#!/usr/bin/env python3
"""Combine per-checkpoint CDF metrics into a cross-ratio CSV."""

from __future__ import annotations

import argparse
import csv
import re
from pathlib import Path


def parse_train_ratio(name: str) -> str:
    match = re.search(r"ratio-([0-9.]+)", name)
    if match:
        return match.group(1)
    return name


def main():
    parser = argparse.ArgumentParser()
    parser.add_argument("--root", required=True, type=Path)
    parser.add_argument("--output", type=Path, default=None)
    parser.add_argument("--method", type=str, default="")
    args = parser.parse_args()

    output = args.output or args.root / "cross_ratio_metrics.csv"
    rows = []
    fieldnames = None
    for metrics_path in sorted(args.root.glob("*/metrics.csv")):
        run_name = metrics_path.parent.name
        train_ratio = parse_train_ratio(run_name)
        with metrics_path.open("r", encoding="utf-8", newline="") as f:
            reader = csv.DictReader(f)
            for row in reader:
                out = {
                    "method": args.method,
                    "run": run_name,
                    "train_ratio": train_ratio,
                    "eval_ratio": row.get("ratio", ""),
                }
                out.update(row)
                rows.append(out)
                if fieldnames is None:
                    fieldnames = ["method", "run", "train_ratio", "eval_ratio"] + list(row.keys())

    if fieldnames is None:
        fieldnames = ["method", "run", "train_ratio", "eval_ratio"]

    output.parent.mkdir(parents=True, exist_ok=True)
    with output.open("w", encoding="utf-8", newline="") as f:
        writer = csv.DictWriter(f, fieldnames=fieldnames)
        writer.writeheader()
        for row in rows:
            writer.writerow({key: row.get(key, "") for key in fieldnames})
    print(f"Wrote {len(rows)} rows to {output}")


if __name__ == "__main__":
    main()