#!/usr/bin/env python3
"""Augment a pinned Hub repository inventory with Xet file identities.

The ordinary Hub repository response contains file paths, sizes, and
LFS-compatible SHA-256 values. A non-following request to each resolve URL also
returns the Xet file ID used by this dataset's ``hub_xet_hash`` field. Only
response headers are requested; file payloads are not intentionally fetched.
"""

from __future__ import annotations

import argparse
import json
import time
from concurrent.futures import ThreadPoolExecutor, as_completed
from pathlib import Path
from urllib.error import HTTPError, URLError
from urllib.parse import quote
from urllib.request import HTTPRedirectHandler, Request, build_opener


class NoRedirect(HTTPRedirectHandler):
    def redirect_request(self, req, fp, code, msg, headers, newurl):  # noqa: ANN001
        return None


def clean_etag(value: str | None) -> str:
    return (value or "").strip().strip('"')


def read_identity(url: str, timeout: int, retries: int) -> dict[str, object]:
    opener = build_opener(NoRedirect)
    last_error: Exception | None = None
    for attempt in range(retries + 1):
        request = Request(url, method="HEAD")
        try:
            response = opener.open(request, timeout=timeout)
            headers = response.headers
        except HTTPError as exc:
            if exc.code not in {301, 302, 303, 307, 308}:
                last_error = exc
                headers = None
            else:
                headers = exc.headers
        except URLError as exc:
            last_error = exc
            headers = None

        if headers is not None:
            xet_hash = headers.get("X-Xet-Hash")
            linked_size = headers.get("X-Linked-Size")
            linked_etag = clean_etag(headers.get("X-Linked-ETag"))
            repo_commit = headers.get("X-Repo-Commit")
            if xet_hash and linked_size and linked_etag and repo_commit:
                return {
                    "xetHash": xet_hash.lower(),
                    "linkedSize": int(linked_size),
                    "linkedEtag": linked_etag.lower(),
                    "repoCommit": repo_commit,
                }
            last_error = ValueError("resolve headers omitted an identity field")

        if attempt < retries:
            time.sleep(0.5 * (attempt + 1))

    raise RuntimeError(str(last_error or "unable to read resolve headers"))


def main() -> None:
    parser = argparse.ArgumentParser()
    parser.add_argument("--repo-json", type=Path, required=True)
    parser.add_argument("--repo-id", default="maxwellinked/time-lapse-artifacts")
    parser.add_argument("--revision", required=True)
    parser.add_argument("--output", type=Path, required=True)
    parser.add_argument("--suffix", default=".mp4")
    parser.add_argument("--workers", type=int, default=12)
    parser.add_argument("--timeout", type=int, default=30)
    parser.add_argument("--retries", type=int, default=2)
    args = parser.parse_args()

    inventory = json.loads(args.repo_json.read_text(encoding="utf-8"))
    siblings = inventory.get("siblings") if isinstance(inventory, dict) else None
    if not isinstance(siblings, list):
        raise SystemExit("repository JSON must contain a siblings list")

    targets: list[tuple[dict[str, object], str, str]] = []
    for item in siblings:
        if not isinstance(item, dict) or not isinstance(item.get("rfilename"), str):
            continue
        path = item["rfilename"]
        if not path.lower().endswith(args.suffix.lower()):
            continue
        encoded_path = quote(path, safe="/")
        url = (
            f"https://huggingface.co/datasets/{args.repo_id}/"
            f"resolve/{args.revision}/{encoded_path}"
        )
        targets.append((item, path, url))

    failures: list[dict[str, str]] = []
    completed = 0
    with ThreadPoolExecutor(max_workers=args.workers) as executor:
        futures = {
            executor.submit(read_identity, url, args.timeout, args.retries): (item, path)
            for item, path, url in targets
        }
        for future in as_completed(futures):
            item, path = futures[future]
            try:
                identity = future.result()
                lfs = item.get("lfs")
                expected_etag = lfs.get("sha256") if isinstance(lfs, dict) else None
                expected_size = item.get("size")
                if expected_etag and identity["linkedEtag"] != str(expected_etag).lower():
                    raise ValueError("resolve LFS identity differs from repository inventory")
                if expected_size is not None and identity["linkedSize"] != int(expected_size):
                    raise ValueError("resolve size differs from repository inventory")
                if identity["repoCommit"] != args.revision:
                    raise ValueError("resolve response came from a different revision")
                item.update(identity)
            except Exception as exc:  # noqa: BLE001
                failures.append({"path": path, "error": str(exc)})
            completed += 1
            if completed % 25 == 0 or completed == len(targets):
                print(f"resolved {completed}/{len(targets)}", flush=True)

    if failures:
        print(json.dumps({"failures": failures}, indent=2))
        raise SystemExit(1)

    args.output.parent.mkdir(parents=True, exist_ok=True)
    args.output.write_text(
        json.dumps(inventory, indent=2, sort_keys=True) + "\n", encoding="utf-8"
    )
    print(json.dumps({"resolved_files": len(targets), "output": str(args.output)}, indent=2))


if __name__ == "__main__":
    main()