replayRecording.ts

/* Copyright 2022 Record Replay Inc. */

import { sample, sampleSize, random, flattenDeep, flatten } from "lodash";
import { MsPerSecond } from "../shared/utils";
import { defer } from "../shared/promise";
import { assert } from "../shared/assert";
import { waitForTime } from "../shared/timer";
import {
  CommandMethods,
  CommandParams,
  CommandResult,
  createPauseResult,
  ExecutionPoint,
  findStepOverTargetResult,
  Location,
  newSource,
  NodeBounds,
  Object as ProtocolObject,
  PauseData,
  SameLineSourceLocations,
  TimeStampedPoint,
} from "@replayio/protocol";
import sharp from "sharp";
import { pingTelemetry } from "../shared/instanceUtils";
import { RecordingClient, uploadSessionScript } from "./recording-client";
import { logDebug } from "../shared/logger";

function log(label: string, args = {}) {
  console.log(new Date(), label, JSON.stringify(args));
}

function logError(label: string, error: unknown) {
  console.error(new Date(), label, error);
}

const lowEnd = 3;
const highEnd = 10;

async function withTimeout<T>(name: string, cbk: () => Promise<T>) {
  return Promise.race([
    cbk(),
    waitForTime(60 * 1000).then(() => {
      throw new Error(`Method timedout ${name}`);
    }),
  ]);
}

async function selectSample<T, U>(
  items: Array<T>,
  cbk: (item: T) => Promise<U>
): Promise<Array<U>> {
  const n = random(lowEnd, highEnd);
  const sampledItems = sampleSize(items, n);
  const results = [];
  for (let i = 0; i < sampledItems.length; i++) {
    const result = await cbk(sampledItems[i]);
    results.push(result);
  }
  // const results = await Promise.all(sampledItems.map(item => cbk(item)));
  return [...results];
}

async function randomTimes<T>(item: T, cbk: (item: T) => Promise<T>): Promise<Array<T>> {
  const n = random(lowEnd, highEnd);
  const results = [item];

  for (let i = 0; i < n; i++) {
    results.push(await cbk(results[results.length - 1]));
  }

  return results;
}

function comparePoints(p1: string, p2: string) {
  const b1 = BigInt(p1);
  const b2 = BigInt(p2);
  return b1 < b2 ? -1 : b1 > b2 ? 1 : 0;
}

function findRectangle(
  pixelTest: (x: number, y: number) => boolean,
  width: number,
  height: number,
  minSize = 8
) {
  for (let x = 0; x < width; x += minSize) {
    for (let y = 0; y < width; y += minSize) {
      if (pixelTest(x, y)) {
        const rect = growRectangle(x, y);
        if (rect.right - rect.left > minSize && rect.bottom - rect.top > minSize) {
          return rect;
        }
      }
    }
  }

  function growRectangle(x: number, y: number) {
    let left = x;
    while (left > 0 && pixelTest(left - 1, y)) {
      left--;
    }
    let right = x;
    while (right < width - 1 && pixelTest(right + 1, y)) {
      right++;
    }

    const lineTest = (y: number) => {
      for (let x = left; x < right; x++) {
        if (!pixelTest(x, y)) {
          return false;
        }
      }
      return true;
    };
    let top = y;
    while (top > 0 && lineTest(top - 1)) {
      top--;
    }
    let bottom = y;
    while (bottom < height - 1 && lineTest(bottom + 1)) {
      bottom++;
    }
    return { left, right, top, bottom };
  }
}

