app.py

# If running in a notebook:
# !pip install gradio

import gradio as gr

Inventory = [
    (1, "Apples", 250),
    (2, "Cherry", 650),
    (3, "Chickoo", 50),
    (4, "Grapes", 90),
    (5, "Mangoes", 150),
]

Your_Cart = []

def add_item_to_cart(item_id, inventory):
    """Adds an item from the inventory to the shopping cart."""
    try:
        item = inventory[item_id - 1]
        Your_Cart.append(item)
        return f"{'>'*10} The item '{item[1]}' has been added to the cart. {'<'*10}\n\n"
    except (IndexError, TypeError):
        return f"Invalid item ID: {item_id}\n\n"

def remove_item(cart_index, cart_items):
    """Removes an item from the shopping cart by displayed index."""
    try:
        removed_item = cart_items.pop(cart_index - 1)
        return f"{'>'*10} The item '{removed_item[1]}' has been removed from the cart, and your shopping cart has been updated. {'<'*10}\n\n"
    except (IndexError, TypeError):
        return "Invalid cart index or cart is empty.\n\n"

def display_cart(cart_items):
    """Displays the items in the shopping cart (stable, one line per item in cart order)."""
    if not cart_items:
        return f"{'>'*10} Your cart is empty !!!, Why not buy Fruits from us ... {'<'*10}\n\n"

    cart_str = ""
    cart_str += "+" * 70 + "\n"
    cart_str += f"{'Your Cart'.center(60)}\n"
    cart_str += "+" * 70 + "\n"
    cart_str += f"{'Index':<10} {'Name':<20} {'Price Per KG':<15}\n"
    cart_str += "-" * 70 + "\n"

    total = 0
    for idx, item in enumerate(cart_items, start=1):
        cart_str += f"{idx:<10} {item[1]:<20} ${item[2]:<15.2f}\n"
        total += item[2]

    cart_str += "-" * 70 + "\n"
    cart_str += f"{'Total Cost':<32} ${total:<10.2f}\n"
    return cart_str

def total_cost(cart_items):
    """Calculates total cost of all items in the cart."""
    total = sum(item[2] for item in cart_items)
    return "~" * 40 + "\n" + f"Total cost: {total}".center(40) + "\n" + "~" * 40 + "\n\n"

def gradio_interface(item_id, cart_index):
    """
    Handles adding/removing items, displaying the cart, and calculating total cost.
    """
    # Convert inputs (Gradio Numbers are floats)
    def to_int(x):
        try:
            if x is None:
                return 0
            return int(x)
        except (ValueError, TypeError):
            return 0

    item_id = to_int(item_id)
    cart_index = to_int(cart_index)

    add_msg = ""
    if item_id > 0:
        add_msg = add_item_to_cart(item_id, Inventory)

    remove_msg = ""
    if cart_index > 0:
        remove_msg = remove_item(cart_index, Your_Cart)

    cart_display = display_cart(Your_Cart)
    cost_msg = total_cost(Your_Cart)

    return cart_display, add_msg, remove_msg, cost_msg

def launch_gradio():
    with gr.Blocks() as demo:
        gr.Markdown("### Fruit Shopping Cart System")
        gr.Markdown(
            "Inventory:\n"
            + "\n".join([f"- {pid}: {name} (${price}/kg)" for pid, name, price in Inventory])
        )

        with gr.Row():
            item_id_input = gr.Number(label="Enter Product ID to Add to Cart", precision=0)
            cart_index_input = gr.Number(label="Enter Cart Index to Remove", precision=0)

        # Hidden zero inputs created ONCE (don’t create components inside .click)
        zero_item = gr.Number(value=0, visible=False, precision=0)
        zero_cart = gr.Number(value=0, visible=False, precision=0)

        with gr.Row():
            add_button = gr.Button("Add to Cart")
            remove_button = gr.Button("Remove from Cart")
            refresh_button = gr.Button("Refresh Cart View")

        cart_display_output = gr.Textbox(label="Your Cart", interactive=False, lines=12)
        add_message_output = gr.Textbox(label="Add Item Message", interactive=False, lines=2)
        remove_message_output = gr.Textbox(label="Remove Item Message", interactive=False, lines=2)
        total_cost_output = gr.Textbox(label="Total Cost", interactive=False, lines=4)

        add_button.click(
            fn=gradio_interface,
            inputs=[item_id_input, zero_cart],
            outputs=[cart_display_output, add_message_output, remove_message_output, total_cost_output]
        )

        remove_button.click(
            fn=gradio_interface,
            inputs=[zero_item, cart_index_input],
            outputs=[cart_display_output, add_message_output, remove_message_output, total_cost_output]
        )

        refresh_button.click(
            fn=gradio_interface,
            inputs=[zero_item, zero_cart],
            outputs=[cart_display_output, add_message_output, remove_message_output, total_cost_output]
        )

    demo.launch()

if __name__ == "__main__":
    launch_gradio()