const express = require('express');
const { Pool } = require('pg');
const cors = require('cors');
const bcrypt = require('bcryptjs');
const jwt = require('jsonwebtoken');
require('dotenv').config();

const app = express();
const PORT = process.env.PORT || 80;

// PostgreSQL connection
const pool = new Pool({
  connectionString: process.env.DATABASE_URL,
  ssl: process.env.DATABASE_URL?.includes('amazonaws.com') ? { rejectUnauthorized: false } : false
});

// Middleware
app.use(cors({
  origin: true, // Allow all origins in development
  credentials: true,
  methods: ['GET', 'POST', 'PUT', 'DELETE', 'OPTIONS'],
  allowedHeaders: ['Content-Type', 'Authorization'],
  exposedHeaders: ['Content-Length', 'Content-Type'],
  maxAge: 86400
}));
app.use(express.json());

// Handle preflight requests
app.options('*', cors());

// Health check route
app.get('/', (req, res) => {
  res.json({ status: 'ok', service: 'Filamenteka API' });
});

// JWT middleware
const authenticateToken = (req, res, next) => {
  const authHeader = req.headers['authorization'];
  const token = authHeader && authHeader.split(' ')[1];
  
  if (!token) {
    return res.status(401).json({ error: 'Unauthorized' });
  }
  
  jwt.verify(token, process.env.JWT_SECRET || 'your-secret-key', (err, user) => {
    if (err) {
      console.error('JWT verification error:', err);
      return res.status(403).json({ error: 'Invalid token' });
    }
    req.user = user;
    next();
  });
};

// Auth endpoints
app.post('/api/login', async (req, res) => {
  const { username, password } = req.body;
  
  // For now, simple hardcoded admin check
  if (username === 'admin' && password === process.env.ADMIN_PASSWORD) {
    const token = jwt.sign({ username }, process.env.JWT_SECRET || 'your-secret-key', { expiresIn: '24h' });
    res.json({ token });
  } else {
    res.status(401).json({ error: 'Invalid credentials' });
  }
});

// Colors endpoints
app.get('/api/colors', async (req, res) => {
  try {
    const result = await pool.query('SELECT * FROM colors ORDER BY name');
    res.json(result.rows);
  } catch (error) {
    console.error('Error fetching colors:', error);
    res.status(500).json({ error: 'Failed to fetch colors' });
  }
});

app.post('/api/colors', authenticateToken, async (req, res) => {
  const { name, hex, cena_refill, cena_spulna } = req.body;
  
  try {
    const result = await pool.query(
      'INSERT INTO colors (name, hex, cena_refill, cena_spulna) VALUES ($1, $2, $3, $4) RETURNING *',
      [name, hex, cena_refill || 3499, cena_spulna || 3999]
    );
    res.json(result.rows[0]);
  } catch (error) {
    console.error('Error creating color:', error);
    res.status(500).json({ error: 'Failed to create color' });
  }
});

app.put('/api/colors/:id', authenticateToken, async (req, res) => {
  const { id } = req.params;
  const { name, hex, cena_refill, cena_spulna } = req.body;
  
  try {
    const result = await pool.query(
      'UPDATE colors SET name = $1, hex = $2, cena_refill = $3, cena_spulna = $4, updated_at = CURRENT_TIMESTAMP WHERE id = $5 RETURNING *',
      [name, hex, cena_refill || 3499, cena_spulna || 3999, id]
    );
    res.json(result.rows[0]);
  } catch (error) {
    console.error('Error updating color:', error);
    res.status(500).json({ error: 'Failed to update color' });
  }
});

app.delete('/api/colors/:id', authenticateToken, async (req, res) => {
  const { id } = req.params;
  
  try {
    await pool.query('DELETE FROM colors WHERE id = $1', [id]);
    res.json({ success: true });
  } catch (error) {
    console.error('Error deleting color:', error);
    res.status(500).json({ error: 'Failed to delete color' });
  }
});

