#!/usr/bin/env python3
# :Author: David Goodger, Günter Milde
#          Based on the html4css1 writer by David Goodger.
# :Maintainer: docutils-develop@lists.sourceforge.net
# :Revision: $Revision: 9292 $
# :Date: $Date: 2005-06-28$
# :Copyright: © 2016 David Goodger, Günter Milde
# :License: Released under the terms of the `2-Clause BSD license`_, in short:
#
#    Copying and distribution of this file, with or without modification,
#    are permitted in any medium without royalty provided the copyright
#    notice and this notice are preserved.
#    This file is offered as-is, without any warranty.
#
# .. _2-Clause BSD license: https://opensource.org/licenses/BSD-2-Clause

"""common definitions for Docutils HTML writers"""

import base64
import mimetypes
import os
import os.path
import re
from urllib.request import unquote as unquote_url
from urllib.request import url2pathname  # unquote and use local path sep
import warnings

import docutils
from docutils import frontend, languages, nodes, utils, writers
from docutils.parsers.rst.directives import length_or_percentage_or_unitless
from docutils.parsers.rst.directives.images import PIL
from docutils.transforms import writer_aux
from docutils.utils.math import unichar2tex, pick_math_environment, math2html, latex2mathml, tex2mathml_extern


class Writer(writers.Writer):
    supported = ("html", "xhtml")  # update in subclass
    """Formats this writer supports."""

    settings_spec = (
        "HTML Writer Options",
        None,
        (
            (
                "Specify the template file (UTF-8 encoded). " "(default: writer dependent)",
                ["--template"],
                {"metavar": "<file>"},
            ),
            (
                "Comma separated list of stylesheet URLs. "
                "Overrides previous --stylesheet and --stylesheet-path settings.",
                ["--stylesheet"],
                {
                    "metavar": "<URL[,URL,...]>",
                    "overrides": "stylesheet_path",
                    "validator": frontend.validate_comma_separated_list,
                },
            ),
            (
                "Comma separated list of stylesheet paths. "
                "Relative paths are expanded if a matching file is found in "
                "the --stylesheet-dirs. With --link-stylesheet, "
                "the path is rewritten relative to the output HTML file. "
                "(default: writer dependent)",
                ["--stylesheet-path"],
                {
                    "metavar": "<file[,file,...]>",
                    "overrides": "stylesheet",
                    "validator": frontend.validate_comma_separated_list,
                },
            ),
            (
                "Comma-separated list of directories where stylesheets are found. "
                "Used by --stylesheet-path when expanding relative path arguments. "
                "(default: writer dependent)",
                ["--stylesheet-dirs"],
                {"metavar": "<dir[,dir,...]>", "validator": frontend.validate_comma_separated_list},
            ),
            (
                "Embed the stylesheet(s) in the output HTML file.  The stylesheet "
                "files must be accessible during processing. (default)",
                ["--embed-stylesheet"],
                {"default": 1, "action": "store_true", "validator": frontend.validate_boolean},
            ),
            (
                "Link to the stylesheet(s) in the output HTML file. ",
                ["--link-stylesheet"],
                {"dest": "embed_stylesheet", "action": "store_false"},
            ),
            (
                "Specify the initial header level. "
                "Does not affect document title & subtitle (see --no-doc-title)."
                "(default: writer dependent).",
                ["--initial-header-level"],
                {"choices": "1 2 3 4 5 6".split(), "default": "2", "metavar": "<level>"},
            ),
            (
                'Format for footnote references: one of "superscript" or ' '"brackets". (default: "brackets")',
                ["--footnote-references"],
                {
                    "choices": ["superscript", "brackets"],
                    "default": "brackets",
                    "metavar": "<format>",
                    "overrides": "trim_footnote_reference_space",
                },
            ),
            (
                "Format for block quote attributions: "
                'one of "dash" (em-dash prefix), "parentheses"/"parens", or "none". '
                '(default: "dash")',
                ["--attribution"],
                {"choices": ["dash", "parentheses", "parens", "none"], "default": "dash", "metavar": "<format>"},
            ),
            (
                'Remove extra vertical whitespace between items of "simple" bullet '
                "lists and enumerated lists. (default)",
                ["--compact-lists"],
                {"default": True, "action": "store_true", "validator": frontend.validate_boolean},
            ),
            (
                "Disable compact simple bullet and enumerated lists.",
                ["--no-compact-lists"],
                {"dest": "compact_lists", "action": "store_false"},
            ),
            (
                "Remove extra vertical whitespace between items of simple field " "lists. (default)",
                ["--compact-field-lists"],
                {"default": True, "action": "store_true", "validator": frontend.validate_boolean},
            ),
            (
                "Disable compact simple field lists.",
                ["--no-compact-field-lists"],
                {"dest": "compact_field_lists", "action": "store_false"},
            ),
            (
                "Added to standard table classes. "
                "Defined styles: borderless, booktabs, "
                "align-left, align-center, align-right, "
                "colwidths-auto, colwidths-grid.",
                ["--table-style"],
                {"default": ""},
            ),
            (
                'Math output format (one of "MathML", "HTML", "MathJax", '
                'or "LaTeX") and option(s). '
                '(default: "HTML math.css")',
                ["--math-output"],
                {"default": "HTML math.css"},
            ),
            (
                "Prepend an XML declaration. ",
                ["--xml-declaration"],
                {"default": False, "action": "store_true", "validator": frontend.validate_boolean},
            ),
            (
                "Omit the XML declaration.",
                ["--no-xml-declaration"],
                {"dest": "xml_declaration", "action": "store_false"},
            ),
            (
                "Obfuscate email addresses to confuse harvesters while still "
                "keeping email links usable with standards-compliant browsers.",
                ["--cloak-email-addresses"],
                {"action": "store_true", "validator": frontend.validate_boolean},
            ),
        ),
    )

    settings_defaults = {"output_encoding_error_handler": "xmlcharrefreplace"}

    config_section = "html base writer"  # overwrite in subclass
    config_section_dependencies = ("writers", "html writers")

    visitor_attributes = (
        "head_prefix",
        "head",
        "stylesheet",
        "body_prefix",
        "body_pre_docinfo",
        "docinfo",
        "body",
        "body_suffix",
        "title",
        "subtitle",
        "header",
        "footer",
        "meta",
        "fragment",
        "html_prolog",
        "html_head",
        "html_title",
        "html_subtitle",
        "html_body",
    )

    def get_transforms(self):
        return super().get_transforms() + [writer_aux.Admonitions]

    def translate(self):
        self.visitor = visitor = self.translator_class(self.document)
        self.document.walkabout(visitor)
        for attr in self.visitor_attributes:
            setattr(self, attr, getattr(visitor, attr))
        self.output = self.apply_template()

    def apply_template(self):
        with open(self.document.settings.template, encoding="utf-8") as fp:
            template = fp.read()
        subs = self.interpolation_dict()
        return template % subs

    def interpolation_dict(self):
        subs = {}
        settings = self.document.settings
        for attr in self.visitor_attributes:
            subs[attr] = "".join(getattr(self, attr)).rstrip("\n")
        subs["encoding"] = settings.output_encoding
        subs["version"] = docutils.__version__
        return subs

    def assemble_parts(self):
        writers.Writer.assemble_parts(self)
        for part in self.visitor_attributes:
            self.parts[part] = "".join(getattr(self, part))


class HTMLTranslator(nodes.NodeVisitor):

    """
    Generic Docutils to HTML translator.

