import os
import re
import shutil
import tempfile

from django.utils._os import upath

source_code_dir = os.path.dirname(upath(__file__))


def copytree(src, dst):
    shutil.copytree(src, dst, ignore=shutil.ignore_patterns('*.pyc', '__pycache__'))


class POFileAssertionMixin(object):

    def _assertPoKeyword(self, keyword, expected_value, haystack, use_quotes=True):
        q = '"'
        if use_quotes:
            expected_value = '"%s"' % expected_value
            q = "'"
        needle = '%s %s' % (keyword, expected_value)
        expected_value = re.escape(expected_value)
        return self.assertTrue(
            re.search('^%s %s' % (keyword, expected_value), haystack, re.MULTILINE),
            'Could not find %(q)s%(n)s%(q)s in generated PO file' % {'n': needle, 'q': q}
        )

    def assertMsgId(self, msgid, haystack, use_quotes=True):
        return self._assertPoKeyword('msgid', msgid, haystack, use_quotes=use_quotes)


class RunInTmpDirMixin(object):
    """
    Allow i18n tests that need to generate .po/.mo files to run in an isolated
    temporary filesystem tree created by tempfile.mkdtemp() that contains a
    clean copy of the relevant test code.

    Test classes using this mixin need to define a `work_subdir` attribute
    which designates the subdir under `tests/i18n/` that will be copied to the
    temporary tree from which its test cases will run.

    The setUp() method sets the current working dir to the temporary tree.
    It'll be removed when cleaning up.
    """

    def setUp(self):
        self._cwd = os.getcwd()
        self.work_dir = tempfile.mkdtemp(prefix='i18n_')
        self.test_dir = os.path.abspath(os.path.join(self.work_dir, self.work_subdir))
        copytree(os.path.join(source_code_dir, self.work_subdir), self.test_dir)
        # Step out of the temporary working tree before removing it to avoid
        # deletion problems on Windows. Cleanup actions registered with
        # addCleanup() are called in reverse so preserve this ordering.
        self.addCleanup(self._rmrf, self.test_dir)
        self.addCleanup(os.chdir, self._cwd)
        os.chdir(self.test_dir)

    def _rmrf(self, dname):
        if os.path.commonprefix([self.test_dir, os.path.abspath(dname)]) != self.test_dir:
            return
        shutil.rmtree(dname)

    def rmfile(self, filepath):
        if os.path.exists(filepath):
            os.remove(filepath)