from __future__ import annotations

import json
from datetime import date
import os
from pathlib import Path

import joblib
import pandas as pd
from huggingface_hub import HfApi
from sklearn.metrics import mean_absolute_error
from xgboost import XGBRegressor

from data_pipeline import FEATURES, build_training_frame, cache_histories, fetch_fixtures, fetch_players

ROOT = Path(__file__).resolve().parent
MODEL_PATH = ROOT / "xgb_model.joblib"
METADATA_PATH = ROOT / "model_metadata.json"
CACHE_PATH = ROOT / ".cache" / "player_histories"
MODEL_REPO_ID = os.getenv("MODEL_REPO_ID", "").strip()


def new_model() -> XGBRegressor:
    return XGBRegressor(
        n_estimators=200,
        learning_rate=0.05,
        max_depth=3,
        objective="reg:squarederror",
        random_state=42,
    )


def evaluate_by_gameweek(frame: pd.DataFrame):
    """Use whole future gameweeks as validation sets, avoiding row leakage."""
    gameweeks = sorted(frame["gameweek"].unique())
    if len(gameweeks) < 3:
        raise ValueError("At least three completed gameweeks are required for validation.")
    split_at = max(1, int(len(gameweeks) * 0.8))
    train_weeks, test_weeks = gameweeks[:split_at], gameweeks[split_at:]
    train = frame[frame["gameweek"].isin(train_weeks)]
    test = frame[frame["gameweek"].isin(test_weeks)]
    validation_model = new_model().fit(train[FEATURES], train["points"])
    predictions = validation_model.predict(test[FEATURES])
    return mean_absolute_error(test["points"], predictions), train_weeks, test_weeks


def main() -> None:
    print("Fetching FPL data and player histories...")
    players = fetch_players()
    fixtures = fetch_fixtures()
    histories = cache_histories(players, CACHE_PATH)
    frame = build_training_frame(players, histories, fixtures)
    if frame.empty:
        raise RuntimeError("No valid training rows were created.")

    mae, train_weeks, test_weeks = evaluate_by_gameweek(frame)
    model = new_model().fit(frame[FEATURES], frame["points"])
    joblib.dump(model, MODEL_PATH)
    metadata = {
        "trained_on": date.today().isoformat(),
        "features": FEATURES,
        "training_rows": len(frame),
        "gameweeks": sorted(int(week) for week in frame["gameweek"].unique()),
        "validation_mae": round(float(mae), 4),
        "validation_training_gameweeks": [int(week) for week in train_weeks],
        "validation_test_gameweeks": [int(week) for week in test_weeks],
    }
    METADATA_PATH.write_text(json.dumps(metadata, indent=2), encoding="utf-8")
    print(f"Validation MAE: {mae:.2f}")
    print(f"Saved model to {MODEL_PATH}")
    print(f"Saved metadata to {METADATA_PATH}")

    if MODEL_REPO_ID:
        api = HfApi()
        api.create_repo(repo_id=MODEL_REPO_ID, repo_type="model", exist_ok=True)
        for artifact in (MODEL_PATH, METADATA_PATH):
            api.upload_file(
                path_or_fileobj=str(artifact),
                path_in_repo=artifact.name,
                repo_id=MODEL_REPO_ID,
                repo_type="model",
                commit_message=f"Retrain model on {metadata['trained_on']}",
            )
        print(f"Uploaded model artifacts to {MODEL_REPO_ID}")


if __name__ == "__main__":
    main()