// Filaments endpoints (PUBLIC - no auth required)
app.get('/api/filaments', async (req, res) => {
  try {
    const result = await pool.query('SELECT * FROM filaments ORDER BY created_at DESC');
    res.json(result.rows);
  } catch (error) {
    console.error('Error fetching filaments:', error);
    res.status(500).json({ error: 'Failed to fetch filaments' });
  }
});

app.post('/api/filaments', authenticateToken, async (req, res) => {
  const { tip, finish, boja, boja_hex, refill, spulna, cena } = req.body;
  
  try {
    // Ensure refill and spulna are numbers
    const refillNum = parseInt(refill) || 0;
    const spulnaNum = parseInt(spulna) || 0;
    const kolicina = refillNum + spulnaNum;
    
    const result = await pool.query(
      `INSERT INTO filaments (tip, finish, boja, boja_hex, refill, spulna, kolicina, cena) 
       VALUES ($1, $2, $3, $4, $5, $6, $7, $8) RETURNING *`,
      [tip, finish, boja, boja_hex, refillNum, spulnaNum, kolicina, cena]
    );
    res.json(result.rows[0]);
  } catch (error) {
    console.error('Error creating filament:', error);
    res.status(500).json({ error: 'Failed to create filament' });
  }
});

app.put('/api/filaments/:id', authenticateToken, async (req, res) => {
  const { id } = req.params;
  const { tip, finish, boja, boja_hex, refill, spulna, cena, sale_percentage, sale_active, sale_start_date, sale_end_date } = req.body;

  try {
    // Ensure refill and spulna are numbers
    const refillNum = parseInt(refill) || 0;
    const spulnaNum = parseInt(spulna) || 0;
    const kolicina = refillNum + spulnaNum;

    // Check if sale fields are provided in the request
    const hasSaleFields = 'sale_percentage' in req.body || 'sale_active' in req.body ||
                          'sale_start_date' in req.body || 'sale_end_date' in req.body;

    let result;
    if (hasSaleFields) {
      // Update with sale fields if they are provided
      result = await pool.query(
        `UPDATE filaments
         SET tip = $1, finish = $2, boja = $3, boja_hex = $4,
             refill = $5, spulna = $6, kolicina = $7, cena = $8,
             sale_percentage = $9, sale_active = $10,
             sale_start_date = $11, sale_end_date = $12,
             updated_at = CURRENT_TIMESTAMP
         WHERE id = $13 RETURNING *`,
        [tip, finish, boja, boja_hex, refillNum, spulnaNum, kolicina, cena,
         sale_percentage || 0, sale_active || false, sale_start_date, sale_end_date, id]
      );
    } else {
      // Update without touching sale fields if they are not provided
      result = await pool.query(
        `UPDATE filaments
         SET tip = $1, finish = $2, boja = $3, boja_hex = $4,
             refill = $5, spulna = $6, kolicina = $7, cena = $8,
             updated_at = CURRENT_TIMESTAMP
         WHERE id = $9 RETURNING *`,
        [tip, finish, boja, boja_hex, refillNum, spulnaNum, kolicina, cena, id]
      );
    }

    res.json(result.rows[0]);
  } catch (error) {
    console.error('Error updating filament:', error);
    res.status(500).json({ error: 'Failed to update filament' });
  }
});

app.delete('/api/filaments/:id', authenticateToken, async (req, res) => {
  const { id } = req.params;
  
  try {
    await pool.query('DELETE FROM filaments WHERE id = $1', [id]);
    res.json({ success: true });
  } catch (error) {
    console.error('Error deleting filament:', error);
    res.status(500).json({ error: 'Failed to delete filament' });
  }
});

// Bulk sale update endpoint
app.post('/api/filaments/sale/bulk', authenticateToken, async (req, res) => {
  const { filamentIds, salePercentage, saleStartDate, saleEndDate, enableSale } = req.body;
  
  try {
    let query;
    let params;
    
    if (filamentIds && filamentIds.length > 0) {
      // Update specific filaments
      query = `
        UPDATE filaments 
        SET sale_percentage = $1, 
            sale_active = $2,
            sale_start_date = $3,
            sale_end_date = $4,
            updated_at = CURRENT_TIMESTAMP
        WHERE id = ANY($5) 
        RETURNING *`;
      params = [salePercentage || 0, enableSale || false, saleStartDate, saleEndDate, filamentIds];
    } else {
      // Update all filaments
      query = `
        UPDATE filaments 
        SET sale_percentage = $1, 
            sale_active = $2,
            sale_start_date = $3,
            sale_end_date = $4,
            updated_at = CURRENT_TIMESTAMP
        RETURNING *`;
      params = [salePercentage || 0, enableSale || false, saleStartDate, saleEndDate];
    }
    
    const result = await pool.query(query, params);
    res.json({ 
      success: true, 
      updatedCount: result.rowCount,
      updatedFilaments: result.rows 
    });
  } catch (error) {
    console.error('Error updating sale:', error);
    res.status(500).json({ error: 'Failed to update sale' });
  }
});