// This is the algorithm that is also used by the node picker in devtools
function pickNode(elements: NodeBounds[], x: number, y: number) {
  for (const { node, rect, rects, clipBounds, visibility, pointerEvents } of elements) {
    if (visibility === "hidden" || pointerEvents === "none") {
      continue;
    }
    if (
      (clipBounds?.left !== undefined && x < clipBounds.left) ||
      (clipBounds?.right !== undefined && x > clipBounds.right) ||
      (clipBounds?.top !== undefined && y < clipBounds.top) ||
      (clipBounds?.bottom !== undefined && y > clipBounds.bottom)
    ) {
      continue;
    }

    for (const r of rects || [rect]) {
      const [left, top, right, bottom] = r;
      if (x >= left && x <= right && y >= top && y <= bottom) {
        return node;
      }
    }
  }
}

interface PauseInfo extends TimeStampedPoint {
  pauseId: string;
}

export class Fuzzer {
  dispatchAddress: string;
  recordingId: string;
  url: string | undefined;
  analysis: Map<string, Array<string>> = new Map();
  sessionId: string | undefined;
  client: RecordingClient | undefined;

  constructor(dispatchAddress: string, recordingId: string, url?: string) {
    this.dispatchAddress = dispatchAddress;
    this.recordingId = recordingId;
    this.url = url;
  }

  async destroy() {
    const { client, sessionId } = this;
    if (client) {
      if (sessionId) {
        await this.sendCommand("Recording.releaseSession", { sessionId });
      }
      client.close();
    }
    log("ReplayRecording Finished");
  }

  // Creates a session and replays the recording. Returns null if there was an error
  // while replaying.
  async setup(options: ReplayOptions): Promise<string | null> {
    const { recordingId } = this;
    this.client = new RecordingClient(this.dispatchAddress, {
      onError: e => log(`Socket error ${e}`, { recordingId }),
      onClose: (code, reason) => log(`Socket closed`, { code, reason, recordingId }),
    });

    const successWaiter = defer<boolean>();

    this.client.addEventListener("Recording.sessionError", e => {
      log(`sessionError`, { error: e, recordingId });
      successWaiter.resolve(false);
    });
    this.client.addEventListener("Recording.uploadedData", () => {
      // No-op handler so that we don't log warnings about unknown messages if the
      // recording is still in the process of uploading when this script runs.
    });

    if (options.apiKey) {
      await this.sendCommand("Authentication.setAccessToken", {
        accessToken: options.apiKey,
      });
    }

    let experimentalSettings;

    const result = await this.sendCommand("Recording.createSession", {
      recordingId,
      experimentalSettings,
    });

    const { sessionId } = result;
    log(`New Session`, { sessionId, recordingId });

    this.client
      .sendCommand("Session.ensureProcessed", { level: "basic" }, sessionId)
      .then(
        () => successWaiter.resolve(true),
        err => {
          logError("Failed to ensure processed", { error: err });
          successWaiter.resolve(false);
        }
      );

    const success = await successWaiter.promise;
    if (!success) {
      return null;
    }

    this.sessionId = sessionId;
    return sessionId;
  }

  async sendCommandWithTimeout<M extends CommandMethods>(
    command: M,
    params: CommandParams<M>,
    sessionId?: string,
    pauseId?: string
  ) {
    return Promise.race([
      this.sendCommand(command, params, sessionId, pauseId),
      waitForTime(20 * 1000).then(() => {
        throw new Error(`Command timedout ${command}`);
      }),
    ]);
  }

  async sendCommand<M extends CommandMethods>(
    command: M,
    params: CommandParams<M>,
    sessionId?: string,
    pauseId?: string
  ): Promise<CommandResult<M>> {
    let result;
    try {
      const initialTime = new Date();
      assert(this.client);
      result = await this.client.sendCommand(command, params, sessionId, pauseId);
      const duration = +new Date() - +initialTime;

      log(`sendCommand ${command}`, {
        duration,
        params,
        sessionId: this.sessionId,
        pauseId,
        recordingId: this.recordingId,
      });
    } catch (e) {
      logError(`Command failed ${command}`, { error: e, recordingId: this.recordingId });
      throw e;
    }

    return result;
  }

  pingTelemetry(event: string, tags: any = {}) {
    pingTelemetry(event, {
      recordingId: this.recordingId,
      sessionId: this.sessionId,
      ...tags,
      service_name: "testinbox",
    });
  }

  async fetchEnabledFeatures() {
    const { sessionId } = this;
    assert(sessionId);
    const result = await this.sendCommand("Session.getBuildId", {}, sessionId);

    const isGecko = result.buildId.includes("gecko");
    const isChromium = result.buildId.includes("chromium");

    return {
      elements: isGecko,
      graphics: isGecko || isChromium,
    };
  }

  async fetchSources() {
    const { client, sessionId } = this;
    assert(client);

