backend/src/services/lab9/product.service.js - main - Coderdev/web-nodejs-labs

backend/src/services/lab9/product.service.js
106 строк3 KB
Coderdev
23 апр 2026, 22:48
23 апр 2026, 22:48fe8b855
class ProductService {
  async getAll(pg) {
    const { rows } = await pg.query('SELECT * FROM lab9.products ORDER BY id DESC');
    return rows;
  }

  async search(pg, q) {
    const { rows } = await pg.query(
      'SELECT * FROM lab9.products WHERE LOWER(title) LIKE LOWER($1) ORDER BY id DESC',
      [`%${q}%`]
    );
    return rows;
  }

  async getStock(pg) {
    const { rows } = await pg.query(`
      SELECT
        COUNT(*)::int AS total_products,
        COALESCE(SUM(amount), 0)::int AS total_items,
        COALESCE(SUM(price * amount), 0)::bigint AS total_value
      FROM lab9.products
    `);
    return rows[0];
  }

  async getById(pg, id) {
    const { rows } = await pg.query('SELECT * FROM lab9.products WHERE id = $1', [id]);
    return rows[0];
  }

  async create(pg, data) {
    const { title, price, amount } = data;
    const { rows } = await pg.query(
      'INSERT INTO lab9.products (title, price, amount) VALUES ($1, $2, $3) RETURNING *',
      [title, price, amount]
    );
    return rows[0];
  }

  async update(pg, id, data) {
    const { title, price, amount } = data;
    const { rows } = await pg.query(
      'UPDATE lab9.products SET title = $1, price = $2, amount = $3 WHERE id = $4 RETURNING *',
      [title, price, amount, id]
    );
    return rows[0];
  }

  async delete(pg, id) {
    const { rows } = await pg.query('DELETE FROM lab9.products WHERE id = $1 RETURNING id', [id]);
    return rows[0];
  }

  async verifyCart(pg, items) {
    const problems = [];
    for (const item of items) {
      const product = await this.getById(pg, item.id);
      if (!product) {
        problems.push({ id: item.id, error: 'Product not found', available: 0 });
        continue;
      }
      if (item.qty < 1 || item.qty > 5) {
        problems.push({ id: item.id, title: product.title, error: 'Invalid quantity', available: product.amount });
        continue;
      }
      if (product.amount < item.qty) {
        problems.push({ id: item.id, title: product.title, error: 'Not enough stock', available: product.amount, requested: item.qty });
      }
    }
    return { ok: problems.length === 0, items: problems };
  }

  async buy(pg, items) {
    const client = await pg.connect();
    try {
      await client.query('BEGIN');
      const verify = await this.verifyCart(client, items);
      if (!verify.ok) {
        await client.query('ROLLBACK');
        return { ok: false, items: verify.items };
      }
      const purchased = [];
      for (const item of items) {
        const { rows } = await client.query(
          'UPDATE lab9.products SET amount = amount - $1 WHERE id = $2 RETURNING *',
          [item.qty, item.id]
        );
        purchased.push({
          id: rows[0].id,
          title: rows[0].title,
          bought: item.qty,
          remaining: rows[0].amount,
          price: rows[0].price
        });
      }
      await client.query('COMMIT');
      return { ok: true, purchased };
    } catch (error) {
      await client.query('ROLLBACK');
      throw error;
    } finally {
      client.release();
    }
  }
}
export default new ProductService();