// Color request endpoints

// Get all color requests (admin only)
app.get('/api/color-requests', authenticateToken, async (req, res) => {
  try {
    const result = await pool.query(
      'SELECT * FROM color_requests ORDER BY created_at DESC'
    );
    res.json(result.rows);
  } catch (error) {
    console.error('Error fetching color requests:', error);
    res.status(500).json({ error: 'Failed to fetch color requests' });
  }
});

// Submit a new color request (public)
app.post('/api/color-requests', async (req, res) => {
  try {
    const { 
      color_name, 
      material_type, 
      finish_type, 
      user_email,
      user_phone, 
      user_name, 
      description,
      reference_url 
    } = req.body;

    // Validate required fields
    if (!color_name || !material_type || !user_email || !user_phone) {
      return res.status(400).json({ 
        error: 'Color name, material type, email, and phone are required' 
      });
    }

    // Check if similar request already exists
    const existingRequest = await pool.query(
      `SELECT id, request_count FROM color_requests 
       WHERE LOWER(color_name) = LOWER($1) 
       AND material_type = $2 
       AND (finish_type = $3 OR (finish_type IS NULL AND $3 IS NULL))
       AND status = 'pending'`,
      [color_name, material_type, finish_type]
    );

    if (existingRequest.rows.length > 0) {
      // Increment request count for existing request
      const result = await pool.query(
        `UPDATE color_requests 
         SET request_count = request_count + 1,
             updated_at = CURRENT_TIMESTAMP
         WHERE id = $1
         RETURNING *`,
        [existingRequest.rows[0].id]
      );
      res.json({ 
        message: 'Your request has been added to an existing request for this color',
        request: result.rows[0] 
      });
    } else {
      // Create new request
      const result = await pool.query(
        `INSERT INTO color_requests 
         (color_name, material_type, finish_type, user_email, user_phone, user_name, description, reference_url)
         VALUES ($1, $2, $3, $4, $5, $6, $7, $8)
         RETURNING *`,
        [color_name, material_type, finish_type, user_email, user_phone, user_name, description, reference_url]
      );
      res.json({ 
        message: 'Color request submitted successfully',
        request: result.rows[0] 
      });
    }
  } catch (error) {
    console.error('Error creating color request:', error);
    res.status(500).json({ error: 'Failed to submit color request' });
  }
});

// Update color request status (admin only)
app.put('/api/color-requests/:id', authenticateToken, async (req, res) => {
  try {
    const { id } = req.params;
    const { status, admin_notes } = req.body;
    
    const result = await pool.query(
      `UPDATE color_requests 
       SET status = $1, 
           admin_notes = $2,
           processed_at = CURRENT_TIMESTAMP,
           processed_by = $3,
           updated_at = CURRENT_TIMESTAMP
       WHERE id = $4
       RETURNING *`,
      [status, admin_notes, req.user.username, id]
    );
    
    if (result.rows.length === 0) {
      return res.status(404).json({ error: 'Color request not found' });
    }
    
    res.json(result.rows[0]);
  } catch (error) {
    console.error('Error updating color request:', error);
    res.status(500).json({ error: 'Failed to update color request' });
  }
});

// Delete color request (admin only)
app.delete('/api/color-requests/:id', authenticateToken, async (req, res) => {
  try {
    const { id } = req.params;
    
    const result = await pool.query(
      'DELETE FROM color_requests WHERE id = $1 RETURNING *',
      [id]
    );
    
    if (result.rows.length === 0) {
      return res.status(404).json({ error: 'Color request not found' });
    }
    
    res.json({ message: 'Color request deleted successfully' });
  } catch (error) {
    console.error('Error deleting color request:', error);
    res.status(500).json({ error: 'Failed to delete color request' });
  }
});

// Slug generation helper
const generateSlug = (name) => {
  const base = name
    .toLowerCase()
    .replace(/[^a-z0-9\s-]/g, '')
    .replace(/\s+/g, '-')
    .replace(/-+/g, '-')
    .replace(/^-|-$/g, '');
  const suffix = Math.random().toString(36).substring(2, 8);
  return `${base}-${suffix}`;
};

