import { NextRequest, NextResponse } from 'next/server'
import { Prisma } from '@prisma/client'
import { auth } from '@/auth'
import { prisma } from '@/lib/prisma'
import type { FlashcardStyle } from '@/lib/flashcards/generate-flashcards'

interface CardInput {
  front: string
  back: string
  type?: string
}

export async function POST(request: NextRequest) {
  try {
    if (!prisma.flashcard || !prisma.flashcardDeck) {
      return NextResponse.json(
        { error: 'Flashcards client outdated. Restart the app after prisma generate.', errorKey: 'flashcards.schemaMissing' },
        { status: 503 },
      )
    }

    const session = await auth()
    if (!session?.user?.id) {
      return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
    }

    const body = await request.json()
    const noteId = typeof body.noteId === 'string' ? body.noteId : null
    const deckIdInput = typeof body.deckId === 'string' ? body.deckId : null
    const cards = Array.isArray(body.cards) ? body.cards as CardInput[] : []

    if (cards.length === 0) {
      return NextResponse.json({ error: 'No cards to save' }, { status: 400 })
    }

    let notebookId: string | null = null
    let noteName = 'Sans titre'
    if (noteId) {
      const note = await prisma.note.findFirst({
        where: { id: noteId, userId: session.user.id },
        select: { notebookId: true, title: true },
      })
      if (!note) {
        return NextResponse.json({ error: 'Note not found' }, { status: 404 })
      }
      notebookId = note.notebookId
      noteName = note.title?.trim() || 'Sans titre'
    }

    let deckId = deckIdInput
    if (!deckId) {
      if (noteId) {
        // Chercher un deck déjà créé pour CETTE note spécifique
        const existingFromNote = await prisma.flashcard.findFirst({
          where: { noteId, deck: { userId: session.user.id } },
          select: { deckId: true },
        })
        if (existingFromNote) {
          deckId = existingFromNote.deckId
        }
      }
      if (!deckId) {
        // Créer un nouveau deck nommé d'après la note (pas le carnet)
        const deck = await prisma.flashcardDeck.create({
          data: { userId: session.user.id, notebookId, name: noteName },
        })
        deckId = deck.id
      }
    } else {
      const deck = await prisma.flashcardDeck.findFirst({
        where: { id: deckId, userId: session.user.id },
      })
      if (!deck) {
        return NextResponse.json({ error: 'Deck not found' }, { status: 404 })
      }
    }

    const sanitized = cards
      .map((c) => ({
        front: typeof c.front === 'string' ? c.front.trim().slice(0, 500) : '',
        back: typeof c.back === 'string' ? c.back.trim().slice(0, 800) : '',
        type: (['qa', 'cloze', 'concept'].includes(c.type || '') ? c.type : 'qa') as FlashcardStyle,
      }))
      .filter((c) => c.front && c.back)

    if (sanitized.length === 0) {
      return NextResponse.json({ error: 'No valid cards' }, { status: 400 })
    }

    await prisma.flashcard.createMany({
      data: sanitized.map((c) => ({
        deckId: deckId!,
        noteId,
        front: c.front,
        back: c.back,
        type: c.type,
      })),
    })

    await prisma.flashcardDeck.update({
      where: { id: deckId! },
      data: { updatedAt: new Date() },
    })

    return NextResponse.json({
      deckId,
      savedCount: sanitized.length,
    })
  } catch (error) {
    console.error('[flashcards/save]', error)
    if (error instanceof Prisma.PrismaClientKnownRequestError) {
      if (error.code === 'P2021' || error.code === 'P2022') {
        return NextResponse.json(
          { error: 'Flashcards schema not migrated. Run prisma migrate deploy.', errorKey: 'flashcards.schemaMissing' },
          { status: 503 },
        )
      }
    }
    const message = error instanceof Error ? error.message : 'Failed to save flashcards'
    return NextResponse.json({ error: message }, { status: 500 })
  }
}