import express from "express";
import { Application, Request, Response, NextFunction } from 'express';
import * as http from 'http';
import config from './config';
import { Cluster } from 'puppeteer-cluster';
const puppeteerConfig = require('../puppeteer.config.json');
if (config.PUPPETEER.EXEC_PATH) {
puppeteerConfig.executablePath = config.PUPPETEER.EXEC_PATH;
}
class Server {
private server: http.Server | undefined;
private app: Application;
cluster?: Cluster;
mempoolHost: string;
constructor() {
this.app = express();
this.mempoolHost = config.MEMPOOL.HTTP_HOST + (config.MEMPOOL.HTTP_PORT ? ':' + config.MEMPOOL.HTTP_PORT : '');
this.startServer();
}
async startServer() {
this.app
.use((req: Request, res: Response, next: NextFunction) => {
res.setHeader('Access-Control-Allow-Origin', '*');
next();
})
.use(express.urlencoded({ extended: true }))
.use(express.text())
;
this.cluster = await Cluster.launch({
concurrency: Cluster.CONCURRENCY_CONTEXT,
maxConcurrency: config.PUPPETEER.CLUSTER_SIZE,
puppeteerOptions: puppeteerConfig,
});
await this.cluster?.task(async (args) => { return this.renderPreviewTask(args) });
this.setUpRoutes();
this.server = http.createServer(this.app);
this.server.listen(config.SERVER.HTTP_PORT, () => {
console.log(`Mempool Unfurl Server is running on port ${config.SERVER.HTTP_PORT}`);
});
}
setUpRoutes() {
this.app.get('/render*', async (req, res) => { return this.renderPreview(req, res) })
this.app.get('*', (req, res) => { return this.renderHTML(req, res) })
}
async renderPreviewTask({ page, data: url }) {
await page.goto(url, { waitUntil: "domcontentloaded" });
await page.evaluate(async () => {
// wait for all images to finish loading
const imgs = Array.from(document.querySelectorAll("img"));
await Promise.all([
document.fonts.ready,
...imgs.map((img) => {
if (img.complete) {
if (img.naturalHeight !== 0) return;
throw new Error("Image failed to load");
}
return new Promise((resolve, reject) => {
img.addEventListener("load", resolve);
img.addEventListener("error", reject);
});
}),
]);
});
return page.screenshot();
}
async renderPreview(req, res) {
try {
const img = await this.cluster?.execute(this.mempoolHost + req.params[0]);
res.contentType('image/png');
res.send(img);
} catch (e) {
console.log(e);
res.status(500).send(e instanceof Error ? e.message : e);
}
}
renderHTML(req, res) {
let lang = '';
let path = req.originalUrl
// extract the language setting (if any)
const parts = path.split(/^\/(ar|bg|bs|ca|cs|da|de|et|el|es|eo|eu|fa|fr|gl|ko|hr|id|it|he|ka|lv|lt|hu|mk|ms|nl|ja|nb|nn|pl|pt|pt-BR|ro|ru|sk|sl|sr|sh|fi|sv|th|tr|uk|vi|zh|hi)\//)
if (parts.length > 1) {
lang = "/" + parts[1];
path = "/" + parts[2];
}
const ogImageUrl = config.SERVER.HOST + '/render' + lang + "/preview" + path;
res.send(`
mempool - Bitcoin Explorer
`);
}
}
const server = new Server();