    See the `html4css1` and `html5_polyglot` writers for full featured
    HTML writers.

    .. IMPORTANT::
      The `visit_*` and `depart_*` methods use a
      heterogeneous stack, `self.context`.
      When subclassing, make sure to be consistent in its use!

      Examples for robust coding:

      a) Override both `visit_*` and `depart_*` methods, don't call the
         parent functions.

      b) Extend both and unconditionally call the parent functions::

           def visit_example(self, node):
               if foo:
                   self.body.append('<div class="foo">')
               html4css1.HTMLTranslator.visit_example(self, node)

           def depart_example(self, node):
               html4css1.HTMLTranslator.depart_example(self, node)
               if foo:
                   self.body.append('</div>')

      c) Extend both, calling the parent functions under the same
         conditions::

           def visit_example(self, node):
               if foo:
                   self.body.append('<div class="foo">\n')
               else: # call the parent method
                   _html_base.HTMLTranslator.visit_example(self, node)

           def depart_example(self, node):
               if foo:
                   self.body.append('</div>\n')
               else: # call the parent method
                   _html_base.HTMLTranslator.depart_example(self, node)

      d) Extend one method (call the parent), but don't otherwise use the
         `self.context` stack::

           def depart_example(self, node):
               _html_base.HTMLTranslator.depart_example(self, node)
               if foo:
                   # implementation-specific code
                   # that does not use `self.context`
                   self.body.append('</div>\n')

      This way, changes in stack use will not bite you.
    """

    doctype = "<!DOCTYPE html>\n"
    doctype_mathml = doctype

    head_prefix_template = (
        '<html xmlns="http://www.w3.org/1999/xhtml"' ' xml:lang="%(lang)s" lang="%(lang)s">\n<head>\n'
    )
    content_type = '<meta charset="%s" />\n'
    generator = (
        f'<meta name="generator" content="Docutils {docutils.__version__}: ' 'https://docutils.sourceforge.io/" />\n'
    )
    # `starttag()` arguments for the main document (HTML5 uses <main>)
    documenttag_args = {"tagname": "div", "CLASS": "document"}

    # Template for the MathJax script in the header:
    mathjax_script = '<script type="text/javascript" src="%s"></script>\n'

    mathjax_url = "file:/usr/share/javascript/mathjax/MathJax.js"
    """
    URL of the MathJax javascript library.

    The MathJax library ought to be installed on the same
    server as the rest of the deployed site files and specified
    in the `math-output` setting appended to "mathjax".
    See `Docutils Configuration`__.

    __ https://docutils.sourceforge.io/docs/user/config.html#math-output

    The fallback tries a local MathJax installation at
    ``/usr/share/javascript/mathjax/MathJax.js``.
    """

    stylesheet_link = '<link rel="stylesheet" href="%s" type="text/css" />\n'
    embedded_stylesheet = '<style type="text/css">\n\n%s\n</style>\n'
    words_and_spaces = re.compile(r"[^ \n]+| +|\n")
    # wrap point inside word:
    in_word_wrap_point = re.compile(r".+\W\W.+|[-?].+")
    lang_attribute = "lang"  # name changes to 'xml:lang' in XHTML 1.1

    special_characters = {
        ord("&"): "&amp;",
        ord("<"): "&lt;",
        ord('"'): "&quot;",
        ord(">"): "&gt;",
        ord("@"): "&#64;",  # may thwart address harvesters
    }
    """Character references for characters with a special meaning in HTML."""

    def __init__(self, document):
        nodes.NodeVisitor.__init__(self, document)
        # process settings
        self.settings = settings = document.settings
        self.language = languages.get_language(settings.language_code, document.reporter)
        self.initial_header_level = int(settings.initial_header_level)
        # image_loading (only defined for HTML5 writer)
        self.image_loading = getattr(settings, "image_loading", None)
        # legacy setting embed_images:
        if getattr(settings, "embed_images", None) is True:
            warnings.warn(
                'The configuration setting "embed_images" '
                "will be removed in Docutils 2.0. "
                'Use "image_loading: embed".',
                FutureWarning,
                stacklevel=8,
            )
            if self.image_loading is None:
                self.image_loading = "embed"
        if getattr(settings, "embed_images", None) is False:
            warnings.warn(
                'The configuration setting "embed_images" '
                "will be removed in Docutils 2.0. "
                'Use "image_loading: link".',
                FutureWarning,
                stacklevel=8,
            )
        if self.image_loading is None:
            self.image_loading = "link"  # default
        self.math_output = settings.math_output.split()
        self.math_output_options = self.math_output[1:]
        self.math_output = self.math_output[0].lower()

        # set up "parts" (cf. docs/api/publisher.html#publish-parts-details)
        #
        self.body = []  # equivalent to `fragment`, ≠ `html_body`
        self.body_prefix = ["</head>\n<body>\n"]  # + optional header
        self.body_pre_docinfo = []  # document heading (title and subtitle)
        self.body_suffix = ["</body>\n</html>\n"]  # + optional footer
        self.docinfo = []
        self.footer = []
        self.fragment = []  # main content of the document ("naked" body)
        self.head = []
        self.head_prefix = []  # everything up to and including <head>
        self.header = []
        self.html_body = []
        self.html_head = [self.content_type]  # charset not interpolated
        self.html_prolog = []
        self.html_subtitle = []
        self.html_title = []
        self.meta = [self.generator]
        self.stylesheet = [self.stylesheet_call(path) for path in utils.get_stylesheet_list(settings)]
        self.title = []
        self.subtitle = []
        if settings.xml_declaration:
            self.head_prefix.append(utils.xml_declaration(settings.output_encoding))
            self.html_prolog.append(utils.xml_declaration("%s"))  # encoding not interpolated
        if settings.output_encoding and settings.output_encoding.lower() != "unicode":
            self.meta.insert(0, self.content_type % settings.output_encoding)

        # bookkeeping attributes; reflect state of translator
        #
        self.context = []
        """Heterogeneous stack.

