gulp.task('build', function (done) {
    
    gulp.src('./source/**/*.js')
        .pipe(sourcemaps.init())
        // transform the files here.
        // .pipe(include({ hardFail: true})).on('error', console.log)            
        .pipe(insert.transform(function (contents, file) {
            // console.log(file);
            contents = contents.replace(/require\(['"]!([\.\/\\\w\d\-_]+)['"]\)/g, function (match, group, index, content) {
                // console.log(arguments);
                if (!fs.existsSync(group)) console.warn(`File "${group}" does not exists`);
                else {
                    return '`' + fs.readFileSync(group).toString().replace(/`/g, '\\`') + '`';
                }
            });
            return contents
        })).on('finish', () => {
            console.log('files prepared...');
        })        
        .pipe(rollup({
            // any option supported by Rollup can be set here.
            ...config,
            allowRealFiles: true,
        })).on('error', function() {
            console.log(arguments);
        })
        .pipe(sourcemaps.write())

        .pipe(gulp.dest('./build')).on('finish', function() {
            done()
        });
    
})

// Usage: 

export const libs = {
    

    "/dom.d.ts": require('!./ts/typescript/libs/lib.dom.d.ts'),
    "/lib.es5.d.ts": require('!./ts/typescript/libs/lib.es5.d.ts'),    
    "/lib.es2015.core.d.ts": require('!./ts/typescript/libs/lib.es2015.core.d.ts'),
    "/lib.es2015.collection.d.ts": require('!./ts/typescript/libs/lib.es2015.collection.d.ts'),
    "/lib.es2015.promise.d.ts": require('!./ts/typescript/libs/lib.es2015.promise.d.ts'),
    
    "/lib.es2015.d.ts": require('!./ts/typescript/libs/lib.es2015.d.ts'),
    "/es2015.d.ts": require('!./ts/typescript/libs/lib.es2015.d.ts'),

    // "tsconfig.json": '{"lib": ["dom"]}'
};