// services/seller/sellerService.js
const { findSeller, findSellers } = require("../db/seller.db")
const dealService = require("./deal.service")
const { listSellersFromRedis, setSellerInRedis, setSellersInRedis } = require("./redis/sellerCache.service")
const { getRecentDealIdsBySeller, getSellerDealIndexCount } = require("./redis/sellerDealIndex.service")
const { getDealsByIdsFromRedis } = require("./redis/hotDealList.service")

const DEFAULT_LIMIT = 10
const MAX_LIMIT = 50

function normalizeSellerName(value) {
  return String(value || "").trim()
}

function normalizeSeller(seller = {}) {
  const id = Number(seller.id)
  if (!Number.isInteger(id) || id <= 0) return null
  return {
    id,
    name: String(seller.name || "").trim(),
    url: seller.url ?? null,
    sellerLogo: seller.sellerLogo ?? null,
    isActive: seller.isActive !== undefined ? Boolean(seller.isActive) : true,
  }
}

async function listSellersCached() {
  let sellers = await listSellersFromRedis()
  if (sellers.length) return sellers

  sellers = await findSellers(
    {},
    { select: { id: true, name: true, url: true, sellerLogo: true, isActive: true }, orderBy: { name: "asc" } }
  )
  if (sellers.length) {
    await setSellersInRedis(sellers)
  }
  return sellers
}

function clampPagination({ page, limit }) {
  const rawPage = Number(page)
  const rawLimit = Number(limit)
  const normalizedPage = Number.isFinite(rawPage) ? Math.max(1, Math.floor(rawPage)) : 1
  let normalizedLimit = Number.isFinite(rawLimit) ? Math.max(1, Math.floor(rawLimit)) : DEFAULT_LIMIT
  normalizedLimit = Math.min(MAX_LIMIT, normalizedLimit)
  const skip = (normalizedPage - 1) * normalizedLimit
  return { page: normalizedPage, limit: normalizedLimit, skip }
}

function normalizeDealCardFromRedis(deal = {}) {
  return {
    ...deal,
    id: Number(deal.id),
    score: Number.isFinite(deal.score) ? deal.score : 0,
    commentCount: Number.isFinite(deal.commentCount) ? deal.commentCount : 0,
    price: deal.price ?? null,
    originalPrice: deal.originalPrice ?? null,
    shippingPrice: deal.shippingPrice ?? null,
    discountValue: deal.discountValue ?? null,
  }
}

function hasSellerFilters(filters = {}) {
  if (!filters || typeof filters !== "object") return false
  const keys = [
    "status",
    "categoryId",
    "categoryIds",
    "saleType",
    "affiliateType",
    "minPrice",
    "maxPrice",
    "priceMin",
    "priceMax",
    "minScore",
    "maxScore",
    "sortBy",
    "sortDir",
    "createdAfter",
    "createdBefore",
    "from",
    "to",
    "hasImage",
  ]

  return keys.some((key) => {
    const value = filters[key]
    return value !== undefined && value !== null && String(value).trim() !== ""
  })
}

async function getSellerByName(name) {
  const normalized = normalizeSellerName(name)
  if (!normalized) {
    const err = new Error("SELLER_NAME_REQUIRED")
    err.statusCode = 400
    throw err
  }

  const sellers = await listSellersCached()
  const lower = normalized.toLowerCase()
  const cached = sellers
    .map(normalizeSeller)
    .filter(Boolean)
    .find((seller) => seller.name.toLowerCase() === lower)

  if (cached) {
    return { id: cached.id, name: cached.name, url: cached.url, sellerLogo: cached.sellerLogo }
  }

  const seller = await findSeller(
    { name: { equals: normalized, mode: "insensitive" } },
    { select: { id: true, name: true, url: true, sellerLogo: true, isActive: true } }
  )

  if (seller) {
    await setSellerInRedis(seller)
    return { id: seller.id, name: seller.name, url: seller.url, sellerLogo: seller.sellerLogo }
  }

  return null
}

async function getDealsBySellerName(name, { page = 1, limit = 10, filters = {}, viewer = null, scope = "USER" } = {}) {
  const seller = await getSellerByName(name)
  if (!seller) {
    const err = new Error("SELLER_NOT_FOUND")
    err.statusCode = 404
    throw err
  }

  const searchTerm = String(filters?.q || "").trim()
  const useSellerIndex = !searchTerm && !hasSellerFilters(filters)

  if (useSellerIndex) {
    const pagination = clampPagination({ page, limit })
    const [total, ids] = await Promise.all([
      getSellerDealIndexCount(seller.id),
      getRecentDealIdsBySeller({
        sellerId: seller.id,
        offset: pagination.skip,
        limit: pagination.limit,
      }),
    ])

    if (!total) {
      return {
        seller,
        payload: {
          page: pagination.page,
          total: 0,
          totalPages: 0,
          results: [],
        },
      }
    }

    if (!ids.length) {
      return {
        seller,
        payload: {
          page: pagination.page,
          total,
          totalPages: Math.ceil(total / pagination.limit),
          results: [],
        },
      }
    }

    const viewerId = viewer?.userId ? Number(viewer.userId) : null
    const deals = await getDealsByIdsFromRedis(ids, viewerId)
    if (deals.length === ids.length) {
      const activeDeals = deals.filter((deal) => String(deal?.status || "").toUpperCase() === "ACTIVE")
      if (activeDeals.length === ids.length) {
        return {
          seller,
          payload: {
            page: pagination.page,
            total,
            totalPages: Math.ceil(total / pagination.limit),
            results: activeDeals.map(normalizeDealCardFromRedis),
          },
        }
      }
    }
  }

  const payload = await dealService.getDeals({
    preset: "NEW",
    q: searchTerm || undefined,
    page,
    limit,
    viewer,
    scope,
    baseWhere: { sellerId: seller.id, status: "ACTIVE" },
    filters,
    useRedisSearch: true,
  })

  return { seller, payload }
}

async function getActiveSellers() {
  const sellers = await listSellersCached()
  return sellers
    .map(normalizeSeller)
    .filter((seller) => seller && seller.isActive)
    .sort((a, b) => a.name.localeCompare(b.name))
    .map((seller) => ({
      name: seller.name,
      sellerLogo: seller.sellerLogo,
    }))
}

module.exports = {
  getSellerByName,
  getDealsBySellerName,
  getActiveSellers,
}