Add product detail price summaries

src/schema.ts

@@ -58,6 +58,11 @@ export const typeDefs = `#graphql
     categoryName: String!
     unit: String!
     imageUrl: String
+    offersCount: Int
+    averagePrice: Float
+    priceVariationPercent: Float
+    priceSeries: [Float!]!
+    currency: String
     description: String
     isActive: Boolean!
     createdAt: String!
@@ -167,6 +172,34 @@ function productData(input: ProductInput) {
   }
 }
 
+async function productWithPriceSummary(uuid: string) {
+  const product = await prisma.product.findUnique({ where: { uuid } })
+  if (product === null) return null
+
+  const quotes = await prisma.quote.findMany({
+    where: { productId: product.id, status: 'active' },
+    select: { pricePerUnit: true, currency: true },
+    orderBy: { pricePerUnit: 'asc' },
+    take: 100,
+  })
+  const priceSeries = quotes.map(quote => Number(quote.pricePerUnit))
+  const averagePrice = priceSeries.length === 0
+    ? null
+    : priceSeries.reduce((sum, price) => sum + price, 0) / priceSeries.length
+  const priceVariationPercent = averagePrice === null || averagePrice <= 0
+    ? 0
+    : ((priceSeries.at(-1)! - priceSeries[0]) / 2 / averagePrice) * 100
+
+  return {
+    ...product,
+    offersCount: quotes.length,
+    averagePrice,
+    priceVariationPercent,
+    priceSeries,
+    currency: quotes[0]?.currency ?? 'USD',
+  }
+}
+
 async function quoteData(input: QuoteInput) {
   const supplier = await prisma.supplier.findUnique({ where: { uuid: input.supplierUuid } })
   if (supplier === null) throw new Error(`Supplier ${input.supplierUuid} does not exist`)
@@ -219,8 +252,7 @@ export const resolvers = {
         orderBy: { name: 'asc' },
       }),
 
-    product: (_: unknown, args: { uuid: string }) =>
-      prisma.product.findUnique({ where: { uuid: args.uuid } }),
+    product: (_: unknown, args: { uuid: string }) => productWithPriceSummary(args.uuid),
 
     quotes: async (_: unknown, args: { productUuid?: string; supplierUuid?: string; status?: string; limit?: number; offset?: number }) => {
       const product = args.productUuid ? await prisma.product.findUnique({ where: { uuid: args.productUuid } }) : null