gstack/browse/src/read-commands.ts

/**
 * Read commands — extract data from pages without side effects
 *
 * text, html, links, forms, accessibility, js, eval, css, attrs,
 * console, network, cookies, storage, perf
 */

import type { TabSession } from './tab-session';
import type { BrowserManager } from './browser-manager';
import { consoleBuffer, networkBuffer, dialogBuffer } from './buffers';
import type { Page, Frame } from 'playwright';
import * as fs from 'fs';
import * as path from 'path';
import { TEMP_DIR } from './platform';
import { inspectElement, formatInspectorResult, getModificationHistory } from './cdp-inspector';
import { validateReadPath, validateOutputPath } from './path-security';
import { stripLoneSurrogates } from './sanitize';
// Re-export for backward compatibility (tests import from read-commands)
export { validateReadPath } from './path-security';

// Redaction patterns for sensitive cookie/storage values — exported for test coverage
export const SENSITIVE_COOKIE_NAME = /(^|[_.-])(token|secret|key|password|credential|auth|jwt|session|csrf|sid)($|[_.-])|api.?key/i;
export const SENSITIVE_COOKIE_VALUE = /^(eyJ|sk-|sk_live_|sk_test_|pk_live_|pk_test_|rk_live_|sk-ant-|ghp_|gho_|github_pat_|xox[bpsa]-|AKIA[A-Z0-9]{16}|AIza|SG\.|Bearer\s|sbp_)/;

/** Detect await keyword, ignoring comments. Accepted risk: await in string literals triggers wrapping (harmless). */
function hasAwait(code: string): boolean {
  const stripped = code.replace(/\/\/.*$/gm, '').replace(/\/\*[\s\S]*?\*\//g, '');
  return /\bawait\b/.test(stripped);
}

/** Detect whether code needs a block wrapper {…} vs expression wrapper (…) inside an async IIFE. */
function needsBlockWrapper(code: string): boolean {
  const trimmed = code.trim();
  if (trimmed.split('\n').length > 1) return true;
  if (/\b(const|let|var|function|class|return|throw|if|for|while|switch|try)\b/.test(trimmed)) return true;
  if (trimmed.includes(';')) return true;
  return false;
}

/** Wrap code for page.evaluate(), using async IIFE with block or expression body as needed. */
function wrapForEvaluate(code: string): string {
  if (!hasAwait(code)) return code;
  const trimmed = code.trim();
  return needsBlockWrapper(trimmed)
    ? `(async()=>{\n${code}\n})()`
    : `(async()=>(${trimmed}))()`;
}

/** Flags split out of `js`/`eval` args by parseOutArgs. */
export interface OutArgs {
  outPath?: string;
  raw: boolean;
  rest: string[];
}

/**
 * Parse `--out <path>` / `--out=<path>` and `--raw` / `--raw=true|false` out of an
 * arg list, returning the flags plus the remaining positional args (`rest`).
 *
 * Single source of truth shared by the js/eval handlers and the write-capability
 * gate in server.ts, so the two never disagree on what counts as an `--out`
 * invocation. Throws on malformed usage (repeated `--out`, missing value, bad
 * `--raw` value) so the user gets a clear error instead of a silent misparse.
 */
export function parseOutArgs(args: string[]): OutArgs {
  let outPath: string | undefined;
  let raw = false;
  const rest: string[] = [];
  for (let i = 0; i < args.length; i++) {
    const a = args[i];
    if (a === '--out') {
      if (outPath !== undefined) throw new Error('--out specified more than once');
      const val = args[i + 1];
      if (val === undefined || val.startsWith('--')) throw new Error('--out requires a file path');
      outPath = val;
      i++;
    } else if (a.startsWith('--out=')) {
      if (outPath !== undefined) throw new Error('--out specified more than once');
      const val = a.slice('--out='.length);
      if (val === '') throw new Error('--out requires a file path');
      outPath = val;
    } else if (a === '--raw') {
      raw = true;
    } else if (a.startsWith('--raw=')) {
      const v = a.slice('--raw='.length).toLowerCase();
      if (v !== 'true' && v !== 'false') throw new Error('--raw must be true or false');
      raw = v === 'true';
    } else {
      rest.push(a);
    }
  }
  return { outPath, raw, rest };
}

