feat: Promo Codes and Coupon System

BACKEND/app.js

@@ -14,6 +14,7 @@ import wishlistRoutes from "./routes/wishlist.route.js";
 import newsletterRoutes from "./routes/newsletter.route.js";
 import ordersRoutes from "./routes/orders.route.js";
 import userRoutes from "./routes/user.route.js";
+import couponRoutes from "./routes/coupon.route.js";
 import analyticsRoutes from "./routes/analytics.route.js";
 import referralRoutes from "./routes/referral.route.js";
 import passport from "./config/passport.js";
@@ -113,6 +114,7 @@ app.use("/api/wishlist", wishlistRoutes);
 app.use("/api/orders", ordersRoutes);
 app.use("/api/user", userRoutes);
 app.use("/api/newsletter", newsletterRoutes);
+app.use("/api/coupons", couponRoutes);
 app.use("/api/admin/analytics", analyticsRoutes);
 app.use("/api/referrals", referralRoutes);
 

BACKEND/controllers/checkout.controller.js

@@ -1,5 +1,6 @@
 import Product from '../models/product.model.js';
 import Order from '../models/order.model.js';
+import Coupon from '../models/coupon.model.js';
 import mongoose from 'mongoose';
 import Stripe from 'stripe';
 import { processReferralOnPurchase } from '../services/referral.service.js';
@@ -29,7 +30,7 @@ async function restoreStock(deductions) {
 
 export const createCheckoutSession = async (req, res) => {
     try {
-        const { items } = req.body;
+        const { items, couponCode } = req.body;
 
         if (!items || !Array.isArray(items) || items.length === 0) {
             return res.status(400).json({ success: false, message: "Cart is empty or invalid" });
@@ -78,6 +79,37 @@ export const createCheckoutSession = async (req, res) => {
             });
         }
 
+        // Validate and apply coupon discount if provided
+        let couponDoc = null;
+        let discountAmount = 0;
+        if (couponCode) {
+            const rawTotal = lineItems.reduce((sum, li) => sum + li.price_data.unit_amount * li.quantity, 0) / 100;
+            couponDoc = await Coupon.findOne({ code: couponCode.trim().toUpperCase(), isActive: true });
+
+            if (!couponDoc) {
+                return res.status(400).json({ success: false, message: 'Invalid or expired coupon code' });
+            }
+            if (couponDoc.expiresAt && new Date() > couponDoc.expiresAt) {
+                return res.status(400).json({ success: false, message: 'This coupon has expired' });
+            }
+            if (couponDoc.maxUses !== null && couponDoc.usedCount >= couponDoc.maxUses) {
+                return res.status(400).json({ success: false, message: 'Coupon usage limit reached' });
+            }
+            if (rawTotal < couponDoc.minOrderAmount) {
+                return res.status(400).json({ success: false, message: `Minimum order of $${couponDoc.minOrderAmount.toFixed(2)} required` });
+            }
+
+            discountAmount = couponDoc.type === 'percentage'
+                ? (rawTotal * couponDoc.value) / 100
+                : Math.min(couponDoc.value, rawTotal);
+
+            // Apply discount by scaling each line item's unit_amount proportionally
+            const ratio = 1 - discountAmount / rawTotal;
+            for (const li of lineItems) {
+                li.price_data.unit_amount = Math.max(1, Math.round(li.price_data.unit_amount * ratio));
+            }
+        }
+
         const session = await stripe.checkout.sessions.create({
             payment_method_types: ['card'],
             line_items: lineItems,
@@ -89,6 +121,8 @@ export const createCheckoutSession = async (req, res) => {
                   items.map((item) => ({ _id: item._id, quantity: item.quantity }))
                 ),
                 userId: req.user?._id?.toString() || '',
+                couponCode: couponDoc ? couponDoc.code : '',
+                discountAmount: discountAmount.toFixed(2),
             },
         });
 
@@ -183,6 +217,14 @@ export const stripeWebhook = async (req, res) => {
           paymentStatus: "completed",
         });
 
