import os
import sys
import joblib
import pandas as pd
from sklearn.pipeline import Pipeline
from sklearn.preprocessing import FunctionTransformer, StandardScaler, OneHotEncoder
from sklearn.compose import ColumnTransformer
from sklearn.ensemble import RandomForestClassifier
from custom_transformers import FeatureExtractor, cyclical_features
def resource_path(relative_path):
    return os.path.join(getattr(sys, '_MEIPASS', os.path.abspath(".")), relative_path)

MODEL_PATH = resource_path("model.pkl")

_model = None
_pipeline = None
_last_model_mtime = None


def build_pipeline():
    cyclical_transform = FunctionTransformer(cyclical_features)

    preprocessor = ColumnTransformer([
        ("num", StandardScaler(), ["price", "rating", "smart_score", "review_count"]),
        ("cat", OneHotEncoder(handle_unknown="ignore"), ["name"])
    ], remainder="passthrough")

    pipeline = Pipeline([
        ("extract", FeatureExtractor()),
        ("cyclical", cyclical_transform),
        ("preprocess", preprocessor)
    ])

    return pipeline


def load_model():
    global _model, _last_model_mtime

    if not os.path.exists(MODEL_PATH):
        raise FileNotFoundError(f"Model file not found: {MODEL_PATH}")

    mtime = os.path.getmtime(MODEL_PATH)
    if _model is None or mtime > (_last_model_mtime or 0):
        _model = joblib.load(MODEL_PATH)
        _last_model_mtime = mtime


def inference(input_df):
    global _pipeline
    load_model()

    if _pipeline is None:
        if not os.path.exists(PIPELINE_PATH):
            raise FileNotFoundError("Missing saved preprocessing pipeline (pipeline.pkl)")
        _pipeline = joblib.load(PIPELINE_PATH)

    processed = _pipeline.transform(input_df)  # Only transform (no fit)
    return _model.predict(processed)



PIPELINE_PATH = resource_path("pipeline.pkl")

def retrain_model(df, target_col="decision"):
    global _pipeline
    pipeline = build_pipeline()
    _pipeline = pipeline  # Save for reuse

    X = pipeline.fit_transform(df)
    y = df[target_col].map({"buy": 0, "wait": 1}).astype(int)

    model = RandomForestClassifier(
        n_estimators=100, random_state=42,
        max_depth=3, max_leaf_nodes=2,
        min_samples_split=3, min_samples_leaf=2, n_jobs=-1
    )
    model.fit(X, y)

    joblib.dump(model, MODEL_PATH)
    joblib.dump(pipeline, PIPELINE_PATH)
    print("✅ Model and pipeline saved.")



if __name__ == "__main__":
    # dummy data
    data = {
        "name": ["Product A", "Product B", "Product C"],
        "price": [1000, 1500, 2000],
        "rating": [4.5, 4.0, 3.5],
        "smart_score": [0.05, 0.03, 0.02],
        "review_count": [100, 50, 30],
        "datetime": ["2023-10-01 12:00:00", "2023-10-02 13:00:00", "2023-10-03 14:00:00"],
        "decision": ["buy", "wait", "buy"]
    }
    df = pd.DataFrame(data)

    required_cols = [
        "name", "price", "rating", "smart_score", "review_count", "datetime",
    ]
    if not all(col in df.columns for col in required_cols):
        raise ValueError("Missing required columns")

    df["date"] = df["datetime"]  # match training format
    print("---- Retraining ----")
    retrain_model(df)
    print("Model and pipeline updated.")

    print("---- Inference ----")
    predictions = inference(df)
    print("Predictions:", predictions)