/**
 * True iff an arg list contains an `--out` flag in any accepted form
 * (`--out <path>` or `--out=<path>`). Used by the write-capability gate to
 * decide whether an otherwise-read command (`js`/`eval`) is actually a write
 * invocation. Mirrors parseOutArgs's `--out` recognition exactly. Never throws —
 * a malformed `--out=` still counts as an out attempt (fail safe: gate it).
 */
export function hasOutArg(args: string[]): boolean {
  return args.some(a => a === '--out' || a.startsWith('--out='));
}

/**
 * Convert an evaluate() result to its string form — the exact conversion `js`/`eval`
 * used inline before `--out` existed. Kept byte-for-byte: `typeof === 'object'`
 * (which includes `null`) goes through JSON.stringify (so `null` → `"null"`);
 * everything else via `String(result ?? '')` (so `undefined` → `''`). JSON.stringify
 * still throws on circular / BigInt-bearing results, same as before.
 */
export function resultToString(result: unknown): string {
  return typeof result === 'object'
    ? JSON.stringify(result, null, 2)
    : String(result ?? '');
}

/**
 * Write an evaluate result string to disk for `--out`, returning bytes written.
 *
 * When the result is a base64 data URL (`data:<type>;...;base64,<payload>`) and
 * `raw` is false, decode the payload to raw bytes — this is the Excalidraw / og-image
 * path where a render function returns a PNG data URL. The header is parsed
 * case-insensitively and split on the FIRST comma (data URLs can contain commas in
 * the payload). The payload is validated against the base64 charset before decoding,
 * because `Buffer.from(_, 'base64')` silently drops invalid characters and would
 * otherwise write corrupted bytes. `--raw` forces a literal write even for data URLs.
 *
 * Non-base64 strings are surrogate-sanitized (matching what the stdout egress path
 * did before) and written as UTF-8. Parent directories are created — validateOutputPath
 * gates the location but does not mkdir.
 */
export function writeEvalResult(outPath: string, str: string, opts: { raw: boolean }): number {
  validateOutputPath(outPath);
  fs.mkdirSync(path.dirname(path.resolve(outPath)), { recursive: true });

  if (!opts.raw && str.startsWith('data:')) {
    const comma = str.indexOf(',');
    if (comma !== -1) {
      const header = str.slice('data:'.length, comma);
      const tokens = header.split(';').map(t => t.trim().toLowerCase());
      if (tokens.includes('base64')) {
        const payload = str.slice(comma + 1).replace(/\s+/g, '');
        if (!/^[A-Za-z0-9+/]*={0,2}$/.test(payload)) {
          throw new Error('--out: malformed base64 in data URL (decode would corrupt output)');
        }
        const buf = Buffer.from(payload, 'base64');
        fs.writeFileSync(outPath, buf);
        return buf.length;
      }
    }
  }

  const buf = Buffer.from(stripLoneSurrogates(str), 'utf-8');
  fs.writeFileSync(outPath, buf);
  return buf.length;
}

/**
 * Extract clean text from a page (strips script/style/noscript/svg).
 * Exported for DRY reuse in meta-commands (diff).
 */
export async function getCleanText(page: Page | Frame): Promise<string> {
  const raw = await page.evaluate(() => {
    const body = document.body;
    if (!body) return '';
    const clone = body.cloneNode(true) as HTMLElement;
    clone.querySelectorAll('script, style, noscript, svg').forEach(el => el.remove());
    return clone.innerText
      .split('\n')
      .map(line => line.trim())
      .filter(line => line.length > 0)
      .join('\n');
  });
  return stripLoneSurrogates(raw);
}

/**
 * When cookies have been imported for specific domains, block JS execution
 * on pages whose origin doesn't match any imported cookie domain.
 * Prevents cross-origin cookie exfiltration via `js document.cookie` or
 * similar when the agent navigates to an untrusted page.
 */
function assertJsOriginAllowed(bm: BrowserManager, pageUrl: string): void {
  if (!bm.hasCookieImports()) return;

  let hostname: string;
  try {
    hostname = new URL(pageUrl).hostname;
  } catch {
    return; // about:blank, data: URIs — allow (no cookies at risk)
  }

  const importedDomains = bm.getCookieImportedDomains();
  const allowed = [...importedDomains].some(domain => {
    // Exact match or subdomain match (e.g., ".github.com" matches "api.github.com")
    const normalized = domain.startsWith('.') ? domain : '.' + domain;
    return hostname === domain.replace(/^\./, '') || hostname.endsWith(normalized);
  });

