#!/usr/bin/env python3
"""Reproducibly generate the Python Shard-protocol stubs from the schema.

This is the documented, no-manual-copy generation entry point referenced by
``evidence/DGR-002/README.md``. It runs the pinned ``grpc_tools.protoc`` with the
same flags ``meshnet_node.native_protocol.generate()`` uses on demand, but is
kept self-contained (it does not import ``meshnet_node``) so it works regardless
of which checkout the editable install points at.

Usage (from the project .venv):

    python packages/node/native/scripts/generate_python.py

Output: ``packages/node/native/build/python/shard_runtime_pb2{,_grpc}.py``
(``build/`` is gitignored).
"""

from __future__ import annotations

import pathlib
import sys

_NATIVE_ROOT = pathlib.Path(__file__).resolve().parents[1]
PROTO_DIR = _NATIVE_ROOT / "proto"
PROTO_FILE = PROTO_DIR / "shard_runtime.proto"
GEN_DIR = _NATIVE_ROOT / "build" / "python"


def _well_known_include() -> str | None:
    try:
        import grpc_tools

        candidate = pathlib.Path(grpc_tools.__file__).parent / "_proto"
        return str(candidate) if candidate.is_dir() else None
    except Exception:
        return None


def main() -> int:
    if not PROTO_FILE.exists():
        print(f"schema not found: {PROTO_FILE}", file=sys.stderr)
        return 2
    try:
        from grpc_tools import protoc
    except ImportError:
        print(
            "grpc_tools is required (pip install grpcio-tools); it is present in "
            "the project .venv.",
            file=sys.stderr,
        )
        return 3

    GEN_DIR.mkdir(parents=True, exist_ok=True)
    well_known = _well_known_include()
    args = [
        "grpc_tools.protoc",
        f"-I{PROTO_DIR}",
        *([f"-I{well_known}"] if well_known else []),
        f"--python_out={GEN_DIR}",
        f"--grpc_python_out={GEN_DIR}",
        PROTO_FILE.name,
    ]
    rc = protoc.main(args)
    if rc != 0:
        print(f"grpc_tools.protoc exited with status {rc}", file=sys.stderr)
        return rc

    print(f"generated Python stubs into: {GEN_DIR}")
    for name in ("shard_runtime_pb2.py", "shard_runtime_pb2_grpc.py"):
        target = GEN_DIR / name
        print(f"  {name}: {'ok' if target.exists() else 'MISSING'}")
    return 0


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