"""Mimic doctest in Sphinx.

The extension automatically execute code snippets and checks their results.
"""

import doctest
import re
import sys
import time
from io import StringIO
from os import path
from typing import (TYPE_CHECKING, Any, Callable, Dict, Iterable, List, Optional, Sequence,
                    Set, Tuple, Type)

from docutils import nodes
from docutils.nodes import Element, Node, TextElement
from docutils.parsers.rst import directives
from packaging.specifiers import InvalidSpecifier, SpecifierSet
from packaging.version import Version

import sphinx
from sphinx.builders import Builder
from sphinx.locale import __
from sphinx.util import logging
from sphinx.util.console import bold  # type: ignore
from sphinx.util.docutils import SphinxDirective
from sphinx.util.osutil import relpath
from sphinx.util.typing import OptionSpec

if TYPE_CHECKING:
    from sphinx.application import Sphinx


logger = logging.getLogger(__name__)

blankline_re = re.compile(r'^\s*<BLANKLINE>', re.MULTILINE)
doctestopt_re = re.compile(r'#\s*doctest:.+$', re.MULTILINE)


def is_allowed_version(spec: str, version: str) -> bool:
    """Check `spec` satisfies `version` or not.

    This obeys PEP-440 specifiers:
    https://peps.python.org/pep-0440/#version-specifiers

    Some examples:

        >>> is_allowed_version('<=3.5', '3.3')
        True
        >>> is_allowed_version('<=3.2', '3.3')
        False
        >>> is_allowed_version('>3.2, <4.0', '3.3')
        True
    """
    return Version(version) in SpecifierSet(spec)


# set up the necessary directives

class TestDirective(SphinxDirective):
    """
    Base class for doctest-related directives.
    """

    has_content = True
    required_arguments = 0
    optional_arguments = 1
    final_argument_whitespace = True

    def run(self) -> List[Node]:
        # use ordinary docutils nodes for test code: they get special attributes
        # so that our builder recognizes them, and the other builders are happy.
        code = '\n'.join(self.content)
        test = None
        if self.name == 'doctest':
            if '<BLANKLINE>' in code:
                # convert <BLANKLINE>s to ordinary blank lines for presentation
                test = code
                code = blankline_re.sub('', code)
            if doctestopt_re.search(code) and 'no-trim-doctest-flags' not in self.options:
                if not test:
                    test = code
                code = doctestopt_re.sub('', code)
        nodetype: Type[TextElement] = nodes.literal_block
        if self.name in ('testsetup', 'testcleanup') or 'hide' in self.options:
            nodetype = nodes.comment
        if self.arguments:
            groups = [x.strip() for x in self.arguments[0].split(',')]
        else:
            groups = ['default']
        node = nodetype(code, code, testnodetype=self.name, groups=groups)
        self.set_source_info(node)
        if test is not None:
            # only save if it differs from code
            node['test'] = test
        if self.name == 'doctest':
            node['language'] = 'pycon'
        elif self.name == 'testcode':
            node['language'] = 'python'
        elif self.name == 'testoutput':
            # don't try to highlight output
            node['language'] = 'none'
        node['options'] = {}
        if self.name in ('doctest', 'testoutput') and 'options' in self.options:
            # parse doctest-like output comparison flags
            option_strings = self.options['options'].replace(',', ' ').split()
            for option in option_strings:
                prefix, option_name = option[0], option[1:]
                if prefix not in '+-':
                    self.state.document.reporter.warning(
                        __("missing '+' or '-' in '%s' option.") % option,
                        line=self.lineno)
                    continue
                if option_name not in doctest.OPTIONFLAGS_BY_NAME:
                    self.state.document.reporter.warning(
                        __("'%s' is not a valid option.") % option_name,
                        line=self.lineno)
                    continue
                flag = doctest.OPTIONFLAGS_BY_NAME[option[1:]]
                node['options'][flag] = (option[0] == '+')
        if self.name == 'doctest' and 'pyversion' in self.options:
            try:
                spec = self.options['pyversion']
                python_version = '.'.join([str(v) for v in sys.version_info[:3]])
                if not is_allowed_version(spec, python_version):
                    flag = doctest.OPTIONFLAGS_BY_NAME['SKIP']
                    node['options'][flag] = True  # Skip the test
            except InvalidSpecifier:
                self.state.document.reporter.warning(
                    __("'%s' is not a valid pyversion option") % spec,
                    line=self.lineno)
        if 'skipif' in self.options:
            node['skipif'] = self.options['skipif']
        if 'trim-doctest-flags' in self.options:
            node['trim_flags'] = True
        elif 'no-trim-doctest-flags' in self.options:
            node['trim_flags'] = False
        return [node]


