Create app.py

app.py

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+import gradio as gr
+
+# -----------------------------
+# Module 1: Data Structures
+# -----------------------------
+
+Inventory = [
+    (101, "Hammer", 120),
+    (102, "Screwdriver Set", 350),
+    (103, "Drill Machine", 2500),
+    (104, "Pliers", 180),
+    (105, "Wrench", 220),
+]
+
+# Convert to a lookup dictionary for fast access
+inventory_lookup = {item[0]: {"name": item[1], "price": item[2]} for item in Inventory}
+
+# Cart is a list of item IDs
+My_Cart = []
+
+
+# -----------------------------
+# Module 2: Business Logic
+# -----------------------------
+
+def add_to_cart(item_id):
+    if item_id in inventory_lookup:
+        My_Cart.append(item_id)
+        return f"Added: {inventory_lookup[item_id]['name']}"
+    return "Invalid item ID."
+
+def remove_from_cart(item_id):
+    if item_id in My_Cart:
+        My_Cart.remove(item_id)
+        return f"Removed: {inventory_lookup[item_id]['name']}"
+    return "Item not in cart."
+
+def get_cart_contents():
+    if not My_Cart:
+        return "Cart is empty."
+    lines = []
+    for item_id in My_Cart:
+        item = inventory_lookup[item_id]
+        lines.append(f"{item_id} - {item['name']} - ₹{item['price']}")
+    return "\n".join(lines)
+
+def calculate_total():
+    total = sum(inventory_lookup[item_id]["price"] for item_id in My_Cart)
+    return f"Total Amount: ₹{total}"
+
+
+# -----------------------------
+# Module 3: Gradio Callbacks
+# -----------------------------
+
+def handle_add(selected_id):
+    msg = add_to_cart(selected_id)
+    return get_cart_contents(), msg
+
+def handle_remove(selected_id):
+    msg = remove_from_cart(selected_id)
+    return get_cart_contents(), msg
+
+def handle_total():
+    return calculate_total()
+
+
+# -----------------------------
+# Module 4: Gradio Interface
+# -----------------------------
+
+with gr.Blocks(title="Hardware Store Billing System") as demo:
+
+    gr.Markdown("## 🧰 Hardware Store Billing System")
+
+    with gr.Row():
+        add_dropdown = gr.Dropdown(
+            choices=[item[0] for item in Inventory],
+            label="Select Item to Add (by ID)"
+        )
+        add_button = gr.Button("Add Tool")
+
+    with gr.Row():
+        remove_dropdown = gr.Dropdown(
+            choices=[item[0] for item in Inventory],
+            label="Select Item to Remove (by ID)"
+        )
+        remove_button = gr.Button("Remove Tool")
+
+    cart_display = gr.Textbox(label="Cart Contents", lines=8)
+    message_display = gr.Textbox(label="Status Message")
+
+    total_button = gr.Button("Calculate Total")
+    total_output = gr.Textbox(label="Total Amount")
+
+    # Bind callbacks
+    add_button.click(handle_add, inputs=add_dropdown, outputs=[cart_display, message_display])
+    remove_button.click(handle_remove, inputs=remove_dropdown, outputs=[cart_display, message_display])
+    total_button.click(handle_total, outputs=total_output)
+
+if __name__ == "__main__":
+    demo.launch()