import streamlit as st
import pandas as pd
import math

def calculate_emi(principal, annual_rate, months):
    monthly_rate = annual_rate / 12 / 100
    emi = principal * monthly_rate * (math.pow(1 + monthly_rate, months)) / (math.pow(1 + monthly_rate, months) - 1)
    return emi

def generate_schedule(principal, annual_rate, months, emi):
    monthly_rate = annual_rate / 12 / 100
    balance = principal
    schedule = []

    for month in range(1, months + 1):
        interest = balance * monthly_rate
        principal_payment = emi - interest
        balance -= principal_payment
        schedule.append({
            "Month": month,
            "EMI": round(emi, 2),
            "Principal Payment": round(principal_payment, 2),
            "Interest": round(interest, 2),
            "Balance": round(balance, 2)
        })

        if balance < 0:
            balance = 0

    return pd.DataFrame(schedule)

# Streamlit UI
st.sidebar.header("EMI Calculator")

# Inputs
loan_amount = st.sidebar.number_input("Loan Amount (₹)", min_value=0.0, value=100000.0, step=1000.0)
tenure_months = st.sidebar.number_input("Tenure (Months)", min_value=1, value=12, step=1)
interest_rate = st.sidebar.number_input("Annual Interest Rate (%)", min_value=0.0, value=10.0, step=0.1)

if st.sidebar.button("Calculate"):
    emi = calculate_emi(loan_amount, interest_rate, tenure_months)

    st.write(f"### EMI: ₹{round(emi, 2)} per month")

    schedule = generate_schedule(loan_amount, interest_rate, tenure_months, emi)
    st.write("### Payback Schedule")
    st.dataframe(schedule)