class TestsetupDirective(TestDirective):
    option_spec: OptionSpec = {
        'skipif': directives.unchanged_required
    }


class TestcleanupDirective(TestDirective):
    option_spec: OptionSpec = {
        'skipif': directives.unchanged_required
    }


class DoctestDirective(TestDirective):
    option_spec: OptionSpec = {
        'hide': directives.flag,
        'no-trim-doctest-flags': directives.flag,
        'options': directives.unchanged,
        'pyversion': directives.unchanged_required,
        'skipif': directives.unchanged_required,
        'trim-doctest-flags': directives.flag,
    }


class TestcodeDirective(TestDirective):
    option_spec: OptionSpec = {
        'hide': directives.flag,
        'no-trim-doctest-flags': directives.flag,
        'pyversion': directives.unchanged_required,
        'skipif': directives.unchanged_required,
        'trim-doctest-flags': directives.flag,
    }


class TestoutputDirective(TestDirective):
    option_spec: OptionSpec = {
        'hide': directives.flag,
        'no-trim-doctest-flags': directives.flag,
        'options': directives.unchanged,
        'pyversion': directives.unchanged_required,
        'skipif': directives.unchanged_required,
        'trim-doctest-flags': directives.flag,
    }


parser = doctest.DocTestParser()


# helper classes

class TestGroup:
    def __init__(self, name: str) -> None:
        self.name = name
        self.setup: List[TestCode] = []
        self.tests: List[List[TestCode]] = []
        self.cleanup: List[TestCode] = []

    def add_code(self, code: "TestCode", prepend: bool = False) -> None:
        if code.type == 'testsetup':
            if prepend:
                self.setup.insert(0, code)
            else:
                self.setup.append(code)
        elif code.type == 'testcleanup':
            self.cleanup.append(code)
        elif code.type == 'doctest':
            self.tests.append([code])
        elif code.type == 'testcode':
            self.tests.append([code, None])
        elif code.type == 'testoutput':
            if self.tests and len(self.tests[-1]) == 2:
                self.tests[-1][1] = code
        else:
            raise RuntimeError(__('invalid TestCode type'))

    def __repr__(self) -> str:
        return 'TestGroup(name=%r, setup=%r, cleanup=%r, tests=%r)' % (
            self.name, self.setup, self.cleanup, self.tests)


class TestCode:
    def __init__(self, code: str, type: str, filename: str,
                 lineno: int, options: Optional[Dict] = None) -> None:
        self.code = code
        self.type = type
        self.filename = filename
        self.lineno = lineno
        self.options = options or {}

    def __repr__(self) -> str:
        return 'TestCode(%r, %r, filename=%r, lineno=%r, options=%r)' % (
            self.code, self.type, self.filename, self.lineno, self.options)


class SphinxDocTestRunner(doctest.DocTestRunner):
    def summarize(self, out: Callable, verbose: bool = None  # type: ignore
                  ) -> Tuple[int, int]:
        string_io = StringIO()
        old_stdout = sys.stdout
        sys.stdout = string_io
        try:
            res = super().summarize(verbose)
        finally:
            sys.stdout = old_stdout
        out(string_io.getvalue())
        return res

