backend updated for counter login

backend/src/main/java/com/rit/canteen/sales/controller/ProductController.java

@@ -19,6 +19,9 @@ public class ProductController {
     @Autowired
     private com.rit.canteen.sales.repository.StallRepository stallRepository;
 
+    @Autowired
+    private StockUpdateController stockUpdateController;
+
     @GetMapping
     public org.springframework.data.domain.Page<Product> getAllProducts(
             @RequestParam(required = false) String search,
@@ -32,9 +35,12 @@ public class ProductController {
 
     @GetMapping("/category/{categoryName}")
     public List<Product> getProductsByCategory(@PathVariable String categoryName) {
-        return productRepository.findAll().stream()
+        return productRepository.findByCategory(categoryName);
-                .filter(p -> categoryName.equals(p.getCategory()))
+    }
-                .toList();
+    
+    @GetMapping("/categories")
+    public List<String> getAllCategories() {
+        return productRepository.findDistinctCategories();
     }
 
     @PostMapping
@@ -81,6 +87,9 @@ public class ProductController {
                     Product updated = productRepository.save(product);
                     updateStallAssociations(updated, productDetails.getStalls());
                     
+                    // Broadcast update
+                    stockUpdateController.broadcastStockUpdate(updated.getId(), updated.getStock());
+                    
                     return ResponseEntity.ok(productRepository.findById(updated.getId()).orElse(updated));
                 })
                 .orElse(ResponseEntity.notFound().build());
@@ -127,8 +136,40 @@ public class ProductController {
                 .map(product -> {
                     Integer currentStock = product.getStock() != null ? product.getStock() : 0;
                     product.setStock(currentStock > 0 ? 0 : 99); // Toggle between Out of Stock and In Stock
-                    return ResponseEntity.ok(productRepository.save(product));
+                    Product saved = productRepository.save(product);
+                    stockUpdateController.broadcastStockUpdate(saved.getId(), saved.getStock());
+                    return ResponseEntity.ok(saved);
                 })
                 .orElse(ResponseEntity.notFound().build());
     }
+
+    @PatchMapping("/{id}/stock-adjust")
+    public ResponseEntity<Product> adjustStock(@PathVariable Long id, @RequestParam int delta) {
+        return productRepository.findById(id)
+                .map(product -> {
+                    int currentStock = product.getStock() != null ? product.getStock() : 0;
+                    product.setStock(Math.max(0, currentStock + delta));
+                    Product saved = productRepository.save(product);
+                    stockUpdateController.broadcastStockUpdate(saved.getId(), saved.getStock());
+                    return ResponseEntity.ok(saved);
+                })
+                .orElse(ResponseEntity.notFound().build());
+    }
+
+    @PatchMapping("/batch-assign-category")
+    @org.springframework.transaction.annotation.Transactional
+    public ResponseEntity<Void> batchAssignCategory(@RequestBody java.util.Map<String, Object> payload) {
+        String categoryName = (String) payload.get("categoryName");
+        List<Integer> productIds = (List<Integer>) payload.get("productIds");
+        
+        if (categoryName == null || productIds == null) return ResponseEntity.badRequest().build();
+        
+        for (Integer id : productIds) {
+            productRepository.findById(id.longValue()).ifPresent(p -> {
+                p.setCategory(categoryName);
+                productRepository.save(p);
+            });
+        }
+        return ResponseEntity.ok().build();
+    }
 }

backend/src/main/java/com/rit/canteen/sales/controller/StockUpdateController.java

@@ -0,0 +1,60 @@
+package com.rit.canteen.sales.controller;
+
+import org.springframework.http.MediaType;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.RestController;
+import org.springframework.web.servlet.mvc.method.annotation.SseEmitter;
+
+import java.io.IOException;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.CopyOnWriteArrayList;
+
+@RestController
+@RequestMapping("/api/stock")
+public class StockUpdateController {
+
+    private final List<SseEmitter> emitters = new CopyOnWriteArrayList<>();
+
+    @GetMapping(value = "/stream", produces = MediaType.TEXT_EVENT_STREAM_VALUE)
+    public SseEmitter streamStockUpdates() {
+        SseEmitter emitter = new SseEmitter(Long.MAX_VALUE);
+        this.emitters.add(emitter);
+
+        emitter.onCompletion(() -> this.emitters.remove(emitter));
+        emitter.onTimeout(() -> this.emitters.remove(emitter));
+        emitter.onError((e) -> this.emitters.remove(emitter));
+
+        // Send initial heartbeat to keep connection alive
+        try {
+            emitter.send(SseEmitter.event()
+                    .name("init")
+                    .data("Connection Established"));
+        } catch (IOException e) {
+            this.emitters.remove(emitter);
+        }
+
+        return emitter;
+    }
+
+    public void broadcastStockUpdate(Long productId, Integer stock) {
+        List<SseEmitter> deadEmitters = new CopyOnWriteArrayList<>();
+        Map<String, Object> payload = Map.of(
+            "productId", productId,
+            "stock", stock
+        );
+
+        this.emitters.forEach(emitter -> {
+            try {
+                emitter.send(SseEmitter.event()
+                        .name("stockUpdate")
+                        .data(payload));
+            } catch (Exception e) {
+                deadEmitters.add(emitter);
+            }
+        });
+
+        this.emitters.removeAll(deadEmitters);
+    }
+}

backend/src/main/java/com/rit/canteen/sales/repository/ProductRepository.java

@@ -20,5 +20,8 @@ public interface ProductRepository extends JpaRepository<Product, Long> {
     
     List<Product> findByCategory(String category);
     
+    @Query("SELECT DISTINCT p.category FROM Product p WHERE p.category IS NOT NULL")
+    List<String> findDistinctCategories();
+    
     boolean existsByNameAndCategory(String name, String category);
 }

frontend/src/pages/Products.tsx

@@ -114,6 +114,27 @@ const Products = () => {
 
   useEffect(() => {
     fetchProducts();
+
+    // SSE Real-time stock updates
+    const host = window.location.hostname;
+    const eventSource = new EventSource(`http://${host}:8080/api/stock/stream`);
+
+    eventSource.addEventListener('stockUpdate', (event: any) => {
+      try {
+        const update = JSON.parse(event.data);
+        setProducts(prevProducts => 
+          prevProducts.map(p => 
+            p.id === update.productId ? { ...p, stock: update.stock } : p
+          )
+        );
+      } catch (err) {
+        console.error('Error processing stock update:', err);
+      }
+    });
+
+    return () => {
+      eventSource.close();
+    };
   }, [currentPage, pageSize, debouncedSearchTerm]);
 
   useEffect(() => {