Margin_Calculator_Web_App

import streamlit as st

# ---- TITLE ----
st.title("Margin Calculator")
st.markdown("To calculate profit margin, enter cost and revenue. "
            "Alternatively, enter cost and profit margin, to calculate revenue.")
st.write("---")

# ---- COST ----
cost = st.number_input(label="COST ($)",
                       key="cost",
                       min_value=0.00,
                       help="Cost is the total price associated "
                            "with the purchase of an asset. The original cost "
                            "of an asset takes into consideration all of the "
                            "items that can be attributed to its purchase and "
                            "to putting the asset to use."
                       )


# ---- FUNCTIONALITY ----
def calculate_margin():
    try:
        st.session_state.margin_percent = (
                                                  st.session_state.sell_price - st.session_state.cost) / \
                                          st.session_state.sell_price * 100
    except ZeroDivisionError:
        return None


def calculate_selling_price():
    st.session_state.sell_price = st.session_state.cost / (1 - (st.session_state.margin_percent / 100))


# ---- SELLING PRICE (OPTIONAL) ----
revenue = st.number_input(label="REVENUE ($)",
                          key="sell_price",
                          on_change=calculate_margin,
                          min_value=0.00,
                          help="Revenue is the price the product is sold for.")

# ---- MARGIN (OPTIONAL) ----
profit_margin = st.number_input(label="PROFIT MARGIN (%)",
                                key="margin_percent",
                                on_change=calculate_selling_price,
                                min_value=0.00,
                                max_value=99.99,
                                help="Profit margin is the money a company makes from each sale after subtracting "
                                     "the costs. It shows how much profit the company keeps out of the total revenue."
                                )

# ---- GROSS PROFIT ----
profit = revenue - cost

if profit < 0:
    st.subheader(f"GROSS PROFIT: :red[${profit:.2f}]",
                 help="Gross profit is sales minus the cost of goods sold.")
else:
    st.subheader(f"GROSS PROFIT: :green[${profit:.2f}]",
                 help="Gross profit is sales minus the cost of goods sold.")


# ---- BACKGROUND IMAGE ----
def add_bg_from_url():
    st.markdown(
        f"""
             <style>
             .stApp {{
                 background-image: url("https://w0.peakpx.com/wallpaper/274/758/HD-wallpaper-stock-of-abstract-accounting-aircraft.jpg");
                 background-attachment: fixed;
                 background-size: cover
             }}
             </style>
             """,
        unsafe_allow_html=True
    )


add_bg_from_url()