    // sources are files that can have possible breakpoint locations in them
    const sources: Array<newSource> = [];
    client.addEventListener("Debugger.newSource", source => {
      sources.push(source);
    });
    await this.sendCommand("Debugger.findSources", {}, sessionId);
    return sources;
  }

  async getPossibleBreakpoints(
    source: newSource
  ): Promise<Array<SameLineSourceLocations>> {
    assert(this.client);
    const result = await this.sendCommand(
      "Debugger.getPossibleBreakpoints",
      { sourceId: source.sourceId },
      this.sessionId
    );

    return result.lineLocations;
  }

  async getLogpoints(location: Location): Promise<Array<PauseInfo>> {
    try {
      const values: Array<PauseInfo> = [];
      const initialTime = new Date();

      assert(this.client);
      assert(this.sessionId);
      this.client.addEventListener("Analysis.analysisResult", ({ results }) => {
        values.push(...results.map(r => r.value));
      });
      this.client.addEventListener("Analysis.analysisPoints", _ => {});

      const result = await this.sendCommand(
        "Analysis.createAnalysis",
        {
          mapper: `
        const { point, time, pauseId } = input;
        return [{
          key: point,
          value: { time, pauseId, point }
        }];`,
          effectful: true,
        },
        this.sessionId
      );
      const { analysisId } = result;

      this.analysis.set(analysisId, []);

      await this.sendCommand(
        "Analysis.addLocation",
        {
          location,
          analysisId,
        },
        this.sessionId
      );

      await Promise.all([
        this.sendCommandWithTimeout(
          "Analysis.runAnalysis",
          { analysisId },
          this.sessionId
        ),
        this.sendCommandWithTimeout(
          "Analysis.findAnalysisPoints",
          { analysisId },
          this.sessionId
        ),
      ]);
      log(`Logpoints results`, {
        duration: +new Date() - +initialTime,
        results: values.length,
        recordingId: this.recordingId,
      });

      return values;
    } catch (e) {
      log(`Analysis failed for location`, { location });
      console.error(e);
      return [];
    }
  }

  async step(fromPoint: ExecutionPoint): Promise<TimeStampedPoint> {
    const directions: CommandMethods[] = ["Debugger.findStepOverTarget"];
    const dir = sample(directions);
    assert(dir);
    const result = await this.sendCommand(dir, { point: fromPoint }, this.sessionId);
    const { point, time } = (result as findStepOverTargetResult).target;
    return { point, time };
  }

  async expandObject(object: ProtocolObject | undefined, pause: createPauseResult) {
    if (!object || !object.objectId) {
      return;
    }

    const preview = await this.sendCommand(
      "Pause.getObjectPreview",
      { object: object.objectId },
      this.sessionId,
      pause.pauseId
    );

    const newObject = sample(preview.data.objects);
    return newObject;
  }

  fetchPause(point: ExecutionPoint): Promise<createPauseResult> {
    const result = this.sendCommand("Session.createPause", { point }, this.sessionId);
    return result;
  }

  // place logpoints in random locations for a given source
  async randomLogpoints(source: newSource): Promise<Array<Array<PauseInfo>>> {
    const lineLocations = await this.getPossibleBreakpoints(source);
    return selectSample(lineLocations, async ({ line, columns }) => {
      const column = sample(columns);
      assert(typeof column === "number");
      const location = { sourceId: source.sourceId, line, column };
      const logpoints = await this.getLogpoints(location);
      return logpoints;
    });
  }

  async getEndpoint() {
    const { endpoint } = await this.sendCommand(
      "Session.getEndpoint",
      {},
      this.sessionId
    );
    return endpoint;
  }

  async getBody(pauseId: string) {
    const { document } = await this.sendCommand(
      "DOM.getDocument",
      {},
      this.sessionId,
      pauseId
    );
    const { result, data } = await this.sendCommand(
      "DOM.querySelector",
      { node: document, selector: "body" },
      this.sessionId,
      pauseId
    );
    return data.objects?.find(o => o.objectId === result);
  }

