"""Throughput per (experiment, solution): mean and sample SD in Gbps."""
from pathlib import Path

import pandas as pd


def compute(derived: Path) -> tuple[dict[str, str], list[Path]]:
    out: dict[str, str] = {}
    sources: list[Path] = []
    for exp_dir in sorted(p for p in derived.iterdir() if p.is_dir()):
        runs = exp_dir / "runs.csv"
        if not runs.exists():
            continue
        sources.append(runs)
        df = pd.read_csv(runs)
        for sol, sub in df.groupby("solution", sort=True):
            thr = sub["throughput_bps"].to_numpy() / 1e9
            base = f"{exp_dir.name}/throughput/{sol}"
            out[f"{base}/mean-gbps"] = f"{thr.mean():.3f}"
            out[f"{base}/sd-gbps"]   = f"{thr.std(ddof=1):.3f}"
            out[f"{base}/n-runs"]    = str(len(thr))
    return out, sources