  if (!allowed) {
    throw new Error(
      `JS execution blocked: current page (${hostname}) does not match any cookie-imported domain. ` +
      `Imported cookies for: ${[...importedDomains].join(', ')}. ` +
      `This prevents cross-origin cookie exfiltration. Navigate to an imported domain or run without imported cookies.`
    );
  }
}

export async function handleReadCommand(
  command: string,
  args: string[],
  session: TabSession,
  bm: BrowserManager,
): Promise<string> {
  const page = session.getPage();
  // Frame-aware target for content extraction
  const target = session.getActiveFrameOrPage();

  switch (command) {
    case 'text': {
      return getCleanText(target);
    }

    case 'html': {
      const selector = args[0];
      if (selector) {
        const resolved = await session.resolveRef(selector);
        if ('locator' in resolved) {
          return stripLoneSurrogates(await resolved.locator.innerHTML({ timeout: 5000 }));
        }
        return stripLoneSurrogates(await target.locator(resolved.selector).innerHTML({ timeout: 5000 }));
      }
      // page.content() is page-only; use evaluate for frame compat
      const doctype = await target.evaluate(() => {
        const dt = document.doctype;
        return dt ? `<!DOCTYPE ${dt.name}>` : '';
      });
      const html = await target.evaluate(() => document.documentElement.outerHTML);
      return stripLoneSurrogates(doctype ? `${doctype}\n${html}` : html);
    }

    case 'links': {
      const links = await target.evaluate(() =>
        [...document.querySelectorAll('a[href]')].map(a => ({
          text: a.textContent?.trim().slice(0, 120) || '',
          href: (a as HTMLAnchorElement).href,
        })).filter(l => l.text && l.href)
      );
      return links.map(l => `${l.text} → ${l.href}`).join('\n');
    }

    case 'forms': {
      const forms = await target.evaluate(() => {
        return [...document.querySelectorAll('form')].map((form, i) => {
          const fields = [...form.querySelectorAll('input, select, textarea')].map(el => {
            const input = el as HTMLInputElement;
            return {
              tag: el.tagName.toLowerCase(),
              type: input.type || undefined,
              name: input.name || undefined,
              id: input.id || undefined,
              placeholder: input.placeholder || undefined,
              required: input.required || undefined,
              value: input.type === 'password'
                || (input.name && /(^|[_.-])(token|secret|key|password|credential|auth|jwt|session|csrf|sid)($|[_.-])|api.?key/i.test(input.name))
                || (input.id && /(^|[_.-])(token|secret|key|password|credential|auth|jwt|session|csrf|sid)($|[_.-])|api.?key/i.test(input.id))
                ? '[redacted]' : (input.value || undefined),
              options: el.tagName === 'SELECT'
                ? [...(el as HTMLSelectElement).options].map(o => ({ value: o.value, text: o.text }))
                : undefined,
            };
          });
          return {
            index: i,
            action: form.action || undefined,
            method: form.method || 'get',
            id: form.id || undefined,
            fields,
          };
        });
      });
      return JSON.stringify(forms, null, 2);
    }

    case 'accessibility': {
      const snapshot = await target.locator("body").ariaSnapshot();
      return stripLoneSurrogates(snapshot);
    }

    case 'js': {
      const { outPath, raw, rest } = parseOutArgs(args);
      const expr = rest[0];
      if (!expr) throw new Error('Usage: browse js <expression> [--out <file>] [--raw]');
      assertJsOriginAllowed(bm, page.url());
      const wrapped = wrapForEvaluate(expr);
      const result = await target.evaluate(wrapped);
      const str = resultToString(result);
      if (outPath) {
        const n = writeEvalResult(outPath, str, { raw });
        return `JS result written: ${outPath} (${n} bytes)`;
      }
      return str;
    }

    case 'eval': {
      const { outPath, raw, rest } = parseOutArgs(args);
      const filePath = rest[0];
      if (!filePath) throw new Error('Usage: browse eval <js-file> [--out <file>] [--raw]');
      assertJsOriginAllowed(bm, page.url());
      validateReadPath(filePath);
      if (!fs.existsSync(filePath)) throw new Error(`File not found: ${filePath}`);
      const code = fs.readFileSync(filePath, 'utf-8');
      const wrapped = wrapForEvaluate(code);
      const result = await target.evaluate(wrapped);
      const str = resultToString(result);
      if (outPath) {
        const n = writeEvalResult(outPath, str, { raw });
        return `Eval result written: ${outPath} (${n} bytes)`;
      }
      return str;
    }