  async getObject(objectId: string, pauseId: string) {
    const res = await this.sendCommand(
      "Pause.getObjectPreview",
      { object: objectId },
      this.sessionId,
      pauseId
    );
    return res.data.objects?.find(o => o.objectId === objectId);
  }

  async getChildNodeIds(nodeId: string, pauseId: string) {
    const object = await this.getObject(nodeId, pauseId);
    return object?.preview?.node?.childNodes || [];
  }

  async loadStyles(nodeId: string, pauseId: string) {
    const node = nodeId;
    try {
      await Promise.all([
        this.sendCommand("CSS.getComputedStyle", { node }, this.sessionId, pauseId),
        this.sendCommand("CSS.getAppliedRules", { node }, this.sessionId, pauseId),
        this.sendCommand("DOM.getEventListeners", { node }, this.sessionId, pauseId),
        this.sendCommand("DOM.getBoxModel", { node }, this.sessionId, pauseId),
        this.sendCommand("DOM.getBoundingClientRect", { node }, this.sessionId, pauseId),
      ]);
    } catch (e: any) {
      log(`Load styles for node ${nodeId} failed`, e.message);
    }
  }

  async loadBoundingClientRects(pauseId: string) {
    try {
      const result = await this.sendCommand(
        "DOM.getAllBoundingClientRects",
        {},
        this.sessionId,
        pauseId
      );
      log(`getAllBoundingClientRects results`, {
        elementCount: result.elements.length,
        pauseId: pauseId,
        sessionId: this.sessionId,
      });
      return result.elements;
    } catch (e: any) {
      log(`getAllBoundingClientRects failed`, e.message);
    }
  }

  async repaintGraphics(pauseId: string) {
    try {
      const result = await this.sendCommand(
        "DOM.repaintGraphics",
        {},
        this.sessionId,
        pauseId
      );
      log(`repaintGraphics result`, { keys: Object.keys(result) });
      return result;
    } catch (e: any) {
      log(`repaintGraphics failed`, e.message);
    }
  }

  async repaintAndLookForBlackRectangle(pause: PauseInfo, paintPoints: string[]) {
    const repaintResult = await this.repaintGraphics(pause.pauseId);
    if (!repaintResult?.screenShot?.data) {
      return;
    }

    const closestPaintPoint = paintPoints.find(p => comparePoints(p, pause.point) >= 0);
    if (!closestPaintPoint) {
      return;
    }
    const graphicsResult = await this.loadGraphics(closestPaintPoint);
    const recordedImage = sharp(Buffer.from(graphicsResult.screen.data, "base64"));
    const { width, height } = await recordedImage.metadata();
    if (!width || !height) {
      return;
    }

    const repaintedImage = sharp(Buffer.from(repaintResult.screenShot.data, "base64"));
    const { width: width2, height: height2 } = await repaintedImage.metadata();
    if (width2 !== width || height2 !== height) {
      return;
    }

    const recordedPixels = await recordedImage.raw().toBuffer();
    const repaintedPixels = await repaintedImage.raw().toBuffer();
    const pixelTest = (x: number, y: number) => {
      const offset = (x + y * width) * 3;
      return (
        repaintedPixels[offset] === 0 &&
        repaintedPixels[offset + 1] === 0 &&
        repaintedPixels[offset + 2] === 0 &&
        (recordedPixels[offset] !== 0 ||
          recordedPixels[offset + 1] !== 0 ||
          recordedPixels[offset + 2] !== 0)
      );
    };
    const rect = findRectangle(pixelTest, width, height);
    if (rect) {
      log("Found a black rectangle", rect);
      this.pingTelemetry("fuzzer.BlackRectangleInRepaintedGraphics", {
        point: pause.point,
        time: pause.time,
        ...rect,
      });
    }
  }

