import fs from 'node:fs/promises'
import path from 'node:path'
import process from 'node:process'
import { fileURLToPath } from 'node:url'

const __filename = fileURLToPath(import.meta.url)
const __dirname = path.dirname(__filename)

function isPlainObject(v) {
  return v != null && typeof v === 'object' && !Array.isArray(v)
}

function flattenKeys(obj, prefix = '') {
  const out = new Set()
  if (!isPlainObject(obj)) return out
  for (const k of Object.keys(obj)) {
    const next = prefix ? `${prefix}.${k}` : k
    const v = obj[k]
    if (isPlainObject(v)) {
      for (const sub of flattenKeys(v, next)) out.add(sub)
    } else {
      out.add(next)
    }
  }
  return out
}

function diff(a, b) {
  // items in a but not in b
  const out = []
  for (const x of a) if (!b.has(x)) out.push(x)
  out.sort()
  return out
}

async function readJson(p) {
  const raw = await fs.readFile(p, 'utf8')
  return JSON.parse(raw)
}

async function main() {
  const root = path.resolve(__dirname, '../src/locales')
  const files = {
    zh: path.join(root, 'zh.json'),
    en: path.join(root, 'en.json'),
    ja: path.join(root, 'ja.json')
  }

  const [zh, en, ja] = await Promise.all([readJson(files.zh), readJson(files.en), readJson(files.ja)])

  const keysZh = flattenKeys(zh)
  const keysEn = flattenKeys(en)
  const keysJa = flattenKeys(ja)

  const missingEn = diff(keysZh, keysEn)
  const missingJa = diff(keysZh, keysJa)
  const extraEn = diff(keysEn, keysZh)
  const extraJa = diff(keysJa, keysZh)

  const problems = []
  if (missingEn.length) problems.push({ title: 'en 缺少 key', items: missingEn })
  if (missingJa.length) problems.push({ title: 'ja 缺少 key', items: missingJa })
  if (extraEn.length) problems.push({ title: 'en 多余 key', items: extraEn })
  if (extraJa.length) problems.push({ title: 'ja 多余 key', items: extraJa })

  if (problems.length) {
    console.error('[i18n-check] locales key mismatch found:')
    for (const p of problems) {
      console.error(`\n- ${p.title}（${p.items.length}）`)
      for (const it of p.items) console.error(`  - ${it}`)
    }
    process.exit(1)
  }

  console.log(`[i18n-check] OK: ${keysZh.size} keys in sync (zh/en/ja).`)
}

main().catch((err) => {
  console.error('[i18n-check] Failed:', err)
  process.exit(1)
})