import { Language } from '../types'
import { FAQEntry } from './types'
import { PRESENTER_FAQ } from './presenter-faq'

/**
 * Match a user query against pre-cached FAQ entries.
 * Returns the best match if score exceeds threshold, or null for LLM fallback.
 */
export function matchFAQ(query: string, lang: Language): FAQEntry | null {
  const normalized = query.toLowerCase().trim()
  const queryWords = normalized.split(/\s+/)

  let bestMatch: FAQEntry | null = null
  let bestScore = 0

  for (const entry of PRESENTER_FAQ) {
    let score = 0

    // Check keyword matches
    for (const keyword of entry.keywords) {
      const kwLower = keyword.toLowerCase()
      if (kwLower.includes(' ')) {
        // Multi-word keyword: check if phrase appears in query
        if (normalized.includes(kwLower)) {
          score += 3 * entry.priority / 10
        }
      } else {
        // Single keyword: check word-level match
        if (queryWords.some(w => w === kwLower || w.startsWith(kwLower) || kwLower.startsWith(w))) {
          score += 1
        }
        // Also check if keyword appears anywhere in query (partial match)
        if (normalized.includes(kwLower)) {
          score += 0.5
        }
      }
    }

    // Check if query matches the question text closely
    const questionText = lang === 'de' ? entry.question_de : entry.question_en
    const questionWords = questionText.toLowerCase().split(/\s+/)
    const overlapCount = queryWords.filter(w =>
      w.length > 2 && questionWords.some(qw => qw.includes(w) || w.includes(qw))
    ).length
    if (overlapCount >= 2) {
      score += overlapCount * 0.5
    }

    // Weight by priority
    score *= (entry.priority / 10)

    if (score > bestScore) {
      bestScore = score
      bestMatch = entry
    }
  }

  // Threshold: need meaningful match to avoid false positives
  // Require at least 2 keyword hits or strong phrase match
  if (bestScore < 1.5) {
    return null
  }

  return bestMatch
}

/**
 * Get FAQ answer text in the requested language
 */
export function getFAQAnswer(entry: FAQEntry, lang: Language): string {
  return lang === 'de' ? entry.answer_de : entry.answer_en
}