    def _DocTestRunner__patched_linecache_getlines(self, filename: str,
                                                   module_globals: Any = None) -> Any:
        # this is overridden from DocTestRunner adding the try-except below
        m = self._DocTestRunner__LINECACHE_FILENAME_RE.match(filename)  # type: ignore
        if m and m.group('name') == self.test.name:
            try:
                example = self.test.examples[int(m.group('examplenum'))]
            # because we compile multiple doctest blocks with the same name
            # (viz. the group name) this might, for outer stack frames in a
            # traceback, get the wrong test which might not have enough examples
            except IndexError:
                pass
            else:
                return example.source.splitlines(True)
        return self.save_linecache_getlines(filename, module_globals)  # type: ignore


# the new builder -- use sphinx-build.py -b doctest to run

class DocTestBuilder(Builder):
    """
    Runs test snippets in the documentation.
    """
    name = 'doctest'
    epilog = __('Testing of doctests in the sources finished, look at the '
                'results in %(outdir)s/output.txt.')

    def init(self) -> None:
        # default options
        self.opt = self.config.doctest_default_flags

        # HACK HACK HACK
        # doctest compiles its snippets with type 'single'. That is nice
        # for doctest examples but unusable for multi-statement code such
        # as setup code -- to be able to use doctest error reporting with
        # that code nevertheless, we monkey-patch the "compile" it uses.
        doctest.compile = self.compile  # type: ignore

        sys.path[0:0] = self.config.doctest_path

        self.type = 'single'

        self.total_failures = 0
        self.total_tries = 0
        self.setup_failures = 0
        self.setup_tries = 0
        self.cleanup_failures = 0
        self.cleanup_tries = 0

        date = time.strftime('%Y-%m-%d %H:%M:%S')

        self.outfile = open(path.join(self.outdir, 'output.txt'), 'w', encoding='utf-8')
        self.outfile.write(('Results of doctest builder run on %s\n'
                            '==================================%s\n') %
                           (date, '=' * len(date)))

    def _out(self, text: str) -> None:
        logger.info(text, nonl=True)
        self.outfile.write(text)

    def _warn_out(self, text: str) -> None:
        if self.app.quiet or self.app.warningiserror:
            logger.warning(text)
        else:
            logger.info(text, nonl=True)
        self.outfile.write(text)

    def get_target_uri(self, docname: str, typ: Optional[str] = None) -> str:
        return ''

    def get_outdated_docs(self) -> Set[str]:
        return self.env.found_docs

    def finish(self) -> None:
        # write executive summary
        def s(v: int) -> str:
            return 's' if v != 1 else ''
        repl = (self.total_tries, s(self.total_tries),
                self.total_failures, s(self.total_failures),
                self.setup_failures, s(self.setup_failures),
                self.cleanup_failures, s(self.cleanup_failures))
        self._out('''
Doctest summary
===============
%5d test%s
%5d failure%s in tests
%5d failure%s in setup code
%5d failure%s in cleanup code
''' % repl)
        self.outfile.close()

        if self.total_failures or self.setup_failures or self.cleanup_failures:
            self.app.statuscode = 1

    def write(self, build_docnames: Iterable[str], updated_docnames: Sequence[str],
              method: str = 'update') -> None:
        if build_docnames is None:
            build_docnames = sorted(self.env.all_docs)

        logger.info(bold('running tests...'))
        for docname in build_docnames:
            # no need to resolve the doctree
            doctree = self.env.get_doctree(docname)
            self.test_doc(docname, doctree)

    def get_filename_for_node(self, node: Node, docname: str) -> str:
        """Try to get the file which actually contains the doctest, not the
        filename of the document it's included in."""
        try:
            filename = relpath(node.source, self.env.srcdir)\
                .rsplit(':docstring of ', maxsplit=1)[0]
        except Exception:
            filename = self.env.doc2path(docname, False)
        return filename

