import sys
import distutils.core
import distutils.extension

from setuptools.dist import _get_unpatched

_Extension = _get_unpatched(distutils.core.Extension)

# Prefer Cython to Pyrex
pyrex_impls = 'Cython.Distutils.build_ext', 'Pyrex.Distutils.build_ext'
for pyrex_impl in pyrex_impls:
    try:
        # from (pyrex_impl) import build_ext
        build_ext = __import__(pyrex_impl, fromlist=['build_ext']).build_ext
        break
    except:
        pass
have_pyrex = 'build_ext' in globals()


class Extension(_Extension):
    """Extension that uses '.c' files in place of '.pyx' files"""

    def __init__(self, *args, **kw):
        _Extension.__init__(self, *args, **kw)
        if not have_pyrex:
            self._convert_pyx_sources_to_c()

    def _convert_pyx_sources_to_c(self):
        "convert .pyx extensions to .c"
        self.sources = [source[:-3] + 'c' for source in self.sources
            if source.endswith('.pyx')]

class Library(Extension):
    """Just like a regular Extension, but built as a library instead"""

distutils.core.Extension = Extension
distutils.extension.Extension = Extension
if 'distutils.command.build_ext' in sys.modules:
    sys.modules['distutils.command.build_ext'].Extension = Extension