Function transformer

packages/next-codemod/transforms/next-lint-to-eslint-cli.ts:1045–1208

(
  files: string[],
  options: TransformerOptions = {}
)

}

export default function transformer(
  files: string[],
  options: TransformerOptions = {}
): void {
  // The codemod CLI passes arguments as an array for consistency with file-based transforms,
  // but project-level transforms like this one only process a single directory.
  // Usage: npx @next/codemod next-lint-to-eslint-cli <project-directory>
  const dir = files[0]
  if (!dir) {
    console.error('Error: Please specify a directory path')
    return
  }

  // Allow skipping installation via option
  const skipInstall = options.skipInstall === true

  const projectRoot = path.resolve(dir)
  const packageJsonPath = path.join(projectRoot, 'package.json')

  if (!existsSync(packageJsonPath)) {
    console.error('Error: package.json not found in the specified directory')
    return
  }

  const isTypeScript = detectTypeScript(projectRoot)

  console.log('Migrating from next lint to the ESLint CLI...')

  // Check for existing ESLint config
  const existingConfig = findExistingEslintConfig(projectRoot)

  // If no existing ESLint config found, create a new one.
  if (existingConfig.exists === false) {
    // Create new ESLint flat config
    const eslintConfigPath = path.join(projectRoot, 'eslint.config.mjs')
    const template = isTypeScript
      ? ESLINT_CONFIG_TEMPLATE_TYPESCRIPT
      : ESLINT_CONFIG_TEMPLATE_JAVASCRIPT

    try {
      writeFileSync(eslintConfigPath, template)
      console.log(`   Created ${path.basename(eslintConfigPath)}`)
    } catch (error) {
      console.error('   Error creating ESLint config:', error)
    }
  } else {
    let eslintConfigFilename = path.basename(existingConfig.path)
    let eslintConfigPath = existingConfig.path

    // If legacy config found, run ESLint migration tool first. It will
    // use FlatCompat, so will continue to migrate using Flat config format.
    if (existingConfig.isLegacy && existingConfig.path) {
      console.log(`   Found legacy ESLint config: ${eslintConfigFilename}`)

      // Run npx @eslint/migrate-config
      const command = `npx @eslint/migrate-config ${existingConfig.path}`
      console.log(`   Running "${command}" to convert legacy config...`)
      try {