    @staticmethod
    def get_line_number(node: Node) -> Optional[int]:
        """Get the real line number or admit we don't know."""
        # TODO:  Work out how to store or calculate real (file-relative)
        #       line numbers for doctest blocks in docstrings.
        if ':docstring of ' in path.basename(node.source or ''):
            # The line number is given relative to the stripped docstring,
            # not the file.  This is correct where it is set, in
            # `docutils.nodes.Node.setup_child`, but Sphinx should report
            # relative to the file, not the docstring.
            return None
        if node.line is not None:
            # TODO: find the root cause of this off by one error.
            return node.line - 1
        return None

    def skipped(self, node: Element) -> bool:
        if 'skipif' not in node:
            return False
        else:
            condition = node['skipif']
            context: Dict[str, Any] = {}
            if self.config.doctest_global_setup:
                exec(self.config.doctest_global_setup, context)
            should_skip = eval(condition, context)
            if self.config.doctest_global_cleanup:
                exec(self.config.doctest_global_cleanup, context)
            return should_skip

    def test_doc(self, docname: str, doctree: Node) -> None:
        groups: Dict[str, TestGroup] = {}
        add_to_all_groups = []
        self.setup_runner = SphinxDocTestRunner(verbose=False,
                                                optionflags=self.opt)
        self.test_runner = SphinxDocTestRunner(verbose=False,
                                               optionflags=self.opt)
        self.cleanup_runner = SphinxDocTestRunner(verbose=False,
                                                  optionflags=self.opt)

        self.test_runner._fakeout = self.setup_runner._fakeout  # type: ignore
        self.cleanup_runner._fakeout = self.setup_runner._fakeout  # type: ignore

        if self.config.doctest_test_doctest_blocks:
            def condition(node: Node) -> bool:
                return (isinstance(node, (nodes.literal_block, nodes.comment)) and
                        'testnodetype' in node) or \
                    isinstance(node, nodes.doctest_block)
        else:
            def condition(node: Node) -> bool:
                return isinstance(node, (nodes.literal_block, nodes.comment)) \
                    and 'testnodetype' in node
        for node in doctree.findall(condition):  # type: Element
            if self.skipped(node):
                continue

            source = node['test'] if 'test' in node else node.astext()
            filename = self.get_filename_for_node(node, docname)
            line_number = self.get_line_number(node)
            if not source:
                logger.warning(__('no code/output in %s block at %s:%s'),
                               node.get('testnodetype', 'doctest'),
                               filename, line_number)
            code = TestCode(source, type=node.get('testnodetype', 'doctest'),
                            filename=filename, lineno=line_number,
                            options=node.get('options'))
            node_groups = node.get('groups', ['default'])
            if '*' in node_groups:
                add_to_all_groups.append(code)
                continue
            for groupname in node_groups:
                if groupname not in groups:
                    groups[groupname] = TestGroup(groupname)
                groups[groupname].add_code(code)
        for code in add_to_all_groups:
            for group in groups.values():
                group.add_code(code)
        if self.config.doctest_global_setup:
            code = TestCode(self.config.doctest_global_setup,
                            'testsetup', filename=None, lineno=0)
            for group in groups.values():
                group.add_code(code, prepend=True)
        if self.config.doctest_global_cleanup:
            code = TestCode(self.config.doctest_global_cleanup,
                            'testcleanup', filename=None, lineno=0)
            for group in groups.values():
                group.add_code(code)
        if not groups:
            return

        self._out('\nDocument: %s\n----------%s\n' %
                  (docname, '-' * len(docname)))
        for group in groups.values():
            self.test_group(group)
        # Separately count results from setup code
        res_f, res_t = self.setup_runner.summarize(self._out, verbose=False)
        self.setup_failures += res_f
        self.setup_tries += res_t
        if self.test_runner.tries:
            res_f, res_t = self.test_runner.summarize(self._out, verbose=True)
            self.total_failures += res_f
            self.total_tries += res_t
        if self.cleanup_runner.tries:
            res_f, res_t = self.cleanup_runner.summarize(self._out,
                                                         verbose=True)
            self.cleanup_failures += res_f
            self.cleanup_tries += res_t

