app.py

# ─── streamlit_app.py ────────────────────────────────────────────────────────

import streamlit as st

# ─── MUST BE FIRST ───────────────────────────────────────────────────────────
st.set_page_config(page_title="Keystroke Dynamics Auth", layout="wide")

import pandas as pd
import numpy as np
import joblib
import tensorflow as tf
from io import StringIO

# ─── Caching loaders so they only run once per session ───────────────────────
@st.cache_resource
def load_preprocessor(path="preprocessor.pkl"):
    return joblib.load(path)

@st.cache_resource
def load_label_encoder(path="label_encoder.pkl"):
    return joblib.load(path)

@st.cache_resource
def load_model(path="keystroke_dnn.h5"):
    return tf.keras.models.load_model(path)

# ─── Prediction helper ───────────────────────────────────────────────────────
def predict_subjects(df_raw):
    preprocessor  = load_preprocessor()
    label_encoder = load_label_encoder()
    model         = load_model()

    # Drop non-feature columns if present
    for c in ("subject", "sessionIndex", "rep"):
        if c in df_raw.columns:
            df_raw = df_raw.drop(columns=[c])

    # Re-order and validate features
    feature_cols = preprocessor.transformers_[0][2]
    df_features  = df_raw[feature_cols]

    # Predict
    X_scaled = preprocessor.transform(df_features)
    y_prob   = model.predict(X_scaled)
    idx_pred = np.argmax(y_prob, axis=1)
    labels   = label_encoder.categories_[0][idx_pred]

    # Build result
    df_out = pd.DataFrame({"Predicted Subject": labels})
    for i, cls in enumerate(label_encoder.categories_[0]):
        df_out[f"Probability {cls}"] = y_prob[:, i]

    return df_out

# ─── Streamlit App ────────────────────────────────────────────────────────────
def main():
    st.title("🔐 Keystroke Dynamics Authenticator")
    st.markdown("""
    This app uses **keystroke timing data** to identify who typed a password based on their typing rhythm.

    **How it works:**  
    You paste one row of keystroke data (copied from Excel or CSV), and the system predicts the subject who likely typed it.  
    """)
    
    with st.expander("ℹ️ About the data format", expanded=False):
        st.markdown("""
        Each row includes 34 values:
        - First 3 columns (optional):  
          `subject` (ID like s002), `sessionIndex` (1-8), and `rep` (1-50)
        - Next 31 columns:  
          Hold times (how long each key was pressed) and latency features:
            - `H.key`: time a key was held
            - `DD.key1.key2`: time between pressing key1 and key2
            - `UD.key1.key2`: time between releasing key1 and pressing key2

        **Example row (tab or comma‑separated):**
        ```
        s002	1	1	0.1491	0.3979	0.2488	...	0.0742
        ```

        You can copy this directly from Excel or a CSV file.
        """)

    # Load features list
    preprocessor = load_preprocessor()
    feature_cols = preprocessor.transformers_[0][2]

    st.markdown("### 🧾 Feature Format")
    st.code(", ".join(feature_cols), language="text")

    # Textarea for user input
    input_text = st.text_area(
        "Paste **one row** of keystroke timing data below:",
        placeholder="s002\t1\t1\t0.1491\t0.3979\t0.2488\t... (31 timing values)",
        height=140
    )

    if st.button("🔍 Predict"):
        if not input_text.strip():
            st.warning("⚠️ Please paste a row of values to proceed.")
            return

        try:
            # Use tab if present, else comma
            delimiter = '\t' if '\t' in input_text else ','

            df_input = pd.read_csv(StringIO(input_text.strip()), header=None, sep=delimiter)

            # Trim leading columns until the number matches feature_cols
            while df_input.shape[1] > len(feature_cols):
                df_input = df_input.drop(columns=[df_input.columns[0]])

            if df_input.shape[1] != len(feature_cols):
                st.error(f"❌ Expected {len(feature_cols)} feature values, but got {df_input.shape[1]}.")
                return

            df_input.columns = feature_cols

        except Exception as e:
            st.error(f"❌ Could not parse input: {e}")
            return

        if df_input.shape[0] != 1:
            st.error(f"❌ Expected exactly 1 row, but got {df_input.shape[0]}.")
            return

        st.success("✅ Row parsed successfully!")
        st.write("### 🔍 Parsed Input")
        st.dataframe(df_input, use_container_width=True)

        try:
            df_pred = predict_subjects(df_input)
            st.write("### 🎯 Prediction Result")
            st.dataframe(df_pred, use_container_width=True)
        except KeyError as e:
            st.error(f"Missing feature (typo?): {e}")
        except Exception as e:
            st.error(f"Prediction error: {e}")

if __name__ == "__main__":
    main()