frappe/rollup/watch.js

const path = require('path');
const chalk = require('chalk');
const rollup = require('rollup');
const log = console.log; // eslint-disable-line
const {
	apps_list
} = require('./rollup.utils');

const {
	get_options_for
} = require('./config');

watch_assets();

function watch_assets() {
	let watchOptions = [];
	apps_list.map(app => {
		watchOptions.push(...get_watch_options(app));
	});
	log(chalk.green(`\nRollup Watcher Started`));
	let watcher = rollup.watch(watchOptions);

	watcher.on('event', event => {
		switch(event.code) {
			case 'START': {
				log(chalk.yellow(`\nWatching...`));
				break;
			}

			case 'BUNDLE_START': {
				const output = event.output[0];
				if (output.endsWith('.js')) {
					log('Rebuilding', path.basename(event.output[0]));
				}
				break;
			}

			default: break;
		}
	});
}

function get_watch_options(app) {
	const options = get_options_for(app);

	return options.map(({ inputOptions, outputOptions, output_file}) => {
		return Object.assign({}, inputOptions, {
			output: outputOptions,
			plugins: [log_css_change({output: output_file})].concat(inputOptions.plugins)
		});
	});
}

function log_css_change({output}) {
	return {
		name: 'log-css-change',
		ongenerate() {
			if (!output.endsWith('.css')) return null;
			log('Rebuilding', path.basename(output));
			return null;
		}
	};
}