const { ApolloServer } = require('@apollo/server');
const { startStandaloneServer } = require('@apollo/server/standalone');
const { Pool } = require('pg');
require('dotenv').config();

// 1. Inisialisasi Pool PostgreSQL
const pool = new Pool({
  connectionString: process.env.DATABASE_URL,
  ssl: {
    rejectUnauthorized: false,
  },
});

// 2. Definisi Schema GraphQL (typeDefs)
const typeDefs = `#graphql
  type Category {
    id: ID!
    name: String!
    description: String
    products: [Product!]!
  }

  type Product {
    id: ID!
    title: String!
    price: Float!
    category_id: Int
    created_by: ID
    category: Category
  }

  type Query {
    categories: [Category!]!
    category(id: ID!): Category
    products: [Product!]!
    product(id: ID!): Product
  }
`;

// 3. Definisi Resolver (Query + Nested Resolvers)
const resolvers = {
  Query: {
    categories: async () => {
      const result = await pool.query('SELECT * FROM categories ORDER BY id ASC');
      return result.rows;
    },
    category: async (_, { id }) => {
      const result = await pool.query('SELECT * FROM categories WHERE id = $1', [id]);
      return result.rows[0] || null;
    },
    products: async () => {
      // price di-cast ke float agar cocok dengan tipe Float di GraphQL
      const result = await pool.query('SELECT id, title, price::float, category_id, created_by FROM products ORDER BY id ASC');
      return result.rows;
    },
    product: async (_, { id }) => {
      const result = await pool.query('SELECT id, title, price::float, category_id, created_by FROM products WHERE id = $1', [id]);
      return result.rows[0] || null;
    },
  },

  // Resolver Relasi Category -> Products (One-to-Many)
  Category: {
    products: async (parent) => {
      const result = await pool.query(
        'SELECT id, title, price::float, category_id, created_by FROM products WHERE category_id = $1 ORDER BY id ASC',
        [parent.id]
      );
      return result.rows;
    },
  },

  // Resolver Relasi Product -> Category (Many-to-One)
  Product: {
    category: async (parent) => {
      if (!parent.category_id) return null;
      const result = await pool.query('SELECT * FROM categories WHERE id = $1', [parent.category_id]);
      return result.rows[0] || null;
    },
  },
};

// 4. Inisialisasi Apollo Server
const server = new ApolloServer({
  typeDefs,
  resolvers,
  introspection: true, // Wajib aktif untuk Apollo Sandbox publik
});

// 5. Jalankan Server
async function startServer() {
  const port = process.env.PORT || 4000;
  const { url } = await startStandaloneServer(server, {
    listen: { port: Number(port) },
  });
  console.log(`Server GraphQL siap di: ${url}`);
}

startServer();