classifier/inference.py

import sys
import os

PROJECT_ROOT = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
sys.path.append(PROJECT_ROOT)

import numpy as np
import pandas as pd
import xgboost as xgb

# -------------------------------
# IMPORT FEATURE EXTRACTORS
# -------------------------------
from featureextraction.step1_statistical_extraction.step1_statistical_extraction import extract_features as extract_stat
from featureextraction.step2_ast_extraction.step2_ast_extraction import extract_ast_features
from featureextraction.step3_stylometry_extraction.step3_stylometry_extraction import extract_stylometry_features
from featureextraction.semantic_features.unixcoder_embedding import get_unixcoder_embedding

# XAI modules
from xai.shaplayer import shap_explain
from xai.grouping import group_shap_explanations
from xai.text_explainer import generate_text_explanation

# -------------------------------
# LOAD MODEL
# -------------------------------
model = xgb.XGBClassifier()
model.load_model("classifier/xgboost_final_model.json")

# -------------------------------
# LANGUAGE ONE-HOT
# -------------------------------
def encode_language(language):
    language = language.lower()
    if language == "python":
        return np.array([1, 0])
    elif language == "java":
        return np.array([0, 1])
    else:
        raise ValueError("Language must be python or java")

# -------------------------------
# BUILD FEATURES FROM CODE
# -------------------------------
def build_features_from_code(code, language):

    df = pd.DataFrame({
        "normalized_code": [code],
        "Language": [language]
    })

    stat_df = extract_stat(df)
    ast_df = extract_ast_features(df)
    style_df = extract_stylometry_features(df)

    X_stat = stat_df.drop(columns=["language"]).values.flatten()
    X_ast = ast_df.values.flatten()
    X_style = style_df.values.flatten()
    X_lang = encode_language(language)
    X_sem = get_unixcoder_embedding(code)

    X_final = np.hstack([
        X_stat,
        X_ast,
        X_style,
        X_lang,
        X_sem
    ]).reshape(1, -1)

    return X_final

# -------------------------------
# BASIC PREDICT FUNCTION
# -------------------------------
def predict_from_features(X_final):
    prediction = model.predict(X_final)[0]
    probability = model.predict_proba(X_final)[0][1]
    label_name = "AI" if prediction == 1 else "Human"
    return label_name, probability

# -------------------------------
# INTERACTIVE CLI
# -------------------------------
if __name__ == "__main__":

    print("\n======================================")
    print("  AI vs Human Code Classification")
    print("======================================")

    language = input("Choose language (python/java): ").strip().lower()

    print("\nPaste your code below.")
    print("Type 'END' on a new line when finished.\n")

    lines = []
    while True:
        line = input()
        if line.strip() == "END":
            break
        lines.append(line)

    code_input = "\n".join(lines)

    # build features
    X_final = build_features_from_code(code_input, language)

    # predict
    label, prob = predict_from_features(X_final)

    # shap
    shap_result = shap_explain(model, X_final)

    # grouping
    grouped = group_shap_explanations(shap_result)

    # text explanation
    text_reason = generate_text_explanation(grouped, label, prob)

    print("\n========== RESULT ==========")
    print("Prediction :", label)
    print("Confidence :", prob)

    print("\nTop SHAP features:")
    for e in shap_result:
        print(f"Feature {e['feature_index']} → {e['impact']} ({e['pushes_toward']})")

    print("\nGrouped SHAP importance:", grouped)

    print("\nExplanation:\n")
    print(text_reason)