app/src/editor-language.mjs

const extensions = {
  html: 'markup', htm: 'markup', xml: 'markup', svg: 'markup', vue: 'markup',
  css: 'css', js: 'javascript', mjs: 'javascript', cjs: 'javascript', jsx: 'jsx',
  ts: 'typescript', mts: 'typescript', cts: 'typescript', tsx: 'tsx',
  json: 'json', ipynb: 'json', md: 'markdown', markdown: 'markdown',
  py: 'python', pyw: 'python', sh: 'bash', bash: 'bash', zsh: 'bash',
  yml: 'yaml', yaml: 'yaml', toml: 'toml', sql: 'sql', csv: 'csv',
  c: 'c', h: 'c', cpp: 'cpp', cc: 'cpp', cxx: 'cpp', hpp: 'cpp',
  cs: 'csharp', java: 'java', go: 'go', rs: 'rust', diff: 'diff', patch: 'diff',
};

export function editorLanguage(path = '') {
  const name = path.split('/').at(-1).toLowerCase();
  if (/^dockerfile(?:\.|$)/.test(name)) return 'docker';
  if (/^\.(?:bashrc|bash_profile|zshrc|profile)$/.test(name)) return 'bash';
  return extensions[name.split('.').at(-1)] ?? null;
}

// Bound both tokenization and the amount of highlighted DOM on the main thread.
export function canHighlight(text) {
  if (text.length > 200_000) return false;
  let lines = 1;
  for (let i = 0; i < text.length; i++) if (text.charCodeAt(i) === 10 && ++lines > 5000) return false;
  return true;
}