import gradio as gr

# -----------------------------
# Inventory Data
# -----------------------------
inventory = [
    (101, "Hammer", 120),
    (102, "Screwdriver Set", 350),
    (103, "Drill Machine", 2500),
    (104, "Pliers", 180),
    (105, "Wrench", 220)
]

# Convert inventory into dictionary for quick lookup
inventory_dict = {item[0]: {"name": item[1], "price": item[2]} for item in inventory}

# Cart
my_cart = []

# -----------------------------
# Functions
# -----------------------------

def add_to_cart(item_id):
    if item_id is None:
        return my_cart, "Please select an item"

    item = inventory_dict[item_id]
    my_cart.append(item)

    return my_cart, f"{item['name']} added to cart"

def remove_from_cart(index):
    if index is None or index >= len(my_cart):
        return my_cart, "Invalid selection"

    removed_item = my_cart.pop(index)
    return my_cart, f"{removed_item['name']} removed from cart"

def display_cart():
    if not my_cart:
        return "Cart is empty"

    cart_text = ""
    for i, item in enumerate(my_cart):
        cart_text += f"{i}. {item['name']} - ${item['price']}\n"

    return cart_text

def calculate_total():
    total = sum(item["price"] for item in my_cart)
    return f"Total Bill: ${total}"

# -----------------------------
# Gradio Interface
# -----------------------------

with gr.Blocks() as demo:
    gr.Markdown("# 🧾 Hardware Store Billing System")

    # Dropdown to select inventory item
    item_dropdown = gr.Dropdown(
        choices=[(f"{item[1]} (${item[2]})", item[0]) for item in inventory],
        label="Select Item from Inventory"
    )

    add_button = gr.Button("Add to Cart")

    # Dropdown for cart items (by index)
    remove_dropdown = gr.Dropdown(label="Select Cart Item Index to Remove")
    remove_button = gr.Button("Remove from Cart")

    cart_display = gr.Textbox(label="Cart Contents", lines=8)
    total_output = gr.Textbox(label="Total Bill")
    status_output = gr.Textbox(label="Status")

    # -----------------------------
    # Event Handlers
    # -----------------------------

    def update_remove_dropdown(cart):
        return gr.Dropdown(
            choices=[(f"{i}: {item['name']}", i) for i, item in enumerate(cart)]
        )

    add_button.click(
        add_to_cart,
        inputs=item_dropdown,
        outputs=[remove_dropdown, status_output]
    ).then(display_cart, outputs=cart_display).then(update_remove_dropdown, inputs=remove_dropdown, outputs=remove_dropdown)

    remove_button.click(
        remove_from_cart,
        inputs=remove_dropdown,
        outputs=[remove_dropdown, status_output]
    ).then(display_cart, outputs=cart_display).then(update_remove_dropdown, inputs=remove_dropdown, outputs=remove_dropdown)

    gr.Button("Calculate Total").click(
        calculate_total,
        outputs=total_output
    )

demo.launch()