+        // Increment coupon usage after successful fulfillment
+        if (session.metadata?.couponCode) {
+          await Coupon.findOneAndUpdate(
+            { code: session.metadata.couponCode },
+            { $inc: { usedCount: 1 } }
+          );
+        }
+
         // Trigger referral reward
         if (order.user) {
           processReferralOnPurchase(order._id).catch(err => {

BACKEND/controllers/coupon.controller.js

@@ -0,0 +1,91 @@
+import Coupon from '../models/coupon.model.js';
+
+export const validateCoupon = async (req, res) => {
+  try {
+    const { code, orderTotal } = req.body;
+    if (!code) return res.status(400).json({ success: false, message: 'Coupon code is required' });
+
+    const coupon = await Coupon.findOne({ code: code.trim().toUpperCase(), isActive: true });
+
+    if (!coupon) return res.status(404).json({ success: false, message: 'Invalid or expired coupon code' });
+
+    if (coupon.expiresAt && new Date() > coupon.expiresAt) {
+      return res.status(400).json({ success: false, message: 'This coupon has expired' });
+    }
+
+    if (coupon.maxUses !== null && coupon.usedCount >= coupon.maxUses) {
+      return res.status(400).json({ success: false, message: 'This coupon has reached its usage limit' });
+    }
+
+    const total = Number(orderTotal) || 0;
+    if (total < coupon.minOrderAmount) {
+      return res.status(400).json({
+        success: false,
+        message: `Minimum order amount of $${coupon.minOrderAmount.toFixed(2)} required`,
+      });
+    }
+
+    const discount =
+      coupon.type === 'percentage'
+        ? (total * coupon.value) / 100
+        : Math.min(coupon.value, total);
+
+    res.json({
+      success: true,
+      data: {
+        code: coupon.code,
+        type: coupon.type,
+        value: coupon.value,
+        discount: Math.round(discount * 100) / 100,
+        finalTotal: Math.round((total - discount) * 100) / 100,
+      },
+    });
+  } catch (err) {
+    console.error('[Coupon] validate error:', err.message);
+    res.status(500).json({ success: false, message: 'Failed to validate coupon' });
+  }
+};
+
+// Admin: create coupon
+export const createCoupon = async (req, res) => {
+  try {
+    const { code, type, value, minOrderAmount, maxUses, expiresAt } = req.body;
+    if (!code || !type || value === undefined) {
+      return res.status(400).json({ success: false, message: 'code, type, and value are required' });
+    }
+    if (type === 'percentage' && (value <= 0 || value > 100)) {
+      return res.status(400).json({ success: false, message: 'Percentage must be between 1 and 100' });
+    }
+    const coupon = await Coupon.create({ code, type, value, minOrderAmount, maxUses, expiresAt });
+    res.status(201).json({ success: true, data: coupon });
+  } catch (err) {
+    if (err.code === 11000) return res.status(409).json({ success: false, message: 'Coupon code already exists' });
+    console.error('[Coupon] create error:', err.message);
+    res.status(500).json({ success: false, message: 'Failed to create coupon' });
+  }
+};
+
+// Admin: list all coupons
+export const listCoupons = async (req, res) => {
+  try {
+    const coupons = await Coupon.find().sort({ createdAt: -1 });
+    res.json({ success: true, data: coupons });
+  } catch (err) {
+    res.status(500).json({ success: false, message: 'Failed to fetch coupons' });
+  }
+};
+
+// Admin: deactivate coupon
+export const deactivateCoupon = async (req, res) => {
+  try {
+    const coupon = await Coupon.findOneAndUpdate(
+      { code: req.params.code.toUpperCase() },
+      { isActive: false },
+      { new: true }
+    );
+    if (!coupon) return res.status(404).json({ success: false, message: 'Coupon not found' });
+    res.json({ success: true, data: coupon });
+  } catch (err) {
+    res.status(500).json({ success: false, message: 'Failed to deactivate coupon' });
+  }
+};

