"""
    sphinx.transforms
    ~~~~~~~~~~~~~~~~~

    Docutils transforms used by Sphinx when reading documents.

    :copyright: Copyright 2007-2020 by the Sphinx team, see AUTHORS.
    :license: BSD, see LICENSE for details.
"""

import re
from typing import Any, Dict, Generator, List, Tuple

from docutils import nodes
from docutils.nodes import Element, Node, Text
from docutils.transforms import Transform, Transformer
from docutils.transforms.parts import ContentsFilter
from docutils.transforms.universal import SmartQuotes
from docutils.utils import normalize_language_tag
from docutils.utils.smartquotes import smartchars

from sphinx import addnodes
from sphinx.config import Config
from sphinx.deprecation import RemovedInSphinx40Warning, deprecated_alias
from sphinx.locale import _, __
from sphinx.util import docutils
from sphinx.util import logging
from sphinx.util.docutils import new_document
from sphinx.util.i18n import format_date
from sphinx.util.nodes import NodeMatcher, apply_source_workaround, is_smartquotable

if False:
    # For type annotation
    from sphinx.application import Sphinx
    from sphinx.domain.std import StandardDomain
    from sphinx.environment import BuildEnvironment


logger = logging.getLogger(__name__)

default_substitutions = {
    'version',
    'release',
    'today',
}


class SphinxTransform(Transform):
    """A base class of Transforms.

    Compared with ``docutils.transforms.Transform``, this class improves accessibility to
    Sphinx APIs.
    """

    @property
    def app(self) -> "Sphinx":
        """Reference to the :class:`.Sphinx` object."""
        return self.env.app

    @property
    def env(self) -> "BuildEnvironment":
        """Reference to the :class:`.BuildEnvironment` object."""
        return self.document.settings.env

    @property
    def config(self) -> Config:
        """Reference to the :class:`.Config` object."""
        return self.env.config


class SphinxTransformer(Transformer):
    """
    A transformer for Sphinx.
    """

    document = None  # type: nodes.document
    env = None  # type: BuildEnvironment

    def set_environment(self, env: "BuildEnvironment") -> None:
        self.env = env

    def apply_transforms(self) -> None:
        if isinstance(self.document, nodes.document):
            if not hasattr(self.document.settings, 'env') and self.env:
                self.document.settings.env = self.env

            super().apply_transforms()
        else:
            # wrap the target node by document node during transforming
            try:
                document = new_document('')
                if self.env:
                    document.settings.env = self.env
                document += self.document
                self.document = document
                super().apply_transforms()
            finally:
                self.document = self.document[0]


class DefaultSubstitutions(SphinxTransform):
    """
    Replace some substitutions if they aren't defined in the document.
    """
    # run before the default Substitutions
    default_priority = 210

    def apply(self, **kwargs: Any) -> None:
        # only handle those not otherwise defined in the document
        to_handle = default_substitutions - set(self.document.substitution_defs)
        for ref in self.document.traverse(nodes.substitution_reference):
            refname = ref['refname']
            if refname in to_handle:
                text = self.config[refname]
                if refname == 'today' and not text:
                    # special handling: can also specify a strftime format
                    text = format_date(self.config.today_fmt or _('%b %d, %Y'),
                                       language=self.config.language)
                ref.replace_self(nodes.Text(text, text))


class MoveModuleTargets(SphinxTransform):
    """
    Move module targets that are the first thing in a section to the section
    title.

    XXX Python specific
    """
    default_priority = 210

    def apply(self, **kwargs: Any) -> None:
        for node in self.document.traverse(nodes.target):
            if not node['ids']:
                continue
            if ('ismod' in node and
                    node.parent.__class__ is nodes.section and
                    # index 0 is the section title node
                    node.parent.index(node) == 1):
                node.parent['ids'][0:0] = node['ids']
                node.parent.remove(node)


class HandleCodeBlocks(SphinxTransform):
    """
    Several code block related transformations.
    """
    default_priority = 210

    def apply(self, **kwargs: Any) -> None:
        # move doctest blocks out of blockquotes
        for node in self.document.traverse(nodes.block_quote):
            if all(isinstance(child, nodes.doctest_block) for child
                   in node.children):
                node.replace_self(node.children)
        # combine successive doctest blocks
        # for node in self.document.traverse(nodes.doctest_block):
        #    if node not in node.parent.children:
        #        continue
        #    parindex = node.parent.index(node)
        #    while len(node.parent) > parindex+1 and \
        #            isinstance(node.parent[parindex+1], nodes.doctest_block):
        #        node[0] = nodes.Text(node[0] + '\n\n' +
        #                             node.parent[parindex+1][0])
        #        del node.parent[parindex+1]