  loadRandomNodes = (pauseId: string) =>
    withTimeout(`loadRandomNodes for ${pauseId}`, async () => {
      const body = await this.getBody(pauseId);
      let childNodeIds = body?.preview?.node?.childNodes || [];
      // we descend 10 levels into the document and on each level we load styling information
      // of all children of the nodes selected on the previous level and randomly select
      // some children for the next level
      for (let i = 0; i < highEnd; i++) {
        // Only load styles for one node at a time, which is what will happen when people
        // are using the devtools.
        for (const nodeId of childNodeIds) {
          await this.loadStyles(nodeId, pauseId);
        }
        childNodeIds = flatten(
          await selectSample(childNodeIds, nodeId =>
            this.getChildNodeIds(nodeId, pauseId)
          )
        );
      }
    });

  loadFrames(pauseId: string) {
    return this.sendCommand("Pause.getAllFrames", {}, this.sessionId, pauseId);
  }

  loadFrameSteps(pauseId: string, frameId: string) {
    return this.sendCommand("Pause.getFrameSteps", { frameId }, this.sessionId, pauseId);
  }

  loadScope(pauseId: string, scopeId: string) {
    return this.sendCommand(
      "Pause.getScope",
      { scope: scopeId },
      this.sessionId,
      pauseId
    );
  }

  evaluateInFrame(pauseId: string, frameId: string, expression: string) {
    return this.sendCommand(
      "Pause.evaluateInFrame",
      { frameId, expression },
      this.sessionId,
      pauseId
    );
  }

  evaluateInGlobal(pauseId: string, expression: string) {
    return this.sendCommand(
      "Pause.evaluateInGlobal",
      { expression },
      this.sessionId,
      pauseId
    );
  }

  async loadPaintPoints() {
    const promise = this.sendCommand("Graphics.findPaints", {}, this.sessionId);
    const paintPoints: string[] = [];
    assert(this.client);
    this.client.addEventListener("Graphics.paintPoints", result => {
      paintPoints.push(...result.paints.map(paint => paint.point));
    });
    await promise;
    paintPoints.sort(comparePoints);
    return paintPoints;
  }

  loadGraphics(point: string) {
    return this.sendCommand(
      "Graphics.getPaintContents",
      { mimeType: "image/jpeg", point },
      this.sessionId
    );
  }

  async getWindowSize(pauseId: string) {
    const width = (await this.evaluateInGlobal(pauseId, "innerWidth")).result?.returned
      ?.value;
    const height = (await this.evaluateInGlobal(pauseId, "innerHeight")).result?.returned
      ?.value;
    return { width, height };
  }

  async checkNodeAtPosition(
    pauseInfo: PauseInfo,
    elements: NodeBounds[],
    x: number,
    y: number
  ) {
    const reason = await this.isPickingWrongNode(pauseInfo.pauseId, elements, x, y);
    if (reason) {
      const url = `https://app.replay.io/recording/${this.recordingId}?point=${pauseInfo.point}&time=${pauseInfo.time}&hasFrames=true`;
      const locationResult = await this.evaluateInGlobal(
        pauseInfo.pauseId,
        "location.href"
      );
      const recordingUrl = locationResult.result.returned?.value;
      log("Our stacking algorithm picked the wrong node", {
        recordingId: this.recordingId,
        sessionId: this.sessionId,
        point: pauseInfo.point,
        time: pauseInfo.time,
        x,
        y,
        recordingUrl,
        url,
        reason,
      });
      this.pingTelemetry("fuzzer.PickedWrongNode", {
        point: pauseInfo.point,
        time: pauseInfo.time,
        x,
        y,
        recordingUrl,
        url,
        reason,
      });
    }
  }

  async isPickingWrongNode(pauseId: string, bounds: NodeBounds[], x: number, y: number) {
    const { result } = await this.evaluateInGlobal(
      pauseId,
      `document.elementFromPoint(${x}, ${y})`
    );
    const nodeId = result.returned?.object;
    if (!nodeId) {
      // elementFromPoint didn't pick a node
      return "no-reference-node";
    }

    const pickedNodeId = pickNode(bounds, x, y);
    if (!pickedNodeId) {
      // our algorithm didn't pick a node
      return "no-picked-node";
    }
    if (pickedNodeId === nodeId) {
      // we picked the right node!
      return false;
    }

