Add screenshot server

og-screenshot/src/screenshot.ts

@@ -0,0 +1,86 @@
+import { chromium, type Browser, type BrowserContext } from 'playwright';
+
+const VIEWPORT = { width: 1200, height: 630 };
+const NAVIGATION_TIMEOUT = 15_000;
+const TILE_BUFFER_MS = 500;
+const MAX_CONCURRENT = 2;
+
+let browser: Browser | null = null;
+let concurrency = 0;
+const queue: Array<{ resolve: () => void }> = [];
+
+async function ensureBrowser(): Promise<Browser> {
+  if (!browser || !browser.isConnected()) {
+    browser = await chromium.launch({
+      args: [
+        '--no-sandbox',
+        '--disable-dev-shm-usage',
+        '--use-gl=angle',
+        '--use-angle=swiftshader',
+      ],
+    });
+  }
+  return browser;
+}
+
+async function acquireSlot(): Promise<void> {
+  if (concurrency < MAX_CONCURRENT) {
+    concurrency++;
+    return;
+  }
+  return new Promise<void>((resolve) => {
+    queue.push({ resolve });
+  });
+}
+
+function releaseSlot(): void {
+  concurrency--;
+  const next = queue.shift();
+  if (next) {
+    concurrency++;
+    next.resolve();
+  }
+}
+
+export async function takeScreenshot(url: string): Promise<Buffer> {
+  await acquireSlot();
+  let context: BrowserContext | null = null;
+
+  try {
+    const instance = await ensureBrowser();
+    context = await instance.newContext({
+      viewport: VIEWPORT,
+      deviceScaleFactor: 1,
+    });
+    const page = await context.newPage();
+
+    await page.goto(url, { waitUntil: 'networkidle', timeout: NAVIGATION_TIMEOUT });
+
+    // Wait for the frontend to signal readiness
+    try {
+      await page.waitForFunction('window.__og_ready === true', {
+        timeout: NAVIGATION_TIMEOUT,
+      });
+    } catch {
+      // Proceed anyway — partial screenshot is better than nothing
+    }
+
+    // Extra buffer for map tiles to finish rendering
+    await page.waitForTimeout(TILE_BUFFER_MS);
+
+    const screenshot = await page.screenshot({ type: 'png' });
+    return Buffer.from(screenshot);
+  } finally {
+    if (context) {
+      await context.close().catch(() => {});
+    }
+    releaseSlot();
+  }
+}
+
+export async function closeBrowser(): Promise<void> {
+  if (browser) {
+    await browser.close().catch(() => {});
+    browser = null;
+  }
+}