Clean up screenshot capture code

app/screenshots/HttpServer.mjs

@@ -10,7 +10,7 @@ export default class HttpServer
     return this.#server.address().port;
   }
 
-  start() {
+  open() {
     return new Promise((resolve, reject) => {
       if (this.#server) {
         return resolve();
@@ -23,7 +23,7 @@ export default class HttpServer
     });
   }
 
-  async stop() {
+  async close() {
     if (this.#server) {
       await this.#server.close();
       this.#server = null;

app/screenshots/ScreenshotHelper.mjs

@@ -0,0 +1,94 @@
+import { URL } from 'url';
+import puppeteer from 'puppeteer';
+import HttpServer from './HttpServer.mjs';
+
+const defaultViewport = {
+  // Using a 16:9 ratio here by default to match Twitter's image card dimensions
+  width: 1200,
+  height: 675,
+  deviceScaleFactor: 2,
+};
+
+export default class ScreenshotHelper
+{
+  /** @type {HttpServer} */
+  #httpServer = null;
+  /** @type {puppeteer.Browser} */
+  #browser = null;
+  /** @type {puppeteer.Page} */
+  #page = null;
+  /** @type {puppeteer.Viewport} */
+  #viewport = null;
+
+  get isOpen() {
+    return !!this.#browser;
+  }
+
+  /** @type {puppeteer.Page} */
+  get page() {
+    return this.#page;
+  }
+
+  async open() {
+    await this.close();
+
+    // Start the HTTP server
+    this.#httpServer = new HttpServer;
+    await this.#httpServer.open();
+
+    // Launch a new Chrome instance
+    this.#browser = await puppeteer.launch({
+      args: [
+        '--no-sandbox', // Allow running as root inside the Docker container
+      ],
+      // headless: false, // For testing
+    });
+
+    // Create a new page and set the viewport
+    this.#page = await this.#browser.newPage();
+    await this.setViewport();
+  }
+
+  async setViewport(viewport = {}) {
+    this.#viewport = { ...defaultViewport, viewport };
+
+    if (this.#page) {
+      await this.#page.setViewport(this.#viewport);
+    }
+  }
+
+  async capture(path, options = {}) {
+    if (!this.isOpen) {
+      await this.open();
+    }
+
+    await this.setViewport(options.viewport);
+
+    // Navigate to the URL
+    let url = new URL(`http://localhost:${this.#httpServer.port}/screenshots/`);
+    url.hash = path;
+    await this.#page.goto(url, {
+        waitUntil: 'networkidle0', // Wait until the network is idle
+    });
+
+    // Take the screenshot
+    return await this.#page.screenshot();
+  }
+
+  async close() {
+    if (this.#httpServer) {
+      await this.#httpServer.close();
+    }
+    this.#httpServer = null;
+
+    if (this.#page) {
+      await this.#page.close();
+    }
+    this.#page = null;
+
+    if (this.#browser) {
+      await this.#browser.close();
+    }
+    this.#browser = null;
+  }
+}

app/screenshots/captureScreenshot.mjs

@@ -1,44 +0,0 @@
-import { URL } from 'url';
-import puppeteer from 'puppeteer';
-import HttpServer from './HttpServer.mjs';
-
-const defaultViewport = {
-    // Using a 16:9 ratio here by default to match Twitter's image card dimensions
-    width: 1200,
-    height: 675,
-    deviceScaleFactor: 2,
-};
-
-export async function captureScreenshot(path, options = {}) {
-  const httpServer = new HttpServer;
-  await httpServer.start();
-
-  // Launch a new Chrome instance
-  const browser = await puppeteer.launch({
-    args: [
-      '--no-sandbox', // Allow running as root inside the Docker container
-    ],
-    // headless: false, // For testing
-  });
-
-  // Create a new page and set the viewport
-  const page = await browser.newPage();
-  const viewport = { ...defaultViewport, ...options.viewport };
-  await page.setViewport(viewport);
-
-  // Navigate to the URL
-  let url = new URL(`http://localhost:${httpServer.port}/screenshots/`);
-  url.hash = path;
-  await page.goto(url, {
-      waitUntil: 'networkidle0', // Wait until the network is idle
-  });
-
-  // Take the screenshot
-  let result = await page.screenshot();
-
-  // Close the browser and HTTP server
-  await browser.close();
-  await httpServer.stop();
-
-  return result;
-}

app/twitter/TwitterManager.mjs

@@ -1,17 +1,22 @@
+import ScreenshotHelper from "../screenshots/ScreenshotHelper.mjs";
 import TweetGenerator from "./generators/TweetGenerator.mjs";
 import TwitterClient from "./TwitterClient.mjs";
 
 export default class TwitterManager
 {
-  /** @var {TweetGenerator[]} */
+  /** @type {TweetGenerator[]} */
   generators;
 
-  /** @var {TwitterClient} */
+  /** @type {TwitterClient} */
   client;
 
+  /** @type {ScreenshotHelper} */
+  screenshotHelper;
+
   constructor(generators = []) {
     this.generators = generators;
     this.client = new TwitterClient;
+    this.screenshotHelper = new ScreenshotHelper;
   }
 
   async sendTweets() {
@@ -20,9 +25,11 @@ export default class TwitterManager
         continue;
       }
 
-      let tweet = await generator.getTweet();
+      let tweet = await generator.getTweet(this.screenshotHelper);
 
       await this.client.send(tweet);
     }
+
+    await this.screenshotHelper.close();
   }
 }

app/twitter/generators/CountdownTweet.mjs

@@ -1,6 +1,6 @@
 import TweetGenerator from "./TweetGenerator.mjs";
-import { captureScreenshot } from "../../screenshots/captureScreenshot.mjs";
 import Media from "../Media.mjs";
+import ScreenshotHelper from "../../screenshots/ScreenshotHelper.mjs";
 
 const releaseDate = new Date('2022-09-09');
 
@@ -25,9 +25,10 @@ export default class CountdownTweet extends TweetGenerator
     }
   }
 
-  async _getMedia() {
+  /** @param {ScreenshotHelper} screenshotHelper */
+  async _getMedia(screenshotHelper) {
     let media = new Media;
-    media.file = await captureScreenshot('countdown');
+    media.file = await screenshotHelper.capture('countdown');
 
     return media;
   }

app/twitter/generators/TweetGenerator.mjs

@@ -1,3 +1,4 @@
+import ScreenshotHelper from '../../screenshots/ScreenshotHelper.mjs';
 import Tweet from '../Tweet.mjs';
 
 export default class TweetGenerator
@@ -6,11 +7,12 @@ export default class TweetGenerator
     return true;
   }
 
-  async getTweet() {
+  /** @param {ScreenshotHelper} screenshotHelper */
+  async getTweet(screenshotHelper) {
     const tweet = new Tweet;
     tweet.status = await this._getStatus();
 
-    let media = await this._getMedia();
+    let media = await this._getMedia(screenshotHelper);
     if (media && !Array.isArray(media)) {
       media = [media];
     }
@@ -23,7 +25,8 @@ export default class TweetGenerator
     //
   }
 
-  async _getMedia() {
+  /** @param {ScreenshotHelper} screenshotHelper */
+  async _getMedia(screenshotHelper) {
     //
   }
 }