closure-compiler-modules.js

module.exports = function(grunt) {

    'use strict';

    var exec = require('child_process').exec,
        fs = require('fs'),
        path = require('path'),
        gzip = require('zlib').gzip;

    // ==========================================================================
    // TASKS
    // ==========================================================================

    grunt.registerMultiTask('closure-compiler', 'Minify JS files using Closure Compiler.', function() {

        var closurePath = '',
            reportFile = '',
            data = this.data,
            done = this.async();

        // Check for closure path.
        if (data.closurePath) {
            closurePath = data.closurePath;
        } else if (process.env.CLOSURE_PATH) {
            closurePath = process.env.CLOSURE_PATH;
        } else {
            grunt.log.error('' +
                '/!\\'.red +
                ' Set an environment variable called ' +
                'CLOSURE_PATH'.red + ' or the build parameter' + 'closurePath'.red +
                ' and\nmake it point to your root install of Closure Compiler.' +
                '\n');
            return false;
        }

        var command = 'java -jar "' + closurePath + '/build/compiler.jar"';

        data.cwd = data.cwd || './';

        var output_mode;

        // --module mode
        if ("modules" in data) {
            output_mode = 'modules';
        } else { // --js mode
            output_mode = 'js';

            data.js = grunt.file.expand({
                cwd: data.cwd
            }, data.js);

            // Sanitize options passed.
            if (!data.js.length) {
                // This task requires a minima an input file.
                grunt.warn('Missing js property.');
                return false;
            }

            // Build command line.
            command += ' --js "' + data.js.join('" --js "') + '"';

            if (data.jsOutputFile) {
                if (!grunt.file.isPathAbsolute(data.jsOutputFile)) {
                    data.jsOutputFile = path.resolve('./') + '/' + data.jsOutputFile;
                }
                command += ' --js_output_file "' + data.jsOutputFile + '"';
                reportFile = data.reportFile || data.jsOutputFile + '.report.txt';
            }
        }

        if (data.externs) {
            data.externs = grunt.file.expand(data.externs);
            command += ' --externs ' + data.externs.join(' --externs ');

            if (!data.externs.length) {
                delete data.externs;
            }
        }

        if (data.options.externs) {
            data.options.externs = grunt.file.expand(data.options.externs);

            if (!data.options.externs.length) {
                delete data.options.externs;
            }
        }

        for (var directive in data.options) {
            if (Array.isArray(data.options[directive])) {
                command += ' --' + directive + ' ' + data.options[directive].join(' --' + directive + ' ');
            } else if (data.options[directive] === undefined || data.options[directive] === null) {
                command += ' --' + directive;
            } else {
                command += ' --' + directive + ' "' + String(data.options[directive]) + '"';
            }
        }

        if (output_mode === 'js') {
            // because closure compiler does not create dirs.
            grunt.file.write(data.jsOutputFile, '');
        } else { // modules

            for (var module in data.modules) {

                data.modules[module].src.forEach(function(src) {
                    command += ' --js "' + src + '"';
                });

                command += ' --chunk "' + module + ':' + data.modules[module].src.length + ':';

                // add dependency
                if (data.modules[module].dep) {
                    command += data.modules[module].dep.join(',');
                    command += ':';
                }
                command += '"';

                // @todo add --define option for modules
                if (data.modules[module].define) {
                    if (typeof data.modules[module].define === 'object') {
                        var value;
                        for (var key in data.modules[module].define) {
                            if (data.modules[module].define.hasOwnProperty(key)) {

                                value = data.modules[module].define[key];

                                command += ' --define="' + String(key) + '=';
                                if (typeof value === 'boolean') {
                                    command += data.modules[module].define[key];
                                } else if (!isNaN(parseFloat(data.modules[module].define[key]))) {
                                    command += String(data.modules[module].define[key]);
                                } else {
                                    // escape quotes
                                    command += '\'' + String(data.modules[module].define[key]).replace(/'/g, '\\\'').replace(/"/g, '\\"') + '\'';
                                }

                                command += '"';
                            }
                        }
                    }
                }

                command += ' --assume_function_wrapper';
                command += ' --isolation_mode IIFE';
            }

            // module output directory
            command += ' --chunk_output_path_prefix ' + data.moduleOutputPath;

        }

        // Minify WebGraph class.
        exec(command, {
            maxBuffer: data.maxBuffer * 1024,
            cwd: data.cwd
        }, function(err, stdout, stderr) {
            if (err) {
                grunt.warn(err);
                done(false);
            }

            if (stdout) {
                grunt.log.writeln(stdout);
            }

            var p = [];
            for (var module in data.modules) {

                // If OK, calculate gzipped file size.
                //if (reportFile.length) {
                (function(module) {
                    p.push(new Promise(function(resolve, reject) {
                        var min = fs.readFileSync(data.moduleOutputPath + module + '.js', 'utf8');
                        min_info(module + '.js', min, function(err) {
                            if (err) {
                                grunt.warn(err);
                                done(false);
                            }

                            //if (data.noreport) {
                            /*} else {
                                // Write compile report to a file.
                                fs.writeFile(reportFile, stderr, function(err) {
                                    if (err) {
                                        grunt.warn(err);
                                        done(false);
                                    }

                                    grunt.log.writeln('A report is saved in ' + reportFile + '.');
                                    done();
                                });
                            }*/

                        });
                    }));
                })(module);
            }

            Promise.all(p).then(done);
            /*} else {
                if (data.report) {
                    grunt.log.error(stderr);
                }
                done();
            }*/

        });

    });

    // Output some size info about a file.
    function min_info(name, min, onComplete) {
        gzip(min, function(err, buffer) {
            if (err) {
                onComplete.call(this, err);
            }

            var gzipSize = buffer.toString().length;
            grunt.log.writeln(name, 'Size: ' + String((min.length / 1024).toFixed(2)).green + ' kb (' + String(min.length).green + ' bytes) Gzip: ' + String((gzipSize / 1024).toFixed(2)).green + ' kb (' + String(gzipSize).green + ' bytes).');

            onComplete.call(this, null);
        });
    }

};