"""Build hook for dlp-io.

Default builds (``python -m build``) stay pure Python and produce the
``py3-none-any`` wheel declared in ``pyproject.toml``.

Setting ``DLP_IO_PYD=1`` compiles the single ``dlp_io`` module into a C
extension with Cython, producing a platform wheel (for example
``cp313-cp313-win_amd64``) that ships one ``.pyd`` binary instead of
the ``.py`` source.
"""

from __future__ import annotations

import os

from setuptools import setup

_BUILD_PYD = os.environ.get("DLP_IO_PYD") == "1"
_MODULE = "dlp_io"

if _BUILD_PYD:
    from Cython.Build import cythonize

    setup(
        ext_modules=cythonize(
            [f"{_MODULE}.py"],
            build_dir=os.path.join("build", "cython"),
            compiler_directives={"language_level": "3"},
        ),
        py_modules=[],
    )
else:
    setup(py_modules=[_MODULE])