import { Router } from 'express'
import { auth } from '../middleware/auth.js'

// Point at a self-hosted LanguageTool instance by setting LANGUAGETOOL_URL.
// Falls back to the free public API (rate-limited but good for personal use).
const LT_URL = (process.env.LANGUAGETOOL_URL || 'https://api.languagetoolplus.com/v2').replace(/\/$/, '')

const router = Router()
router.use(auth)

router.post('/check', async (req, res) => {
  const { text, language = 'en-US' } = req.body || {}
  if (!text || typeof text !== 'string') return res.status(400).json({ error: 'text required' })

  try {
    const body = new URLSearchParams({
      text,
      language,
      // Suppress cosmetic rules that aren't useful in a creative-writing context
      disabledRules: 'WHITESPACE_RULE,WORD_CONTAINS_UPPERCASE,EN_UNPAIRED_BRACKETS,DASH_RULE',
    })

    const r = await fetch(`${LT_URL}/check`, {
      method:  'POST',
      headers: { 'Content-Type': 'application/x-www-form-urlencoded', Accept: 'application/json' },
      body:    body.toString(),
      signal:  AbortSignal.timeout(30000),
    })

    if (!r.ok) {
      const msg = await r.text().catch(() => '')
      throw new Error(`LanguageTool ${r.status}: ${msg.slice(0, 200)}`)
    }

    const data = await r.json()

    // Send only what the client needs — keep the payload small
    res.json({
      matches: (data.matches || []).map(m => ({
        message:      m.message,
        offset:       m.offset,
        length:       m.length,
        replacements: (m.replacements || []).slice(0, 6).map(r => r.value),
        kind:         m.rule?.category?.id === 'TYPOS' ? 'spelling' : 'grammar',
        ruleId:       m.rule?.id ?? '',
      })),
    })
  } catch (err) {
    console.error('[lint] LanguageTool error:', err.message)
    res.status(502).json({ error: err.message })
  }
})

export default router