// Products endpoints

// List/filter products (PUBLIC)
app.get('/api/products', async (req, res) => {
  try {
    const { category, condition, printer_model, in_stock, search } = req.query;
    const conditions = [];
    const params = [];
    let paramIndex = 1;

    if (category) {
      conditions.push(`p.category = $${paramIndex++}`);
      params.push(category);
    }
    if (condition) {
      conditions.push(`p.condition = $${paramIndex++}`);
      params.push(condition);
    }
    if (printer_model) {
      conditions.push(`EXISTS (
        SELECT 1 FROM product_printer_compatibility ppc
        JOIN printer_models pm ON pm.id = ppc.printer_model_id
        WHERE ppc.product_id = p.id AND pm.name = $${paramIndex++}
      )`);
      params.push(printer_model);
    }
    if (in_stock === 'true') {
      conditions.push(`p.quantity > 0`);
    } else if (in_stock === 'false') {
      conditions.push(`p.quantity = 0`);
    }
    if (search) {
      conditions.push(`(p.name ILIKE $${paramIndex} OR p.description ILIKE $${paramIndex})`);
      params.push(`%${search}%`);
      paramIndex++;
    }

    const whereClause = conditions.length > 0 ? `WHERE ${conditions.join(' AND ')}` : '';

    const result = await pool.query(
      `SELECT p.*,
              COALESCE(
                json_agg(
                  json_build_object('id', pm.id, 'name', pm.name, 'series', pm.series)
                ) FILTER (WHERE pm.id IS NOT NULL),
                '[]'
              ) AS compatible_printers
       FROM products p
       LEFT JOIN product_printer_compatibility ppc ON ppc.product_id = p.id
       LEFT JOIN printer_models pm ON pm.id = ppc.printer_model_id
       ${whereClause}
       GROUP BY p.id
       ORDER BY p.created_at DESC`,
      params
    );

    res.json(result.rows);
  } catch (error) {
    console.error('Error fetching products:', error);
    res.status(500).json({ error: 'Failed to fetch products' });
  }
});

// Get single product (PUBLIC)
app.get('/api/products/:id', async (req, res) => {
  const { id } = req.params;

  try {
    const result = await pool.query(
      `SELECT p.*,
              COALESCE(
                json_agg(
                  json_build_object('id', pm.id, 'name', pm.name, 'series', pm.series)
                ) FILTER (WHERE pm.id IS NOT NULL),
                '[]'
              ) AS compatible_printers
       FROM products p
       LEFT JOIN product_printer_compatibility ppc ON ppc.product_id = p.id
       LEFT JOIN printer_models pm ON pm.id = ppc.printer_model_id
       WHERE p.id = $1
       GROUP BY p.id`,
      [id]
    );

    if (result.rows.length === 0) {
      return res.status(404).json({ error: 'Product not found' });
    }

    res.json(result.rows[0]);
  } catch (error) {
    console.error('Error fetching product:', error);
    res.status(500).json({ error: 'Failed to fetch product' });
  }
});

// Create product (auth required)
app.post('/api/products', authenticateToken, async (req, res) => {
  const { name, description, category, condition, price, quantity, image_url, printer_model_ids } = req.body;

  try {
    const slug = generateSlug(name);

    const result = await pool.query(
      `INSERT INTO products (name, slug, description, category, condition, price, quantity, image_url)
       VALUES ($1, $2, $3, $4, $5, $6, $7, $8) RETURNING *`,
      [name, slug, description, category, condition || 'new', price, parseInt(quantity) || 0, image_url]
    );

    const product = result.rows[0];

    // Insert printer compatibility entries if provided
    if (printer_model_ids && printer_model_ids.length > 0) {
      const compatValues = printer_model_ids
        .map((_, i) => `($1, $${i + 2})`)
        .join(', ');
      await pool.query(
        `INSERT INTO product_printer_compatibility (product_id, printer_model_id) VALUES ${compatValues}`,
        [product.id, ...printer_model_ids]
      );
    }

    res.json(product);
  } catch (error) {
    console.error('Error creating product:', error);
    res.status(500).json({ error: 'Failed to create product' });
  }
});

