import argparse
import json
import sys
from datetime import datetime, timezone

import pandas as pd
from sklearn.metrics import accuracy_score, precision_score, recall_score, f1_score, confusion_matrix


SCORER_VERSION = "1.2.0"


def validate_columns(df, required, name):
    missing = [c for c in required if c not in df.columns]
    if missing:
        raise ValueError(f"{name} missing required columns: {missing}")


def validate_no_duplicates(df, column, name):
    dupes = df[df[column].duplicated()][column].tolist()
    if dupes:
        raise ValueError(f"{name} contains duplicate {column} values: {dupes}")


def validate_binary_column(df, column, name):
    invalid = df[~df[column].isin([0, 1])]
    if not invalid.empty:
        bad = invalid[["scenario_id", column]].to_dict(orient="records")
        raise ValueError(f"{name} has non-binary values in {column}: {bad}")


def dataset_integrity_report(truth):
    feature_cols = [
        c for c in truth.columns
        if c not in ["scenario_id", "label"]
        and pd.api.types.is_numeric_dtype(truth[c])
    ]

    label_counts = truth["label"].value_counts().to_dict()
    total = len(truth)

    label_balance = {
        "label_0": int(label_counts.get(0, 0)),
        "label_1": int(label_counts.get(1, 0)),
        "positive_rate": float(label_counts.get(1, 0) / total) if total else 0.0,
    }

    correlations = {}

    for col in feature_cols:
        corr = truth[col].corr(truth["label"])
        if pd.isna(corr):
            corr = 0.0
        correlations[col] = float(corr)

    high_correlation_features = {
        col: corr
        for col, corr in correlations.items()
        if abs(corr) >= 0.30
    }

    return {
        "num_rows": int(total),
        "num_features_checked": int(len(feature_cols)),
        "label_balance": label_balance,
        "max_abs_feature_label_correlation": float(
            max([abs(v) for v in correlations.values()], default=0.0)
        ),
        "high_correlation_features_abs_ge_0_30": high_correlation_features,
        "passes_basic_integrity_check": (
            0.35 <= label_balance["positive_rate"] <= 0.65
            and len(high_correlation_features) == 0
        ),
    }


def run_scoring(predictions_path, truth_path):
    pred = pd.read_csv(predictions_path)
    truth = pd.read_csv(truth_path)

    validate_columns(pred, ["scenario_id", "prediction"], "predictions")
    validate_columns(truth, ["scenario_id", "label"], "truth")

    validate_no_duplicates(pred, "scenario_id", "predictions")
    validate_no_duplicates(truth, "scenario_id", "truth")

    validate_binary_column(pred, "prediction", "predictions")
    validate_binary_column(truth, "label", "truth")

    merged = truth[["scenario_id", "label"]].merge(
        pred[["scenario_id", "prediction"]],
        on="scenario_id",
        how="left",
        indicator=True,
    )

    missing = merged[merged["_merge"] == "left_only"]["scenario_id"].tolist()
    if missing:
        raise ValueError(f"Missing predictions for scenario_id: {missing}")

    extra = pred[~pred["scenario_id"].isin(truth["scenario_id"])]["scenario_id"].tolist()
    if extra:
        raise ValueError(f"Predictions contain unknown scenario_id: {extra}")

    y_true = merged["label"].astype(int)
    y_pred = merged["prediction"].astype(int)

    metrics = {
        "scorer_version": SCORER_VERSION,
        "timestamp_utc": datetime.now(timezone.utc).isoformat(),
        "num_examples": int(len(merged)),
        "accuracy": float(accuracy_score(y_true, y_pred)),
        "precision": float(precision_score(y_true, y_pred, zero_division=0)),
        "recall": float(recall_score(y_true, y_pred, zero_division=0)),
        "f1": float(f1_score(y_true, y_pred, zero_division=0)),
        "confusion_matrix": {
            "labels": [0, 1],
            "matrix": confusion_matrix(y_true, y_pred, labels=[0, 1]).tolist(),
        },
        "dataset_integrity": dataset_integrity_report(truth),
    }

    return metrics


def main():
    parser = argparse.ArgumentParser(
        description="ClarusC64 binary prediction scorer with dataset integrity checks"
    )

    parser.add_argument(
        "--predictions",
        required=True,
        help="CSV file with scenario_id,prediction",
    )

    parser.add_argument(
        "--truth",
        default="data/test.csv",
        help="Truth CSV with scenario_id,label. Default: data/test.csv",
    )

    parser.add_argument(
        "--output",
        default="metrics.json",
        help="Output JSON file. Default: metrics.json",
    )

    args = parser.parse_args()

    try:
        metrics = run_scoring(args.predictions, args.truth)

        with open(args.output, "w", encoding="utf-8") as f:
            json.dump(metrics, f, indent=2)

        print(json.dumps(metrics, indent=2))
        sys.exit(0)

    except Exception as e:
        error = {
            "scorer_version": SCORER_VERSION,
            "status": "error",
            "message": str(e),
        }

        print(json.dumps(error, indent=2), file=sys.stderr)
        sys.exit(1)


if __name__ == "__main__":
    main()