"""Helpers to check build environment before actual build of scikit-learn"""

import os
import sys
import glob
import tempfile
import textwrap
import subprocess

from distutils.sysconfig import customize_compiler
from numpy.distutils.ccompiler import new_compiler


def compile_test_program(code, extra_preargs=[], extra_postargs=[]):
    """Check that some C code can be compiled and run"""
    ccompiler = new_compiler()
    customize_compiler(ccompiler)

    # extra_(pre/post)args can be a callable to make it possible to get its
    # value from the compiler
    if callable(extra_preargs):
        extra_preargs = extra_preargs(ccompiler)
    if callable(extra_postargs):
        extra_postargs = extra_postargs(ccompiler)

    start_dir = os.path.abspath('.')

    with tempfile.TemporaryDirectory() as tmp_dir:
        try:
            os.chdir(tmp_dir)

            # Write test program
            with open('test_program.c', 'w') as f:
                f.write(code)

            os.mkdir('objects')

            # Compile, test program
            ccompiler.compile(['test_program.c'], output_dir='objects',
                              extra_postargs=extra_postargs)

            # Link test program
            objects = glob.glob(
                os.path.join('objects', '*' + ccompiler.obj_extension))
            ccompiler.link_executable(objects, 'test_program',
                                      extra_preargs=extra_preargs,
                                      extra_postargs=extra_postargs)

            # Run test program
            # will raise a CalledProcessError if return code was non-zero
            output = subprocess.check_output('./test_program')
            output = output.decode(sys.stdout.encoding or 'utf-8').splitlines()
        except Exception:
            raise
        finally:
            os.chdir(start_dir)

    return output


def basic_check_build():
    """Check basic compilation and linking of C code"""
    code = textwrap.dedent(
        """\
        #include <stdio.h>
        int main(void) {
        return 0;
        }
        """)
    compile_test_program(code)