#!/usr/bin/env python3
import argparse
import json
from pathlib import Path

import numpy as np


def main():
    p = argparse.ArgumentParser(description="Create a tiny subset of ds16k dataset for smoke testing")
    p.add_argument("--dataset-root", required=True)
    p.add_argument("--out-root", required=True)
    p.add_argument("--per-class", type=int, default=64)
    args = p.parse_args()

    src = Path(args.dataset_root).expanduser().resolve()
    out = Path(args.out_root).expanduser().resolve()
    out.mkdir(parents=True, exist_ok=True)

    classes = sorted([d for d in src.iterdir() if d.is_dir() and d.name.startswith("expert_")])
    if not classes:
        raise SystemExit("no expert_* dirs found")

    summary = {
        "source": str(src),
        "out": str(out),
        "per_class": int(args.per_class),
        "classes": [],
    }

    for c in classes:
        t = np.load(c / "traces.npy", mmap_mode="r")
        ids = np.load(c / "trial_ids.npy")
        k = min(int(args.per_class), int(t.shape[0]))

        c_out = out / c.name
        c_out.mkdir(parents=True, exist_ok=True)
        np.save(c_out / "traces.npy", np.array(t[:k], dtype=np.float32))
        np.save(c_out / "trial_ids.npy", np.array(ids[:k], dtype=np.int32))

        meta = {
            "class": c.name,
            "rows": int(k),
            "trace_len": int(t.shape[1]),
            "trial_id_min": int(ids[:k].min()),
            "trial_id_max": int(ids[:k].max()),
        }
        with open(c_out / "meta.json", "w") as f:
            json.dump(meta, f, indent=2)
        summary["classes"].append(meta)

    for fn in ["README.md", "capture_meta.json", "downsample_summary.json"]:
        pth = src / fn
        if pth.exists():
            (out / fn).write_bytes(pth.read_bytes())

    with open(out / "subset_summary.json", "w") as f:
        json.dump(summary, f, indent=2)

    print("[ok] wrote subset", out)
    print("[ok] class_count", len(classes), "per_class", int(args.per_class), "total", len(classes) * int(args.per_class))


if __name__ == "__main__":
    main()