    // is the node picked by our algorithm in an iframe?
    const parentsResult = await this.sendCommand(
      "DOM.getParentNodes",
      { node: pickedNodeId },
      this.sessionId,
      pauseId
    );
    const nodes = parentsResult.data.objects || [];
    if (result.data.objects) {
      nodes.push(...result.data.objects);
    }
    let currentNodeId: string | undefined = pickedNodeId;
    while (currentNodeId) {
      const currentNode = nodes.find(node => node.objectId === currentNodeId);
      if (!currentNode) {
        break;
      }
      if (currentNode.className === "HTMLIFrameElement") {
        const currentNodeBounds = bounds.find(element => element.node === currentNodeId);
        if (!currentNodeBounds) {
          break;
        }
        const [left, top, right, bottom] = currentNodeBounds.rect;
        if (x < left || x > right || y < top || y > bottom) {
          // our algorithm picked a node inside an iframe but the coordinates
          // are outside the iframe's bounds
          return "iframe-overflow-693";
        }
        if (currentNodeBounds.pointerEvents === "none") {
          // our algorithm picked a node inside an iframe but the iframe has
          // pointer-events set to "none", which should be applied to all children
          return "iframe-pointerevents-692";
        }
        break;
      }
      currentNodeId = currentNode.preview?.node?.parentNode;
    }

    const nodeName = (
      await this.evaluateInGlobal(
        pauseId,
        `document.elementFromPoint(${x}, ${y}).nodeName`
      )
    ).result.returned?.value;
    if (nodeName === "IFRAME") {
      // elementFromPoint picked an iframe
      return "iframe";
    }
    if (this.findClassName(nodeId, result.data)?.startsWith("SVG")) {
      // elementFromPoint picked an svg element
      return "svg";
    }

    const pickedNodePreview = await this.sendCommand(
      "Pause.getObjectPreview",
      { object: pickedNodeId },
      this.sessionId,
      pauseId
    );
    const pickedNodeClass = this.findClassName(pickedNodeId, pickedNodePreview.data);
    if (pickedNodeClass?.startsWith("SVG")) {
      // our algorithm picked an svg element
      return "svg2";
    }
    if (pickedNodeClass === "HTMLOptionElement") {
      // our algorithm picked an option element
      return "option-698";
    }

    const contentBefore = (
      await this.evaluateInGlobal(
        pauseId,
        `window.getComputedStyle(document.elementFromPoint(${x}, ${y}), ":before")["content"]`
      )
    ).result.returned?.value;
    const contentAfter = (
      await this.evaluateInGlobal(
        pauseId,
        `window.getComputedStyle(document.elementFromPoint(${x}, ${y}), ":after")["content"]`
      )
    ).result.returned?.value;
    if (contentBefore !== "none" || contentAfter !== "none") {
      // elementFromPoint picked an element with a :before or :after pseudo element,
      // this may be the reason why the picked element has a larger selectable area,
      // although we can't be sure
      return "pseudo-element-699";
    }

    const { computedStyle } = await this.sendCommand(
      "CSS.getComputedStyle",
      { node: pickedNodeId },
      this.sessionId,
      pauseId
    );
    const clipValue = computedStyle.find(r => r.name === "clip")?.value;
    if (clipValue && clipValue !== "auto") {
      // our algorithm picked an element with the CSS clip property
      return "clip-700";
    }

    const { rect } = await this.sendCommand(
      "DOM.getBoundingClientRect",
      { node: nodeId },
      this.sessionId,
      pauseId
    );
    const [left, top, right, bottom] = rect;
    if (x < left || x > right || y < top || y > bottom) {
      const rectResult = await this.evaluateInGlobal(
        pauseId,
        `(() => {
          const el = document.elementFromPoint(${x}, ${y});
          const range = document.createRange();
          range.setStart(el, 0);
          range.setEnd(el, el.childNodes.length);
          return range.getBoundingClientRect();
        })()`
      );
      const values = rectResult.result.data.objects?.[0].preview?.getterValues;
      const findValue = (name: string) => values?.find(v => v.name === name)?.value;
      if (
        x < findValue("left") ||
        x > findValue("right") ||
        y < findValue("top") ||
        y > findValue("bottom")
      ) {
        // the coordinates are outside the bounds of the node picked by
        // elementFromPoint but within the bounds of the text in that node
        return "text-outside-bounds-694";
      }
      return "outside-bounds";
    }

