src/streamlit_app.py

import json
import numpy as np
import pandas as pd
import streamlit as st
import os

st.set_page_config(
    page_title="Employee Attrition Prediction",
    page_icon="👩‍💼",
    layout="centered"
)

st.title("👩‍💼 Employee Attrition Prediction (HF Safe Version)")
st.write("This app predicts whether an employee is likely to leave the company.")

# ---------------------------
# Load lightweight JSON model
# ---------------------------
if os.path.exists("lightweight_model.json"):
    st.success("✅ Model loaded successfully!")
    light_model = json.load(open("lightweight_model.json"))

    means = light_model["feature_means"]
    stds = light_model["feature_stds"]

else:
    st.warning("⚠️ lightweight_model.json not found. Using fallback model.")

    means = {
        "Age": 35,
        "MonthlyIncome": 6500,
        "JobSatisfaction": 3,
        "WorkLifeBalance": 3,
        "YearsAtCompany": 5,
        "OverTime": 0.2
    }

    # Avoid divide-by-zero
    stds = {k: 1 for k in means}

# ---------------------------
# Prediction Logic (Simple Logistic)
# ---------------------------
def simple_predict(df):
    # Normalize input
    for col in df.columns:
        df[col] = (df[col] - means[col]) / (stds[col] + 1e-6)

    score = df.sum(axis=1).values[0]
    probability = 1 / (1 + np.exp(-score))
    return probability

# ---------------------------
# Input Form
# ---------------------------
st.header("🔮 Enter Employee Details")

age = st.number_input("Age", min_value=18, max_value=60, value=30)
income = st.number_input("Monthly Income", min_value=1000, max_value=20000, value=5000)
job_sat = st.slider("Job Satisfaction (1–4)", 1, 4, 3)
wlb = st.slider("Work-Life Balance (1–4)", 1, 4, 3)
years = st.number_input("Years at Company", min_value=0, max_value=40, value=5)
overtime = st.selectbox("OverTime", ["Yes", "No"])
overtime_val = 1 if overtime == "Yes" else 0

# Prepare DataFrame
input_df = pd.DataFrame([{
    "Age": age,
    "MonthlyIncome": income,
    "JobSatisfaction": job_sat,
    "WorkLifeBalance": wlb,
    "YearsAtCompany": years,
    "OverTime": overtime_val
}])

# ---------------------------
# Predict
# ---------------------------
if st.button("Predict Attrition"):
    prob = simple_predict(input_df)

    if prob > 0.5:
        st.error(f"⚠️ Employee likely to leave the company. (Confidence: {prob:.2f})")
    else:
        st.success(f"✅ Employee likely to stay. (Confidence: {1 - prob:.2f})")

# ---------------------------
# Footer
# ---------------------------
st.markdown("---")
st.caption("Built with ❤️ using Streamlit — Safe for HuggingFace Spaces")