var gulp         = require('gulp');
var concat       = require('gulp-concat');
var sort         = require('gulp-sort');
var minify       = require('gulp-minify');
var watch        = require('gulp-watch');
var replace      = require('gulp-string-replace');

gulp.task(
    'build',
    function() {
        return gulp.src('./src/r3-*.js')
            .pipe(sort())
            .pipe(concat('r3.js'))
            .pipe(
                replace(new RegExp('__DATE__', 'g'), function (replacement) {
                    return JSON.stringify(new Date().toString());
                })
            )
            .pipe(minify({
                ext:{
                    src:'.js',
                    min:'-min.js'
                }
            }))
            .pipe(gulp.dest('./build/'));
    }
);

gulp.task(
    'default',
    gulp.series('build'),
    function() {
        return watch([
                'src/*.js'
            ],
            function() {
                gulp.start([
                    'merge'
                ]);
            })
    }
);