    case 'css': {
      const [selector, property] = args;
      if (!selector || !property) throw new Error('Usage: browse css <selector> <property>');
      const resolved = await session.resolveRef(selector);
      if ('locator' in resolved) {
        const value = await resolved.locator.evaluate(
          (el, prop) => getComputedStyle(el).getPropertyValue(prop),
          property
        );
        return value;
      }
      const value = await target.evaluate(
        ([sel, prop]) => {
          const el = document.querySelector(sel);
          if (!el) return `Element not found: ${sel}`;
          return getComputedStyle(el).getPropertyValue(prop);
        },
        [resolved.selector, property]
      );
      return value;
    }

    case 'attrs': {
      const selector = args[0];
      if (!selector) throw new Error('Usage: browse attrs <selector>');
      const resolved = await session.resolveRef(selector);
      if ('locator' in resolved) {
        const attrs = await resolved.locator.evaluate((el) => {
          const result: Record<string, string> = {};
          for (const attr of el.attributes) {
            result[attr.name] = attr.value;
          }
          return result;
        });
        return JSON.stringify(attrs, null, 2);
      }
      const attrs = await target.evaluate((sel: string) => {
        const el = document.querySelector(sel);
        if (!el) return `Element not found: ${sel}`;
        const result: Record<string, string> = {};
        for (const attr of el.attributes) {
          result[attr.name] = attr.value;
        }
        return result;
      }, resolved.selector);
      return typeof attrs === 'string' ? attrs : JSON.stringify(attrs, null, 2);
    }

    case 'console': {
      if (args[0] === '--clear') {
        consoleBuffer.clear();
        return 'Console buffer cleared.';
      }
      const entries = args[0] === '--errors'
        ? consoleBuffer.toArray().filter(e => e.level === 'error' || e.level === 'warning')
        : consoleBuffer.toArray();
      if (entries.length === 0) return args[0] === '--errors' ? '(no console errors)' : '(no console messages)';
      return entries.map(e =>
        `[${new Date(e.timestamp).toISOString()}] [${e.level}] ${e.text}`
      ).join('\n');
    }

    case 'network': {
      if (args[0] === '--clear') {
        networkBuffer.clear();
        return 'Network buffer cleared.';
      }

      // Network capture extensions
      if (args[0] === '--capture') {
        const {
          startCapture, stopCapture, getCaptureListener, isCaptureActive,
        } = await import('./network-capture');

        if (args[1] === 'stop') {
          // Detach listener from current page
          const page = bm.getPage();
          const listener = getCaptureListener();
          if (listener) page.removeListener('response', listener);
          const result = stopCapture();
          return `Network capture stopped. ${result.count} responses captured (${result.sizeKB}KB).`;
        }

        // Start capture
        if (isCaptureActive()) return 'Capture already active. Use --capture stop first.';
        const filterIdx = args.indexOf('--filter');
        const filterPattern = filterIdx >= 0 ? args[filterIdx + 1] : undefined;
        const info = startCapture(filterPattern);
        // Attach listener to current page
        const page = bm.getPage();
        const listener = getCaptureListener();
        if (listener) page.on('response', listener);
        return `Network capture started${info.filter ? ` (filter: ${info.filter})` : ''}. Use --capture stop to stop.`;
      }

      if (args[0] === '--export') {
        const { exportCapture } = await import('./network-capture');
        const { validateOutputPath: vop } = await import('./path-security');
        const exportPath = args[1];
        if (!exportPath) throw new Error('Usage: network --export <path>');
        vop(exportPath);
        const count = exportCapture(exportPath);
        return `Exported ${count} captured responses to ${exportPath}`;
      }

      if (args[0] === '--bodies') {
        const { getCaptureBuffer } = await import('./network-capture');
        return getCaptureBuffer().summary();
      }

