"""Tải dataset pix2pockets (F2 Bước 2, BRIEF 05/08/2026) — idempotent.

Nguồn CHÍNH THỨC: repo của paper pix2pockets (arXiv 2504.12045, SCIA 2025)
https://github.com/viktorseba/pix2pockets — tác giả ship sẵn bản export
Roboflow `8-Ball-Pool-3.zip` (~41 MB) ngay trong root repo, nên KHÔNG cần
Roboflow API key (project gốc: universe.roboflow.com/bachelorthesis/
8-ball-pool-l530o, **License: CC BY 4.0** — ghi trong README.dataset.txt
và data.yaml của bản export).

Zip v3 dồn CẢ 247 ảnh vào train/ (val/test trong data.yaml gốc trỏ thư mục
không tồn tại) → script dựng thêm split 80/20 TẤT ĐỊNH (sort tên + shuffle
seed 20260805) ở `yolo/`, copy ảnh chứ không symlink (Windows), bản gốc
`8-Ball-Pool-3/` giữ nguyên không sửa.

Chạy lại thoải mái: mỗi bước tự skip nếu sản phẩm đã có. Xoá thư mục
`datasets/pix2pockets/` nếu muốn ép làm mới toàn bộ.

    python scripts/cv/fetch_dataset.py            # tải + giải + split + tóm tắt
    python scripts/cv/fetch_dataset.py --summary  # chỉ in tóm tắt
"""

from __future__ import annotations

import argparse
import random
import shutil
import sys
import urllib.request
import zipfile
from collections import Counter
from pathlib import Path

ROOT = Path(__file__).resolve().parents[2]  # poolcoach-rl/

ZIP_URL = "https://github.com/viktorseba/pix2pockets/raw/main/8-Ball-Pool-3.zip"
DATASET_DIR = ROOT / "datasets" / "pix2pockets"
ZIP_PATH = DATASET_DIR / "8-Ball-Pool-3.zip"
RAW_DIR = DATASET_DIR / "8-Ball-Pool-3"  # bản gốc từ zip — KHÔNG sửa
YOLO_DIR = DATASET_DIR / "yolo"  # split 80/20 dựng lại cho ultralytics

SPLIT_SEED = 20260805
VAL_FRACTION = 0.2
CLASS_NAMES = ["Black", "Cue", "Dot", "Solid", "Striped"]

IMG_EXTS = {".jpg", ".jpeg", ".png", ".bmp"}


def _download() -> None:
    if ZIP_PATH.exists() and zipfile.is_zipfile(ZIP_PATH):
        print(f"[skip] zip already present and valid: {ZIP_PATH}")
        return
    DATASET_DIR.mkdir(parents=True, exist_ok=True)
    print(f"[down] {ZIP_URL}")
    tmp = ZIP_PATH.with_suffix(".zip.part")
    urllib.request.urlretrieve(ZIP_URL, tmp)  # noqa: S310 — URL cố định https github
    if not zipfile.is_zipfile(tmp):
        tmp.unlink(missing_ok=True)
        sys.exit("[ERROR] Downloaded file is not a zip - check URL/network and retry.")
    tmp.replace(ZIP_PATH)
    print(f"[ok]   {ZIP_PATH} ({ZIP_PATH.stat().st_size / 1e6:.1f} MB)")


def _extract() -> None:
    if (RAW_DIR / "data.yaml").exists():
        print(f"[skip] already extracted: {RAW_DIR}")
        return
    print(f"[unzip] -> {DATASET_DIR}")
    with zipfile.ZipFile(ZIP_PATH) as zf:
        zf.extractall(DATASET_DIR)


def _make_split() -> None:
    """Split 80/20 tất định từ 247 ảnh train gốc — copy, không đụng bản gốc."""
    if (YOLO_DIR / "data.yaml").exists():
        print(f"[skip] split already built: {YOLO_DIR}")
        return
    src_img = RAW_DIR / "train" / "images"
    src_lbl = RAW_DIR / "train" / "labels"
    stems = sorted(p.stem for p in src_img.iterdir() if p.suffix.lower() in IMG_EXTS)
    if not stems:
        sys.exit(f"[ERROR] No images found under {src_img}")
    rng = random.Random(SPLIT_SEED)
    rng.shuffle(stems)
    n_val = round(len(stems) * VAL_FRACTION)
    splits = {"valid": set(stems[:n_val]), "train": set(stems[n_val:])}
    print(f"[split] seed={SPLIT_SEED}: train={len(splits['train'])} valid={n_val}")

    for split, chosen in splits.items():
        (YOLO_DIR / split / "images").mkdir(parents=True, exist_ok=True)
        (YOLO_DIR / split / "labels").mkdir(parents=True, exist_ok=True)
    for img in src_img.iterdir():
        if img.suffix.lower() not in IMG_EXTS:
            continue
        split = "valid" if img.stem in splits["valid"] else "train"
        shutil.copy2(img, YOLO_DIR / split / "images" / img.name)
        lbl = src_lbl / (img.stem + ".txt")
        if lbl.exists():
            shutil.copy2(lbl, YOLO_DIR / split / "labels" / lbl.name)

    names_yaml = "\n".join(f"  - {n}" for n in CLASS_NAMES)
    (YOLO_DIR / "data.yaml").write_text(
        "# Split 80/20 tat dinh tu pix2pockets 8-Ball-Pool-3 (CC BY 4.0)\n"
        f"# sinh boi scripts/cv/fetch_dataset.py, seed={SPLIT_SEED}\n"
        f"path: {YOLO_DIR.as_posix()}\n"
        "train: train/images\n"
        "val: valid/images\n"
        f"nc: {len(CLASS_NAMES)}\n"
        f"names:\n{names_yaml}\n",
        encoding="utf-8",
    )
    print(f"[ok]   {YOLO_DIR / 'data.yaml'}")


def _count_split(base: Path) -> None:
    for split in ("train", "valid", "test"):
        img_dir = base / split / "images"
        lbl_dir = base / split / "labels"
        if not img_dir.is_dir():
            continue
        imgs = [p for p in img_dir.iterdir() if p.suffix.lower() in IMG_EXTS]
        n_boxes = 0
        cls_counter: Counter[int] = Counter()
        if lbl_dir.is_dir():
            for lbl in lbl_dir.glob("*.txt"):
                for line in lbl.read_text().splitlines():
                    parts = line.split()
                    if parts:
                        n_boxes += 1
                        cls_counter[int(parts[0])] += 1
        per_class = {CLASS_NAMES[k]: v for k, v in sorted(cls_counter.items())}
        print(f"  {split:>5}: {len(imgs):4d} imgs, {n_boxes:5d} box, per-class {per_class}")


def _summary() -> None:
    print("\n===== DATASET SUMMARY =====")
    readme = RAW_DIR / "README.dataset.txt"
    if readme.exists():
        print(f"--- {readme.name} ---")
        print(readme.read_text(encoding="utf-8", errors="replace").strip())
    else:
        print("[!] README.dataset.txt NOT found - license unconfirmed from zip.")
    print("\n--- raw export (as shipped) ---")
    _count_split(RAW_DIR)
    print(f"--- rebuilt split (seed={SPLIT_SEED}) ---")
    _count_split(YOLO_DIR)


def main() -> None:
    ap = argparse.ArgumentParser(description="Fetch pix2pockets dataset (idempotent)")
    ap.add_argument("--summary", action="store_true", help="only print summary, no download")
    args = ap.parse_args()
    if not args.summary:
        _download()
        _extract()
        _make_split()
    _summary()


if __name__ == "__main__":
    main()