"""Small dependency-free loader for a downloaded ARMBench-VL release."""

from __future__ import annotations

import json
import re
from pathlib import Path
from typing import Any, Iterator


def _config(root: Path) -> dict[str, dict[str, Any]]:
    return json.loads((root / "dataset_config.json").read_text(encoding="utf-8"))


def load_records(root: str | Path, task: str) -> list[dict[str, Any]]:
    root = Path(root)
    task_config = _config(root)[task]
    annotation_path = root / task_config["annotations"]
    with annotation_path.open(encoding="utf-8") as handle:
        return [json.loads(line) for line in handle if line.strip()]


def resolve_images(
    root: str | Path, task: str, record: dict[str, Any]
) -> list[Path]:
    root = Path(root)
    resource_root = root / _config(root)[task]["resource_root"]
    return [resource_root / image for image in record.get("images", [])]


def iter_document_pages(root: str | Path, doc_id: str) -> Iterator[Path]:
    """Yield individual page images in numeric order, excluding composites."""
    root = Path(root)
    resource_root = root / _config(root)["multimodal_long_document_qa"][
        "resource_root"
    ]
    stem = Path(doc_id).stem
    pattern = re.compile(rf"^{re.escape(stem)}_(\d+)\.(?:jpg|jpeg|png|webp)$", re.I)
    pages: list[tuple[int, Path]] = []
    for path in resource_root.glob(f"{stem}_*"):
        match = pattern.match(path.name)
        if match:
            pages.append((int(match.group(1)), path))
    for _, path in sorted(pages):
        yield path


if __name__ == "__main__":
    import argparse

    parser = argparse.ArgumentParser()
    parser.add_argument("root", type=Path)
    parser.add_argument(
        "task",
        choices=(
            "fine_grained_perception",
            "multimodal_long_document_qa",
            "multimodal_instruction_following",
        ),
    )
    args = parser.parse_args()
    records = load_records(args.root, args.task)
    print(f"{args.task}: {len(records)} examples")
    print("first image(s):", *resolve_images(args.root, args.task, records[0]))