      // Default: show request metadata
      if (networkBuffer.length === 0) return '(no network requests)';
      return networkBuffer.toArray().map(e =>
        `${e.method} ${e.url} → ${e.status || 'pending'} (${e.duration || '?'}ms, ${e.size || '?'}B)`
      ).join('\n');
    }

    case 'dialog': {
      if (args[0] === '--clear') {
        dialogBuffer.clear();
        return 'Dialog buffer cleared.';
      }
      if (dialogBuffer.length === 0) return '(no dialogs captured)';
      return dialogBuffer.toArray().map(e =>
        `[${new Date(e.timestamp).toISOString()}] [${e.type}] "${e.message}" → ${e.action}${e.response ? ` "${e.response}"` : ''}`
      ).join('\n');
    }

    case 'is': {
      const property = args[0];
      const selector = args[1];
      if (!property || !selector) throw new Error('Usage: browse is <property> <selector>\nProperties: visible, hidden, enabled, disabled, checked, editable, focused');

      const resolved = await session.resolveRef(selector);
      let locator;
      if ('locator' in resolved) {
        locator = resolved.locator;
      } else {
        locator = target.locator(resolved.selector);
      }

      switch (property) {
        case 'visible':  return String(await locator.isVisible());
        case 'hidden':   return String(await locator.isHidden());
        case 'enabled':  return String(await locator.isEnabled());
        case 'disabled': return String(await locator.isDisabled());
        case 'checked':  return String(await locator.isChecked());
        case 'editable': return String(await locator.isEditable());
        case 'focused': {
          const isFocused = await locator.evaluate(
            (el) => el === document.activeElement
          );
          return String(isFocused);
        }
        default:
          throw new Error(`Unknown property: ${property}. Use: visible, hidden, enabled, disabled, checked, editable, focused`);
      }
    }

    case 'cookies': {
      const cookies = await page.context().cookies();
      // Redact cookie values that look like secrets (consistent with storage redaction)
      const redacted = cookies.map(c => {
        if (SENSITIVE_COOKIE_NAME.test(c.name) || SENSITIVE_COOKIE_VALUE.test(c.value)) {
          return { ...c, value: `[REDACTED — ${c.value.length} chars]` };
        }
        return c;
      });
      return JSON.stringify(redacted, null, 2);
    }

    case 'storage': {
      if (args[0] === 'set' && args[1]) {
        const key = args[1];
        const value = args[2] || '';
        await target.evaluate(([k, v]: string[]) => localStorage.setItem(k, v), [key, value]);
        return `Set localStorage["${key}"]`;
      }
      const storage = await target.evaluate(() => ({
        localStorage: { ...localStorage },
        sessionStorage: { ...sessionStorage },
      }));
      // Redact values that look like secrets (tokens, keys, passwords, JWTs)
      const SENSITIVE_KEY = /(^|[_.-])(token|secret|key|password|credential|auth|jwt|session|csrf)($|[_.-])|api.?key/i;
      const SENSITIVE_VALUE = /^(eyJ|sk-|sk_live_|sk_test_|pk_live_|pk_test_|rk_live_|sk-ant-|ghp_|gho_|github_pat_|xox[bpsa]-|AKIA[A-Z0-9]{16}|AIza|SG\.|Bearer\s|sbp_)/;
      const redacted = JSON.parse(JSON.stringify(storage));
      for (const storeType of ['localStorage', 'sessionStorage'] as const) {
        const store = redacted[storeType];
        if (!store) continue;
        for (const [key, value] of Object.entries(store)) {
          if (typeof value !== 'string') continue;
          if (SENSITIVE_KEY.test(key) || SENSITIVE_VALUE.test(value)) {
            store[key] = `[REDACTED — ${value.length} chars]`;
          }
        }
      }
      return JSON.stringify(redacted, null, 2);
    }

    case 'perf': {
      const timings = await page.evaluate(() => {
        const nav = performance.getEntriesByType('navigation')[0] as PerformanceNavigationTiming;
        if (!nav) return 'No navigation timing data available.';
        return {
          dns: Math.round(nav.domainLookupEnd - nav.domainLookupStart),
          tcp: Math.round(nav.connectEnd - nav.connectStart),
          ssl: Math.round(nav.secureConnectionStart > 0 ? nav.connectEnd - nav.secureConnectionStart : 0),
          ttfb: Math.round(nav.responseStart - nav.requestStart),
          download: Math.round(nav.responseEnd - nav.responseStart),
          domParse: Math.round(nav.domInteractive - nav.responseEnd),
          domReady: Math.round(nav.domContentLoadedEventEnd - nav.startTime),
          load: Math.round(nav.loadEventEnd - nav.startTime),
          total: Math.round(nav.loadEventEnd - nav.startTime),
        };
      });
      if (typeof timings === 'string') return timings;
      return Object.entries(timings)
        .map(([k, v]) => `${k.padEnd(12)} ${v}ms`)
        .join('\n');
    }

    case 'inspect': {
      // Parse flags
      let includeUA = false;
      let showHistory = false;
      let selector: string | undefined;

      for (const arg of args) {
        if (arg === '--all') {
          includeUA = true;
        } else if (arg === '--history') {
          showHistory = true;
        } else if (!selector) {
          selector = arg;
        }
      }

