var Handlebars = require('handlebars');
var _ = require('underscore');
var less = require('less');

module.exports = function (config) {

	var sourceHead =
		'<script src="//cdnjs.cloudflare.com/ajax/libs/modernizr/2.6.2/modernizr.min.js"></script>\n' +
			'{{#if debug}}' +
			'<link href="/content/{{collection}}/{{name}}/style.css" media="all" rel="stylesheet/less" type="text/css">\n' +
			'<script src="//cdnjs.cloudflare.com/ajax/libs/less.js/1.3.3/less.min.js"></script>\n' +
			'{{else}}' +
			'<link href="/content/{{collection}}/{{name}}/style.css" media="all" rel="stylesheet" type="text/css">\n' +
			'{{/if}}';

	var sourceBody =
		'<script src="//cdnjs.cloudflare.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>\n' +
		'<script src="//cdnjs.cloudflare.com/ajax/libs/knockout/2.2.1/knockout-min.js"></script>\n' +
		'<script src="//cdnjs.cloudflare.com/ajax/libs/knockout-validation/1.0.2/knockout.validation.min.js"></script>\n' +
		'<script src="//cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/2.3.1/js/bootstrap.min.js"></script>\n' +
		'<script src="/content/{{collection}}/{{name}}/behaviour.js"></script>\n';

	var templateHead = Handlebars.compile(sourceHead);
	var templateBody = Handlebars.compile(sourceBody);


	var getCSS = function (callback) {
		contentInstance.getAllOrderedObjects('Stylesheet', function (err, dataObjects) {
			if (err) {
				return callback(err);
			}

			var stylesheets = _.map(dataObjects, function(dataObject) {
				return "\n/*	-- " + dataObject.get('title') + ' --	*/\n\n' +
					dataObject.get('body');
			}).join('\n');

			function lessCompilationError(stylesheets, err, callback){
				stylesheets  = "/*\n	-- The following ERROR(s) occurred during less compilation:\n\n" +
					err.message +
					"\n\n	-- you can add ?debug to the preview url to enable browser side less compilation." +
					"\n\n0: this is line 0 */\n" +
					stylesheets;
				return callback(null, stylesheets);
			}

			try {
				less.render(stylesheets, function (err, css) {
					if (err) {
						return lessCompilationError(stylesheets, err, callback);
					}
					return callback(err, css);
				});
			} catch (err){
				return lessCompilationError(stylesheets, err, callback);
			}
		});
	};

	var getJS = function (callback) {
		contentInstance.getAllOrderedObjects('Behaviour', function (err, dataObjects) {
			if (err) {
				return callback(err);
			}

			var scripts = _.map(dataObjects, function(dataObject) {
				return dataObject.get('body');
			}).join('\n');

			callback(null, scripts);
		});
	};

	var getPreviewHTML = function (options, content, callback) {

		var html = replaceMarkers(content, templateHead(options), templateBody(options));

		callback(null, html);
	};

	var replaceMarkers = function (html, styleMarkerReplacement, jsMarkerReplacement) {

		function replace(marker, replacement) {
			var regExp = new RegExp('<!--\\s*@@' + marker + '\\s*-->');
			if (html.match(regExp)){
				html = html.replace(regExp, replacement);
			} else {
				html = html.replace('</head>', '<script>if (typeof window.console !== "undefined"){console.log("WARNING: Missing <!--@@' + marker + '-->");}</script>\n</head>');
			}
		}

		replace('ipe_style_marker', styleMarkerReplacement);
		replace('ipe_js_marker', jsMarkerReplacement);

		return html;
	};


	return {
		getCSS: getCSS,
		getJS: getJS,
		getPreviewHTML: getPreviewHTML,
		_replaceMarkers: replaceMarkers
	};
};