        Used by visit_* and depart_* functions in conjunction with the tree
        traversal. Make sure that the pops correspond to the pushes.
        """
        self.section_level = 0
        self.colspecs = []
        self.compact_p = True
        self.compact_simple = False
        self.compact_field_list = False
        self.in_docinfo = False
        self.in_sidebar = False
        self.in_document_title = 0  # len(self.body) or 0
        self.in_mailto = False
        self.author_in_authors = False  # for html4css1
        self.math_header = []

    def astext(self):
        return "".join(
            self.head_prefix
            + self.head
            + self.stylesheet
            + self.body_prefix
            + self.body_pre_docinfo
            + self.docinfo
            + self.body
            + self.body_suffix
        )

    def encode(self, text):
        """Encode special characters in `text` & return."""
        # Use only named entities known in both XML and HTML
        # other characters are automatically encoded "by number" if required.
        # @@@ A codec to do these and all other HTML entities would be nice.
        text = str(text)
        return text.translate(self.special_characters)

    def cloak_mailto(self, uri):
        """Try to hide a mailto: URL from harvesters."""
        # Encode "@" using a URL octet reference (see RFC 1738).
        # Further cloaking with HTML entities will be done in the
        # `attval` function.
        return uri.replace("@", "%40")

    def cloak_email(self, addr):
        """Try to hide the link text of a email link from harversters."""
        # Surround at-signs and periods with <span> tags.  ("@" has
        # already been encoded to "&#64;" by the `encode` method.)
        addr = addr.replace("&#64;", "<span>&#64;</span>")
        return addr.replace(".", "<span>&#46;</span>")

    def attval(self, text, whitespace=re.compile("[\n\r\t\v\f]")):
        """Cleanse, HTML encode, and return attribute value text."""
        encoded = self.encode(whitespace.sub(" ", text))
        if self.in_mailto and self.settings.cloak_email_addresses:
            # Cloak at-signs ("%40") and periods with HTML entities.
            encoded = encoded.replace("%40", "&#37;&#52;&#48;")
            encoded = encoded.replace(".", "&#46;")
        return encoded

    def stylesheet_call(self, path, adjust_path=None):
        """Return code to reference or embed stylesheet file `path`"""
        if adjust_path is None:
            adjust_path = bool(self.settings.stylesheet_path)
        if self.settings.embed_stylesheet:
            try:
                with open(path, encoding="utf-8") as f:
                    content = f.read()
            except OSError as err:
                msg = f"Cannot embed stylesheet: {err}"
                self.document.reporter.error(msg)
                return "<--- %s --->\n" % msg
            else:
                self.settings.record_dependencies.add(path)
            return self.embedded_stylesheet % content
        # else link to style file:
        if adjust_path:
            # rewrite path relative to output (cf. config.html#stylesheet-path)
            path = utils.relative_path(self.settings._destination, path)
        return self.stylesheet_link % self.encode(path)

    def starttag(self, node, tagname, suffix="\n", empty=False, **attributes):
        """
        Construct and return a start tag given a node (id & class attributes
        are extracted), tag name, and optional attributes.
        """
        tagname = tagname.lower()
        prefix = []
        atts = {}
        for name, value in attributes.items():
            atts[name.lower()] = value
        classes = atts.pop("classes", [])
        languages = []
        # unify class arguments and move language specification
        for cls in node.get("classes", []) + atts.pop("class", "").split():
            if cls.startswith("language-"):
                languages.append(cls[9:])
            elif cls.strip() and cls not in classes:
                classes.append(cls)
        if languages:
            # attribute name is 'lang' in XHTML 1.0 but 'xml:lang' in 1.1
            atts[self.lang_attribute] = languages[0]
        # filter classes that are processed by the writer:
        internal = ("colwidths-auto", "colwidths-given", "colwidths-grid")
        if isinstance(node, nodes.table):
            classes = [cls for cls in classes if cls not in internal]
        if classes:
            atts["class"] = " ".join(classes)
        assert "id" not in atts
        ids = node.get("ids", [])
        ids.extend(atts.pop("ids", []))
        if ids:
            atts["id"] = ids[0]
            for id in ids[1:]:
                # Add empty "span" elements for additional IDs.  Note
                # that we cannot use empty "a" elements because there
                # may be targets inside of references, but nested "a"
                # elements aren't allowed in XHTML (even if they do
                # not all have a "href" attribute).
                if empty or isinstance(node, (nodes.Sequential, nodes.docinfo, nodes.table)):
                    # Insert target right in front of element.
                    prefix.append('<span id="%s"></span>' % id)
                else:
                    # Non-empty tag.  Place the auxiliary <span> tag
                    # *inside* the element, as the first child.
                    suffix += '<span id="%s"></span>' % id
        attlist = sorted(atts.items())
        parts = [tagname]
        for name, value in attlist:
            # value=None was used for boolean attributes without
            # value, but this isn't supported by XHTML.
            assert value is not None
            if isinstance(value, list):
                values = [str(v) for v in value]
                parts.append('%s="%s"' % (name.lower(), self.attval(" ".join(values))))
            else:
                parts.append('%s="%s"' % (name.lower(), self.attval(str(value))))
        if empty:
            infix = " /"
        else:
            infix = ""
        return "".join(prefix) + "<%s%s>" % (" ".join(parts), infix) + suffix

    def emptytag(self, node, tagname, suffix="\n", **attributes):
        """Construct and return an XML-compatible empty tag."""
        return self.starttag(node, tagname, suffix, empty=True, **attributes)

    def set_class_on_child(self, node, class_, index=0):
        """
        Set class `class_` on the visible child no. index of `node`.
        Do nothing if node has fewer children than `index`.
        """
        children = [n for n in node if not isinstance(n, nodes.Invisible)]
        try:
            child = children[index]
        except IndexError:
            return
        child["classes"].append(class_)

    def visit_Text(self, node):
        text = node.astext()
        encoded = self.encode(text)
        if self.in_mailto and self.settings.cloak_email_addresses:
            encoded = self.cloak_email(encoded)
        self.body.append(encoded)

    def depart_Text(self, node):
        pass

    def visit_abbreviation(self, node):
        # @@@ implementation incomplete ("title" attribute)
        self.body.append(self.starttag(node, "abbr", ""))

    def depart_abbreviation(self, node):
        self.body.append("</abbr>")

    def visit_acronym(self, node):
        # @@@ implementation incomplete ("title" attribute)
        self.body.append(self.starttag(node, "acronym", ""))

    def depart_acronym(self, node):
        self.body.append("</acronym>")

    def visit_address(self, node):
        self.visit_docinfo_item(node, "address", meta=False)
        self.body.append(self.starttag(node, "pre", suffix="", CLASS="address"))

    def depart_address(self, node):
        self.body.append("\n</pre>\n")
        self.depart_docinfo_item()

    def visit_admonition(self, node):
        self.body.append(self.starttag(node, "aside", classes=["admonition"]))

    def depart_admonition(self, node=None):
        self.body.append("</aside>\n")

    attribution_formats = {"dash": ("\u2014", ""), "parentheses": ("(", ")"), "parens": ("(", ")"), "none": ("", "")}

    def visit_attribution(self, node):
        prefix, suffix = self.attribution_formats[self.settings.attribution]
        self.context.append(suffix)
        self.body.append(self.starttag(node, "p", prefix, CLASS="attribution"))

    def depart_attribution(self, node):
        self.body.append(self.context.pop() + "</p>\n")

    def visit_author(self, node):
        if not isinstance(node.parent, nodes.authors):
            self.visit_docinfo_item(node, "author")
        self.body.append("<p>")

    def depart_author(self, node):
        self.body.append("</p>")
        if isinstance(node.parent, nodes.authors):
            self.body.append("\n")
        else:
            self.depart_docinfo_item()

    def visit_authors(self, node):
        self.visit_docinfo_item(node, "authors")

    def depart_authors(self, node):
        self.depart_docinfo_item()

    def visit_block_quote(self, node):
        self.body.append(self.starttag(node, "blockquote"))

    def depart_block_quote(self, node):
        self.body.append("</blockquote>\n")

    def check_simple_list(self, node):
        """Check for a simple list that can be rendered compactly."""
        visitor = SimpleListChecker(self.document)
        try:
            node.walk(visitor)
        except nodes.NodeFound:
            return False
        else:
            return True

