var gutil = require('gulp-util');
var through = require('through2');

/**
 * The parameters for this function has grown during development.
 * Eventually, this function will need to be reorganized. 
 */
//  subModule, extendsRoot, externalUsingBabylon, noBabylonInit
module.exports = function (varName, config) {
    return through.obj(function (file, enc, cb) {

        var extendsAddition =
            `var __extends=this&&this.__extends||function(){var t=Object.setPrototypeOf||{__proto__:[]}instanceof Array&&function(t,o){t.__proto__=o}||function(t,o){for(var n in o)o.hasOwnProperty(n)&&(t[n]=o[n])};return function(o,n){function r(){this.constructor=o}t(o,n),o.prototype=null===n?Object.create(n):(r.prototype=n.prototype,new r)}}();
`;

        var decorateAddition = `var __decorate=this&&this.__decorate||function(e,t,r,c){var o,f=arguments.length,n=f<3?t:null===c?c=Object.getOwnPropertyDescriptor(t,r):c;if("object"==typeof Reflect&&"function"==typeof Reflect.decorate)n=Reflect.decorate(e,t,r,c);else for(var l=e.length-1;l>=0;l--)(o=e[l])&&(n=(f<3?o(n):f>3?o(t,r,n):o(t,r))||n);return f>3&&n&&Object.defineProperty(t,r,n),n};
`;

        if (file.isNull()) {
            cb(null, file);
            return;
        }

        if (file.isStream()) {
            //streams not supported, no need for now.
            return;
        }

        try {
            file.contents = Buffer.from(decorateAddition.concat(extendsAddition).concat(file.contents));
            this.push(file);
        } catch (err) {
            this.emit('error', new gutil.PluginError('gulp-decorate-and-extends', err, { fileName: file.path }));
        }
        cb();
    });
};