create API for exporting

src/api/export.ts

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+import * as child_process from 'child_process';
+import * as path from 'path';
+import * as sander from 'sander';
+import cheerio from 'cheerio';
+import URL from 'url-parse';
+import fetch from 'node-fetch';
+import * as ports from 'port-authority';
+import { EventEmitter } from 'events';
+import { minify_html } from './utils/minify_html';
+import { locations } from '../config';
+
+export default function exporter(opts: {}) {
+	const emitter = new EventEmitter();
+
+	execute(emitter, opts).then(
+		() => {
+			emitter.emit('done', {}); // TODO do we need to pass back any info?
+		},
+		error => {
+			emitter.emit('error', {
+				error
+			});
+		}
+	);
+
+	return emitter;
+}
+
+async function execute(emitter: EventEmitter, {
+	build = 'build',
+	dest = 'export',
+	basepath = ''
+} = {}) {
+	const export_dir = path.join(dest, basepath);
+
+	// Prep output directory
+	sander.rimrafSync(export_dir);
+
+	sander.copydirSync('assets').to(export_dir);
+	sander.copydirSync(build, 'client').to(export_dir, 'client');
+
+	if (sander.existsSync(build, 'service-worker.js')) {
+		sander.copyFileSync(build, 'service-worker.js').to(export_dir, 'service-worker.js');
+	}
+
+	if (sander.existsSync(build, 'service-worker.js.map')) {
+		sander.copyFileSync(build, 'service-worker.js.map').to(export_dir, 'service-worker.js.map');
+	}
+
+	const port = await ports.find(3000);
+
+	const origin = `http://localhost:${port}`;
+
+	const proc = child_process.fork(path.resolve(`${build}/server.js`), [], {
+		cwd: process.cwd(),
+		env: Object.assign({
+			PORT: port,
+			NODE_ENV: 'production',
+			SAPPER_DEST: build,
+			SAPPER_EXPORT: 'true'
+		}, process.env)
+	});
+
+	const seen = new Set();
+	const saved = new Set();
+
+	proc.on('message', message => {
+		if (!message.__sapper__) return;
+
+		let file = new URL(message.url, origin).pathname.slice(1);
+		let { body } = message;
+
+		if (saved.has(file)) return;
+		saved.add(file);
+
+		const is_html = message.type === 'text/html';
+
+		if (is_html) {
+			file = file === '' ? 'index.html' : `${file}/index.html`;
+			body = minify_html(body);
+		}
+
+		emitter.emit('file', {
+			file,
+			size: body.length
+		});
+
+		sander.writeFileSync(export_dir, file, body);
+	});
+
+	async function handle(url: URL) {
+		const r = await fetch(url.href);
+		const range = ~~(r.status / 100);
+
+		if (range >= 4) {
+			emitter.emit('failure', {
+				status: r.status,
+				pathname: url.pathname
+			});
+			return;
+		}
+
+		if (range === 2) {
+			if (r.headers.get('Content-Type') === 'text/html') {
+				const body = await r.text();
+				const $ = cheerio.load(body);
+				const urls: URL[] = [];
+
+				const base = new URL($('base').attr('href') || '/', url.href);
+
+				$('a[href]').each((i: number, $a) => {
+					const url = new URL($a.attribs.href, base.href);
+
+					if (url.origin === origin && !seen.has(url.pathname)) {
+						seen.add(url.pathname);
+						urls.push(url);
+					}
+				});
+
+				for (const url of urls) {
+					await handle(url);
+				}
+			}
+		}
+	}
+
+	return ports.wait(port)
+		.then(() => handle(new URL(`/${basepath}`, origin))) // TODO all static routes
+		.then(() => proc.kill());
+}