cssbuild.js

module.exports = function( grunt ) {
	var requirejs = require( 'requirejs' ),
		async = grunt.util.async;

	requirejs.define('node/print', [], function() {
		return function print(msg) {
			if (msg.substring(0, 5) === 'Error') {
				grunt.log.errorlns(msg);
				grunt.fail.warn('RequireJS failed.');
			} else {
				grunt.log.oklns(msg);
			}
		};
	});

	function expandFiles( files ) {
		return grunt.util._.pluck( grunt.file.expandMapping( files ), "src" );
	}

	grunt.registerMultiTask( 'cssbuild', 'Resolve CSS @imports and concat files', function() {
		var done = this.async(),
			_ = grunt.util._,
			options = _.clone( this.options({
				banner: ''
			})),
			banner = options.banner;

		delete options.banner;

		async.forEach( this.files,
			function( file, callback ) {
				var src = file.src[0],
					dest = file.dest;
				
				grunt.log.debug( "Building '" + src + "' -> '" + dest + "'" );

				async.series([
					function( next ) {
						// pull the includes together using require js
						requirejs.optimize(
							_.extend({
								cssIn: src,
								out: dest
							}, options
						), function( response ) {
							next();
						});
					},
					function( next ) {
						var contents = grunt.file.read( dest );
						if ( banner ) {
							contents = banner + contents;
						}
						grunt.file.write( dest, contents );
						grunt.log.writeln( "File '" + dest + "' written." );
						next();
					}
				], callback );
			}, done
		);
	});
};