#!/usr/bin/env node
// choo-migrate [--dry] <files or directories…>
// Rewrites choo v7 sources toward v8: CJS → ESM for simple top-level
// patterns, package specifiers remapped, and a per-file report of what
// needs human hands. --dry prints the report without writing.

import { readFile, writeFile, readdir, stat } from 'node:fs/promises'
import { join, extname } from 'node:path'

import transform from './lib/transform.js'

const args = process.argv.slice(2)
const dry = args.includes('--dry')
const targets = args.filter((a) => a !== '--dry')

if (targets.length === 0) {
  console.log('usage: choo-migrate [--dry] <files or directories…>')
  process.exit(1)
}

const SKIP = new Set(['node_modules', '.git', 'dist', 'coverage'])

async function * walk (path) {
  const info = await stat(path)
  if (info.isFile()) {
    if (extname(path) === '.js' || extname(path) === '.mjs') yield path
    return
  }
  for (const entry of await readdir(path)) {
    if (SKIP.has(entry)) continue
    yield * walk(join(path, entry))
  }
}

let changedCount = 0
for (const target of targets) {
  for await (const file of walk(target)) {
    const source = await readFile(file, 'utf8')
    const { code, changed, notes } = transform(source)
    if (!changed && notes.length === 0) continue

    console.log(`\n${file}${changed ? (dry ? ' (would change)' : ' (rewritten)') : ''}`)
    for (const note of notes) console.log(`  ⚠ ${note}`)

    if (changed && !dry) {
      await writeFile(file, code)
      changedCount++
    }
  }
}

console.log(`\n${dry ? 'dry run — no files written' : changedCount + ' file(s) rewritten'}. Remember: package.json needs "type": "module" and deps on @uhhm/*.`)