# Licensed under the GPL: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html
# For details: https://github.com/PyCQA/pylint/blob/master/COPYING

"""functional/non regression tests for pylint"""
import contextlib
import functools
import tokenize
from glob import glob
from io import StringIO
from os.path import basename, join, splitext

from pylint import checkers
from pylint.lint import PyLinter
from pylint.testutils.constants import SYS_VERS_STR
from pylint.testutils.output_line import Message
from pylint.testutils.reporter_for_tests import GenericTestReporter
from pylint.utils import ASTWalker


def _get_tests_info(input_dir, msg_dir, prefix, suffix):
    """get python input examples and output messages

    We use following conventions for input files and messages:
    for different inputs:
        test for python  >= x.y    ->  input   =  <name>_pyxy.py
        test for python  <  x.y    ->  input   =  <name>_py_xy.py
    for one input and different messages:
        message for python >=  x.y ->  message =  <name>_pyxy.txt
        lower versions             ->  message with highest num
    """
    result = []
    for fname in glob(join(input_dir, prefix + "*" + suffix)):
        infile = basename(fname)
        fbase = splitext(infile)[0]
        # filter input files :
        pyrestr = fbase.rsplit("_py", 1)[-1]  # like _26 or 26
        if pyrestr.isdigit():  # '24', '25'...
            if SYS_VERS_STR < pyrestr:
                continue
        if pyrestr.startswith("_") and pyrestr[1:].isdigit():
            # skip test for higher python versions
            if SYS_VERS_STR >= pyrestr[1:]:
                continue
        messages = glob(join(msg_dir, fbase + "*.txt"))
        # the last one will be without ext, i.e. for all or upper versions:
        if messages:
            for outfile in sorted(messages, reverse=True):
                py_rest = outfile.rsplit("_py", 1)[-1][:-4]
                if py_rest.isdigit() and SYS_VERS_STR >= py_rest:
                    break
        else:
            # This will provide an error message indicating the missing filename.
            outfile = join(msg_dir, fbase + ".txt")
        result.append((infile, outfile))
    return result


class UnittestLinter:
    """A fake linter class to capture checker messages."""

    # pylint: disable=unused-argument, no-self-use

    def __init__(self):
        self._messages = []
        self.stats = {}

    def release_messages(self):
        try:
            return self._messages
        finally:
            self._messages = []

    def add_message(
        self, msg_id, line=None, node=None, args=None, confidence=None, col_offset=None
    ):
        # Do not test col_offset for now since changing Message breaks everything
        self._messages.append(Message(msg_id, line, node, args, confidence))

    @staticmethod
    def is_message_enabled(*unused_args, **unused_kwargs):
        return True

    def add_stats(self, **kwargs):
        for name, value in kwargs.items():
            self.stats[name] = value
        return self.stats

    @property
    def options_providers(self):
        return linter.options_providers


def set_config(**kwargs):
    """Decorator for setting config values on a checker."""

    def _wrapper(fun):
        @functools.wraps(fun)
        def _forward(self):
            for key, value in kwargs.items():
                setattr(self.checker.config, key, value)
            if isinstance(self, CheckerTestCase):
                # reopen checker in case, it may be interested in configuration change
                self.checker.open()
            fun(self)

        return _forward

    return _wrapper


class CheckerTestCase:
    """A base testcase class for unit testing individual checker classes."""

    CHECKER_CLASS = None
    CONFIG = {}

    def setup_method(self):
        self.linter = UnittestLinter()
        self.checker = self.CHECKER_CLASS(self.linter)  # pylint: disable=not-callable
        for key, value in self.CONFIG.items():
            setattr(self.checker.config, key, value)
        self.checker.open()

    @contextlib.contextmanager
    def assertNoMessages(self):
        """Assert that no messages are added by the given method."""
        with self.assertAddsMessages():
            yield

    @contextlib.contextmanager
    def assertAddsMessages(self, *messages):
        """Assert that exactly the given method adds the given messages.

        The list of messages must exactly match *all* the messages added by the
        method. Additionally, we check to see whether the args in each message can
        actually be substituted into the message string.
        """
        yield
        got = self.linter.release_messages()
        msg = "Expected messages did not match actual.\n" "Expected:\n%s\nGot:\n%s" % (
            "\n".join(repr(m) for m in messages),
            "\n".join(repr(m) for m in got),
        )
        assert list(messages) == got, msg

    def walk(self, node):
        """recursive walk on the given node"""
        walker = ASTWalker(linter)
        walker.add_checker(self.checker)
        walker.walk(node)


# Init
test_reporter = GenericTestReporter()
linter = PyLinter()
linter.set_reporter(test_reporter)
linter.config.persistent = 0
checkers.initialize(linter)


def _tokenize_str(code):
    return list(tokenize.generate_tokens(StringIO(code).readline))