cri.ts

/**
 * cri.ts
 *
 * Chrome Remote Interface
 *
 * Copyright (c) 2022 Posit Software, PBC.
 */

import { decodeBase64 as decode } from "encoding/base64";
import cdp from "./deno-cri/index.js";
import { getBrowserExecutablePath } from "../puppeteer.ts";
import { Semaphore } from "../lib/semaphore.ts";
import { findOpenPort } from "../port.ts";
import { getNamedLifetime, ObjectWithLifetime } from "../lifetimes.ts";
import { sleep } from "../async.ts";
import { InternalError } from "../lib/error.ts";
import { getenv } from "../env.ts";
import { kRenderFileLifetime } from "../../config/constants.ts";
import { debug } from "../../deno_ral/log.ts";
import {
  registerForExitCleanup,
  unregisterForExitCleanup,
} from "../process.ts";

async function waitForServer(port: number, timeout = 3000) {
  const interval = 50;
  let soFar = 0;

  do {
    try {
      const response = await fetch(`http://localhost:${port}/json/list`);
      if (response.status !== 200) {
        throw new Error("");
      }
      return true;
    } catch (_e) {
      soFar += interval;
      await new Promise((resolve) => setTimeout(resolve, interval));
    }
  } while (soFar < timeout);
  return false;
}

const criSemaphore = new Semaphore(1);

export type CriClient = Awaited<ReturnType<typeof criClient>>;

export function withCriClient<T>(
  fn: (client: CriClient) => Promise<T>,
  appPath?: string,
  port?: number,
): Promise<T> {
  if (port === undefined) {
    port = findOpenPort(9222);
  }

  return criSemaphore.runExclusive(async () => {
    const lifetime = getNamedLifetime(kRenderFileLifetime);
    if (lifetime === undefined) {
      throw new InternalError("named lifetime render-file not found");
    }
    let client: CriClient;
    if (lifetime.get("cri-client") === undefined) {
      client = await criClient(appPath, port);
      lifetime.attach({
        client,
        async cleanup() {
          await client.close();
        },
      } as ObjectWithLifetime, "cri-client");
    } else {
      // deno-lint-ignore no-explicit-any
      client = (lifetime.get("cri-client") as any).client as CriClient;
    }

    // this must be awaited since we're in runExclusive.
    return await fn(client);
  });
}

export async function criClient(appPath?: string, port?: number) {
  if (port === undefined) {
    port = findOpenPort(9222);
  }
  const app: string = appPath || await getBrowserExecutablePath();

  // Allow to adapt the headless mode depending on the Chrome version
  const headlessMode = getenv("QUARTO_CHROMIUM_HEADLESS_MODE", "old");

  const cmd = [
    app,
    // TODO: Chrome v128 changed the default from --headless=old to --headless=new
    // in 2024-08. Old headless mode was effectively a separate browser render,
    // and while more performant did not share the same browser implementation as
    // headful Chrome. New headless mode will likely be useful to some, but in Quarto use cases
    // like printing to PDF or screenshoting, we need more work to
    // move to the new mode. We'll use `--headless=old` as the default for now
    // until the new mode is more stable, or until we really pin a version as default to be used.
    // This is also impacting in chromote and pagedown R packages and we could keep syncing with them.
    `--headless${headlessMode == "none" ? "" : "=" + headlessMode}`,
    "--no-sandbox",
    "--disable-gpu",
    "--renderer-process-limit=1",
    `--remote-debugging-port=${port}`,
  ];
  const browser = Deno.run({ cmd, stdout: "piped", stderr: "piped" });

  // Register for cleanup inside exitWithCleanup() in case something goes wrong
  const thisProcessId = registerForExitCleanup(browser);

  if (!(await waitForServer(port as number))) {
    let msg = "Couldn't find open server.";
    // Printing more error information if chrome process errored
    if (!(await browser.status()).success) {
      debug(`[CHROMIUM path]   : ${app}`);
      debug(`[CHROMIUM cmd]   : ${cmd}`);
      const rawError = await browser.stderrOutput();
      const errorString = new TextDecoder().decode(rawError);
      msg = msg + "\n" + `Chrome process error: ${errorString}`;
    }

    throw new Error(msg);
  }

  // deno-lint-ignore no-explicit-any
  let client: any;

  const result = {
    close: async () => {
      await client.close();
      // FIXME: 2024-10
      // We have a bug where `client.close()` doesn't return properly and we don't go below
      // meaning the `browser` process is not killed here, and it will be handled in exitWithCleanup().