    return "unknown";
  }

  findClassName(objectId: string, data: PauseData) {
    for (const objPreview of data.objects || []) {
      if (objPreview.objectId === objectId) {
        return objPreview.className;
      }
    }
  }
}

type ReplayOptions = {
  skipFuzzing?: boolean;
  apiKey?: string;
  uploadSessionRecording?: boolean;
  testSnapshotCallback?: (
    sessionId: string,
    snapshotsCreated: number,
    snapshotsRestored: number,
    crashesAfterRestore: number
  ) => void;
};

// Replay a recording making a random number of random decisions, like which logpoints to set and how many times to step
// if seed is passed uses that seed for all RNG calls. Useful for reproducing errors that are observed in the logs after the fact
export async function replayRecording(
  dispatchAddress: string,
  recordingId: string,
  url?: string,
  options: ReplayOptions = {}
): Promise<boolean> {
  log("Replay recording", recordingId);
  let sessionId: string | null = null;
  const fuzzer = new Fuzzer(dispatchAddress, recordingId, url);
  const startTime = new Date();

  let success = false;
  try {
    sessionId = await fuzzer.setup(options);
    if (!sessionId) {
      await fuzzer.destroy();
      return false;
    }

    if (!options.skipFuzzing) {
      const features = await fuzzer.fetchEnabledFeatures();
      const sources = await fuzzer.fetchSources();
      const paintPoints = await fuzzer.loadPaintPoints();

      log("\n## Randomly add logpoints in various files", { recordingId, sessionId });
      const pauseInfos: Array<PauseInfo> = flattenDeep(
        await selectSample(sources, async source => fuzzer.randomLogpoints(source))
      );

      log("\n## Randomly step through various points", { recordingId, sessionId });
      const stepPoints = flattenDeep(
        await selectSample(pauseInfos, info =>
          randomTimes<TimeStampedPoint>(info, item => fuzzer.step(item.point))
        )
      );

      const endPoint = await fuzzer.getEndpoint();
      const points = [...pauseInfos, ...stepPoints, endPoint];

      log("\n## Randomly fetch frames for various pauses", { recordingId, sessionId });
      await selectSample(pauseInfos, info => fuzzer.loadFrames(info.pauseId));

      log("\n## Randomly fetch pauses for various points", { recordingId, sessionId });
      const pauses = await selectSample(points, async ({ point, time }) => {
        const pause = await fuzzer.fetchPause(point);
        return { point, time, ...pause };
      });

      log("\n## Randomly fetch frame steps for various pauses", {
        recordingId,
        sessionId,
      });
      await selectSample(pauses, pause =>
        selectSample(pause.data.frames!, frame =>
          fuzzer.loadFrameSteps(pause.pauseId, frame.frameId)
        )
      );

      log("\n## Randomly evaluate some global expressions in various pauses");
      await selectSample(pauses, async pause => {
        await fuzzer.evaluateInGlobal(pause.pauseId, "location.href");
        await fuzzer.evaluateInGlobal(
          pause.pauseId,
          'document.querySelectorAll("script")'
        );
      });

      log(
        "\n## Randomly fetch scopes and evaluate variables in them for various pauses",
        { recordingId, sessionId }
      );
      await selectSample(pauses, pause =>
        selectSample(pause.data.frames!, frame =>
          selectSample(frame.scopeChain, async scopeId => {
            const scope = await fuzzer.loadScope(pause.pauseId, scopeId);
            const bindings = scope.data.scopes?.[0].bindings;
            if (bindings) {
              await selectSample(bindings, ({ name }) =>
                fuzzer.evaluateInFrame(pause.pauseId, frame.frameId, name)
              );
            }
          })
        )
      );

