pn-realaudio',
	'ras': 'image/x-cmu-raster',
	'rdf': 'application/rdf+xml',
	'rgb': 'image/x-rgb',
	'rm': 'application/vnd.rn-realmedia',
	'roff': 'application/x-troff',
	'rtf': 'text/rtf',
	'rtx': 'text/richtext',
	'sgm': 'text/sgml',
	'sgml': 'text/sgml',
	'sh': 'application/x-sh',
	'shar': 'application/x-shar',
	'silo': 'model/mesh',
	'sit': 'application/x-stuffit',
	'skd': 'application/x-koan',
	'skm': 'application/x-koan',
	'skp': 'application/x-koan',
	'skt': 'application/x-koan',
	'smi': 'application/smil',
	'smil': 'application/smil',
	'snd': 'audio/basic',
	'so': 'application/octet-stream',
	'spl': 'application/x-futuresplash',
	'src': 'application/x-wais-source',
	'sv4cpio': 'application/x-sv4cpio',
	'sv4crc': 'application/x-sv4crc',
	'svg': 'image/svg+xml',
	'swf': 'application/x-shockwave-flash',
	't': 'application/x-troff',
	'tar': 'application/x-tar',
	'tcl': 'application/x-tcl',
	'tex': 'application/x-tex',
	'texi': 'application/x-texinfo',
	'texinfo': 'application/x-texinfo',
	'tif': 'image/tiff',
	'tiff': 'image/tiff',
	'tr': 'application/x-troff',
	'tsv': 'text/tab-separated-values',
	'txt': 'text/plain',
	'ustar': 'application/x-ustar',
	'vcd': 'application/x-cdlink',
	'vrml': 'model/vrml',
	'vxml': 'application/voicexml+xml',
	'wav': 'audio/x-wav',
	'wbmp': 'image/vnd.wap.wbmp',
	'wbmxl': 'application/vnd.wap.wbxml',
	'wml': 'text/vnd.wap.wml',
	'wmlc': 'application/vnd.wap.wmlc',
	'woff': 'font/woff',
	'wmls': 'text/vnd.wap.wmlscript',
	'wmlsc': 'application/vnd.wap.wmlscriptc',
	'wrl': 'model/vrml',
	'xbm': 'image/x-xbitmap',
	'xht': 'application/xhtml+xml',
	'xhtml': 'application/xhtml+xml',
	'xls': 'application/vnd.ms-excel',
	'xml': 'application/xml',
	'xpm': 'image/x-xpixmap',
	'xsl': 'application/xml',
	'xslt': 'application/xslt+xml',
	'xul': 'application/vnd.mozilla.xul+xml',
	'xwd': 'image/x-xwindowdump',
	'xyz': 'chemical/x-xyz',
	'zip': 'application/zip'
};

function u16(buf, o) {
	return buf[o] << 8 | buf[o + 1];
}

function u32(buf, o) {
	return buf[o] << 24 | buf[o + 1] << 16 | buf[o + 2] << 8 | buf[o + 3];
}

if (typeof(setImmediate) === UNDEFINED) {
	global.setImmediate = function(cb) {
		process.nextTick(cb);
	};
}

exports.extension = function(name) {
	var index = name.lastIndexOf('.');
	if (index !== -1)
		name = name.substring(index + 1);
	return name;
};

exports.contentType = function(ext) {
	return EXTENSION[ext.toLowerCase()] || 'application/octet-stream';
};

if (!String.prototype.padLeft) {
	String.prototype.padLeft = function(max, c) {
		var self = this.toString();
		return new Array(Math.max(0, max - self.length + 1)).join(c || ' ') + self;
	};
}

if (!String.prototype.padRight) {
	String.prototype.padRight = function(max, c) {
		var self = this.toString();
		return self + new Array(Math.max(0, max - self.length + 1)).join(c || ' ');
	};
}

if (!String.prototype.trim) {
	String.prototype.trim = function() {
		return this.replace(/^[\s]+|[\s]+$/g, '');
	};
}

exports.dimensionGIF = function(buffer) {
	return { width: buffer[6], height: buffer[8] };
};

// MIT
// Written by TJ Holowaychuk
// visionmedia
exports.dimensionJPG = function(buffer) {

	var len = buffer.length;
	var o = 0;

	var jpeg = 0xff == buffer[0] && 0xd8 == buffer[1];

	if (!jpeg)
		return null;

	o += 2;

	while (o < len) {
		while (0xff != buffer[o]) o++;
		while (0xff == buffer[o]) o++;

		if (!SOF[buffer[o]]) {
			o += u16(buffer, ++o);
			continue;
		}

		var w = u16(buffer, o + 6);
		var h = u16(buffer, o + 4);
		return { width: w, height: h };
	}

	return null;
};

// MIT
// Written by TJ Holowaychuk
// visionmedia
exports.dimensionPNG = function(buffer) {
	return { width: u32(buffer, 16), height: u32(buffer, 16 + 4) };
};

exports.parseIndex = function(id) {

	var length = id.length;
	var beg = 0;

	id = id.toString().replace(/\-/g, '');

	for (var i = 0; i < length; i++) {
		if (id[i] !== '0') {
			beg = i;
			break;
		}
	}

	return parseInt(id.substring(beg), 10);
};