import { prisma } from '../lib/prisma.js'

export async function registerUserCartRoutes(fastify) {
  fastify.get('/api/me/cart', { preHandler: [fastify.authenticate] }, async (request) => {
    const userId = request.user.sub
    const items = await prisma.cartItem.findMany({
      where: { userId },
      include: { product: { include: { category: true, images: { orderBy: { sort: 'asc' } } } } },
      orderBy: { createdAt: 'asc' },
    })
    return {
      items: items.map((x) => ({
        id: x.id,
        qty: x.qty,
        product: x.product,
      })),
    }
  })

  fastify.post('/api/me/cart/items', { preHandler: [fastify.authenticate] }, async (request, reply) => {
    const userId = request.user.sub
    const productId = String(request.body?.productId || '').trim()
    const qtyRaw = request.body?.qty
    const qty = qtyRaw === undefined || qtyRaw === null || qtyRaw === '' ? 1 : Number(qtyRaw)

    if (!productId) return reply.code(400).send({ error: 'productId обязателен' })
    if (!Number.isFinite(qty) || qty <= 0) return reply.code(400).send({ error: 'qty должен быть > 0' })

    const product = await prisma.product.findFirst({ where: { id: productId, published: true } })
    if (!product) return reply.code(404).send({ error: 'Товар не найден' })

    const available = product.quantity
    const existing = await prisma.cartItem.findUnique({ where: { userId_productId: { userId, productId } } })
    const nextQty = (existing?.qty ?? 0) + Math.floor(qty)
    if (nextQty > available) return reply.code(409).send({ error: `Доступно: ${available} шт.` })

    const item = await prisma.cartItem.upsert({
      where: { userId_productId: { userId, productId } },
      update: { qty: nextQty },
      create: { userId, productId, qty: nextQty },
    })
    return reply.code(201).send({ item })
  })

  fastify.patch('/api/me/cart/items/:id', { preHandler: [fastify.authenticate] }, async (request, reply) => {
    const userId = request.user.sub
    const { id } = request.params
    const qtyRaw = request.body?.qty
    const qty = Number(qtyRaw)
    if (!Number.isFinite(qty) || qty < 0) return reply.code(400).send({ error: 'qty должен быть ≥ 0' })

    const existing = await prisma.cartItem.findFirst({ where: { id, userId }, include: { product: true } })
    if (!existing) return reply.code(404).send({ error: 'Позиция корзины не найдена' })

    if (qty === 0) {
      await prisma.cartItem.delete({ where: { id } })
      return reply.code(204).send()
    }

    const available = existing.product.quantity
    const nextQty = Math.floor(qty)
    if (nextQty > available) return reply.code(409).send({ error: `Доступно: ${available} шт.` })

    const updated = await prisma.cartItem.update({ where: { id }, data: { qty: nextQty } })
    return { item: updated }
  })

  fastify.delete('/api/me/cart/items/:id', { preHandler: [fastify.authenticate] }, async (request, reply) => {
    const userId = request.user.sub
    const { id } = request.params
    const existing = await prisma.cartItem.findFirst({ where: { id, userId } })
    if (!existing) return reply.code(404).send({ error: 'Позиция корзины не найдена' })
    await prisma.cartItem.delete({ where: { id } })
    return reply.code(204).send()
  })
}