# In __init__, call the setup method
self.setup_pos_ui()
self.current_sale_items = {} # Dictionary to store {drug_id: {data, quantity}}

def setup_pos_ui(self):
    main_layout = QHBoxLayout()

    # Left side: Sale and Barcode input
    left_layout = QVBoxLayout()
    
    barcode_group = QGroupBox("Scan Barcode")
    barcode_layout = QVBoxLayout()
    self.barcode_input = QLineEdit()
    self.barcode_input.setPlaceholderText("Scan or type barcode and press Enter...")
    self.barcode_input.returnPressed.connect(self.add_item_to_sale)
    barcode_layout.addWidget(self.barcode_input)
    barcode_group.setLayout(barcode_layout)
    
    self.sales_table = QTableWidget()
    self.sales_table.setColumnCount(5)
    self.sales_table.setHorizontalHeaderLabels(['ID', 'Name', 'Quantity', 'Unit Price', 'Total Price'])
    
    left_layout.addWidget(barcode_group)
    left_layout.addWidget(self.sales_table)
    
    # Right side: Totals and Actions
    right_layout = QVBoxLayout()
    
    total_group = QGroupBox("Sale Summary")
    total_form = QFormLayout()
    self.total_amount_label = QLabel("0.00")
    total_form.addRow("Total Amount:", self.total_amount_label)
    total_group.setLayout(total_form)
    
    complete_sale_btn = QPushButton("Complete Sale")
    complete_sale_btn.clicked.connect(self.complete_sale)
    clear_sale_btn = QPushButton("Clear Sale")
    clear_sale_btn.clicked.connect(self.clear_sale)
    
    right_layout.addWidget(total_group)
    right_layout.addWidget(complete_sale_btn)
    right_layout.addWidget(clear_sale_btn)
    right_layout.addStretch()
    
    main_layout.addLayout(left_layout, stretch=3) # Left side takes 3/4 of space
    main_layout.addLayout(right_layout, stretch=1) # Right side takes 1/4
    
    self.pos_tab.setLayout(main_layout)

#Hashtags: #PointOfSale #BarcodeScanner #UIUX #PyQt5

---

#Step 4: Implementing the Sales Logic

This is the core logic that connects the barcode input to the sales table and the database. When a barcode is entered, we find the drug, add it to the current sale, and update the UI. The "Complete Sale" button will finalize the transaction by updating the database.

Add these methods to the PharmacyApp class:

def add_item_to_sale(self):
    barcode = self.barcode_input.text()
    if not barcode:
        return
    
    drug = db.find_drug_by_barcode(barcode)
    
    if not drug:
        QMessageBox.warning(self, "Not Found", "No drug found with this barcode.")
        self.barcode_input.clear()
        return
    
    drug_id = drug[0]
    
    if drug[3] <= 0: # Check quantity
         QMessageBox.warning(self, "Out of Stock", f"{drug[1]} is out of stock.")
         self.barcode_input.clear()
         return

    if drug_id in self.current_sale_items:
        # Item already in sale, increment quantity
        self.current_sale_items[drug_id]['quantity'] += 1
    else:
        # Add new item to sale
        self.current_sale_items[drug_id] = {
            'data': drug,
            'quantity': 1
        }
    
    self.update_sales_table()
    self.barcode_input.clear()

def update_sales_table(self):
    self.sales_table.setRowCount(len(self.current_sale_items))
    total_sale_amount = 0.0
    
    for row, item in enumerate(self.current_sale_items.values()):
        drug_data = item['data']
        quantity = item['quantity']
        unit_price = drug_data[4]
        total_price = quantity * unit_price
        
        self.sales_table.setItem(row, 0, QTableWidgetItem(str(drug_data[0]))) # ID
        self.sales_table.setItem(row, 1, QTableWidgetItem(drug_data[1]))      # Name
        self.sales_table.setItem(row, 2, QTableWidgetItem(str(quantity)))
        self.sales_table.setItem(row, 3, QTableWidgetItem(f"{unit_price:.2f}"))
        self.sales_table.setItem(row, 4, QTableWidgetItem(f"{total_price:.2f}"))
        
        total_sale_amount += total_price
        
    self.total_amount_label.setText(f"{total_sale_amount:.2f}")

def complete_sale(self):
    if not self.current_sale_items:
        return

    for drug_id, item in self.current_sale_items.items():
        db.update_drug_quantity(drug_id, item['quantity'])
    
    QMessageBox.information(self, "Success", f"Sale completed. Total: {self.total_amount_label.text()}")
    
    self.clear_sale()
    self.load_inventory_data() # Refresh inventory tab to show new quantities

def clear_sale(self):
    self.current_sale_items.clear()
    self.update_sales_table()

#Hashtags: #BusinessLogic #PointOfSale #PythonCode #Transaction

---

#Step 5: Results and Discussion

With all the code in place, you have a fully functional pharmacy management system.

How to Use It:
• Run the main.py script.
• Go to the "Inventory Management" tab and add a few drugs with unique barcodes.
• Go to the "Point of Sale" tab. The cursor will be in the barcode input field.
• Type a barcode of a drug you added and press Enter. The drug will appear in the sales table.
• Scan the same barcode again. The quantity for that drug in the sales table will increase to 2.
• Click "Complete Sale". A success message will appear. The sales table will clear.
• Switch back to the "Inventory Management" tab. You will see that the quantity of the sold drugs has decreased accordingly.