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 inject       = require('gulp-inject-string');

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

        var d = new Date();
        var __DATE__ = JSON.stringify(d.toString());
        console.log("Compiling start at", __DATE__);

        var __EXTENDS__ = "";
        return gulp.src('./src/r3-*.js')
            .pipe(sort())
            .pipe(concat('r3.js'))
            .pipe(
                inject.prepend(
                    "// COMPILE TIME DEFINITIONS (Generated via gulp) \n" +
                    "var __DATE__ = " + __DATE__ + "; \n" +
                    "// END COMPILE TIME DEFINITIONS \n \n"
                )
            )
            .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'
                ]);
            })
    }
);