# testing.py

from contextlib import contextmanager

from pyparsing.core import (
    ParserElement,
    ParseException,
    Keyword,
    __diag__,
    __compat__,
)


class pyparsing_test:
    """
    namespace class for classes useful in writing unit tests
    """

    class reset_pyparsing_context:
        """
        Context manager to be used when writing unit tests that modify pyparsing config values:
         - packrat parsing
         - default whitespace characters.
         - default keyword characters
         - literal string auto-conversion class
         - __diag__ settings

        Example::

            with reset_pyparsing_context():
                # test that literals used to construct a grammar are automatically suppressed
                ParserElement.inlineLiteralsUsing(Suppress)

                term = Word(alphas) | Word(nums)
                group = Group('(' + term[...] + ')')

                # assert that the '()' characters are not included in the parsed tokens
                self.assertParseAndCheckList(group, "(abc 123 def)", ['abc', '123', 'def'])

            # after exiting context manager, literals are converted to Literal expressions again
        """

        def __init__(self):
            self._save_context = {}

        def save(self):
            self._save_context["default_whitespace"] = ParserElement.DEFAULT_WHITE_CHARS
            self._save_context["default_keyword_chars"] = Keyword.DEFAULT_KEYWORD_CHARS
            self._save_context[
                "literal_string_class"
            ] = ParserElement._literalStringClass
            self._save_context["packrat_enabled"] = ParserElement._packratEnabled
            self._save_context["packrat_parse"] = ParserElement._parse
            self._save_context["__diag__"] = {
                name: getattr(__diag__, name) for name in __diag__._all_names
            }
            self._save_context["__compat__"] = {
                "collect_all_And_tokens": __compat__.collect_all_And_tokens
            }
            return self

        def restore(self):
            # reset pyparsing global state
            if (
                ParserElement.DEFAULT_WHITE_CHARS
                != self._save_context["default_whitespace"]
            ):
                ParserElement.setDefaultWhitespaceChars(
                    self._save_context["default_whitespace"]
                )
            Keyword.DEFAULT_KEYWORD_CHARS = self._save_context["default_keyword_chars"]
            ParserElement.inlineLiteralsUsing(
                self._save_context["literal_string_class"]
            )
            for name, value in self._save_context["__diag__"].items():
                (__diag__.enable if value else __diag__.disable)(name)
            ParserElement._packratEnabled = self._save_context["packrat_enabled"]
            ParserElement._parse = self._save_context["packrat_parse"]
            __compat__.collect_all_And_tokens = self._save_context["__compat__"]

        def __enter__(self):
            return self.save()

        def __exit__(self, *args):
            return self.restore()

    class TestParseResultsAsserts:
        """
        A mixin class to add parse results assertion methods to normal unittest.TestCase classes.
        """

        def assertParseResultsEquals(
            self, result, expected_list=None, expected_dict=None, msg=None
        ):
            """
            Unit test assertion to compare a :class:`ParseResults` object with an optional ``expected_list``,
            and compare any defined results names with an optional ``expected_dict``.
            """
            if expected_list is not None:
                self.assertEqual(expected_list, result.asList(), msg=msg)
            if expected_dict is not None:
                self.assertEqual(expected_dict, result.asDict(), msg=msg)

        def assertParseAndCheckList(
            self, expr, test_string, expected_list, msg=None, verbose=True
        ):
            """
            Convenience wrapper assert to test a parser element and input string, and assert that
            the resulting ``ParseResults.asList()`` is equal to the ``expected_list``.
            """
            result = expr.parseString(test_string, parseAll=True)
            if verbose:
                print(result.dump())
            self.assertParseResultsEquals(result, expected_list=expected_list, msg=msg)

        def assertParseAndCheckDict(
            self, expr, test_string, expected_dict, msg=None, verbose=True
        ):
            """
            Convenience wrapper assert to test a parser element and input string, and assert that
            the resulting ``ParseResults.asDict()`` is equal to the ``expected_dict``.
            """
            result = expr.parseString(test_string, parseAll=True)
            if verbose:
                print(result.dump())
            self.assertParseResultsEquals(result, expected_dict=expected_dict, msg=msg)

        def assertRunTestResults(
            self, run_tests_report, expected_parse_results=None, msg=None
        ):
            """
            Unit test assertion to evaluate output of ``ParserElement.runTests()``. If a list of
            list-dict tuples is given as the ``expected_parse_results`` argument, then these are zipped
            with the report tuples returned by ``runTests`` and evaluated using ``assertParseResultsEquals``.
            Finally, asserts that the overall ``runTests()`` success value is ``True``.

            :param run_tests_report: tuple(bool, [tuple(str, ParseResults or Exception)]) returned from runTests
            :param expected_parse_results (optional): [tuple(str, list, dict, Exception)]
            """
            run_test_success, run_test_results = run_tests_report

            if expected_parse_results is not None:
                merged = [
                    (*rpt, expected)
                    for rpt, expected in zip(run_test_results, expected_parse_results)
                ]
                for test_string, result, expected in merged:
                    # expected should be a tuple containing a list and/or a dict or an exception,
                    # and optional failure message string
                    # an empty tuple will skip any result validation
                    fail_msg = next(
                        (exp for exp in expected if isinstance(exp, str)), None
                    )
                    expected_exception = next(
                        (
                            exp
                            for exp in expected
                            if isinstance(exp, type) and issubclass(exp, Exception)
                        ),
                        None,
                    )
                    if expected_exception is not None:
                        with self.assertRaises(
                            expected_exception=expected_exception, msg=fail_msg or msg
                        ):
                            if isinstance(result, Exception):
                                raise result
                    else:
                        expected_list = next(
                            (exp for exp in expected if isinstance(exp, list)), None
                        )
                        expected_dict = next(
                            (exp for exp in expected if isinstance(exp, dict)), None
                        )
                        if (expected_list, expected_dict) != (None, None):
                            self.assertParseResultsEquals(
                                result,
                                expected_list=expected_list,
                                expected_dict=expected_dict,
                                msg=fail_msg or msg,
                            )
                        else:
                            # warning here maybe?
                            print("no validation for {!r}".format(test_string))

            # do this last, in case some specific test results can be reported instead
            self.assertTrue(
                run_test_success, msg=msg if msg is not None else "failed runTests"
            )

        @contextmanager
        def assertRaisesParseException(self, exc_type=ParseException, msg=None):
            with self.assertRaises(exc_type, msg=msg):
                yield
