import gradio as gr
import io
import sys

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

# Existing functions (ensure these are defined or imported in your final app.py)
# get_inventory_string
# get_cart_string
# add_item_to_cart
# remove_item_from_cart

def get_inventory_string(inventory_list):
    output_buffer = io.StringIO()
    print_func = lambda *args, **kwargs: print(*args, file=output_buffer, **kwargs)

    print_func("
" + "=" * 50)
    print_func(" " * 15 + "PRODUCT INVENTORY (PRICES)")
    print_func("=" * 50)
    print_func(f"{'ID':<5}{'Product Name':<20}{'Price/Kg':>15}")
    print_func("-" * 50)
    for item_id, product_name, price_per_kg in inventory_list:
        print_func(f"{item_id:<5}{product_name:<20}{price_per_kg:>15.2f}")
    print_func("=" * 50)
    return output_buffer.getvalue()

def get_cart_string(cart_dict):
    output_buffer = io.StringIO()
    print_func = lambda *args, **kwargs: print(*args, file=output_buffer, **kwargs)

    print_func("
" + "=" * 50)
    print_func(" " * 18 + "SHOPPING CART")
    print_func("=" * 50)
    print_func(f"{'Product Name':<15}{'Quantity(Kg)':>12}{'Price/Kg':>12}{'Subtotal':>11}")
    print_func("-" * 50)
    total_bill = 0
    if not cart_dict:
        print_func(" " * 18 + "Cart is empty!")
    else:
        for product_name, details in cart_dict.items():
            qty = details['quantity']
            price_per_kg = details['price_per_kg']
            item_total = qty * price_per_kg
            total_bill += item_total
            print_func(f"{product_name:<15}{qty:>12.2f}{price_per_kg:>12.2f}{item_total:>11.2f}")
    print_func("=" * 50)
    print_func(f"{'Total Bill:':<38}{total_bill:>11.2f}")
    print_func("=" * 50)
    return output_buffer.getvalue()

def add_item_to_cart(cart, item_id_to_add, quantity_to_add, inventory_list):
    found_in_inventory = False
    for item_id, product_name, price_per_kg in inventory_list:
        if item_id == item_id_to_add:
            found_in_inventory = True
            if product_name in cart:
                cart[product_name]['quantity'] += quantity_to_add
            else:
                cart[product_name] = {'quantity': quantity_to_add, 'price_per_kg': price_per_kg}
            return True, f"Added {quantity_to_add} Kg of {product_name} (ID: {item_id_to_add}) to cart. Price/Kg: ${price_per_kg:.2f}"

    if not found_in_inventory:
        return False, f"Error: Product with ID '{item_id_to_add}' not found in inventory."

def remove_item_from_cart(cart, item_id_to_remove, quantity_to_remove, inventory_list):
    product_name_to_remove = None
    for item_id, product_name, _ in inventory_list:
        if item_id == item_id_to_remove:
            product_name_to_remove = product_name
            break

    if not product_name_to_remove:
        return False, f"Error: Product with ID '{item_id_to_remove}' not found in inventory."

    if product_name_to_remove not in cart:
        return False, f"Error: '{product_name_to_remove}' (ID: {item_id_to_remove}) is not in the cart."

    current_quantity = cart[product_name_to_remove]['quantity']

    if quantity_to_remove >= current_quantity:
        del cart[product_name_to_remove]
        return True, f"Removed all {current_quantity} Kg of '{product_name_to_remove}' (ID: {item_id_to_remove}) from cart."
    else:
        cart[product_name_to_remove]['quantity'] -= quantity_to_remove
        return True, f"Removed {quantity_to_remove} Kg of '{product_name_to_remove}' (ID: {item_id_to_remove}) from cart. Remaining: {cart[product_name_to_remove]['quantity']} Kg."


def gradio_add_item(cart, item_id_to_add, quantity_to_add):
    success, message = add_item_to_cart(cart, item_id_to_add, quantity_to_add, Inventory)
    return cart, message, get_cart_string(cart)

def gradio_remove_item(cart, item_id_to_remove, quantity_to_remove):
    success, message = remove_item_from_cart(cart, item_id_to_remove, quantity_to_remove, Inventory)
    return cart, message, get_cart_string(cart)

def gradio_display_cart_wrapper(cart):
    return get_cart_string(cart)

with gr.Blocks() as demo:
    gr.Markdown("# Shopping Cart Management System")

    cart_state = gr.State(value={})

    with gr.Tab("Add/Remove Items"):
        gr.Markdown("## Inventory")
        gr.Textbox(value=get_inventory_string(Inventory), label="Available Products", interactive=False, lines=10)

        with gr.Row():
            with gr.Column():
                gr.Markdown("### Add Item to Cart")
                add_id = gr.Number(label="Product ID to Add", value=1)
                add_qty = gr.Number(label="Quantity (Kg)", value=1.0)
                add_btn = gr.Button("Add to Cart")
                add_output = gr.Textbox(label="Status", interactive=False)

            with gr.Column():
                gr.Markdown("### Remove Item from Cart")
                remove_id = gr.Number(label="Product ID to Remove", value=1)
                remove_qty = gr.Number(label="Quantity (Kg)", value=1.0)
                remove_btn = gr.Button("Remove from Cart")
                remove_output = gr.Textbox(label="Status", interactive=False)

        current_cart_display = gr.Textbox(label="Current Shopping Cart", interactive=False, lines=None)

        add_btn.click(
            gradio_add_item,
            inputs=[cart_state, add_id, add_qty],
            outputs=[cart_state, add_output, current_cart_display]
        )
        remove_btn.click(
            gradio_remove_item,
            inputs=[cart_state, remove_id, remove_qty],
            outputs=[cart_state, remove_output, current_cart_display]
        )
        
        demo.load(gradio_display_cart_wrapper, inputs=cart_state, outputs=current_cart_display)

    with gr.Tab("View Cart"):
        gr.Markdown("## Your Shopping Cart")
        view_cart_display = gr.Textbox(label="Shopping Cart Contents", interactive=False, lines=None)
        
        cart_state.change(
            gradio_display_cart_wrapper,
            inputs=cart_state,
            outputs=view_cart_display
        )
        # Initial load for the View Cart tab
        demo.load(gradio_display_cart_wrapper, inputs=cart_state, outputs=view_cart_display)

demo.launch(share=True)