app.py

# app.py — Simple Loan EMI Calculator (Hugging Face Gradio)

import math
import pandas as pd
import gradio as gr

def emi_calc(principal, annual_rate, tenure_years):
    # Input validation
    if principal is None or principal <= 0:
        return "Enter a valid principal (> 0).", None
    if annual_rate is None or annual_rate < 0:
        return "Enter a valid annual interest rate (>= 0).", None
    if tenure_years is None or tenure_years <= 0:
        return "Enter a valid tenure in years (> 0).", None

    P = float(principal)
    r_annual = float(annual_rate)
    years = float(tenure_years)

    n = int(round(years * 12))
    r = (r_annual / 100.0) / 12.0  # monthly rate

    if n <= 0:
        return "Tenure is too small. Increase tenure.", None

    # EMI formula
    if r == 0:
        emi = P / n
    else:
        emi = P * r * ((1 + r) ** n) / (((1 + r) ** n) - 1)

    total_payable = emi * n
    total_interest = total_payable - P

    summary = (
        f"### Results\n"
        f"- **Monthly EMI:** ₹{emi:,.2f}\n"
        f"- **Total Interest:** ₹{total_interest:,.2f}\n"
        f"- **Total Amount Payable:** ₹{total_payable:,.2f}\n"
        f"- **Tenure:** {n} months\n"
    )

    # Build amortization schedule
    balance = P
    rows = []
    for m in range(1, n + 1):
        interest = balance * r
        principal_paid = emi - interest
        if r == 0:
            interest = 0.0
            principal_paid = emi

        # last month adjustment (avoid tiny negative balance due to rounding)
        if m == n:
            principal_paid = balance
            emi_last = principal_paid + interest
            balance = 0.0
            rows.append([m, round(emi_last, 2), round(principal_paid, 2), round(interest, 2), round(balance, 2)])
            break

        balance -= principal_paid
        rows.append([m, round(emi, 2), round(principal_paid, 2), round(interest, 2), round(balance, 2)])

    df = pd.DataFrame(rows, columns=["Month", "EMI", "Principal Paid", "Interest Paid", "Balance"])
    return summary, df


with gr.Blocks(title="Loan EMI Calculator") as demo:
    gr.Markdown(
        "<div style='text-align:center;'>"
        "<h2>Simple Loan EMI Calculator</h2>"
        "<p>Enter loan amount, interest rate, and tenure to compute EMI and schedule.</p>"
        "</div>"
    )

    with gr.Row():
        principal = gr.Number(label="Loan Amount (₹)", value=500000, precision=0)
        annual_rate = gr.Number(label="Annual Interest Rate (%)", value=9.0, precision=2)
        tenure_years = gr.Number(label="Tenure (Years)", value=5, precision=2)

    calc_btn = gr.Button("Calculate EMI")

    out_md = gr.Markdown()
    out_table = gr.Dataframe(label="Amortization Schedule", interactive=False)

    calc_btn.click(
        fn=emi_calc,
        inputs=[principal, annual_rate, tenure_years],
        outputs=[out_md, out_table]
    )

demo.launch()