"""Build one rest-gel reference per (date, sensor) for the React dataset.

Each episode is a cut from a continuous per-day recording, so all episodes of a
date share one gel/lighting. This pools every episode's tactile frames for a
date and takes the per-pixel fuzzy mode (the resting gel) -- robust even when an
individual episode is in contact its whole length. Writes:

    data/<task>/reference/<date>/tactile_{left,right}.png
    data/<task>/reference/manifest.json

Then use it instead of a per-episode reference:

    ref = imageio.imread(f"data/{task}/reference/{date}/tactile_{side}.png")
    diff = difference(frame, ref)                    # toolbox.reference

Usage:
    python -m toolbox.build_session_references --root data/motherboard
"""
from __future__ import annotations
import argparse, json
from collections import defaultdict
from pathlib import Path

import numpy as np
import imageio.v2 as imageio

from .io import load_video, episode_paths
from .reference import session_reference


def main():
    ap = argparse.ArgumentParser()
    ap.add_argument("--root", required=True, help="task root, e.g. data/motherboard")
    ap.add_argument("--episodes_jsonl", default=None,
                    help="defaults to <root>/episodes.jsonl")
    ap.add_argument("--stride", type=int, default=3, help="frame subsample for speed")
    ap.add_argument("--max_frames", type=int, default=4000)
    args = ap.parse_args()
    root = Path(args.root)
    jl = Path(args.episodes_jsonl or (root / "episodes.jsonl"))
    eps = [json.loads(l) for l in jl.read_text().splitlines() if l.strip()]

    by_date = defaultdict(list)
    for e in eps:
        by_date[e["date"]].append(e["episode"])

    manifest = {}
    for date, ep_keys in sorted(by_date.items()):
        for side in ("left", "right"):
            frames = []
            for ek in sorted(ep_keys):
                p = episode_paths(root, ek)["tactile_" + side]
                if not Path(p).is_file():
                    continue
                v = load_video(p)                       # (T,H,W,3)
                frames.append(v[:: args.stride])
            if not frames:
                continue
            ref = session_reference(frames, max_frames=args.max_frames)
            out = root / "reference" / date / f"tactile_{side}.png"
            out.parent.mkdir(parents=True, exist_ok=True)
            imageio.imwrite(out, ref)
            manifest[f"{date}/tactile_{side}"] = str(out.relative_to(root))
            print(f"[ref] {date} {side}: pooled {len(frames)} episodes -> {out}")
    (root / "reference" / "manifest.json").write_text(json.dumps(manifest, indent=2))
    print(f"[done] {len(manifest)} references")


if __name__ == "__main__":
    main()