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

backend/src/services/lab9/product.service.js
119 строк4 KB
Coderdev
12 май 2026, 12:34
12 май 2026, 12:34f5e899f
// backend/src/services/lab9/product.service.js

class ProductService {
  // Получить все товары
  async getAll(db) {
    const query = 'SELECT * FROM lab9.products ORDER BY id DESC';
    const { rows } = await db.query(query);
    return rows;
  }

  // Получить один товар по ID
  async getById(db, id) {
    const query = 'SELECT * FROM lab9.products WHERE id = $1';
    const { rows } = await db.query(query, [id]);
    return rows[0] || null;
  }

  // Поиск товаров по подстроке названия
  async search(db, q) {
    let query, params;
    if (q && q.trim().length > 0) {
      query = 'SELECT * FROM lab9.products WHERE title ILIKE $1 ORDER BY id DESC';
      params = [`%${q.trim()}%`];
    } else {
      query = 'SELECT * FROM lab9.products ORDER BY id DESC';
      params = [];
    }
    const { rows } = await db.query(query, params);
    return rows;
  }

  // Статистика склада
  async getStock(db) {
    const query = `
      SELECT
        COUNT(*) AS total_products,
        SUM(amount) AS total_items,
        SUM(price * amount) AS total_value
      FROM lab9.products
    `;
    const { rows } = await db.query(query);
    return {
      total_products: parseInt(rows[0].total_products),
      total_items: parseInt(rows[0].total_items),
      total_value: parseInt(rows[0].total_value),
    };
  }

  // Создать товар
  async create(db, productData) {
    const { title, price, amount } = productData;
    const query = `
      INSERT INTO lab9.products (title, price, amount)
      VALUES ($1, $2, $3)
      RETURNING *
    `;
    const { rows } = await db.query(query, [title, price, amount]);
    return rows[0];
  }

  // Обновить товар (title, price, amount)
  async update(db, id, data) {
    const fields = [];
    const values = [];
    let idx = 1;

    if (data.title !== undefined) { fields.push(`title = $${idx++}`); values.push(data.title); }
    if (data.price !== undefined) { fields.push(`price = $${idx++}`); values.push(data.price); }
    if (data.amount !== undefined) { fields.push(`amount = $${idx++}`); values.push(data.amount); }

    if (fields.length === 0) return null;

    values.push(id);
    const query = `UPDATE lab9.products SET ${fields.join(', ')} WHERE id = $${idx} RETURNING *`;
    const { rows } = await db.query(query, values);
    return rows[0] || null;
  }

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

  // Проверить наличие и купить (для корзины)
  async checkStock(db, items) {
    // items: [{id, qty}]
    const results = [];
    for (const item of items) {
      const { rows } = await db.query('SELECT id, title, amount FROM lab9.products WHERE id = $1', [item.id]);
      if (!rows[0]) {
        results.push({ id: item.id, ok: false, reason: 'not found', available: 0 });
      } else if (rows[0].amount < item.qty) {
        results.push({ id: item.id, title: rows[0].title, ok: false, reason: 'insufficient', available: rows[0].amount });
      } else {
        results.push({ id: item.id, title: rows[0].title, ok: true, available: rows[0].amount });
      }
    }
    return results;
  }

  // Провести покупку (уменьшить количество)
  async purchase(db, items) {
    // Сначала проверяем
    const check = await this.checkStock(db, items);
    const failed = check.filter(r => !r.ok);
    if (failed.length > 0) {
      return { success: false, failed };
    }
    // Списываем
    for (const item of items) {
      await db.query('UPDATE lab9.products SET amount = amount - $1 WHERE id = $2', [item.qty, item.id]);
    }
    return { success: true };
  }
}

export default new ProductService();