""" discover and run doctests in modules and test files."""
from __future__ import absolute_import

import traceback

import pytest
from _pytest._code.code import ExceptionInfo, ReprFileLocation, TerminalRepr
from _pytest.fixtures import FixtureRequest


DOCTEST_REPORT_CHOICE_NONE = 'none'
DOCTEST_REPORT_CHOICE_CDIFF = 'cdiff'
DOCTEST_REPORT_CHOICE_NDIFF = 'ndiff'
DOCTEST_REPORT_CHOICE_UDIFF = 'udiff'
DOCTEST_REPORT_CHOICE_ONLY_FIRST_FAILURE = 'only_first_failure'

DOCTEST_REPORT_CHOICES = (
    DOCTEST_REPORT_CHOICE_NONE,
    DOCTEST_REPORT_CHOICE_CDIFF,
    DOCTEST_REPORT_CHOICE_NDIFF,
    DOCTEST_REPORT_CHOICE_UDIFF,
    DOCTEST_REPORT_CHOICE_ONLY_FIRST_FAILURE,
)

def pytest_addoption(parser):
    parser.addini('doctest_optionflags', 'option flags for doctests',
        type="args", default=["ELLIPSIS"])
    group = parser.getgroup("collect")
    group.addoption("--doctest-modules",
        action="store_true", default=False,
        help="run doctests in all .py modules",
        dest="doctestmodules")
    group.addoption("--doctest-report",
        type=str.lower, default="udiff",
        help="choose another output format for diffs on doctest failure",
        choices=DOCTEST_REPORT_CHOICES,
        dest="doctestreport")
    group.addoption("--doctest-glob",
        action="append", default=[], metavar="pat",
        help="doctests file matching pattern, default: test*.txt",
        dest="doctestglob")
    group.addoption("--doctest-ignore-import-errors",
        action="store_true", default=False,
        help="ignore doctest ImportErrors",
        dest="doctest_ignore_import_errors")


def pytest_collect_file(path, parent):
    config = parent.config
    if path.ext == ".py":
        if config.option.doctestmodules:
            return DoctestModule(path, parent)
    elif _is_doctest(config, path, parent):
        return DoctestTextfile(path, parent)


def _is_doctest(config, path, parent):
    if path.ext in ('.txt', '.rst') and parent.session.isinitpath(path):
        return True
    globs = config.getoption("doctestglob") or ['test*.txt']
    for glob in globs:
        if path.check(fnmatch=glob):
            return True
    return False


class ReprFailDoctest(TerminalRepr):

    def __init__(self, reprlocation, lines):
        self.reprlocation = reprlocation
        self.lines = lines

    def toterminal(self, tw):
        for line in self.lines:
            tw.line(line)
        self.reprlocation.toterminal(tw)


class DoctestItem(pytest.Item):
    def __init__(self, name, parent, runner=None, dtest=None):
        super(DoctestItem, self).__init__(name, parent)
        self.runner = runner
        self.dtest = dtest
        self.obj = None
        self.fixture_request = None

    def setup(self):
        if self.dtest is not None:
            self.fixture_request = _setup_fixtures(self)
            globs = dict(getfixture=self.fixture_request.getfixturevalue)
            for name, value in self.fixture_request.getfixturevalue('doctest_namespace').items():
                globs[name] = value
            self.dtest.globs.update(globs)

    def runtest(self):
        _check_all_skipped(self.dtest)
        self.runner.run(self.dtest)

