var gulp = require('gulp'), //Gulp
    sass = require('gulp-sass'), //Sass
    browserSync = require('browser-sync'), //browser live updating
    concat = require('gulp-concat'), //files concatenation
    uglify = require('gulp-uglifyjs'), //JS minification
    cssnano = require('gulp-cssnano'), //CSS minification
    rename = require('gulp-rename'), //files renaming
    imagemin     = require('gulp-imagemin'), //images minification
    pngquant     = require('imagemin-pngquant'), //work with png
    cache        = require('gulp-cache'), //caching library
    autoprefixer = require('gulp-autoprefixer'); //add prefixes

//SASS compilation
gulp.task('sass', function(){
    return gulp.src('!app/sass/**/*.+(sass|scss)')
        .pipe(sass())
        .pipe(autoprefixer(['last 15 versions', '> 1%', 'ie 8', 'ie 7'], { cascade: true }))
        .pipe(gulp.dest('app/css'))
        .pipe(browserSync.reload({stream: true}))
});

//browser live updating
gulp.task('browser-sync', function() {
    browserSync({
        server: {
            baseDir: 'app' //server directory
        },
        notify: false
    });
});

//build and compress all scripts
gulp.task('scripts', function() {
    return gulp.src([
        // 'app/libs/jquery/dist/jquery.min.js',
        // 'app/libs/magnific-popup/dist/jquery.magnific-popup.min.js'
        ])
        .pipe(concat('libs.min.js'))
        .pipe(uglify())
        .pipe(gulp.dest('app/js'));
});

//files minification
gulp.task('css-libs', ['sass'], function() {
    return gulp.src('app/css/libs.css')
        .pipe(cssnano())
        .pipe(rename({suffix: '.min'}))
        .pipe(gulp.dest('app/css'));
});

//sass, html and js files watching
gulp.task('watch', ['browser-sync', 'css-libs', 'scripts'], function() {
    gulp.watch('app/sass/**/*.+(sass|scss)', ['sass']);
    gulp.watch('app/*.html', browserSync.reload);
    gulp.watch('app/js/**/*.js', browserSync.reload);
});

//images compressing
gulp.task('img', function() {
    return gulp.src('app/img/**/*')
        .pipe(cache(imagemin({
            interlaced: true,
            progressive: true,
            svgoPlugins: [{removeViewBox: false}],
            use: [pngquant()]
        })))
        .pipe(gulp.dest('dist/img'));
});

//transfer files into production folder
gulp.task('build', [, 'img', 'sass', 'scripts'], function() {

    var buildCss = gulp.src([
        'app/css/main.css',
        'app/css/libs.min.css'
        ])
    .pipe(gulp.dest('dist/css'))

    var buildFonts = gulp.src('app/fonts/**/*')
    .pipe(gulp.dest('dist/fonts'))

    var buildJs = gulp.src('app/js/**/*')
    .pipe(gulp.dest('dist/js'))

    var buildHtml = gulp.src('app/*.html')
    .pipe(gulp.dest('dist'));

});

gulp.task('clear', function () {
    return cache.clearAll();
})

gulp.task('default', ['watch']);