      log("\n## Randomly expands objects for various pauses", { recordingId, sessionId });
      await selectSample(pauses, pause =>
        selectSample(pause.data.objects!, object =>
          randomTimes<ProtocolObject | undefined>(object, object =>
            fuzzer.expandObject(object, pause)
          )
        )
      );

      if (features.graphics) {
        log("\n## Randomly repaint and look for black rectangles", {
          recordingId,
          sessionId,
        });
        await selectSample(pauses, async pause => {
          fuzzer.repaintAndLookForBlackRectangle(pause, paintPoints);
        });
      }

      if (features.elements) {
        log("\n## Randomly fetch some DOM nodes", { recordingId, sessionId });
        await selectSample(pauses, pause => fuzzer.loadRandomNodes(pause.pauseId));

        log(
          "\n## Randomly pick nodes and check that our stacking algorithm picks the same",
          { recordingId, sessionId }
        );
        await selectSample(pauses, async pause => {
          const { width, height } = await fuzzer.getWindowSize(pause.pauseId);
          const elements = await fuzzer.loadBoundingClientRects(pause.pauseId);
          if (!elements) {
            return;
          }
          for (let i = 0; i < 20; i++) {
            await fuzzer.checkNodeAtPosition(
              pause,
              elements,
              Math.floor(Math.random() * (width - 18)) + 1,
              Math.floor(Math.random() * (height - 18)) + 1
            );
          }
        });
      }
    }

    log(`\n## Finished Replaying`, {
      recordingId,
      sessionId,
      duration: +new Date() - +startTime,
    });
    success = true;
  } catch (e) {
    logError("Encountered error interacting with recording", {
      error: e,
      recordingId,
      sessionId,
    });

    throw e;
  } finally {
    if (options.uploadSessionRecording && sessionId && fuzzer.client) {
      uploadSessionScript(recordingId, sessionId, fuzzer.client.export()).catch(e => {
        logError("Failed to upload session script", {
          error: e,
          recordingId,
          sessionId,
        });
      });
    } else {
      logDebug<string>("Not uploading session script", {
        fuzzerClient: Boolean(fuzzer.client),
        recordingId,
        sessionId,
        uploadSessionScript: options.uploadSessionRecording,
      });
    }
    await fuzzer.destroy();
  }

  return success;
}

export async function replayRecordingWithTimeout(
  dispatchAddress: string,
  recordingId: string,
  url: string | undefined,
  options: ReplayOptions,
  timeoutSeconds: number
): Promise<boolean> {
  let success = false;
  await Promise.race([
    replayRecording(dispatchAddress, recordingId, url, options).then(rv => {
      success = rv;
    }),
    waitForTime(timeoutSeconds * MsPerSecond, { unref: true }),
  ]);
  return success;
}

// Scratchpad for testing
if (process.argv[1].includes("replayRecording")) {
  let recordingId: string | undefined;
  let url: string | undefined;
  let server: string | undefined = "wss://dispatch.replay.io";

  const options: ReplayOptions = {
    apiKey: process.env.RECORD_REPLAY_API_KEY,
  };

  const args = process.argv.slice(2);
  let arg;

  while ((arg = args.shift()?.toLowerCase())) {
    switch (arg) {
      case "-r":
      case "--recording":
        recordingId = args.shift();
        assert(recordingId && !recordingId.startsWith("-"), "Recording ID missing");
        break;
      case "-u":
      case "--url":
        url = args.shift();
        assert(url && !url.startsWith("-"), "URL is missing");
        break;
      case "-s":
      case "--server":
        server = args.shift();
        assert(server && !server.startsWith("-"), "server is missing");
        break;
      case "-a":
      case "--api-key":
        options.apiKey = args.shift();
        assert(options.apiKey && !options.apiKey.startsWith("-"), "API Key is missing");
        break;
    }
  }

  assert(recordingId, "No recording specified");

  replayRecording(server, recordingId, url, options).catch(() => {
    console.error("Fuzzing failed");
  });
}