    # Compact lists
    # ------------
    # Include definition lists and field lists (in addition to ordered
    # and unordered lists) in the test if a list is "simple"  (cf. the
    # html4css1.HTMLTranslator docstring and the SimpleListChecker class at
    # the end of this file).

    def is_compactable(self, node):
        # explicit class arguments have precedence
        if "compact" in node["classes"]:
            return True
        if "open" in node["classes"]:
            return False
        # check config setting:
        if isinstance(node, (nodes.field_list, nodes.definition_list)) and not self.settings.compact_field_lists:
            return False
        if isinstance(node, (nodes.enumerated_list, nodes.bullet_list)) and not self.settings.compact_lists:
            return False
        # Table of Contents:
        if "contents" in node.parent["classes"]:
            return True
        # check the list items:
        return self.check_simple_list(node)

    def visit_bullet_list(self, node):
        atts = {}
        old_compact_simple = self.compact_simple
        self.context.append((self.compact_simple, self.compact_p))
        self.compact_p = None
        self.compact_simple = self.is_compactable(node)
        if self.compact_simple and not old_compact_simple:
            atts["class"] = "simple"
        self.body.append(self.starttag(node, "ul", **atts))

    def depart_bullet_list(self, node):
        self.compact_simple, self.compact_p = self.context.pop()
        self.body.append("</ul>\n")

    def visit_caption(self, node):
        self.body.append(self.starttag(node, "p", "", CLASS="caption"))

    def depart_caption(self, node):
        self.body.append("</p>\n")

    # Use semantic tag and DPub role (HTML4 uses a table)
    def visit_citation(self, node):
        # role 'doc-bibloentry' requires wrapping in an element with
        # role 'list' and an element with role 'doc-bibliography'
        # https://www.w3.org/TR/dpub-aria-1.0/#doc-biblioentry)
        if not isinstance(node.previous_sibling(), type(node)):
            self.body.append('<div role="list" class="citation-list">\n')
        self.body.append(self.starttag(node, "div", classes=[node.tagname], role="doc-biblioentry"))

    def depart_citation(self, node):
        self.body.append("</div>\n")
        if not isinstance(node.next_node(descend=False, siblings=True), type(node)):
            self.body.append("</div>\n")

    # Use DPub role (overwritten in HTML4)
    def visit_citation_reference(self, node):
        href = "#"
        if "refid" in node:
            href += node["refid"]
        elif "refname" in node:
            href += self.document.nameids[node["refname"]]
        # else: # TODO system message (or already in the transform)?
        # 'Citation reference missing.'
        self.body.append(
            self.starttag(node, "a", suffix="[", href=href, classes=["citation-reference"], role="doc-biblioref")
        )

    def depart_citation_reference(self, node):
        self.body.append("]</a>")

    # classifier
    # ----------
    # don't insert classifier-delimiter here (done by CSS)

    def visit_classifier(self, node):
        self.body.append(self.starttag(node, "span", "", CLASS="classifier"))

    def depart_classifier(self, node):
        self.body.append("</span>")

    def visit_colspec(self, node):
        self.colspecs.append(node)
        # "stubs" list is an attribute of the tgroup element:
        node.parent.stubs.append(node.attributes.get("stub"))

    def depart_colspec(self, node):
        # write out <colgroup> when all colspecs are processed
        if isinstance(node.next_node(descend=False, siblings=True), nodes.colspec):
            return
        if "colwidths-auto" in node.parent.parent["classes"] or (
            "colwidths-grid" not in self.settings.table_style and "colwidths-given" not in node.parent.parent["classes"]
        ):
            return
        self.body.append(self.starttag(node, "colgroup"))
        total_width = sum(node["colwidth"] for node in self.colspecs)
        for node in self.colspecs:
            colwidth = node["colwidth"] / total_width
            self.body.append(self.emptytag(node, "col", style=f"width: {colwidth:.1%}"))
        self.body.append("</colgroup>\n")

    def visit_comment(self, node, sub=re.compile("-(?=-)").sub):
        """Escape double-dashes in comment text."""
        self.body.append("<!-- %s -->\n" % sub("- ", node.astext()))
        # Content already processed:
        raise nodes.SkipNode

    def visit_compound(self, node):
        self.body.append(self.starttag(node, "div", CLASS="compound"))

    def depart_compound(self, node):
        self.body.append("</div>\n")

    def visit_container(self, node):
        self.body.append(self.starttag(node, "div", CLASS="docutils container"))

    def depart_container(self, node):
        self.body.append("</div>\n")

    def visit_contact(self, node):
        self.visit_docinfo_item(node, "contact", meta=False)

    def depart_contact(self, node):
        self.depart_docinfo_item()

    def visit_copyright(self, node):
        self.visit_docinfo_item(node, "copyright")

    def depart_copyright(self, node):
        self.depart_docinfo_item()

    def visit_date(self, node):
        self.visit_docinfo_item(node, "date")

    def depart_date(self, node):
        self.depart_docinfo_item()

    def visit_decoration(self, node):
        pass

    def depart_decoration(self, node):
        pass

    def visit_definition(self, node):
        if "details" in node.parent.parent["classes"]:
            self.body.append("</summary>\n")
        else:
            self.body.append("</dt>\n")
            self.body.append(self.starttag(node, "dd", ""))

    def depart_definition(self, node):
        if "details" not in node.parent.parent["classes"]:
            self.body.append("</dd>\n")

    def visit_definition_list(self, node):
        if "details" in node["classes"]:
            self.body.append(self.starttag(node, "div"))
        else:
            classes = ["simple"] if self.is_compactable(node) else []
            self.body.append(self.starttag(node, "dl", classes=classes))

    def depart_definition_list(self, node):
        if "details" in node["classes"]:
            self.body.append("</div>\n")
        else:
            self.body.append("</dl>\n")

    # Use a "details" disclosure element if parent has "class" arg "details".
    def visit_definition_list_item(self, node):
        if "details" in node.parent["classes"]:
            atts = {}
            if "open" in node.parent["classes"]:
                atts["open"] = "open"
            self.body.append(self.starttag(node, "details", **atts))

    def depart_definition_list_item(self, node):
        if "details" in node.parent["classes"]:
            self.body.append("</details>\n")

    def visit_description(self, node):
        self.body.append(self.starttag(node, "dd", ""))

    def depart_description(self, node):
        self.body.append("</dd>\n")

    def visit_docinfo(self, node):
        self.context.append(len(self.body))
        classes = ["docinfo"]
        if self.is_compactable(node):
            classes.append("simple")
        self.body.append(self.starttag(node, "dl", classes=classes))

    def depart_docinfo(self, node):
        self.body.append("</dl>\n")
        start = self.context.pop()
        self.docinfo = self.body[start:]
        self.body = []

    def visit_docinfo_item(self, node, name, meta=True):
        if meta:
            self.meta.append(f'<meta name="{name}" ' f'content="{self.attval(node.astext())}" />\n')
        self.body.append(f'<dt class="{name}">{self.language.labels[name]}' '<span class="colon">:</span></dt>\n')
        self.body.append(self.starttag(node, "dd", "", CLASS=name))

