import rateLimit from 'express-rate-limit'
import { BIBLE_BOOKS } from '../../shared/bible-books.js'

const passageCache = new Map()
const PASSAGE_CACHE_MAX = 2000
const MAX_CHAPTER = 150
const MAX_VERSE = 176
const MAX_VERSES_PER_REQUEST = 60

const passageRateLimiter = rateLimit({
  windowMs: 60 * 1000,
  max: 60,
  standardHeaders: true,
  legacyHeaders: false,
  message: { message: 'Too many passage requests. Please slow down.' },
})

// Keyed by lowercase, whitespace-stripped book name/alias (matching the format
// the admin's "Bible Book" field and the /api/bible-passage `book` query param
// both use), mapped to bolls.life's numeric book id (canonical order, 1-66).
// Derived from the shared BIBLE_BOOKS list so it can't drift from the client's
// Scripture Index book map (src/App.tsx's SI_BOOK_MAP).
const BOLLS_BOOK_MAP = {}
BIBLE_BOOKS.forEach((b, index) => {
  const bookNum = index + 1
  for (const key of [b.name.toLowerCase(), ...(b.aliases ?? [])]) {
    BOLLS_BOOK_MAP[key.replace(/\s+/g, '')] = bookNum
  }
})

function parseReference(reference) {
  // Accept a leading book name ("Titus 1:1-2", "1 John 2:3"), en/em dashes and verse-part letters ("1:13a")
  const stripped = reference
    .replace(/[–—]/g, '-')
    .replace(/(\d)[a-z]\b/gi, '$1')
    .replace(/^\s*(?:[1-3]\s*)?[a-z][a-z .]*?\s*(?=\d+:)/i, '')
    .trim()
  const match = stripped.match(/^(\d+):(\d+)(?:-(\d+))?$/)
  if (!match) return null
  return {
    chapter: parseInt(match[1], 10),
    verseStart: parseInt(match[2], 10),
    verseEnd: match[3] ? parseInt(match[3], 10) : parseInt(match[2], 10),
  }
}

export function register(app) {
  app.get('/api/bible-passage', passageRateLimiter, async (req, res) => {
    const book = String(req.query.book ?? '').trim().toLowerCase().replace(/[\s-]/g, '')
    const reference = String(req.query.reference ?? '').trim()

    const bookNum = BOLLS_BOOK_MAP[book]
    if (!bookNum) {
      res.status(400).json({ message: 'Unknown book.' })
      return
    }

    const parsed = parseReference(reference)
    if (!parsed) {
      res.status(400).json({ message: 'Invalid reference format. Expected format: chapter:verseStart-verseEnd' })
      return
    }

    if (
      parsed.chapter < 1 || parsed.chapter > MAX_CHAPTER
      || parsed.verseStart < 1 || parsed.verseEnd > MAX_VERSE
      || parsed.verseEnd < parsed.verseStart
      || parsed.verseEnd - parsed.verseStart + 1 > MAX_VERSES_PER_REQUEST
    ) {
      res.status(400).json({ message: `Passage out of range (max ${MAX_VERSES_PER_REQUEST} verses).` })
      return
    }

    const cacheKey = `BSB:${bookNum}:${parsed.chapter}:${parsed.verseStart}:${parsed.verseEnd}`
    if (passageCache.has(cacheKey)) {
      res.json({ text: passageCache.get(cacheKey) })
      return
    }

    try {
      const verseNums = []
      for (let v = parsed.verseStart; v <= parsed.verseEnd; v++) verseNums.push(v)

      const results = await Promise.all(
        verseNums.map(v =>
          fetch(`https://bolls.life/get-verse/BSB/${bookNum}/${parsed.chapter}/${v}/`, { signal: AbortSignal.timeout(8000) })
            .then(r => r.ok ? r.json() : Promise.reject(new Error(`${r.status}`)))
        )
      )

      if (results.length === 0) {
        res.status(404).json({ message: 'Passage not found.' })
        return
      }

      const text = results.map(v => `v. ${v.verse} ${String(v.text).trim()}`).join('\n\n')
      if (passageCache.size >= PASSAGE_CACHE_MAX) passageCache.delete(passageCache.keys().next().value)
      passageCache.set(cacheKey, text)
      res.json({ text })
    } catch {
      res.status(502).json({ message: 'Unable to fetch passage right now.' })
    }
  })
}