Function highlightCode

web/src/components/ai-elements/code-block.tsx:175–237

(
  code: string,
  language: BundledLanguage,
  // oxlint-disable-next-line eslint-plugin-promise(prefer-await-to-callbacks)
  callback?: (result: TokenizedCode) => void
)

// Synchronous highlight with callback for async results
export const highlightCode = (
  code: string,
  language: BundledLanguage,
  // oxlint-disable-next-line eslint-plugin-promise(prefer-await-to-callbacks)
  callback?: (result: TokenizedCode) => void
): TokenizedCode | null => {
  const tokensCacheKey = getTokensCacheKey(code, language);

  // Return cached result if available
  const cached = tokensCache.get(tokensCacheKey);
  if (cached) {
    return cached;
  }

  // Subscribe callback if provided
  if (callback) {
    if (!subscribers.has(tokensCacheKey)) {
      subscribers.set(tokensCacheKey, new Set());
    }
    subscribers.get(tokensCacheKey)?.add(callback);
  }

  // Start highlighting in background - fire-and-forget async pattern
  getHighlighter(language)
    // oxlint-disable-next-line eslint-plugin-promise(prefer-await-to-then)
    .then((highlighter) => {
      const availableLangs = highlighter.getLoadedLanguages();
      const langToUse = availableLangs.includes(language) ? language : "text";

      const result = highlighter.codeToTokens(code, {
        lang: langToUse,
        themes: {
          dark: "github-dark",
          light: "github-light",
        },
      });

      const tokenized: TokenizedCode = {
        bg: result.bg ?? "transparent",
        fg: result.fg ?? "inherit",
        tokens: result.tokens,
      };

      // Cache the result
      tokensCache.set(tokensCacheKey, tokenized);

      // Notify all subscribers
      const subs = subscribers.get(tokensCacheKey);
      if (subs) {
        for (const sub of subs) {
          sub(tokenized);
        }
        subscribers.delete(tokensCacheKey);
      }
    })
    // oxlint-disable-next-line eslint-plugin-promise(prefer-await-to-then), eslint-plugin-promise(prefer-await-to-callbacks)
    .catch((error) => {
      console.error("Failed to highlight code:", error);