#!/usr/bin/env python3
from __future__ import annotations

import argparse
import json
from pathlib import Path
from typing import Any


def parse_args() -> argparse.Namespace:
    parser = argparse.ArgumentParser(description="Compare two rain-model training reports.")
    parser.add_argument("--baseline", required=True, help="Baseline report path (for example 1h).")
    parser.add_argument("--candidate", required=True, help="Candidate report path (for example 4h).")
    return parser.parse_args()


def load_json(path: str) -> dict[str, Any]:
    p = Path(path)
    with p.open("r", encoding="utf-8") as f:
        return json.load(f)


def to_float(v: Any) -> float | None:
    if v is None:
        return None
    try:
        return float(v)
    except (TypeError, ValueError):
        return None


def metric(report: dict[str, Any], split: str, key: str) -> float | None:
    return to_float(report.get(split, {}).get(key))


def delta_str(base: float | None, cand: float | None) -> str:
    if base is None or cand is None:
        return "n/a"
    d = cand - base
    return f"{d:+.4f}"


def main() -> int:
    args = parse_args()
    baseline = load_json(args.baseline)
    candidate = load_json(args.candidate)

    pairs = [
        ("precision", metric(baseline, "test_metrics", "precision"), metric(candidate, "test_metrics", "precision")),
        ("recall", metric(baseline, "test_metrics", "recall"), metric(candidate, "test_metrics", "recall")),
        ("f1", metric(baseline, "test_metrics", "f1"), metric(candidate, "test_metrics", "f1")),
        ("pr_auc", metric(baseline, "test_metrics", "pr_auc"), metric(candidate, "test_metrics", "pr_auc")),
        ("roc_auc", metric(baseline, "test_metrics", "roc_auc"), metric(candidate, "test_metrics", "roc_auc")),
        ("brier", metric(baseline, "test_metrics", "brier"), metric(candidate, "test_metrics", "brier")),
    ]

    print("Rain report comparison:")
    print(
        f"  baseline: version={baseline.get('model_version')} "
        f"horizon={baseline.get('horizon_hours')}h "
        f"target={baseline.get('target_definition')}"
    )
    print(
        f"  candidate: version={candidate.get('model_version')} "
        f"horizon={candidate.get('horizon_hours')}h "
        f"target={candidate.get('target_definition')}"
    )
    print("  metrics (candidate - baseline):")
    for name, base, cand in pairs:
        base_txt = "n/a" if base is None else f"{base:.4f}"
        cand_txt = "n/a" if cand is None else f"{cand:.4f}"
        print(f"    {name}: baseline={base_txt} candidate={cand_txt} delta={delta_str(base, cand)}")

    return 0


if __name__ == "__main__":
    raise SystemExit(main())