"""Initial ssthresh per (solution, qlen) from slowstart raw text files."""
import os
from pathlib import Path

import numpy as np


def _read(path: Path) -> dict[int, np.ndarray]:
    out = {}
    for line in path.read_text().splitlines():
        line = line.strip()
        if not line:
            continue
        qlen, vals = line.split(":", 1)
        out[int(qlen)] = np.array([float(v) for v in vals.split()])
    return out


def compute(derived: Path) -> tuple[dict[str, str], list[Path]]:
    raw_root = Path(os.environ.get("RAW_DATA_ROOT", derived.parent / "raw_data"))
    raw = raw_root / "slowstart"
    files = {"tso": raw / "tso.txt", "tso-pacing": raw / "tso_pacing.txt"}
    if not all(p.exists() for p in files.values()):
        return {}, []

    out: dict[str, str] = {}
    for sol, path in files.items():
        for qlen, vals in _read(path).items():
            base = f"slowstart/{sol}/qlen-{qlen}"
            out[f"{base}/mean-pkts"] = f"{vals.mean():.0f}"
            out[f"{base}/sd-pkts"]   = f"{vals.std(ddof=1):.0f}"
            out[f"{base}/n-runs"]    = str(vals.size)
    return out, list(files.values())