#!/usr/bin/env python3
"""Write the committed cross-language conformance vectors.

The bytes under `packages/node/native/testdata/` are the reference both the
Python and the C++ conformance tests assert against. They are committed so the
C++ test can run without a Python step, and `--check` exists so they can never
drift from the schema unnoticed: if a schema edit changes the canonical
message's encoding, `--check` fails and the change has to be acknowledged.

Usage::

    python scripts/generate_protocol_goldens.py           # rewrite vectors
    python scripts/generate_protocol_goldens.py --check    # fail if stale
"""

from __future__ import annotations

import argparse
import pathlib
import sys

REPO_ROOT = pathlib.Path(__file__).resolve().parent.parent
sys.path.insert(0, str(REPO_ROOT / "packages/node"))

from meshnet_node.native_protocol import conformance  # noqa: E402


def _vectors() -> dict[str, bytes]:
    return {
        conformance.GOLDEN_SESSION_REQUEST: conformance.serialize(
            conformance.canonical_session_request()
        ),
        conformance.GOLDEN_CAPABILITY_REPORT: conformance.serialize(
            conformance.canonical_capability_report()
        ),
    }


def main() -> int:
    parser = argparse.ArgumentParser(description=__doc__)
    parser.add_argument("--check", action="store_true")
    args = parser.parse_args()

    out_dir = conformance.TESTDATA_DIR
    out_dir.mkdir(parents=True, exist_ok=True)
    stale = []

    for name, payload in _vectors().items():
        path = out_dir / name
        if args.check:
            if not path.is_file() or path.read_bytes() != payload:
                stale.append(name)
            continue
        path.write_bytes(payload)
        print(f"wrote {path.relative_to(REPO_ROOT)} ({len(payload)} bytes)")

    if stale:
        print(
            "conformance vectors are stale: " + ", ".join(stale) + "\n"
            "The canonical message no longer encodes to the committed bytes. If "
            "that is intended, run: python scripts/generate_protocol_goldens.py",
            file=sys.stderr,
        )
        return 1
    if args.check:
        print("conformance vectors are up to date")
    return 0


if __name__ == "__main__":
    raise SystemExit(main())