var gulp        = require('gulp');
var browserSync = require('browser-sync').create();
var path        = require('path');
var fs          = require('fs');
var sourcemaps  = require('gulp-sourcemaps');
var source      = require('vinyl-source-stream');
var buffer      = require('vinyl-buffer');
var browserify  = require('browserify');
var watchify    = require('watchify');
var babel       = require('babelify');
var exit        = require('gulp-exit');

//
// Vars

var _publicDir = './public';
var _sourceDir = './source';

var _scriptSource = _sourceDir + '/js';
var _scriptPublic = _publicDir + '/js';

//
// Babel

function compile(watch) {

    var bundler = bundler = watchify(
        browserify({
            // Define the entry point for our application
            entries: [_scriptSource + '/main.js'],
            // Debugging is nice
            debug: true,
            // Allow importing from the following extensions
            extensions: [' ', 'js']
        }).transform(babel.configure({
            // Use all of the ES2015 spec
            presets: ["es2015"]
        }))
    );

    function rebundle() {
        return bundler.bundle()
            .on('error', function(err) { console.error(err); this.emit('end'); })
            .pipe(source('main.js'))
            .pipe(buffer())
            .pipe(sourcemaps.init({ loadMaps: true }))
            .pipe(sourcemaps.write('./'))
            .pipe(gulp.dest(_scriptPublic))
            .pipe(browserSync.stream());
    }

    if (watch) {

        bundler.on('update', function() {
            console.log('-> re-bundling...');
            rebundle();

        });

        rebundle()

    }else {
        rebundle().pipe(exit());
    }

}

function watch() {
    return compile(true);
}

gulp.task('build',function () {

    // compile JS
    compile(false);

});