gulpfile.js

var express = require('express');
var gulp = require('gulp');
var bower = require('gulp-bower');
var concat = require('gulp-concat');
var less = require('gulp-less');
var rimraf = require('rimraf');
var browserify = require('gulp-browserify');
var sequence = require('run-sequence');
var gutil = require('gulp-util');

var SOURCE_DIR = 'src';
var BUILD_TARGET_DIR_SCRIPT = 'frontend/script';
var BUILD_TARGET_DIR_STYLE = 'frontend/style';
var REVEAL_TARGET_DIR = 'frontend/slides/reveal';

gulp.task('clean', function (callback) {
    rimraf(BUILD_TARGET_DIR_SCRIPT, function (error) {
        if (error) return callback(error);

        rimraf(BUILD_TARGET_DIR_STYLE, function(error) {
            if (error) return callback(error);

            rimraf(REVEAL_TARGET_DIR, callback);
        });
    });
});

////////////////////////////////////////////////////// script //////////////////////////////////////////////////

gulp.task('scripts', function () {
    return gulp
        .src(SOURCE_DIR + '/js/app.js')
        .pipe(browserify()).on('error', gutil.log)
        .pipe(gulp.dest(BUILD_TARGET_DIR_SCRIPT));
});

gulp.task('bower_components', function () {
    return bower();
});

gulp.task('libscripts', ['bower_components'], function () {
    return gulp.src([
        'bower_components/jquery/dist/jquery.min.js',
        'bower_components/fabric/dist/fabric.min.js'
    ])
        .pipe(concat('vendor.js'))
        .pipe(gulp.dest(BUILD_TARGET_DIR_SCRIPT));
});

////////////////////////////////////////////////////// style //////////////////////////////////////////////////

gulp.task('style', ['bower_components'], function () {
    return gulp
        .src(['bower_components/bootstrap/dist/css/bootstrap.css'])
        .pipe(concat('external.css'))
        .pipe(gulp.dest(BUILD_TARGET_DIR_STYLE));
});

gulp.task('style_app', function () {
    return gulp
        .src(SOURCE_DIR + '/style/style.less')
        .pipe(less()).on('error', gutil.log)
        .pipe(gulp.dest(BUILD_TARGET_DIR_STYLE));
});

////////////////////////////////////////////////////// slides //////////////////////////////////////////////////

gulp.task('reveal', ['libscripts'], function () {
    return gulp.src('bower_components/reveal.js/**')
        .pipe(gulp.dest(REVEAL_TARGET_DIR));
});

gulp.task('staticserve', function (callback) {
    var port = 8080;

    express()
        .use(express.static(require('path').join(__dirname, 'frontend')))
        .listen(port, function(error) {
            if (error) throw new Error(error);

            console.log('static server running, visit http://localhost:' + port);

            callback();
        });
});

////////////////////////////////////////////////////// manage //////////////////////////////////////////////////

gulp.task('dev', ['staticserve'], function (callback) {
    build(function () {
        gulp.watch(SOURCE_DIR + '/js/**/*.js', ['scripts']);
        gulp.watch(SOURCE_DIR + '/style/**/*.less', ['style_app']);

        callback();
    });
});

gulp.task('build', function (callback) {
    build(callback);
});

gulp.task('serve', function (callback) {
    sequence('build', 'staticserve', callback);
});

function build (callback) {
    sequence('clean', ['style', 'style_app', 'libscripts', 'scripts', 'reveal'], callback);
}