BACKEND/models/coupon.model.js

@@ -0,0 +1,52 @@
+import mongoose from 'mongoose';
+
+const couponSchema = new mongoose.Schema(
+  {
+    code: {
+      type: String,
+      required: [true, 'Coupon code is required'],
+      unique: true,
+      uppercase: true,
+      trim: true,
+      minlength: [3, 'Code must be at least 3 characters'],
+      maxlength: [20, 'Code cannot exceed 20 characters'],
+    },
+    type: {
+      type: String,
+      enum: ['percentage', 'flat'],
+      required: true,
+    },
+    value: {
+      type: Number,
+      required: true,
+      min: [0, 'Discount value cannot be negative'],
+    },
+    minOrderAmount: {
+      type: Number,
+      default: 0,
+      min: 0,
+    },
+    maxUses: {
+      type: Number,
+      default: null, // null = unlimited
+    },
+    usedCount: {
+      type: Number,
+      default: 0,
+    },
+    expiresAt: {
+      type: Date,
+      default: null, // null = never expires
+    },
+    isActive: {
+      type: Boolean,
+      default: true,
+    },
+  },
+  { timestamps: true }
+);
+
+couponSchema.index({ code: 1 });
+
+const Coupon = mongoose.model('Coupon', couponSchema);
+export default Coupon;

BACKEND/routes/coupon.route.js

@@ -0,0 +1,20 @@
+import express from 'express';
+import { validateCoupon, createCoupon, listCoupons, deactivateCoupon } from '../controllers/coupon.controller.js';
+import authMiddleware from '../middleware/authMiddleware.js';
+
+const isAdmin = (req, res, next) => {
+  if (req.user?.role !== 'admin') return res.status(403).json({ success: false, message: 'Admins only' });
+  next();
+};
+
+const router = express.Router();
+
+// Public: validate a coupon during checkout
+router.post('/validate', validateCoupon);
+
+// Admin: manage coupons
+router.post('/', authMiddleware, isAdmin, createCoupon);
+router.get('/', authMiddleware, isAdmin, listCoupons);
+router.patch('/:code/deactivate', authMiddleware, isAdmin, deactivateCoupon);
+
+export default router;

FRONTEND/src/components/ui/Navbar.jsx

@@ -2,7 +2,7 @@ import React, { useState, useEffect, useCallback } from 'react';
 import {
   Button, Container, Flex, HStack, Text, Input, useColorMode, useDisclosure,
   Drawer, DrawerBody, DrawerFooter, DrawerHeader, DrawerOverlay, DrawerContent, DrawerCloseButton,
-  VStack, Box, Badge, useColorModeValue, useToast
+  VStack, Box, Badge, useColorModeValue, useToast, InputGroup, InputRightElement, Tag, TagLabel, TagCloseButton
 } from '@chakra-ui/react';
 import { Link, useNavigate, useLocation } from 'react-router-dom';
 import { useTranslation } from 'react-i18next';
@@ -35,6 +35,9 @@ const Navbar = () => {
   const isAdmin = user?.role === 'admin';
   const [isCheckoutLoading, setIsCheckoutLoading] = useState(false);
   const [isMobileMenuOpen, setIsMobileMenuOpen] = useState(false);
+  const [promoInput, setPromoInput] = useState('');
+  const [promoLoading, setPromoLoading] = useState(false);
+  const [appliedCoupon, setAppliedCoupon] = useState(null); // { code, discount, finalTotal }
 
   const totalItemsCount = cartItems.reduce((acc, item) => acc + item.quantity, 0);
 
@@ -61,6 +64,30 @@ const Navbar = () => {
     return () => window.removeEventListener('open-cart', handleOpenCart);
   }, [handleCartOpen]);
 
