Separate build step (closes #21)

lib/utils/create_watcher.js

@@ -0,0 +1,63 @@
+const path = require('path');
+const chalk = require('chalk');
+const compilers = require('./compilers.js');
+const generate_asset_cache = require('./generate_asset_cache.js');
+
+function deferred() {
+	const d = {};
+
+	d.promise = new Promise((fulfil, reject) => {
+		d.fulfil = fulfil;
+		d.reject = reject;
+	});
+
+	return d;
+}
+
+module.exports = function create_watcher() {
+	const deferreds = {
+		client: deferred(),
+		server: deferred()
+	};
+
+	const invalidate = () => Promise.all([
+		deferreds.client.promise,
+		deferreds.server.promise
+	]).then(([client_stats, server_stats]) => {
+		return generate_asset_cache(
+			client_stats.toJson(),
+			server_stats.toJson()
+		);
+	});
+
+	watcher = {
+		ready: invalidate()
+	};
+
+	function watch_compiler(type) {
+		const compiler = compilers[type];
+
+		compiler.plugin('invalid', filename => {
+			console.log(chalk.red(`${type} bundle invalidated, file changed: ${chalk.bold(filename)}`));
+			deferreds[type] = deferred();
+			watcher.ready = invalidate();
+		});
+
+		compiler.plugin('failed', err => {
+			deferreds[type].reject(err);
+		});
+
+		compiler.watch({}, (err, stats) => {
+			if (stats.hasErrors()) {
+				deferreds[type].reject(stats.toJson().errors[0]);
+			} else {
+				deferreds[type].fulfil(stats);
+			}
+		});
+	}
+
+	watch_compiler('client');
+	watch_compiler('server');
+
+	return watcher;
+};