    def depart_docinfo_item(self):
        self.body.append("</dd>\n")

    def visit_doctest_block(self, node):
        self.body.append(self.starttag(node, "pre", suffix="", classes=["code", "python", "doctest"]))

    def depart_doctest_block(self, node):
        self.body.append("\n</pre>\n")

    def visit_document(self, node):
        title = node.get("title") or os.path.basename(node["source"]) or "untitled Docutils document"
        self.head.append(f"<title>{self.encode(title)}</title>\n")

    def depart_document(self, node):
        self.head_prefix.extend([self.doctype, self.head_prefix_template % {"lang": self.settings.language_code}])
        self.html_prolog.append(self.doctype)
        self.head = self.meta[:] + self.head
        if 'name="dcterms.' in "".join(self.meta):
            self.head.append('<link rel="schema.dcterms"' ' href="http://purl.org/dc/terms/"/>')
        if self.math_header:
            if self.math_output == "mathjax":
                self.head.extend(self.math_header)
            else:
                self.stylesheet.extend(self.math_header)
        # skip content-type meta tag with interpolated charset value:
        self.html_head.extend(self.head[1:])
        self.body_prefix.append(self.starttag(node, **self.documenttag_args))
        self.body_suffix.insert(0, f'</{self.documenttag_args["tagname"]}>\n')
        self.fragment.extend(self.body)  # self.fragment is the "naked" body
        self.html_body.extend(
            self.body_prefix[1:] + self.body_pre_docinfo + self.docinfo + self.body + self.body_suffix[:-1]
        )
        assert not self.context, f"len(context) = {len(self.context)}"

    def visit_emphasis(self, node):
        self.body.append(self.starttag(node, "em", ""))

    def depart_emphasis(self, node):
        self.body.append("</em>")

    def visit_entry(self, node):
        atts = {"classes": []}
        if isinstance(node.parent.parent, nodes.thead):
            atts["classes"].append("head")
        if node.parent.parent.parent.stubs[node.parent.column]:
            # "stubs" list is an attribute of the tgroup element
            atts["classes"].append("stub")
        if atts["classes"]:
            tagname = "th"
        else:
            tagname = "td"
        node.parent.column += 1
        if "morerows" in node:
            atts["rowspan"] = node["morerows"] + 1
        if "morecols" in node:
            atts["colspan"] = node["morecols"] + 1
            node.parent.column += node["morecols"]
        self.body.append(self.starttag(node, tagname, "", **atts))
        self.context.append("</%s>\n" % tagname.lower())

    def depart_entry(self, node):
        self.body.append(self.context.pop())

    def visit_enumerated_list(self, node):
        atts = {"classes": []}
        if "start" in node:
            atts["start"] = node["start"]
        if "enumtype" in node:
            atts["classes"].append(node["enumtype"])
        if self.is_compactable(node):
            atts["classes"].append("simple")
        self.body.append(self.starttag(node, "ol", **atts))

    def depart_enumerated_list(self, node):
        self.body.append("</ol>\n")

    def visit_field_list(self, node):
        atts = {}
        classes = node.setdefault("classes", [])
        for i, cls in enumerate(classes):
            if cls.startswith("field-indent-"):
                try:
                    indent_length = length_or_percentage_or_unitless(cls[13:], "px")
                except ValueError:
                    break
                atts["style"] = "--field-indent: %s;" % indent_length
                classes.pop(i)
                break
        classes.append("field-list")
        if self.is_compactable(node):
            classes.append("simple")
        self.body.append(self.starttag(node, "dl", **atts))

    def depart_field_list(self, node):
        self.body.append("</dl>\n")

    def visit_field(self, node):
        pass

    def depart_field(self, node):
        pass

    # as field is ignored, pass class arguments to field-name and field-body:
    def visit_field_name(self, node):
        self.body.append(self.starttag(node, "dt", "", classes=node.parent["classes"]))

    def depart_field_name(self, node):
        self.body.append('<span class="colon">:</span></dt>\n')

    def visit_field_body(self, node):
        self.body.append(self.starttag(node, "dd", "", classes=node.parent["classes"]))
        # prevent misalignment of following content if the field is empty:
        if not node.children:
            self.body.append("<p></p>")

    def depart_field_body(self, node):
        self.body.append("</dd>\n")

    def visit_figure(self, node):
        atts = {"class": "figure"}
        if node.get("width"):
            atts["style"] = "width: %s" % node["width"]
        if node.get("align"):
            atts["class"] += " align-" + node["align"]
        self.body.append(self.starttag(node, "div", **atts))

    def depart_figure(self, node):
        self.body.append("</div>\n")

    def visit_footer(self, node):
        self.context.append(len(self.body))

    def depart_footer(self, node):
        start = self.context.pop()
        footer = [self.starttag(node, "div", CLASS="footer"), '<hr class="footer" />\n']
        footer.extend(self.body[start:])
        footer.append("\n</div>\n")
        self.footer.extend(footer)
        self.body_suffix[:0] = footer
        del self.body[start:]

    def visit_footnote(self, node):
        # No native HTML element: use <aside> with ARIA role
        # (html4css1 uses tables).
        # Wrap groups of footnotes for easier styling.
        label_style = self.settings.footnote_references  # brackets/superscript
        if not isinstance(node.previous_sibling(), type(node)):
            self.body.append(f'<aside class="footnote-list {label_style}">\n')
        self.body.append(self.starttag(node, "aside", classes=[node.tagname, label_style], role="doc-footnote"))

    def depart_footnote(self, node):
        self.body.append("</aside>\n")
        if not isinstance(node.next_node(descend=False, siblings=True), type(node)):
            self.body.append("</aside>\n")

    def visit_footnote_reference(self, node):
        href = "#" + node["refid"]
        classes = ["footnote-reference", self.settings.footnote_references]
        self.body.append(self.starttag(node, "a", suffix="", classes=classes, role="doc-noteref", href=href))
        self.body.append('<span class="fn-bracket">[</span>')

    def depart_footnote_reference(self, node):
        self.body.append('<span class="fn-bracket">]</span>')
        self.body.append("</a>")