+  const handleApplyPromo = async () => {
+    if (!promoInput.trim()) return;
+    setPromoLoading(true);
+    try {
+      const res = await fetch('/api/coupons/validate', {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json' },
+        body: JSON.stringify({ code: promoInput.trim(), orderTotal: totalPrice ?? 0 }),
+      });
+      const data = await res.json();
+      if (!data.success) {
+        toast({ title: 'Invalid coupon', description: data.message, status: 'error', duration: 3000, isClosable: true });
+        return;
+      }
+      setAppliedCoupon(data.data);
+      setPromoInput('');
+      toast({ title: `Coupon applied!`, description: `You save $${data.data.discount.toFixed(2)}`, status: 'success', duration: 3000, isClosable: true });
+    } catch {
+      toast({ title: 'Error', description: 'Could not validate coupon', status: 'error', duration: 3000, isClosable: true });
+    } finally {
+      setPromoLoading(false);
+    }
+  };
+
   const handleCheckout = async () => {
     if (cartItems.length === 0) return;
     setIsCheckoutLoading(true);
@@ -69,7 +96,7 @@ const Navbar = () => {
       const res = await fetch("/api/checkout", {
         method: "POST",
         headers: { "Content-Type": "application/json" },
-        body: JSON.stringify({ items: cartItems }),
+        body: JSON.stringify({ items: cartItems, couponCode: appliedCoupon?.code || null }),
       });
       if (!res.ok) {
         throw new Error(`Server error: ${res.status} ${res.statusText}`);
@@ -86,6 +113,7 @@ const Navbar = () => {
         });
         return;
       }
+      setAppliedCoupon(null);
       onClose();
       window.location.href = data.url;
     } catch (err) {
@@ -445,12 +473,46 @@ const Navbar = () => {
               )}
             </DrawerBody>
 
-            <DrawerFooter borderTopWidth="1px" display="flex" flexDirection="column" alignItems="stretch">
-              <HStack justify="space-between" mb={4}>
+            <DrawerFooter borderTopWidth="1px" display="flex" flexDirection="column" alignItems="stretch" gap={3}>
+              {/* Promo code input */}
+              {cartItems.length > 0 && (
+                appliedCoupon ? (
+                  <HStack justify="space-between">
+                    <Tag colorScheme="green" size="md" borderRadius="full">
+                      <TagLabel>{appliedCoupon.code} — save ${appliedCoupon.discount.toFixed(2)}</TagLabel>
+                      <TagCloseButton onClick={() => setAppliedCoupon(null)} />
+                    </Tag>
+                  </HStack>
+                ) : (
+                  <InputGroup size="sm">
+                    <Input
+                      placeholder="Promo code"
+                      value={promoInput}
+                      onChange={(e) => setPromoInput(e.target.value.toUpperCase())}
+                      onKeyDown={(e) => e.key === 'Enter' && handleApplyPromo()}
+                      textTransform="uppercase"
+                    />
+                    <InputRightElement width="4.5rem">
+                      <Button h="1.5rem" size="xs" colorScheme="cyan" onClick={handleApplyPromo} isLoading={promoLoading}>
+                        Apply
+                      </Button>
+                    </InputRightElement>
+                  </InputGroup>
+                )
+              )}
+
+              <HStack justify="space-between">
                 <Text fontWeight="bold" fontSize="lg">{t('cart.total')}:</Text>
-                <Text fontWeight="bold" fontSize="lg" color="cyan.500">
-                  {formatPrice(totalPrice ?? 0, currency, rates)}
-                </Text>
+                <VStack align="flex-end" spacing={0}>
+                  {appliedCoupon && (
+                    <Text fontSize="sm" color="gray.400" textDecoration="line-through">
+                      {formatPrice(totalPrice ?? 0, currency, rates)}
+                    </Text>
+                  )}
+                  <Text fontWeight="bold" fontSize="lg" color="cyan.500">
+                    {formatPrice(appliedCoupon ? appliedCoupon.finalTotal : (totalPrice ?? 0), currency, rates)}
+                  </Text>
+                </VStack>
               </HStack>
               <Button colorScheme="blue" size="lg" width="100%" onClick={handleCheckout} isLoading={isCheckoutLoading} isDisabled={cartItems.length === 0}>
                 Proceed to Checkout