"""
Helper functions for testing.
"""
from pathlib import Path
from tempfile import TemporaryDirectory
import locale
import logging
import os
import subprocess
import sys

import matplotlib as mpl
from matplotlib import _api

_log = logging.getLogger(__name__)


def set_font_settings_for_testing():
    mpl.rcParams['font.family'] = 'DejaVu Sans'
    mpl.rcParams['text.hinting'] = 'none'
    mpl.rcParams['text.hinting_factor'] = 8


def set_reproducibility_for_testing():
    mpl.rcParams['svg.hashsalt'] = 'matplotlib'


def setup():
    # The baseline images are created in this locale, so we should use
    # it during all of the tests.

    try:
        locale.setlocale(locale.LC_ALL, 'en_US.UTF-8')
    except locale.Error:
        try:
            locale.setlocale(locale.LC_ALL, 'English_United States.1252')
        except locale.Error:
            _log.warning(
                "Could not set locale to English/United States. "
                "Some date-related tests may fail.")

    mpl.use('Agg')

    with _api.suppress_matplotlib_deprecation_warning():
        mpl.rcdefaults()  # Start with all defaults

    # These settings *must* be hardcoded for running the comparison tests and
    # are not necessarily the default values as specified in rcsetup.py.
    set_font_settings_for_testing()
    set_reproducibility_for_testing()


def subprocess_run_helper(func, *args, timeout, **extra_env):
    """
    Run a function in a sub-process

    Parameters
    ----------
    func : function
        The function to be run.  It must be in a module that is importable.

    *args : str
        Any additional command line arguments to be passed in
        the first argument to subprocess.run

    **extra_env : Dict[str, str]
        Any additional envromental variables to be set for
        the subprocess.

    """
    target = func.__name__
    module = func.__module__
    proc = subprocess.run(
        [sys.executable,
         "-c",
         f"""
from {module} import {target}
{target}()
""",
         *args],
        env={
            **os.environ,
            "SOURCE_DATE_EPOCH": "0",
            **extra_env
        },
        timeout=timeout, check=True,
        stdout=subprocess.PIPE,
        stderr=subprocess.PIPE,
        universal_newlines=True)
    return proc


def _check_for_pgf(texsystem):
    """
    Check if a given TeX system + pgf is available

    Parameters
    ----------
    texsystem : str
        The executable name to check
    """
    with TemporaryDirectory() as tmpdir:
        tex_path = Path(tmpdir, "test.tex")
        tex_path.write_text(r"""
            \documentclass{minimal}
            \usepackage{pgf}
            \begin{document}
            \typeout{pgfversion=\pgfversion}
            \makeatletter
            \@@end
        """)
        try:
            subprocess.check_call(
                [texsystem, "-halt-on-error", str(tex_path)], cwd=tmpdir,
                stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
        except (OSError, subprocess.CalledProcessError):
            return False
        return True


def _has_tex_package(package):
    return bool(mpl.dviread.find_tex_file(f"{package}.sty"))