#!/usr/bin/env python3
"""Fetch the 20 hash-locked PLOS/CRS inputs used by clean_source_pack.py."""

from __future__ import annotations

import hashlib
import json
import os
from pathlib import Path
import urllib.request


SCRIPT_ROOT = Path(__file__).resolve().parent
ROOT = Path(os.environ.get("FRESH10_SOURCE_PACK", SCRIPT_ROOT / "source_pack"))
DESCRIPTOR = SCRIPT_ROOT / "source_pack.json"
USER_AGENT = "fresh10-builder/1.0 (+https://huggingface.co/datasets/quintic/fresh10)"


def digest(data: bytes) -> str:
    return hashlib.sha256(data).hexdigest()


def contained(root: Path, relative: str) -> Path:
    candidate = (root / relative).resolve()
    resolved_root = root.resolve()
    if candidate != resolved_root and resolved_root not in candidate.parents:
        raise RuntimeError(f"unsafe source-pack path: {relative!r}")
    return candidate


def main() -> None:
    payload = json.loads(DESCRIPTOR.read_text(encoding="utf-8"))
    documents = payload.get("documents")
    if not isinstance(documents, list) or len(documents) != 20:
        raise RuntimeError("source_pack.json must describe exactly 20 documents")
    for document in documents:
        target = contained(ROOT, document["raw_file"])
        expected = document["raw_sha256"]
        if target.is_file() and digest(target.read_bytes()) == expected:
            continue
        request = urllib.request.Request(document["source_url"], headers={"User-Agent": USER_AGENT})
        with urllib.request.urlopen(request, timeout=120) as response:
            data = response.read()
        actual = digest(data)
        if actual != expected:
            raise RuntimeError(
                f"{document['id']}: upstream bytes changed "
                f"(expected {expected}, got {actual}); refusing an unreviewed rebuild"
            )
        target.parent.mkdir(parents=True, exist_ok=True)
        temporary = target.with_suffix(target.suffix + ".tmp")
        temporary.write_bytes(data)
        temporary.replace(target)
    print(f"verified {len(documents)} raw source-pack files under {ROOT}")


if __name__ == "__main__":
    main()