ENB version of webpack define plugin

enb-define.js

var vow = require('vow'),
    enb = require('enb'),
    buildFlow = enb.buildFlow || require('enb/lib/build-flow'),
    vfs = enb.asyncFS || require('enb/lib/fs/async-fs'),
    utils = require('enb-source-map/lib/utils'),
    File = require('enb-source-map/lib/file');

module.exports = buildFlow.create()
    .name('define')
    .target('target', '?.js')
    .useFileList(['vanilla.js', 'js', 'browser.js'])
    .defineOption('variables', {})
    .defineOption('sourcemap', false)
    .builder(function (sourceFiles) {
        return this._readSourceFiles(sourceFiles)
            .then(function(sources) {
                var file = new File(this.node.resolvePath(this._target), { sourceMap: this._sourcemap }),
                    variables = this._variables;

                sources.forEach(function(source) {
                    var contents = source.contents.replace(/%%%(.*?)%%%/g, function(match, varName) {
                        if (typeof variables[varName] === 'undefined') throw new Error('There is no value for', varName, 'placeholder');
                        return variables[varName];
                    });

                    file.writeFileContent(source.path, contents);
                });

                console.log('this._sourcemap', this._sourcemap);

                return this._sourcemap ?
                    utils.joinContentAndSourceMap(file.getContent(), file.getSourceMap()) :
                    file.render();
            }, this);
    })
    .methods({
        /**
         * Reads source js files.
         *
         * @protected
         * @param {FileList} files
         * @returns {FileData[]}
         */
        _readSourceFiles: function (files) {
            var node = this.node;

            return vow.all(files.map(function (file) {
                return vfs.read(file.fullname, 'utf8')
                    .then(function (contents) {
                        return {
                            path: file.fullname,
                            relPath: node.relativePath(file.fullname),
                            contents: contents
                        };
                    });
            }));
        }
    })
    .createTech();