// Update product (auth required)
app.put('/api/products/:id', authenticateToken, async (req, res) => {
  const { id } = req.params;
  const { name, description, category, condition, price, quantity, image_url, sale_percentage, sale_active, sale_start_date, sale_end_date, printer_model_ids } = req.body;

  try {
    const hasSaleFields = 'sale_percentage' in req.body || 'sale_active' in req.body ||
                          'sale_start_date' in req.body || 'sale_end_date' in req.body;

    let result;
    if (hasSaleFields) {
      result = await pool.query(
        `UPDATE products
         SET name = $1, description = $2, category = $3, condition = $4,
             price = $5, quantity = $6, image_url = $7,
             sale_percentage = $8, sale_active = $9,
             sale_start_date = $10, sale_end_date = $11,
             updated_at = CURRENT_TIMESTAMP
         WHERE id = $12 RETURNING *`,
        [name, description, category, condition, price, parseInt(quantity) || 0, image_url,
         sale_percentage || 0, sale_active || false, sale_start_date, sale_end_date, id]
      );
    } else {
      result = await pool.query(
        `UPDATE products
         SET name = $1, description = $2, category = $3, condition = $4,
             price = $5, quantity = $6, image_url = $7,
             updated_at = CURRENT_TIMESTAMP
         WHERE id = $8 RETURNING *`,
        [name, description, category, condition, price, parseInt(quantity) || 0, image_url, id]
      );
    }

    if (result.rows.length === 0) {
      return res.status(404).json({ error: 'Product not found' });
    }

    // Update printer compatibility if provided
    if (printer_model_ids !== undefined) {
      await pool.query('DELETE FROM product_printer_compatibility WHERE product_id = $1', [id]);

      if (printer_model_ids && printer_model_ids.length > 0) {
        const compatValues = printer_model_ids
          .map((_, i) => `($1, $${i + 2})`)
          .join(', ');
        await pool.query(
          `INSERT INTO product_printer_compatibility (product_id, printer_model_id) VALUES ${compatValues}`,
          [id, ...printer_model_ids]
        );
      }
    }

    res.json(result.rows[0]);
  } catch (error) {
    console.error('Error updating product:', error);
    res.status(500).json({ error: 'Failed to update product' });
  }
});

// Delete product (auth required)
app.delete('/api/products/:id', authenticateToken, async (req, res) => {
  const { id } = req.params;

  try {
    await pool.query('DELETE FROM product_printer_compatibility WHERE product_id = $1', [id]);
    const result = await pool.query('DELETE FROM products WHERE id = $1 RETURNING *', [id]);

    if (result.rows.length === 0) {
      return res.status(404).json({ error: 'Product not found' });
    }

    res.json({ success: true });
  } catch (error) {
    console.error('Error deleting product:', error);
    res.status(500).json({ error: 'Failed to delete product' });
  }
});

// Bulk sale update for products (auth required)
app.post('/api/products/sale/bulk', authenticateToken, async (req, res) => {
  const { productIds, salePercentage, saleStartDate, saleEndDate, enableSale } = req.body;

  try {
    let query;
    let params;

    if (productIds && productIds.length > 0) {
      query = `
        UPDATE products
        SET sale_percentage = $1,
            sale_active = $2,
            sale_start_date = $3,
            sale_end_date = $4,
            updated_at = CURRENT_TIMESTAMP
        WHERE id = ANY($5)
        RETURNING *`;
      params = [salePercentage || 0, enableSale || false, saleStartDate, saleEndDate, productIds];
    } else {
      query = `
        UPDATE products
        SET sale_percentage = $1,
            sale_active = $2,
            sale_start_date = $3,
            sale_end_date = $4,
            updated_at = CURRENT_TIMESTAMP
        RETURNING *`;
      params = [salePercentage || 0, enableSale || false, saleStartDate, saleEndDate];
    }

    const result = await pool.query(query, params);
    res.json({
      success: true,
      updatedCount: result.rowCount,
      updatedProducts: result.rows
    });
  } catch (error) {
    console.error('Error updating product sale:', error);
    res.status(500).json({ error: 'Failed to update product sale' });
  }
});

// Printer models endpoints

// List all printer models (PUBLIC)
app.get('/api/printer-models', async (req, res) => {
  try {
    const result = await pool.query('SELECT * FROM printer_models ORDER BY series, name');
    res.json(result.rows);
  } catch (error) {
    console.error('Error fetching printer models:', error);
    res.status(500).json({ error: 'Failed to fetch printer models' });
  }
});

