import os
import sys


def set_cc_variables(var_name="CC"):
    cc_var = os.environ.get(var_name)
    if cc_var is not None:
        os.environ["CC"] = cc_var
        if sys.platform == "darwin":
            os.environ["LDSHARED"] = cc_var + " -bundle -undefined dynamic_lookup"
        else:
            os.environ["LDSHARED"] = cc_var + " -shared"

    return cc_var


def get_openmp_flag():
    if sys.platform == "win32":
        return ["/openmp"]
    elif sys.platform == "darwin" and "openmp" in os.getenv("CPPFLAGS", ""):
        return []
    return ["-fopenmp"]