app.py

import streamlit as st
import joblib
import pandas as pd
import numpy as np

# --- 1. CONFIGURATION ---
MODEL_FILE = 'hotel_cancellation_prediction_model_v1_0.joblib'
# The list of features (columns) the model was trained on, in order.
FEATURE_NAMES = [
    'lead_time',
    'no_of_special_requests',
    'avg_price_per_room',
    'no_of_adults',
    'no_of_weekend_nights',
    'required_car_parking_space',
    'no_of_week_nights',
    'arrival_month',
    'market_segment_type_Online'
]

# --- 2. MODEL LOADING ---
# Use cache to load the model just once
@st.cache_resource
def load_model():
    try:
        return joblib.load(MODEL_FILE)
    except Exception as e:
        st.error(f"Error loading model: {e}. Check if '{MODEL_FILE}' exists.")
        return None
model = load_model()

# --- 3. PREDICTION LOGIC ---
def predict_cancellation(inputs, loaded_model):
    """Prepares data and gets the model's prediction and confidence score."""

    # Map user inputs to the format the model expects
    input_data = {
        'lead_time': inputs['lead_time'],
        'no_of_special_requests': inputs['no_of_special_requests'],
        'avg_price_per_room': inputs['avg_price_per_room'],
        'no_of_adults': inputs['no_of_adults'],
        'no_of_weekend_nights': inputs['no_of_weekend_nights'],
        'no_of_week_nights': inputs['no_of_week_nights'],
        'arrival_month': inputs['arrival_month'],

        # Binary encoding for categorical features
        'market_segment_type_Online': 1.0 if inputs['market_segment_type'] == 'Online' else 0.0,
        'required_car_parking_space': 1.0 if inputs['required_car_parking_space'] == "Yes" else 0.0,
    }

    # Create a DataFrame with the correct column order
    input_df = pd.DataFrame([input_data], columns=FEATURE_NAMES)

    # Make prediction (0=Not Cancelled, 1=Cancelled)
    prediction = loaded_model.predict(input_df)[0]

    # Get probability scores for each class (0 and 1)
    # The output is typically [P(Class 0), P(Class 1)]
    probabilities = loaded_model.predict_proba(input_df)[0]
    
    # The confidence score for the predicted class
    if prediction == 1:
        confidence_score = probabilities[1] # Probability of being Cancelled (Class 1)
    else:
        confidence_score = probabilities[0] # Probability of being Not Cancelled (Class 0)
    
    return prediction, confidence_score

# --- 4. STREAMLIT INTERFACE ---
st.title("Hotel Booking Cancellation Predictor")

if model is None:
    st.stop()
    
st.markdown("Enter booking details to predict if the reservation will be cancelled.")
st.markdown("---")

# --- Input Fields (Single Column) ---
# Simple number inputs for basic data types
lead_time = st.number_input("1. Lead Time (Days before arrival)", min_value=0, value=82, step=1)
arrival_month = st.selectbox("2. Arrival Month (1=Jan to 12=Dec)", list(range(1, 13)), index=6) # Default to July (7)
avg_price_per_room = st.number_input("3. Average Price per Room ($)", min_value=0.0, value=101.0, format="%.2f")
no_of_adults = st.number_input("4. Number of Adults", min_value=0, value=2, step=1)
no_of_weekend_nights = st.number_input("5. Number of Weekend Nights", min_value=0, value=1, step=1)
no_of_week_nights = st.number_input("6. Number of Week Nights", min_value=0, value=2, step=1)
no_of_special_requests = st.number_input("7. Number of Special Requests", min_value=0, value=0, step=1)

# Simple select boxes for categorical data
market_segment_type = st.selectbox("8. Market Segment Type", ["Online", "Offline"])
required_car_parking_space = st.selectbox("9. Required Car Parking Space", ["Yes", "No"])

# --- 5. PREDICTION BUTTON AND OUTPUT ---
if st.button("Get Prediction Result", type="primary"):

    # Dictionary to pass inputs easily
    user_inputs = {
        'lead_time': lead_time,
        'market_segment_type': market_segment_type,
        'avg_price_per_room': avg_price_per_room,
        'no_of_adults': no_of_adults,
        'no_of_weekend_nights': no_of_weekend_nights,
        'no_of_week_nights': no_of_week_nights,
        'no_of_special_requests': no_of_special_requests,
        'arrival_month': arrival_month,
        'required_car_parking_space': required_car_parking_space,
    }

    # Get both the prediction and the confidence score
    prediction, confidence_score = predict_cancellation(user_inputs, model)

    st.markdown("---")
    st.subheader("Prediction Result")

    # Display the result based on the prediction
    if prediction == 1:
        st.error("The model predicts the booking will be **CANCELLED**.")
    else:
        st.success("The model predicts the booking will be **Not Cancelled**.")

    # Display the confidence score formatted as a percentage
    st.info(f"Confidence Score: **{confidence_score * 100:.2f}%**")