import { NextRequest, NextResponse } from 'next/server'
import { auth } from '@/auth'
import prisma from '@/lib/prisma'
import { exerciseGeneratorService } from '@/lib/ai/services/exercise-generator.service'
import { reserveUsageOrThrow, QuotaExceededError } from '@/lib/entitlements'
import { preprocessMathInHtml } from '@/lib/text/math-preprocess'
import { hasUserAiConsent, aiConsentForbiddenResponse } from '@/lib/consent/server-consent'

export async function POST(request: NextRequest) {
  try {
    const session = await auth()
    if (!session?.user?.id) {
      return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
    }

    const { noteId, count, language } = await request.json()
    if (!noteId) {
      return NextResponse.json({ error: 'noteId is required' }, { status: 400 })
    }

    if (!(await hasUserAiConsent())) return aiConsentForbiddenResponse()

    try {
      await reserveUsageOrThrow(session.user.id, 'reformulate')
    } catch (err) {
      if (err instanceof QuotaExceededError) {
        const isTierLocked = err.currentQuota === 0
        return NextResponse.json(
          { error: isTierLocked ? 'feature_locked' : 'quota_exceeded', errorKey: isTierLocked ? 'ai.featureLocked' : 'ai.quotaExceeded' },
          { status: 402 },
        )
      }
      throw err
    }

    const note = await prisma.note.findUnique({
      where: { id: noteId },
      select: { id: true, title: true, content: true, notebookId: true },
    })

    if (!note) {
      return NextResponse.json({ error: 'Note not found' }, { status: 404 })
    }

    const exercises = await exerciseGeneratorService.generate(
      note.title || 'Sans titre',
      note.content,
      { count: count || 5, language: language || 'fr' }
    )

    // Create exercise notes in the same notebook
    const lang = language || 'fr'
    const exerciseLabel = lang === 'fr' ? 'Exercice' : lang === 'fa' ? 'تمرین' : lang === 'ar' ? 'تمرين' : lang === 'de' ? 'Übung' : lang === 'es' ? 'Ejercicio' : lang === 'it' ? 'Esercizio' : lang === 'pt' ? 'Exercício' : lang === 'ru' ? 'Упражнение' : lang === 'zh' ? '练习' : lang === 'ja' ? '練習' : lang === 'ko' ? '연습' : lang === 'nl' ? 'Oefening' : lang === 'pl' ? 'Ćwiczenie' : lang === 'hi' ? 'अभ्यास' : 'Exercise'
    const answerLabel = lang === 'fr' ? 'Corrigé' : lang === 'fa' ? 'پاسخ' : lang === 'ar' ? 'الحل' : lang === 'de' ? 'Lösung' : lang === 'es' ? 'Solución' : lang === 'it' ? 'Soluzione' : lang === 'pt' ? 'Solução' : lang === 'ru' ? 'Решение' : lang === 'zh' ? '解答' : lang === 'ja' ? '解答' : lang === 'ko' ? '해답' : lang === 'nl' ? 'Oplossing' : lang === 'pl' ? 'Rozwiązanie' : lang === 'hi' ? 'हल' : 'Solution'
    const statementLabel = lang === 'fr' ? 'Énoncé' : lang === 'fa' ? 'صورت مسئله' : lang === 'ar' ? 'السؤال' : lang === 'de' ? 'Aufgabe' : lang === 'es' ? 'Enunciado' : lang === 'it' ? 'Testo' : lang === 'pt' ? 'Enunciado' : lang === 'ru' ? 'Задание' : lang === 'zh' ? '题目' : lang === 'ja' ? '問題' : lang === 'ko' ? '문제' : lang === 'nl' ? 'Opgave' : lang === 'pl' ? 'Zadanie' : lang === 'hi' ? 'प्रश्न' : 'Statement'
    const revealLabel = lang === 'fr' ? 'cliquer pour révéler' : lang === 'fa' ? 'برای نمایش کلیک کنید' : lang === 'ar' ? 'انقر للكشف' : lang === 'de' ? 'zum Anzeigen klicken' : lang === 'es' ? 'haz clic para ver' : lang === 'it' ? 'clicca per rivelare' : lang === 'pt' ? 'clique para revelar' : lang === 'ru' ? 'нажмите, чтобы открыть' : lang === 'zh' ? '点击查看' : lang === 'ja' ? 'クリックして表示' : lang === 'ko' ? '클릭하여 보기' : lang === 'nl' ? 'klik om te onthullen' : lang === 'pl' ? 'kliknij, aby zobaczyć' : lang === 'hi' ? 'देखने के लिए क्लिक करें' : 'click to reveal'
    const difficultyMap: Record<string, Record<string, string>> = {
      facile: { fr: 'facile', en: 'easy', fa: 'آسان', ar: 'سهل', de: 'einfach', es: 'fácil', it: 'facile', pt: 'fácil', ru: 'лёгкий', zh: '简单', ja: '易しい', ko: '쉬움', nl: 'makkelijk', pl: 'łatwy', hi: 'आसान' },
      moyen: { fr: 'moyen', en: 'medium', fa: 'متوسط', ar: 'متوسط', de: 'mittel', es: 'medio', it: 'medio', pt: 'médio', ru: 'средний', zh: '中等', ja: '普通', ko: '보통', nl: 'gemiddeld', pl: 'średni', hi: 'मध्यम' },
      difficile: { fr: 'difficile', en: 'hard', fa: 'دشوار', ar: 'صعب', de: 'schwer', es: 'difícil', it: 'difficile', pt: 'difícil', ru: 'сложный', zh: '困难', ja: '難しい', ko: '어려움', nl: 'moeilijk', pl: 'trudny', hi: 'कठिन' },
    }

