chromedevtools__chrome-devtools-mcp/scripts/profile/utils.ts

/**
 * @license
 * Copyright 2026 Google LLC
 * SPDX-License-Identifier: Apache-2.0
 */

import type {ProfileScenario} from './types.ts';

export function isObject(value: unknown): value is Record<string, unknown> {
  return typeof value === 'object' && value !== null;
}

export function formatBytes(bytes: number): string {
  return `${(bytes / 1024 / 1024).toFixed(2)} MiB`;
}

export function parseNonNegativeInteger(
  value: string | undefined,
  name: string,
): number {
  if (value === undefined || !/^\d+$/.test(value)) {
    throw new Error(`${name} must be a non-negative integer`);
  }
  const parsed = Number(value);
  if (!Number.isSafeInteger(parsed) || parsed < 0) {
    throw new Error(`${name} must be a non-negative integer`);
  }
  return parsed;
}

export function selectedPageIdFromToolResult(result: unknown): number {
  if (isObject(result) && isObject(result.structuredContent)) {
    const pages = result.structuredContent.pages;
    if (Array.isArray(pages)) {
      for (const page of pages) {
        if (
          isObject(page) &&
          page.selected === true &&
          typeof page.id === 'number'
        ) {
          return page.id;
        }
      }
    }
  }

  if (isObject(result) && Array.isArray(result.content)) {
    for (const content of result.content) {
      if (!isObject(content) || typeof content.text !== 'string') {
        continue;
      }
      const match = /^(\d+): .*\[selected\](?:\s|$)/m.exec(content.text);
      const pageId = match?.[1];
      if (pageId !== undefined) {
        return Number(pageId);
      }
    }
  }

  throw new Error(
    'new_page did not identify the selected page in its response',
  );
}

export function isScenarioModule(value: unknown): value is ProfileScenario {
  return isObject(value) && typeof value.get === 'function';
}

export function uidsFromSnapshotResult(result: unknown): string[] {
  if (isObject(result) && isObject(result.structuredContent)) {
    const snapshot = result.structuredContent.snapshot;
    if (isObject(snapshot)) {
      const uids: string[] = [];
      const collectUids = (node: Record<string, unknown>): void => {
        if (
          typeof node.id === 'string' &&
          node.id.length > 0 &&
          node.role !== 'RootWebArea' &&
          node.role !== 'StaticText'
        ) {
          uids.push(node.id);
        }
        if (Array.isArray(node.children)) {
          for (const child of node.children) {
            if (isObject(child)) {
              collectUids(child);
            }
          }
        }
      };
      collectUids(snapshot);
      if (uids.length > 0) {
        return uids;
      }
    }
  }

  if (isObject(result) && Array.isArray(result.content)) {
    const uids: string[] = [];
    for (const item of result.content) {
      if (isObject(item) && typeof item.text === 'string') {
        for (const line of item.text.split('\n')) {
          if (line.includes('RootWebArea') || line.includes('StaticText')) {
            continue;
          }
          const match = /\buid=([^\s]+)/.exec(line);
          const uid = match?.[1];
          if (uid !== undefined && uid.length > 0) {
            uids.push(uid);
          }
        }
      }
    }
    if (uids.length > 0) {
      return uids;
    }
  }

  throw new Error(
    'take_snapshot did not return any inspectable element UIDs in its response',
  );
}