import streamlit as st
import math

# --- Set Page Configuration ---
st.set_page_config(page_title="Advanced Calculator", page_icon="🧮", layout="centered")

# --- Initialize Calculation History ---
if "history" not in st.session_state:
    st.session_state.history = []

# --- UI: Title and Description ---
st.title("🧮 Advanced Web-Based Calculator")
st.write("Perform basic and advanced arithmetic operations with a clean and interactive UI.")

# --- User Input Fields ---
num1 = st.number_input("Enter First Number", value=0.0, format="%.6f")
num2 = st.number_input("Enter Second Number (if required)", value=0.0, format="%.6f")

# --- Dropdown for Operation Selection ---
operation = st.selectbox(
    "Select Operation",
    [
        "Addition (+)", "Subtraction (-)", "Multiplication (×)", "Division (÷)",
        "Modulus (%)", "Exponentiation (x^y)", "Square Root (√x)", 
        "Logarithm (log base 10)", "Natural Log (ln)", 
        "Sine (sin)", "Cosine (cos)", "Tangent (tan)"
    ]
)

# --- Perform Calculation ---
result = None
if st.button("Calculate"):
    try:
        if operation == "Addition (+)":
            result = num1 + num2
        elif operation == "Subtraction (-)":
            result = num1 - num2
        elif operation == "Multiplication (×)":
            result = num1 * num2
        elif operation == "Division (÷)":
            if num2 == 0:
                st.error("❌ Error: Division by zero is not allowed!")
            else:
                result = num1 / num2
        elif operation == "Modulus (%)":
            if num2 == 0:
                st.error("❌ Error: Modulus by zero is not allowed!")
            else:
                result = num1 % num2
        elif operation == "Exponentiation (x^y)":
            result = num1 ** num2
        elif operation == "Square Root (√x)":
            if num1 < 0:
                st.error("❌ Error: Square root of negative number is not allowed!")
            else:
                result = math.sqrt(num1)
        elif operation == "Logarithm (log base 10)":
            if num1 <= 0:
                st.error("❌ Error: Logarithm of zero or negative number is not allowed!")
            else:
                result = math.log10(num1)
        elif operation == "Natural Log (ln)":
            if num1 <= 0:
                st.error("❌ Error: Natural logarithm of zero or negative number is not allowed!")
            else:
                result = math.log(num1)
        elif operation == "Sine (sin)":
            result = math.sin(math.radians(num1))  # Convert degrees to radians
        elif operation == "Cosine (cos)":
            result = math.cos(math.radians(num1))
        elif operation == "Tangent (tan)":
            result = math.tan(math.radians(num1))

        # Store in History
        if result is not None:
            calculation = f"{num1} {operation.split()[1]} {num2 if '√' not in operation else ''} = {result}"
            st.session_state.history.append(calculation)
            st.success(f"✅ Result: {result}")

    except Exception as e:
        st.error(f"⚠️ An error occurred: {e}")

# --- Show Calculation History ---
if st.session_state.history:
    st.subheader("📜 Calculation History")
    for calc in st.session_state.history[-5:]:  # Show last 5 calculations
        st.write(calc)

# --- Footer ---
st.markdown("---")
st.markdown("🔹 Developed using **Streamlit** | 🚀 Ready for **Hugging Face Spaces** Deployment")