    const createdNotes = []
    for (let i = 0; i < exercises.length; i++) {
      const ex = exercises[i]
      const difficultyEmoji = ex.difficulty === 'facile' ? '🟢' : ex.difficulty === 'moyen' ? '🟡' : '🔴'
      const difficultyLocalized = (difficultyMap[ex.difficulty]?.[lang]) || ex.difficulty

      const rawContent = `
<div data-type="callout-block" data-callout-type="warning"><p><strong>${exerciseLabel} ${i + 1}</strong> — ${difficultyEmoji} ${difficultyLocalized}</p></div>
<h2>${statementLabel}</h2>
<p>${ex.question}</p>
<div data-type="toggle-block" data-opened="false"><p><strong>${answerLabel}</strong> — ${revealLabel}</p><h3>${answerLabel}</h3><p>${ex.answer}</p></div>
`.trim()

      const content = preprocessMathInHtml(rawContent)

      const created = await prisma.note.create({
        data: {
          title: `${exerciseLabel} ${i + 1} — ${note.title || ''}`,
          content,
          userId: session.user.id,
          notebookId: note.notebookId,
          type: 'richtext',
          order: 999 + i,
        },
      })
      createdNotes.push(created)

      void (async () => {
        try {
          const { embeddingService } = await import('@/lib/ai/services/embedding.service')
          const { upsertNoteEmbedding } = await import('@/lib/embeddings')
          const { chunkIndexingService } = await import('@/lib/ai/services/chunk-indexing.service')
          const { embedding } = await embeddingService.generateNoteEmbedding(created.title, content)
          await upsertNoteEmbedding(created.id, embedding)
          await chunkIndexingService.indexNote(created.id, created.title, content)
        } catch {}
      })()
    }


    return NextResponse.json({
      exercises: createdNotes.map(n => ({ id: n.id, title: n.title })),
    })
  } catch (error: any) {
    console.error('[Exercise Generator] Error:', error)
    return NextResponse.json({ error: error.message || 'Failed to generate exercises' }, { status: 500 })
  }
}