const { parallel, src, dest } = require( 'gulp' );
const rollup  = require( 'rollup' ).rollup;
const uglify  = require( 'rollup-plugin-uglify' ).uglify;
const babel   = require( '@rollup/plugin-babel' );
const resolve = require( '@rollup/plugin-node-resolve' ).nodeResolve;
const gzip    = require( 'gulp-gzip' );
const path    = require( 'path' );
const banner  = require( './constants/banner' );


function buildScript( type, minify ) {
	const file  = buildFilename( type, minify );
	const input = `./src/js/build/${ type }/${ type }.js`;

	const plugins = [
		resolve(),
		babel.getBabelOutputPlugin( {
			configFile: path.resolve( __dirname, '../.babelrc' ),
			allowAllFormats: true,
		} ),
	];

	if ( minify ) {
		plugins.push(
			uglify( {
				output: {
					comments: /^!/,
				},
				// mangle: {
				// 	properties: {
				// 		regex: /^_(private)_/,
				// 	},
				// },
			} ),
		);
	}

	return rollup( { input, plugins } )
		.then( bundle => {
			return bundle.write( {
				banner,
				file,
				format   : 'umd',
				name     : 'Splide',
				sourcemap: ! minify,
			} );
		} ).then( () => {
			if ( minify ) {
				return src( file )
					.pipe( gzip() )
					.pipe( dest( './dist/js/' ) );
			}
		} );
}

function buildFilename( type, minify ) {
	if ( type === 'default' ) {
		return `./dist/js/splide${ minify ? '.min' : '' }.js`;
	}

	return `./dist/js/splide-${ type }${ minify ? '.min' : '' }.js`;
}

function buildModule( format ) {
	return rollup( {
		input  : './src/js/build/module/module.js',
		plugins: [
			resolve(),
			babel.getBabelOutputPlugin( {
				presets: [
					[
						'@babel/preset-env',
						{
							modules: false,
							loose  : true,
						}
					]
				],
				allowAllFormats: true,
			} ),
		]
	} ).then( bundle => {
		return bundle.write( {
			banner,
			file  : `./dist/js/splide.${ format }.js`,
			format,
			exports: 'named',
		} );
	} );
}

exports.buildScript = parallel(
	function jsDefault() { return buildScript( 'default' ) },
	function jsMinified() { return buildScript( 'default', true ) },
);

exports.buildModule = parallel(
	function moduleCjs() { return buildModule( 'cjs' ) },
	function moduleEsm() { return buildModule( 'esm' ) },
);