    # Docutils-generated text: put section numbers in a span for CSS styling:
    def visit_generated(self, node):
        if "sectnum" in node["classes"]:
            # get section number (strip trailing no-break-spaces)
            sectnum = node.astext().rstrip(" ")
            self.body.append('<span class="sectnum">%s </span>' % self.encode(sectnum))
            # Content already processed:
            raise nodes.SkipNode

    def depart_generated(self, node):
        pass

    def visit_header(self, node):
        self.context.append(len(self.body))

    def depart_header(self, node):
        start = self.context.pop()
        header = [self.starttag(node, "div", CLASS="header")]
        header.extend(self.body[start:])
        header.append('\n<hr class="header"/>\n</div>\n')
        self.body_prefix.extend(header)
        self.header.extend(header)
        del self.body[start:]

    def visit_image(self, node):
        atts = {}
        uri = node["uri"]
        mimetype = mimetypes.guess_type(uri)[0]
        # image size
        if "width" in node:
            atts["width"] = node["width"]
        if "height" in node:
            atts["height"] = node["height"]
        if "scale" in node:
            if PIL and ("width" not in node or "height" not in node) and self.settings.file_insertion_enabled:
                imagepath = url2pathname(uri)
                try:
                    with PIL.Image.open(imagepath) as img:
                        imgsize = img.size
                except (OSError, UnicodeEncodeError):
                    pass  # TODO: warn?
                else:
                    self.settings.record_dependencies.add(imagepath.replace("\\", "/"))
                    if "width" not in atts:
                        atts["width"] = "%dpx" % imgsize[0]
                    if "height" not in atts:
                        atts["height"] = "%dpx" % imgsize[1]
                    del img
            for att_name in "width", "height":
                if att_name in atts:
                    match = re.match(r"([0-9.]+)(\S*)$", atts[att_name])
                    assert match
                    atts[att_name] = "%s%s" % (float(match.group(1)) * (float(node["scale"]) / 100), match.group(2))
        style = []
        for att_name in "width", "height":
            if att_name in atts:
                if re.match(r"^[0-9.]+$", atts[att_name]):
                    # Interpret unitless values as pixels.
                    atts[att_name] += "px"
                style.append("%s: %s;" % (att_name, atts[att_name]))
                del atts[att_name]
        if style:
            atts["style"] = " ".join(style)
        if isinstance(node.parent, nodes.TextElement) or (
            isinstance(node.parent, nodes.reference) and not isinstance(node.parent.parent, nodes.TextElement)
        ):
            # Inline context or surrounded by <a>...</a>.
            suffix = ""
        else:
            suffix = "\n"
        if "align" in node:
            atts["class"] = "align-%s" % node["align"]
        # Embed image file (embedded SVG or data URI):
        if self.image_loading == "embed":
            try:
                with open(url2pathname(uri), "rb") as imagefile:
                    imagedata = imagefile.read()
            except OSError as err:
                self.document.reporter.error("Cannot embed image %r: %s" % (uri, err.strerror))
            else:
                self.settings.record_dependencies.add(unquote_url(uri))
                # TODO: insert SVG as-is?
                # if mimetype == 'image/svg+xml':
                # read/parse, apply arguments,
                # insert as <svg ....> ... </svg> # (about 1/3 less data)
                data64 = base64.b64encode(imagedata).decode()
                uri = "data:%s;base64,%s" % (mimetype, data64)
        elif self.image_loading == "lazy":
            atts["loading"] = "lazy"
        if mimetype == "application/x-shockwave-flash":
            atts["type"] = mimetype
            # do NOT use an empty tag: incorrect rendering in browsers
            tag = self.starttag(node, "object", "", data=uri, **atts) + node.get("alt", uri) + "</object>" + suffix
        else:
            atts["alt"] = node.get("alt", node["uri"])
            tag = self.emptytag(node, "img", suffix, src=uri, **atts)
        self.body.append(tag)

    def depart_image(self, node):
        pass

    def visit_inline(self, node):
        self.body.append(self.starttag(node, "span", ""))

    def depart_inline(self, node):
        self.body.append("</span>")

    # footnote and citation labels:
    def visit_label(self, node):
        self.body.append('<span class="label">')
        self.body.append('<span class="fn-bracket">[</span>')
        # footnote/citation backrefs:
        if self.settings.footnote_backlinks:
            backrefs = node.parent.get("backrefs", [])
            if len(backrefs) == 1:
                self.body.append('<a role="doc-backlink"' ' href="#%s">' % backrefs[0])

    def depart_label(self, node):
        backrefs = []
        if self.settings.footnote_backlinks:
            backrefs = node.parent.get("backrefs", backrefs)
        if len(backrefs) == 1:
            self.body.append("</a>")
        self.body.append('<span class="fn-bracket">]</span></span>\n')
        if len(backrefs) > 1:
            backlinks = ['<a role="doc-backlink" href="#%s">%s</a>' % (ref, i) for (i, ref) in enumerate(backrefs, 1)]
            self.body.append('<span class="backrefs">(%s)</span>\n' % ",".join(backlinks))

    def visit_legend(self, node):
        self.body.append(self.starttag(node, "div", CLASS="legend"))

    def depart_legend(self, node):
        self.body.append("</div>\n")

    def visit_line(self, node):
        self.body.append(self.starttag(node, "div", suffix="", CLASS="line"))
        if not len(node):
            self.body.append("<br />")

    def depart_line(self, node):
        self.body.append("</div>\n")

    def visit_line_block(self, node):
        self.body.append(self.starttag(node, "div", CLASS="line-block"))

    def depart_line_block(self, node):
        self.body.append("</div>\n")

    def visit_list_item(self, node):
        self.body.append(self.starttag(node, "li", ""))

    def depart_list_item(self, node):
        self.body.append("</li>\n")

    # inline literal
    def visit_literal(self, node):
        # special case: "code" role
        classes = node["classes"]
        if "code" in classes:
            # filter 'code' from class arguments
            classes.pop(classes.index("code"))
            self.body.append(self.starttag(node, "code", ""))
            return
        self.body.append(self.starttag(node, "span", "", CLASS="docutils literal"))
        text = node.astext()
        if not isinstance(node.parent, nodes.literal_block):
            text = text.replace("\n", " ")
        # Protect text like ``--an-option`` and the regular expression
        # ``[+]?(\d+(\.\d*)?|\.\d+)`` from bad line wrapping
        for token in self.words_and_spaces.findall(text):
            if token.strip() and self.in_word_wrap_point.search(token):
                self.body.append('<span class="pre">%s</span>' % self.encode(token))
            else:
                self.body.append(self.encode(token))
        self.body.append("</span>")
        raise nodes.SkipNode  # content already processed

    def depart_literal(self, node):
        # skipped unless literal element is from "code" role:
        self.body.append("</code>")

    def visit_literal_block(self, node):
        self.body.append(self.starttag(node, "pre", "", CLASS="literal-block"))
        if "code" in node["classes"]:
            self.body.append("<code>")

    def depart_literal_block(self, node):
        if "code" in node["classes"]:
            self.body.append("</code>")
        self.body.append("</pre>\n")

    # Mathematics:
    # As there is no native HTML math support, we provide alternatives
    # for the math-output: LaTeX and MathJax simply wrap the content,
    # HTML and MathML also convert the math_code.
    # HTML container
    math_tags = {
        # math_output: (block, inline, class-arguments)
        "html": ("div", "span", "formula"),
        "latex": ("pre", "tt", "math"),
        "mathml": ("div", "", ""),
        "mathjax": ("div", "span", "math"),
    }

    def visit_math(self, node, math_env=""):
        # If the method is called from visit_math_block(), math_env != ''.

