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HTML / CSS / JS

# ----- Input Types -----
input CreateProductInput {
  name: String!
  price: Float!
  description: String
  categoryId: ID!
  tags: [String!]
}

input UpdateProductInput {
  name: String
  price: Float
  description: String
  tags: [String!]
}

type Mutation {
  createProduct(input: CreateProductInput!): Product!
  updateProduct(id: ID!, input: UpdateProductInput!): Product!
  deleteProduct(id: ID!): Boolean!
}

# ----- Custom Scalars -----
scalar Date
scalar DateTime
scalar EmailAddress
scalar URL

type User {
  id: ID!
  email: EmailAddress!
  avatar: URL
  createdAt: DateTime!
  birthDate: Date
}

# Resolver implementation (JavaScript):
# import { GraphQLScalarType, Kind } from 'graphql';
#
# const DateScalar = new GraphQLScalarType({
#   name: 'Date',
#   serialize(value) { return value.toISOString().split('T')[0]; },
#   parseValue(value) { return new Date(value); },
#   parseLiteral(ast) {
#     if (ast.kind === Kind.STRING) return new Date(ast.value);
#     return null;
#   },
# });