pack.js

var encoding = 'utf-8';
var path = require('path');
var fs = require("fs");
var cleanCSS = require('clean-css');
var less = require("less");

module.exports = function() {
    return {
        onPackCallback: null,
        asset: null,
        css: function(files) {
            try {
                var content = this.mergeFiles(files);
                if(this.asset.minify) content = cleanCSS.process(content);
                this.output(content);
            } catch (err) {
                console.log("Error packing CSS", err);
            }
        },
        js: function(files) {
            try {
                var content = this.mergeFiles(files);
                if(this.asset.minify) {
                    var jsp = require("uglify-js").parser;
                    var pro = require("uglify-js").uglify;
                    var ast = jsp.parse(content); // parse code and get the initial AST
                    ast = pro.ast_mangle(ast); // get a new AST with mangled names
                    ast = pro.ast_squeeze(ast); // get an AST with compression optimizations
                    content = pro.gen_code(ast); // compressed code here
                }
                this.output(content);
            } catch (err) {
                for(var i=0; i<files.length; i++) {
                    try {
                        var file = files[i];
                        file = path.normalize(process.cwd() + '/' + file);
                        var content = fs.readFileSync(file, encoding);
                        var jsp = require("uglify-js").parser;
                        var pro = require("uglify-js").uglify;
                        var ast = jsp.parse(content); // parse code and get the initial AST
                        ast = pro.ast_mangle(ast); // get a new AST with mangled names
                        ast = pro.ast_squeeze(ast); // get an AST with compression optimizations
                        content = pro.gen_code(ast); // compressed code here
                    } catch(singleFileErr) {
                        console.log("Error packing JavaScript", {message: singleFileErr.message, line: singleFileErr.line, file: files[i]});
                    }
                }
            }            
        },
        less: function() {
            try {
                var lessConfig = {},
                    self = this;
                fs.readFile(process.cwd() + "/" + this.asset.pack, 'utf8', function(err, indexless) {
                    if(err) throw err;
                    var parser = new(less.Parser)({ 
                        paths: [process.cwd() +"/" + self.asset.watch],
                        rootpath: process.cwd() + "/" + path.dirname(self.asset.pack),
                        relativeUrls: false,
                        strictImports: false
                    });
                    parser.parse(indexless, function (err, tree) {
                        if (err) {
                            console.log("Error packing LESS", {message: err.message, line: err.line, file: err.filename});
                            return;
                        }
                        content = tree.toCSS({
                            compress: self.asset.minify,
                            yuicompress: self.asset.minify
                        });
                        self.output(content);
                    });
                });
            } catch(err) {
                console.log("Error packing LESS", err);
            }
        },
        def: function(files) {
            try {
                var content = this.mergeFiles(files);
                this.output(content);
            } catch(err) {
                console.log("Error packing", err);
            }
        },
        mergeFiles: function(files) {
            var content = files.map(function(file) {
                file = path.normalize(process.cwd() + '/' + file);
                return fs.readFileSync(file, encoding);
            });
            content = content.join('\n');
            return content;
        },
        output: function(content) {
            console.log("----- save: " + this.asset.output);
            fs.writeFileSync(process.cwd() + '/' + this.asset.output, content);
            if(this.onPackCallback) this.onPackCallback(this.asset.output);
        },
        packit: function(a, files, callback) {
            if(!Array.isArray(files)) files = [files];
            this.asset = a;
            this.onPackCallback = callback;
            if(this[this.asset.type]) {
                this[this.asset.type](files);
            } else {
                this.def(files);
            }
        }
    }
}