      // --history mode: return modification history
      if (showHistory) {
        const history = getModificationHistory();
        if (history.length === 0) return '(no style modifications)';
        return history.map((m, i) =>
          `[${i}] ${m.selector} { ${m.property}: ${m.oldValue} → ${m.newValue} } (${m.source}, ${m.method})`
        ).join('\n');
      }

      // If no selector given, check for stored inspector data
      if (!selector) {
        // Access stored inspector data from the server's in-memory state
        // The server stores this when the extension picks an element via POST /inspector/pick
        const stored = (bm as any)._inspectorData;
        const storedTs = (bm as any)._inspectorTimestamp;
        if (stored) {
          const stale = storedTs && (Date.now() - storedTs > 60000);
          let output = formatInspectorResult(stored, { includeUA });
          if (stale) output = '⚠ Data may be stale (>60s old)\n\n' + output;
          return output;
        }
        throw new Error('Usage: browse inspect [selector] [--all] [--history]\nOr pick an element in the Chrome sidebar first.');
      }

      // Direct inspection by selector
      const result = await inspectElement(page, selector, { includeUA });
      // Store for later retrieval
      (bm as any)._inspectorData = result;
      (bm as any)._inspectorTimestamp = Date.now();
      return formatInspectorResult(result, { includeUA });
    }

    case 'media': {
      const { extractMedia } = await import('./media-extract');
      const target = bm.getActiveFrameOrPage();
      const filter = args.includes('--images') ? 'images' as const
        : args.includes('--videos') ? 'videos' as const
        : args.includes('--audio') ? 'audio' as const
        : undefined;
      const selectorArg = args.find(a => !a.startsWith('--'));
      const result = await extractMedia(target, { selector: selectorArg, filter });
      return JSON.stringify(result, null, 2);
    }

    case 'data': {
      const target = bm.getActiveFrameOrPage();
      const wantJsonLd = args.includes('--jsonld') || args.length === 0;
      const wantOg = args.includes('--og') || args.length === 0;
      const wantTwitter = args.includes('--twitter') || args.length === 0;
      const wantMeta = args.includes('--meta') || args.length === 0;

      const result = await target.evaluate(({ wantJsonLd, wantOg, wantTwitter, wantMeta }) => {
        const data: Record<string, any> = {};

        if (wantJsonLd) {
          const scripts = document.querySelectorAll('script[type="application/ld+json"]');
          const jsonLd: any[] = [];
          scripts.forEach(s => {
            try { jsonLd.push(JSON.parse(s.textContent || '')); } catch {}
          });
          data.jsonLd = jsonLd;
        }

        if (wantOg) {
          const og: Record<string, string> = {};
          document.querySelectorAll('meta[property^="og:"]').forEach(m => {
            const prop = m.getAttribute('property')?.replace('og:', '') || '';
            og[prop] = m.getAttribute('content') || '';
          });
          data.openGraph = og;
        }

        if (wantTwitter) {
          const tw: Record<string, string> = {};
          document.querySelectorAll('meta[name^="twitter:"]').forEach(m => {
            const name = m.getAttribute('name')?.replace('twitter:', '') || '';
            tw[name] = m.getAttribute('content') || '';
          });
          data.twitterCards = tw;
        }

        if (wantMeta) {
          const meta: Record<string, string> = {};
          const canonical = document.querySelector('link[rel="canonical"]');
          if (canonical) meta.canonical = canonical.getAttribute('href') || '';
          const desc = document.querySelector('meta[name="description"]');
          if (desc) meta.description = desc.getAttribute('content') || '';
          const keywords = document.querySelector('meta[name="keywords"]');
          if (keywords) meta.keywords = keywords.getAttribute('content') || '';
          const author = document.querySelector('meta[name="author"]');
          if (author) meta.author = author.getAttribute('content') || '';
          const title = document.querySelector('title');
          if (title) meta.title = title.textContent || '';
          data.meta = meta;
        }

        return data;
      }, { wantJsonLd, wantOg, wantTwitter, wantMeta });

      return JSON.stringify(result, null, 2);
    }

    default:
      throw new Error(`Unknown read command: ${command}`);
  }
}