class AutoNumbering(SphinxTransform):
    """
    Register IDs of tables, figures and literal_blocks to assign numbers.
    """
    default_priority = 210

    def apply(self, **kwargs: Any) -> None:
        domain = self.env.get_domain('std')  # type: StandardDomain

        for node in self.document.traverse(nodes.Element):
            if (domain.is_enumerable_node(node) and
                    domain.get_numfig_title(node) is not None and
                    node['ids'] == []):
                self.document.note_implicit_target(node)


class SortIds(SphinxTransform):
    """
    Sort secion IDs so that the "id[0-9]+" one comes last.
    """
    default_priority = 261

    def apply(self, **kwargs: Any) -> None:
        for node in self.document.traverse(nodes.section):
            if len(node['ids']) > 1 and node['ids'][0].startswith('id'):
                node['ids'] = node['ids'][1:] + [node['ids'][0]]


TRANSLATABLE_NODES = {
    'literal-block': nodes.literal_block,
    'doctest-block': nodes.doctest_block,
    'raw': nodes.raw,
    'index': addnodes.index,
    'image': nodes.image,
}


class ApplySourceWorkaround(SphinxTransform):
    """
    update source and rawsource attributes
    """
    default_priority = 10

    def apply(self, **kwargs: Any) -> None:
        for node in self.document.traverse():  # type: Node
            if isinstance(node, (nodes.TextElement, nodes.image)):
                apply_source_workaround(node)


class AutoIndexUpgrader(SphinxTransform):
    """
    Detect old style; 4 column based indices and automatically upgrade to new style.
    """
    default_priority = 210

    def apply(self, **kwargs: Any) -> None:
        for node in self.document.traverse(addnodes.index):
            if 'entries' in node and any(len(entry) == 4 for entry in node['entries']):
                msg = __('4 column based index found. '
                         'It might be a bug of extensions you use: %r') % node['entries']
                logger.warning(msg, location=node)
                for i, entry in enumerate(node['entries']):
                    if len(entry) == 4:
                        node['entries'][i] = entry + (None,)


class ExtraTranslatableNodes(SphinxTransform):
    """
    make nodes translatable
    """
    default_priority = 10

    def apply(self, **kwargs: Any) -> None:
        targets = self.config.gettext_additional_targets
        target_nodes = [v for k, v in TRANSLATABLE_NODES.items() if k in targets]
        if not target_nodes:
            return

        def is_translatable_node(node: Node) -> bool:
            return isinstance(node, tuple(target_nodes))

        for node in self.document.traverse(is_translatable_node):  # type: Element
            node['translatable'] = True


class UnreferencedFootnotesDetector(SphinxTransform):
    """
    detect unreferenced footnotes and emit warnings
    """
    default_priority = 200

    def apply(self, **kwargs: Any) -> None:
        for node in self.document.footnotes:
            if node['names'] == []:
                # footnote having duplicated number.  It is already warned at parser.
                pass
            elif node['names'][0] not in self.document.footnote_refs:
                logger.warning(__('Footnote [%s] is not referenced.'), node['names'][0],
                               type='ref', subtype='footnote',
                               location=node)

        for node in self.document.autofootnotes:
            if not any(ref['auto'] == node['auto'] for ref in self.document.autofootnote_refs):
                logger.warning(__('Footnote [#] is not referenced.'),
                               type='ref', subtype='footnote',
                               location=node)


class DoctestTransform(SphinxTransform):
    """Set "doctest" style to each doctest_block node"""
    default_priority = 500

    def apply(self, **kwargs: Any) -> None:
        for node in self.document.traverse(nodes.doctest_block):
            node['classes'].append('doctest')


class FigureAligner(SphinxTransform):
    """
    Align figures to center by default.
    """
    default_priority = 700

    def apply(self, **kwargs: Any) -> None:
        matcher = NodeMatcher(nodes.table, nodes.figure)
        for node in self.document.traverse(matcher):  # type: Element
            node.setdefault('align', 'default')


class FilterSystemMessages(SphinxTransform):
    """Filter system messages from a doctree."""
    default_priority = 999

    def apply(self, **kwargs: Any) -> None:
        filterlevel = 2 if self.config.keep_warnings else 5
        for node in self.document.traverse(nodes.system_message):
            if node['level'] < filterlevel:
                logger.debug('%s [filtered system message]', node.astext())
                node.parent.remove(node)


class SphinxContentsFilter(ContentsFilter):
    """
    Used with BuildEnvironment.add_toc_from() to discard cross-file links
    within table-of-contents link nodes.
    """
    visit_pending_xref = ContentsFilter.ignore_node_but_process_children

    def visit_image(self, node: nodes.image) -> None:
        raise nodes.SkipNode


class SphinxSmartQuotes(SmartQuotes, SphinxTransform):
    """
    Customized SmartQuotes to avoid transform for some extra node types.