      browser.kill(); // Chromium headless won't terminate on its own, so we need to send kill signal
      browser.close(); // Closing the browser Deno process
      unregisterForExitCleanup(thisProcessId); // All went well so not need to cleanup on quarto exit
    },

    rawClient: () => client,

    open: async (url: string) => {
      const maxTries = 5;
      for (let i = 0; i < maxTries; ++i) {
        try {
          client = await cdp({ port });
          break;
        } catch (e) {
          if (i === maxTries - 1) {
            throw e;
          }
          // sleep(0) caused 42/100 crashes
          // sleep(1) caused 42/100 crashes
          // sleep(2) caused 15/100 crashes
          // sleep(3) caused 13/100 crashes
          // sleep(4) caused 8/100 crashes
          // sleep(5) caused 1/100 crashes
          // sleep(6) caused 1/100 crashes
          // sleep(7) caused 1/100 crashes
          // sleep(8) caused 1/100 crashes
          // sleep(9) caused 0/100 crashes
          // sleep(10) caused 0/100 crashes
          // sleep(11) caused 0/100 crashes
          // sleep(12) caused 0/100 crashes
          // sleep(13) caused 1/100 crashes
          // sleep(14) caused 1/100 crashes
          // sleep(15) caused 0/100 crashes
          // sleep(16) caused 0/100 crashes
          // sleep(17) caused 0/100 crashes

          // https://carlos-scheidegger.quarto.pub/failure-rates-in-cri-initialization/
          // suggests that 44ms is a good value. We use 100ms to try and account for slower
          // machines.
          await sleep(100);
        }
      }
      const { Network, Page } = client;
      await Network.enable();
      await Page.enable();
      await Page.navigate({ url });
      return new Promise((fulfill, _reject) => {
        Page.loadEventFired(() => {
          fulfill(null);
        });
      });
    },

    docQuerySelectorAll: async (cssSelector: string): Promise<number[]> => {
      await client.DOM.enable();
      const doc = await client.DOM.getDocument();
      const nodeIds = await client.DOM.querySelectorAll({
        nodeId: doc.root.nodeId,
        selector: cssSelector,
      });
      return nodeIds.nodeIds;
    },

    contents: async (cssSelector: string): Promise<string[]> => {
      const nodeIds = await result.docQuerySelectorAll(cssSelector);
      return Promise.all(
        // deno-lint-ignore no-explicit-any
        nodeIds.map(async (nodeId: any) => {
          return (await client.DOM.getOuterHTML({ nodeId })).outerHTML;
        }),
      );
    },

    // defaults to screenshotting at 4x scale = 392dpi.
    screenshots: async (
      cssSelector: string,
      scale = 4,
    ): Promise<{ nodeId: number; data: Uint8Array }[]> => {
      const nodeIds = await result.docQuerySelectorAll(cssSelector);
      const lst: { nodeId: number; data: Uint8Array }[] = [];
      for (const nodeId of nodeIds) {
        // the docs say that inline elements might return more than one box
        // TODO what do we do in that case?
        let quad;
        try {
          quad = (await client.DOM.getContentQuads({ nodeId })).quads[0];
        } catch (_e) {
          // TODO report error?
          continue;
        }
        const minX = Math.min(quad[0], quad[2], quad[4], quad[6]);
        const maxX = Math.max(quad[0], quad[2], quad[4], quad[6]);
        const minY = Math.min(quad[1], quad[3], quad[5], quad[7]);
        const maxY = Math.max(quad[1], quad[3], quad[5], quad[7]);
        try {
          const screenshot = await client.Page.captureScreenshot({
            clip: {
              x: minX,
              y: minY,
              width: maxX - minX,
              height: maxY - minY,
              scale,
            },
            fromSurface: true,
            captureBeyondViewport: true,
          });
          const buf = decode(screenshot.data);
          lst.push({ nodeId, data: buf });
        } catch (_e) {
          // TODO report error?
          continue;
        }
      }
      return lst;
    },
  };
  return result;
}