    def repr_failure(self, excinfo):
        import doctest
        if excinfo.errisinstance((doctest.DocTestFailure,
                                  doctest.UnexpectedException)):
            doctestfailure = excinfo.value
            example = doctestfailure.example
            test = doctestfailure.test
            filename = test.filename
            if test.lineno is None:
                lineno = None
            else:
                lineno = test.lineno + example.lineno + 1
            message = excinfo.type.__name__
            reprlocation = ReprFileLocation(filename, lineno, message)
            checker = _get_checker()
            report_choice = _get_report_choice(self.config.getoption("doctestreport"))
            if lineno is not None:
                lines = doctestfailure.test.docstring.splitlines(False)
                # add line numbers to the left of the error message
                lines = ["%03d %s" % (i + test.lineno + 1, x)
                         for (i, x) in enumerate(lines)]
                # trim docstring error lines to 10
                lines = lines[example.lineno - 9:example.lineno + 1]
            else:
                lines = ['EXAMPLE LOCATION UNKNOWN, not showing all tests of that example']
                indent = '>>>'
                for line in example.source.splitlines():
                    lines.append('??? %s %s' % (indent, line))
                    indent = '...'
            if excinfo.errisinstance(doctest.DocTestFailure):
                lines += checker.output_difference(example,
                        doctestfailure.got, report_choice).split("\n")
            else:
                inner_excinfo = ExceptionInfo(excinfo.value.exc_info)
                lines += ["UNEXPECTED EXCEPTION: %s" %
                            repr(inner_excinfo.value)]
                lines += traceback.format_exception(*excinfo.value.exc_info)
            return ReprFailDoctest(reprlocation, lines)
        else:
            return super(DoctestItem, self).repr_failure(excinfo)

    def reportinfo(self):
        return self.fspath, None, "[doctest] %s" % self.name


def _get_flag_lookup():
    import doctest
    return dict(DONT_ACCEPT_TRUE_FOR_1=doctest.DONT_ACCEPT_TRUE_FOR_1,
                DONT_ACCEPT_BLANKLINE=doctest.DONT_ACCEPT_BLANKLINE,
                NORMALIZE_WHITESPACE=doctest.NORMALIZE_WHITESPACE,
                ELLIPSIS=doctest.ELLIPSIS,
                IGNORE_EXCEPTION_DETAIL=doctest.IGNORE_EXCEPTION_DETAIL,
                COMPARISON_FLAGS=doctest.COMPARISON_FLAGS,
                ALLOW_UNICODE=_get_allow_unicode_flag(),
                ALLOW_BYTES=_get_allow_bytes_flag(),
                )


def get_optionflags(parent):
    optionflags_str = parent.config.getini("doctest_optionflags")
    flag_lookup_table = _get_flag_lookup()
    flag_acc = 0
    for flag in optionflags_str:
        flag_acc |= flag_lookup_table[flag]
    return flag_acc


class DoctestTextfile(pytest.Module):
    obj = None

    def collect(self):
        import doctest

        # inspired by doctest.testfile; ideally we would use it directly,
        # but it doesn't support passing a custom checker
        text = self.fspath.read()
        filename = str(self.fspath)
        name = self.fspath.basename
        globs = {'__name__': '__main__'}


        optionflags = get_optionflags(self)
        runner = doctest.DebugRunner(verbose=0, optionflags=optionflags,
                                     checker=_get_checker())

        parser = doctest.DocTestParser()
        test = parser.get_doctest(text, globs, name, filename, 0)
        if test.examples:
            yield DoctestItem(test.name, self, runner, test)


def _check_all_skipped(test):
    """raises pytest.skip() if all examples in the given DocTest have the SKIP
    option set.
    """
    import doctest
    all_skipped = all(x.options.get(doctest.SKIP, False) for x in test.examples)
    if all_skipped:
        pytest.skip('all tests skipped by +SKIP option')


class DoctestModule(pytest.Module):
    def collect(self):
        import doctest
        if self.fspath.basename == "conftest.py":
            module = self.config.pluginmanager._importconftest(self.fspath)
        else:
            try:
                module = self.fspath.pyimport()
            except ImportError:
                if self.config.getvalue('doctest_ignore_import_errors'):
                    pytest.skip('unable to import module %r' % self.fspath)
                else:
                    raise
        # uses internal doctest module parsing mechanism
        finder = doctest.DocTestFinder()
        optionflags = get_optionflags(self)
        runner = doctest.DebugRunner(verbose=0, optionflags=optionflags,
                                     checker=_get_checker())
        for test in finder.find(module, module.__name__):
            if test.examples:  # skip empty doctests
                yield DoctestItem(test.name, self, runner, test)