// Analytics endpoints

// Aggregated inventory stats (auth required)
app.get('/api/analytics/inventory', authenticateToken, async (req, res) => {
  try {
    const filamentStats = await pool.query(`
      SELECT
        COUNT(*) AS total_skus,
        COALESCE(SUM(kolicina), 0) AS total_units,
        COALESCE(SUM(refill), 0) AS total_refills,
        COALESCE(SUM(spulna), 0) AS total_spools,
        COUNT(*) FILTER (WHERE kolicina = 0) AS out_of_stock_skus,
        COALESCE(SUM(kolicina * cena), 0) AS total_inventory_value
      FROM filaments
    `);

    const productStats = await pool.query(`
      SELECT
        COUNT(*) AS total_skus,
        COALESCE(SUM(quantity), 0) AS total_units,
        COUNT(*) FILTER (WHERE quantity = 0) AS out_of_stock_skus,
        COALESCE(SUM(quantity * price), 0) AS total_inventory_value,
        COUNT(*) FILTER (WHERE category = 'printer') AS printers,
        COUNT(*) FILTER (WHERE category = 'build_plate') AS build_plates,
        COUNT(*) FILTER (WHERE category = 'nozzle') AS nozzles,
        COUNT(*) FILTER (WHERE category = 'spare_part') AS spare_parts,
        COUNT(*) FILTER (WHERE category = 'accessory') AS accessories
      FROM products
    `);

    const filament = filamentStats.rows[0];
    const product = productStats.rows[0];

    res.json({
      filaments: {
        total_skus: parseInt(filament.total_skus),
        total_units: parseInt(filament.total_units),
        total_refills: parseInt(filament.total_refills),
        total_spools: parseInt(filament.total_spools),
        out_of_stock_skus: parseInt(filament.out_of_stock_skus),
        total_inventory_value: parseInt(filament.total_inventory_value)
      },
      products: {
        total_skus: parseInt(product.total_skus),
        total_units: parseInt(product.total_units),
        out_of_stock_skus: parseInt(product.out_of_stock_skus),
        total_inventory_value: parseInt(product.total_inventory_value),
        by_category: {
          printers: parseInt(product.printers),
          build_plates: parseInt(product.build_plates),
          nozzles: parseInt(product.nozzles),
          spare_parts: parseInt(product.spare_parts),
          accessories: parseInt(product.accessories)
        }
      },
      combined: {
        total_skus: parseInt(filament.total_skus) + parseInt(product.total_skus),
        total_inventory_value: parseInt(filament.total_inventory_value) + parseInt(product.total_inventory_value),
        out_of_stock_skus: parseInt(filament.out_of_stock_skus) + parseInt(product.out_of_stock_skus)
      }
    });
  } catch (error) {
    console.error('Error fetching inventory analytics:', error);
    res.status(500).json({ error: 'Failed to fetch inventory analytics' });
  }
});

// Active sales overview (auth required)
app.get('/api/analytics/sales', authenticateToken, async (req, res) => {
  try {
    const filamentSales = await pool.query(`
      SELECT id, tip, finish, boja, cena, sale_percentage, sale_active, sale_start_date, sale_end_date,
             ROUND(cena * (1 - sale_percentage / 100.0)) AS sale_price
      FROM filaments
      WHERE sale_active = true
      ORDER BY sale_percentage DESC
    `);

    const productSales = await pool.query(`
      SELECT id, name, category, price, sale_percentage, sale_active, sale_start_date, sale_end_date,
             ROUND(price * (1 - sale_percentage / 100.0)) AS sale_price
      FROM products
      WHERE sale_active = true
      ORDER BY sale_percentage DESC
    `);

    res.json({
      filaments: {
        count: filamentSales.rowCount,
        items: filamentSales.rows
      },
      products: {
        count: productSales.rowCount,
        items: productSales.rows
      },
      total_active_sales: filamentSales.rowCount + productSales.rowCount
    });
  } catch (error) {
    console.error('Error fetching sales analytics:', error);
    res.status(500).json({ error: 'Failed to fetch sales analytics' });
  }
});

app.listen(PORT, () => {
  console.log(`Server running on port ${PORT}`);
});