    refs: sphinx.parsers.RSTParser
    """
    default_priority = 750

    def apply(self, **kwargs: Any) -> None:
        if not self.is_available():
            return

        # override default settings with :confval:`smartquotes_action`
        self.smartquotes_action = self.config.smartquotes_action

        super().apply()

    def is_available(self) -> bool:
        builders = self.config.smartquotes_excludes.get('builders', [])
        languages = self.config.smartquotes_excludes.get('languages', [])

        if self.document.settings.smart_quotes is False:
            # disabled by 3rd party extension (workaround)
            return False
        elif self.config.smartquotes is False:
            # disabled by confval smartquotes
            return False
        elif self.app.builder.name in builders:
            # disabled by confval smartquotes_excludes['builders']
            return False
        elif self.config.language in languages:
            # disabled by confval smartquotes_excludes['languages']
            return False

        # confirm selected language supports smart_quotes or not
        language = self.env.settings['language_code']
        for tag in normalize_language_tag(language):
            if tag in smartchars.quotes:
                return True
        else:
            return False

    def get_tokens(self, txtnodes: List[Text]) -> Generator[Tuple[str, str], None, None]:
        # A generator that yields ``(texttype, nodetext)`` tuples for a list
        # of "Text" nodes (interface to ``smartquotes.educate_tokens()``).
        for txtnode in txtnodes:
            if is_smartquotable(txtnode):
                if docutils.__version_info__ >= (0, 16):
                    # SmartQuotes uses backslash escapes instead of null-escapes
                    text = re.sub(r'(?<=\x00)([-\\\'".`])', r'\\\1', str(txtnode))
                else:
                    text = txtnode.astext()

                yield ('plain', text)
            else:
                # skip smart quotes
                yield ('literal', txtnode.astext())


class DoctreeReadEvent(SphinxTransform):
    """Emit :event:`doctree-read` event."""
    default_priority = 880

    def apply(self, **kwargs: Any) -> None:
        self.app.emit('doctree-read', self.document)


class ManpageLink(SphinxTransform):
    """Find manpage section numbers and names"""
    default_priority = 999

    def apply(self, **kwargs: Any) -> None:
        for node in self.document.traverse(addnodes.manpage):
            manpage = ' '.join([str(x) for x in node.children
                                if isinstance(x, nodes.Text)])
            pattern = r'^(?P<path>(?P<page>.+)[\(\.](?P<section>[1-9]\w*)?\)?)$'  # noqa
            info = {'path': manpage,
                    'page': manpage,
                    'section': ''}
            r = re.match(pattern, manpage)
            if r:
                info = r.groupdict()
            node.attributes.update(info)


from sphinx.domains.citation import (  # NOQA
    CitationDefinitionTransform, CitationReferenceTransform
)

deprecated_alias('sphinx.transforms',
                 {
                     'CitationReferences': CitationReferenceTransform,
                     'SmartQuotesSkipper': CitationDefinitionTransform,
                 },
                 RemovedInSphinx40Warning,
                 {
                     'CitationReferences':
                     'sphinx.domains.citation.CitationReferenceTransform',
                     'SmartQuotesSkipper':
                     'sphinx.domains.citation.CitationDefinitionTransform',
                 })


def setup(app: "Sphinx") -> Dict[str, Any]:
    app.add_transform(ApplySourceWorkaround)
    app.add_transform(ExtraTranslatableNodes)
    app.add_transform(DefaultSubstitutions)
    app.add_transform(MoveModuleTargets)
    app.add_transform(HandleCodeBlocks)
    app.add_transform(SortIds)
    app.add_transform(DoctestTransform)
    app.add_transform(FigureAligner)
    app.add_transform(AutoNumbering)
    app.add_transform(AutoIndexUpgrader)
    app.add_transform(FilterSystemMessages)
    app.add_transform(UnreferencedFootnotesDetector)
    app.add_transform(SphinxSmartQuotes)
    app.add_transform(DoctreeReadEvent)
    app.add_transform(ManpageLink)

    return {
        'version': 'builtin',
        'parallel_read_safe': True,
        'parallel_write_safe': True,
    }