    def compile(self, code: str, name: str, type: str, flags: Any, dont_inherit: bool) -> Any:
        return compile(code, name, self.type, flags, dont_inherit)

    def test_group(self, group: TestGroup) -> None:
        ns: Dict = {}

        def run_setup_cleanup(runner: Any, testcodes: List[TestCode], what: Any) -> bool:
            examples = []
            for testcode in testcodes:
                example = doctest.Example(testcode.code, '', lineno=testcode.lineno)
                examples.append(example)
            if not examples:
                return True
            # simulate a doctest with the code
            sim_doctest = doctest.DocTest(examples, {},
                                          '%s (%s code)' % (group.name, what),
                                          testcodes[0].filename, 0, None)
            sim_doctest.globs = ns
            old_f = runner.failures
            self.type = 'exec'  # the snippet may contain multiple statements
            runner.run(sim_doctest, out=self._warn_out, clear_globs=False)
            if runner.failures > old_f:
                return False
            return True

        # run the setup code
        if not run_setup_cleanup(self.setup_runner, group.setup, 'setup'):
            # if setup failed, don't run the group
            return

        # run the tests
        for code in group.tests:
            if len(code) == 1:
                # ordinary doctests (code/output interleaved)
                try:
                    test = parser.get_doctest(code[0].code, {}, group.name,
                                              code[0].filename, code[0].lineno)
                except Exception:
                    logger.warning(__('ignoring invalid doctest code: %r'), code[0].code,
                                   location=(code[0].filename, code[0].lineno))
                    continue
                if not test.examples:
                    continue
                for example in test.examples:
                    # apply directive's comparison options
                    new_opt = code[0].options.copy()
                    new_opt.update(example.options)
                    example.options = new_opt
                self.type = 'single'  # as for ordinary doctests
            else:
                # testcode and output separate
                output = code[1].code if code[1] else ''
                options = code[1].options if code[1] else {}
                # disable <BLANKLINE> processing as it is not needed
                options[doctest.DONT_ACCEPT_BLANKLINE] = True
                # find out if we're testing an exception
                m = parser._EXCEPTION_RE.match(output)  # type: ignore
                if m:
                    exc_msg = m.group('msg')
                else:
                    exc_msg = None
                example = doctest.Example(code[0].code, output, exc_msg=exc_msg,
                                          lineno=code[0].lineno, options=options)
                test = doctest.DocTest([example], {}, group.name,
                                       code[0].filename, code[0].lineno, None)
                self.type = 'exec'  # multiple statements again
            # DocTest.__init__ copies the globs namespace, which we don't want
            test.globs = ns
            # also don't clear the globs namespace after running the doctest
            self.test_runner.run(test, out=self._warn_out, clear_globs=False)

        # run the cleanup
        run_setup_cleanup(self.cleanup_runner, group.cleanup, 'cleanup')


def setup(app: "Sphinx") -> Dict[str, Any]:
    app.add_directive('testsetup', TestsetupDirective)
    app.add_directive('testcleanup', TestcleanupDirective)
    app.add_directive('doctest', DoctestDirective)
    app.add_directive('testcode', TestcodeDirective)
    app.add_directive('testoutput', TestoutputDirective)
    app.add_builder(DocTestBuilder)
    # this config value adds to sys.path
    app.add_config_value('doctest_path', [], False)
    app.add_config_value('doctest_test_doctest_blocks', 'default', False)
    app.add_config_value('doctest_global_setup', '', False)
    app.add_config_value('doctest_global_cleanup', '', False)
    app.add_config_value(
        'doctest_default_flags',
        doctest.DONT_ACCEPT_TRUE_FOR_1 | doctest.ELLIPSIS | doctest.IGNORE_EXCEPTION_DETAIL,
        False)
    return {'version': sphinx.__display_version__, 'parallel_read_safe': True}
