"""
Cythonize the .pyx file for sdist, and compile it for wheels.
NB: produced wheels are not valid, but the sdist should be.
"""

import os
from Cython.Build import cythonize
from subprocess import check_output, CalledProcessError, DEVNULL, call
from tempfile import TemporaryFile

from setuptools.command.build_py import build_py


def check_include(library_name, header):
    command = [os.environ.get("PKG_CONFIG", "pkg-config"), "--cflags", library_name]
    try:
        cflags = check_output(command).decode("utf-8").split()
    except FileNotFoundError:
        print("pkg-config not found.")
        return False
    except CalledProcessError:
        # pkg-config already prints the missing libraries on stderr.
        return False
    command = [os.environ.get("CC", "cc")] + cflags + ["-E", "-"]
    with TemporaryFile("w+") as c_file:
        c_file.write("#include <%s>" % header)
        c_file.seek(0)
        try:
            return call(command, stdin=c_file, stdout=DEVNULL, stderr=DEVNULL) == 0
        except FileNotFoundError:
            print("%s headers not found." % library_name)
            return False


class Build(build_py):
    def run(self):
        self.run_command("build_ext")
        return super().run()

    def initialize_options(self):
        super().initialize_options()

        has_python_headers = check_include("python3", "Python.h")
        has_stringprep_headers = check_include("libidn", "stringprep.h")

        if has_python_headers and has_stringprep_headers:
            self.distribution.ext_modules = cythonize("slixmpp/stringprep.pyx")

        else:
            print("Falling back to the slow stringprep module.")