var utils = {
	generateUUID: function() {
		return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function(c) {
			var r = Math.random()*16|0, v = c == 'x' ? r : (r&0x3|0x8);
			return v.toString(16);
		});
	},
	
	relativeTime: function(timestamp) {
		var	now = +new Date(),
			difference = now - Math.floor(parseFloat(timestamp));

		difference = Math.floor(difference / 1000);
		
		if (difference < 60) return difference + ' second' + (difference !== 1 ? 's' : '');
		
		difference = Math.floor(difference / 60);
		if (difference < 60) return difference + ' minute' + (difference !== 1 ? 's' : '');

		difference = Math.floor(difference / 60);
		if (difference < 24) return difference + ' hour' + (difference !== 1 ? 's' : '');

		difference = Math.floor(difference / 24);
		if (difference < 30) return difference + ' day' + (difference !== 1 ? 's' : '');

		difference = Math.floor(difference / 30);
		if (difference < 12) return difference + ' month' + (difference !== 1 ? 's' : '');

		difference = Math.floor(difference / 12);
		return difference + ' year' + (difference !== 1 ? 's' : '');
	},
	
	//http://dense13.com/blog/2009/05/03/converting-string-to-slug-javascript/
	slugify: function(str) {
		str = str.replace(/^\s+|\s+$/g, ''); // trim
		str = str.toLowerCase();

		// remove accents, swap ñ for n, etc
		var from = "àáäâèéëêìíïîòóöôùúüûñç·/_,:;";
		var to   = "aaaaeeeeiiiioooouuuunc------";
		for (var i=0, l=from.length ; i<l ; i++) {
			str = str.replace(new RegExp(from.charAt(i), 'g'), to.charAt(i));
		}

		str = str.replace(/[^a-z0-9 -]/g, '') // remove invalid chars
				.replace(/\s+/g, '-') // collapse whitespace and replace by -
				.replace(/-+/g, '-'); // collapse dashes

		return str;
	},

	// Willingly stolen from: http://phpjs.org/functions/strip_tags/
	'strip_tags': function(input, allowed) {
		allowed = (((allowed || "") + "").toLowerCase().match(/<[a-z][a-z0-9]*>/g) || []).join(''); // making sure the allowed arg is a string containing only tags in lowercase (<a><b><c>)
		var	tags = /<\/?([a-z][a-z0-9]*)\b[^>]*>/gi,
			commentsAndPhpTags = /<!--[\s\S]*?-->|<\?(?:php)?[\s\S]*?\?>/gi;

		return input.replace(commentsAndPhpTags, '').replace(tags, function ($0, $1) {
			return allowed.indexOf('<' + $1.toLowerCase() + '>') > -1 ? $0 : '';
		});
	}
}

module.exports = utils;