h5bp/lib/layers/less.js

HTML5 boilerplate (H5BP) inspired server config for node.js

'use strict';

/** deps */
var path = require('path'),
	fs = require('fs'),
	processor = require('less'),
	CleanCSS = require('clean-css'),
	cleancss = new CleanCSS(),
	Cache = require('../cache'),
	cache = new Cache();

/**
 * Configures less layer.
 * @type {Function}
 */
module.exports = function(options) {
	var files = options.stylesheets.files,
		envDev = 'development' == process.env.NODE_ENV;

	// automatically minify in production env
	options.minify = options.minify || ('production' == options.env);

	// removes all leading slashs if any
	files = files.map(function(entry) {
		return ('/' == entry.charAt('/') ? entry.slice(1) : entry);
	});

	function cacheKey(url) {
		return url + (options.minify ? '#min' : '');
	}

	function respond(res, entry, cacheHeader) {
		res.setHeader('Content-Type', 'text/css');
		res.setHeader('X-Cache', cacheHeader);
		res.send(entry[0]);
	}

	/**
	 * The actual LESS layer, invoked for each request hit.
	 * Compiles a LESS file into a CSS file.
	 *
	 * This is meant to be used with cache busting.
	 */
	return function less(req, res, next) {
		var baseUrl = req.baseUrl.slice(1),
			url = req.url.slice(1),
			entry,
			config = {
				silent: true,
				verbose: false,
				ieCompat: true,
				compress: false,
				yuicompress: false,
				maxLineLen: -1,
				strictMaths: true,
				strictUnits: false
			};

		if (~files.indexOf(url)) {
			// cache hit!
			if (!envDev && (entry = cache.get(cacheKey(baseUrl)))) {
				respond(res, entry, 'HIT');
				return;
			}

			// cache miss
			var filename = path.join(options.root, url).replace(/\.css$/, '.less');
			fs.readFile(filename, 'utf8', function(err, content) {
				if (err) {
					next(500);
					return;
				}
				config.paths = [path.dirname(filename)];
				config.filename = filename;

				processor.render(content, config, function(err, content) {
					if (err) {
						next(500);
						return;
					}

					content = content.css;

					if (content) {
						// minify
						if (options.minify) {
							content = cleancss.minify(content).styles;
						}

						entry = cache.add(cacheKey(baseUrl));
						entry.push(content);
						respond(res, entry, 'MISS');
					}
				});
			});
		}
		else {
			next(null, req, res);
		}
	};
};