        if self.math_output not in self.math_tags:
            self.document.reporter.error(
                f'math-output format "{self.math_output}" not supported ' 'falling back to "latex"'
            )
            self.math_output = "latex"
        tag = self.math_tags[self.math_output][math_env == ""]
        clsarg = self.math_tags[self.math_output][2]
        # LaTeX container
        wrappers = {
            # math_mode: (inline, block)
            "html": ("$%s$", "\\begin{%s}\n%s\n\\end{%s}"),
            "latex": (None, None),
            "mathml": ("$%s$", "\\begin{%s}\n%s\n\\end{%s}"),
            "mathjax": (r"\(%s\)", "\\begin{%s}\n%s\n\\end{%s}"),
        }
        wrapper = wrappers[self.math_output][math_env != ""]
        if self.math_output == "mathml" and (
            not self.math_output_options or self.math_output_options[0] == "blahtexml"
        ):
            wrapper = None
        # get and wrap content
        math_code = node.astext().translate(unichar2tex.uni2tex_table)
        if wrapper:
            try:  # wrapper with three "%s"
                math_code = wrapper % (math_env, math_code, math_env)
            except TypeError:  # wrapper with one "%s"
                math_code = wrapper % math_code
        # settings and conversion
        if self.math_output in ("latex", "mathjax"):
            math_code = self.encode(math_code)
        if self.math_output == "mathjax" and not self.math_header:
            try:
                self.mathjax_url = self.math_output_options[0]
            except IndexError:
                self.document.reporter.warning("No MathJax URL specified, " "using local fallback " "(see config.html)")
            # append configuration, if not already present in the URL:
            # input LaTeX with AMS, output common HTML
            if "?" not in self.mathjax_url:
                self.mathjax_url += "?config=TeX-AMS_CHTML"
            self.math_header = [self.mathjax_script % self.mathjax_url]
        elif self.math_output == "html":
            if self.math_output_options and not self.math_header:
                self.math_header = [
                    self.stylesheet_call(utils.find_file_in_dirs(s, self.settings.stylesheet_dirs), adjust_path=True)
                    for s in self.math_output_options[0].split(",")
                ]
            # TODO: fix display mode in matrices and fractions
            math2html.DocumentParameters.displaymode = math_env != ""
            math_code = math2html.math2html(math_code)
        elif self.math_output == "mathml":
            if "XHTML 1" in self.doctype:
                self.doctype = self.doctype_mathml
                self.content_type = self.content_type_mathml
            converter = " ".join(self.math_output_options).lower()
            try:
                if converter == "latexml":
                    math_code = tex2mathml_extern.latexml(math_code, self.document.reporter)
                elif converter == "ttm":
                    math_code = tex2mathml_extern.ttm(math_code, self.document.reporter)
                elif converter == "blahtexml":
                    math_code = tex2mathml_extern.blahtexml(
                        math_code, inline=(not math_env), reporter=self.document.reporter
                    )
                elif converter == "pandoc":
                    math_code = tex2mathml_extern.pandoc(math_code, reporter=self.document.reporter)
                elif not converter:
                    math_code = latex2mathml.tex2mathml(math_code, inline=(not math_env))
                else:
                    self.document.reporter.error('option "%s" not supported ' 'with math-output "MathML"')
            except OSError:
                raise OSError('is "latexmlmath" in your PATH?')
            except SyntaxError as err:
                err_node = self.document.reporter.error(err, base_node=node)
                self.visit_system_message(err_node)
                self.body.append(self.starttag(node, "p"))
                self.body.append(",".join(err.args))
                self.body.append("</p>\n")
                self.body.append(self.starttag(node, "pre", CLASS="literal-block"))
                self.body.append(self.encode(math_code))
                self.body.append("\n</pre>\n")
                self.depart_system_message(err_node)
                raise nodes.SkipNode
        # append to document body
        if tag:
            self.body.append(self.starttag(node, tag, suffix="\n" * bool(math_env), CLASS=clsarg))
        self.body.append(math_code)
        if math_env:  # block mode (equation, display)
            self.body.append("\n")
        if tag:
            self.body.append("</%s>" % tag)
        if math_env:
            self.body.append("\n")
        # Content already processed:
        raise nodes.SkipNode

    def depart_math(self, node):
        pass  # never reached

    def visit_math_block(self, node):
        math_env = pick_math_environment(node.astext())
        self.visit_math(node, math_env=math_env)

    def depart_math_block(self, node):
        pass  # never reached

    # Meta tags: 'lang' attribute replaced by 'xml:lang' in XHTML 1.1
    # HTML5/polyglot recommends using both
    def visit_meta(self, node):
        self.meta.append(self.emptytag(node, "meta", **node.non_default_attributes()))

    def depart_meta(self, node):
        pass

    def visit_option(self, node):
        self.body.append(self.starttag(node, "span", "", CLASS="option"))

    def depart_option(self, node):
        self.body.append("</span>")
        if isinstance(node.next_node(descend=False, siblings=True), nodes.option):
            self.body.append(", ")

    def visit_option_argument(self, node):
        self.body.append(node.get("delimiter", " "))
        self.body.append(self.starttag(node, "var", ""))

    def depart_option_argument(self, node):
        self.body.append("</var>")

    def visit_option_group(self, node):
        self.body.append(self.starttag(node, "dt", ""))
        self.body.append("<kbd>")

    def depart_option_group(self, node):
        self.body.append("</kbd></dt>\n")

    def visit_option_list(self, node):
        self.body.append(self.starttag(node, "dl", CLASS="option-list"))

    def depart_option_list(self, node):
        self.body.append("</dl>\n")

    def visit_option_list_item(self, node):
        pass

    def depart_option_list_item(self, node):
        pass

    def visit_option_string(self, node):
        pass

    def depart_option_string(self, node):
        pass

    def visit_organization(self, node):
        self.visit_docinfo_item(node, "organization")

    def depart_organization(self, node):
        self.depart_docinfo_item()

    # Do not omit <p> tags
    # --------------------
    #
    # The HTML4CSS1 writer does this to "produce
    # visually compact lists (less vertical whitespace)". This writer
    # relies on CSS rules for visual compactness.
    #
    # * In XHTML 1.1, e.g., a <blockquote> element may not contain
    #   character data, so you cannot drop the <p> tags.
    # * Keeping simple paragraphs in the field_body enables a CSS
    #   rule to start the field-body on a new line if the label is too long
    # * it makes the code simpler.
    #
    # TODO: omit paragraph tags in simple table cells?

    def visit_paragraph(self, node):
        self.body.append(self.starttag(node, "p", ""))

    def depart_paragraph(self, node):
        self.body.append("</p>")
        if not (isinstance(node.parent, (nodes.list_item, nodes.entry)) and (len(node.parent) == 1)):
            self.body.append("\n")

    def visit_problematic(self, node):
        if node.hasattr("refid"):
            self.body.append('<a href="#%s">' % node["refid"])
            self.context.append("</a>")
        else:
            self.context.append("")
        self.body.append(self.starttag(node, "span", "", CLASS="problematic"))

    def depart_problematic(self, node):
        self.body.append("</span>")
        self.body.append(self.context.pop())

    def visit_raw(self, node):
        if "html" in node.get("format", "").split():
            if isinstance(node.parent, nodes.TextElement):
                tagname = "span"
            else:
                tagname = "div"
            if node["classes"]:
                self.body.append(self.starttag(node, tagname, suffix=""))
            self.body.append(node.astext())
            if node["classes"]:
                self.body.append("</%s>" % tagname)
        # Keep non-HTML raw text out of output:
        raise nodes.SkipNode