def _setup_fixtures(doctest_item):
    """
    Used by DoctestTextfile and DoctestItem to setup fixture information.
    """
    def func():
        pass

    doctest_item.funcargs = {}
    fm = doctest_item.session._fixturemanager
    doctest_item._fixtureinfo = fm.getfixtureinfo(node=doctest_item, func=func,
                                                  cls=None, funcargs=False)
    fixture_request = FixtureRequest(doctest_item)
    fixture_request._fillfixtures()
    return fixture_request


def _get_checker():
    """
    Returns a doctest.OutputChecker subclass that takes in account the
    ALLOW_UNICODE option to ignore u'' prefixes in strings and ALLOW_BYTES
    to strip b'' prefixes.
    Useful when the same doctest should run in Python 2 and Python 3.

    An inner class is used to avoid importing "doctest" at the module
    level.
    """
    if hasattr(_get_checker, 'LiteralsOutputChecker'):
        return _get_checker.LiteralsOutputChecker()

    import doctest
    import re

    class LiteralsOutputChecker(doctest.OutputChecker):
        """
        Copied from doctest_nose_plugin.py from the nltk project:
            https://github.com/nltk/nltk

        Further extended to also support byte literals.
        """

        _unicode_literal_re = re.compile(r"(\W|^)[uU]([rR]?[\'\"])", re.UNICODE)
        _bytes_literal_re = re.compile(r"(\W|^)[bB]([rR]?[\'\"])", re.UNICODE)

        def check_output(self, want, got, optionflags):
            res = doctest.OutputChecker.check_output(self, want, got,
                                                     optionflags)
            if res:
                return True

            allow_unicode = optionflags & _get_allow_unicode_flag()
            allow_bytes = optionflags & _get_allow_bytes_flag()
            if not allow_unicode and not allow_bytes:
                return False

            else:  # pragma: no cover
                def remove_prefixes(regex, txt):
                    return re.sub(regex, r'\1\2', txt)

                if allow_unicode:
                    want = remove_prefixes(self._unicode_literal_re, want)
                    got = remove_prefixes(self._unicode_literal_re, got)
                if allow_bytes:
                    want = remove_prefixes(self._bytes_literal_re, want)
                    got = remove_prefixes(self._bytes_literal_re, got)
                res = doctest.OutputChecker.check_output(self, want, got,
                                                         optionflags)
                return res

    _get_checker.LiteralsOutputChecker = LiteralsOutputChecker
    return _get_checker.LiteralsOutputChecker()


def _get_allow_unicode_flag():
    """
    Registers and returns the ALLOW_UNICODE flag.
    """
    import doctest
    return doctest.register_optionflag('ALLOW_UNICODE')


def _get_allow_bytes_flag():
    """
    Registers and returns the ALLOW_BYTES flag.
    """
    import doctest
    return doctest.register_optionflag('ALLOW_BYTES')


def _get_report_choice(key):
    """
    This function returns the actual `doctest` module flag value, we want to do it as late as possible to avoid
    importing `doctest` and all its dependencies when parsing options, as it adds overhead and breaks tests.
    """
    import doctest

    return {
        DOCTEST_REPORT_CHOICE_UDIFF: doctest.REPORT_UDIFF,
        DOCTEST_REPORT_CHOICE_CDIFF: doctest.REPORT_CDIFF,
        DOCTEST_REPORT_CHOICE_NDIFF: doctest.REPORT_NDIFF,
        DOCTEST_REPORT_CHOICE_ONLY_FIRST_FAILURE: doctest.REPORT_ONLY_FIRST_FAILURE,
        DOCTEST_REPORT_CHOICE_NONE: 0,
    }[key]

@pytest.fixture(scope='session')
def doctest_namespace():
    """
    Inject names into the doctest namespace.
    """
    return dict()