    def visit_reference(self, node):
        atts = {"class": "reference"}
        if "refuri" in node:
            atts["href"] = node["refuri"]
            if self.settings.cloak_email_addresses and atts["href"].startswith("mailto:"):
                atts["href"] = self.cloak_mailto(atts["href"])
                self.in_mailto = True
            atts["class"] += " external"
        else:
            assert "refid" in node, 'References must have "refuri" or "refid" attribute.'
            atts["href"] = "#" + node["refid"]
            atts["class"] += " internal"
        if len(node) == 1 and isinstance(node[0], nodes.image):
            atts["class"] += " image-reference"
        if not isinstance(node.parent, nodes.TextElement):
            assert len(node) == 1 and isinstance(node[0], nodes.image)
            atts["class"] += " image-reference"
        self.body.append(self.starttag(node, "a", "", **atts))

    def depart_reference(self, node):
        self.body.append("</a>")
        if not isinstance(node.parent, nodes.TextElement):
            self.body.append("\n")
        self.in_mailto = False

    def visit_revision(self, node):
        self.visit_docinfo_item(node, "revision", meta=False)

    def depart_revision(self, node):
        self.depart_docinfo_item()

    def visit_row(self, node):
        self.body.append(self.starttag(node, "tr", ""))
        node.column = 0

    def depart_row(self, node):
        self.body.append("</tr>\n")

    def visit_rubric(self, node):
        self.body.append(self.starttag(node, "p", "", CLASS="rubric"))

    def depart_rubric(self, node):
        self.body.append("</p>\n")

    def visit_section(self, node):
        self.section_level += 1
        self.body.append(self.starttag(node, "div", CLASS="section"))

    def depart_section(self, node):
        self.section_level -= 1
        self.body.append("</div>\n")

    # TODO: use the new HTML5 element <aside>
    def visit_sidebar(self, node):
        self.body.append(self.starttag(node, "div", CLASS="sidebar"))
        self.in_sidebar = True

    def depart_sidebar(self, node):
        self.body.append("</div>\n")
        self.in_sidebar = False

    def visit_status(self, node):
        self.visit_docinfo_item(node, "status", meta=False)

    def depart_status(self, node):
        self.depart_docinfo_item()

    def visit_strong(self, node):
        self.body.append(self.starttag(node, "strong", ""))

    def depart_strong(self, node):
        self.body.append("</strong>")

    def visit_subscript(self, node):
        self.body.append(self.starttag(node, "sub", ""))

    def depart_subscript(self, node):
        self.body.append("</sub>")

    def visit_substitution_definition(self, node):
        """Internal only."""
        raise nodes.SkipNode

    def visit_substitution_reference(self, node):
        self.unimplemented_visit(node)

    # h1–h6 elements must not be used to markup subheadings, subtitles,
    # alternative titles and taglines unless intended to be the heading for a
    # new section or subsection.
    # -- http://www.w3.org/TR/html51/sections.html#headings-and-sections
    def visit_subtitle(self, node):
        if isinstance(node.parent, nodes.sidebar):
            classes = ["sidebar-subtitle"]
        elif isinstance(node.parent, nodes.document):
            classes = ["subtitle"]
            self.in_document_title = len(self.body) + 1
        elif isinstance(node.parent, nodes.section):
            classes = ["section-subtitle"]
        self.body.append(self.starttag(node, "p", "", classes=classes))

    def depart_subtitle(self, node):
        self.body.append("</p>\n")
        if isinstance(node.parent, nodes.document):
            self.subtitle = self.body[self.in_document_title : -1]
            self.in_document_title = 0
            self.body_pre_docinfo.extend(self.body)
            self.html_subtitle.extend(self.body)
            del self.body[:]

    def visit_superscript(self, node):
        self.body.append(self.starttag(node, "sup", ""))

    def depart_superscript(self, node):
        self.body.append("</sup>")

    def visit_system_message(self, node):
        self.body.append(self.starttag(node, "aside", CLASS="system-message"))
        self.body.append('<p class="system-message-title">')
        backref_text = ""
        if len(node["backrefs"]):
            backrefs = node["backrefs"]
            if len(backrefs) == 1:
                backref_text = '; <em><a href="#%s">backlink</a></em>' % backrefs[0]
            else:
                i = 1
                backlinks = []
                for backref in backrefs:
                    backlinks.append('<a href="#%s">%s</a>' % (backref, i))
                    i += 1
                backref_text = "; <em>backlinks: %s</em>" % ", ".join(backlinks)
        if node.hasattr("line"):
            line = ", line %s" % node["line"]
        else:
            line = ""
        self.body.append(
            "System Message: %s/%s "
            '(<span class="docutils literal">%s</span>%s)%s</p>\n'
            % (node["type"], node["level"], self.encode(node["source"]), line, backref_text)
        )

    def depart_system_message(self, node):
        self.body.append("</aside>\n")

    def visit_table(self, node):
        atts = {"classes": self.settings.table_style.replace(",", " ").split()}
        if "align" in node:
            atts["classes"].append("align-%s" % node["align"])
        if "width" in node:
            atts["style"] = "width: %s;" % node["width"]
        tag = self.starttag(node, "table", **atts)
        self.body.append(tag)

    def depart_table(self, node):
        self.body.append("</table>\n")

    def visit_target(self, node):
        if "refuri" not in node and "refid" not in node and "refname" not in node:
            self.body.append(self.starttag(node, "span", "", CLASS="target"))
            self.context.append("</span>")
        else:
            self.context.append("")

    def depart_target(self, node):
        self.body.append(self.context.pop())

    # no hard-coded vertical alignment in table body
    def visit_tbody(self, node):
        self.body.append(self.starttag(node, "tbody"))

    def depart_tbody(self, node):
        self.body.append("</tbody>\n")

    def visit_term(self, node):
        if "details" in node.parent.parent["classes"]:
            self.body.append(self.starttag(node, "summary", suffix=""))
        else:
            # The parent node (definition_list_item) is omitted in HTML.
            self.body.append(
                self.starttag(node, "dt", suffix="", classes=node.parent["classes"], ids=node.parent["ids"])
            )

    def depart_term(self, node):
        # Leave the end tag to `self.visit_definition()`,
        # in case there's a classifier.
        pass

    def visit_tgroup(self, node):
        self.colspecs = []
        node.stubs = []

    def depart_tgroup(self, node):
        pass

    def visit_thead(self, node):
        self.body.append(self.starttag(node, "thead"))

    def depart_thead(self, node):
        self.body.append("</thead>\n")

    def section_title_tags(self, node):
        atts = {}
        h_level = self.section_level + self.initial_header_level - 1
        # Only 6 heading levels have dedicated HTML tags.
        tagname = "h%i" % min(h_level, 6)
        if h_level > 6:
            atts["aria-level"] = h_level
        start_tag = self.starttag(node, tagname, "", **atts)
        if node.hasattr("refid"):
            atts = {}
            atts["class"] = "toc-backref"
            atts["role"] = "doc-backlink"  # HTML5 only
            atts["href"] = "#" + node["refid"]
            start_tag += self.starttag(nodes.reference(), "a", "", **atts)
            close_tag = "</a></%s>\n" % tagname
        else:
            close_tag = "</%s>\n" % tagname
        return start_tag, close_tag

    def visit_title(self, node):
        close_tag = "</p>\n"
        if isinstance(node.parent, nodes.topic):
            # TODO: use role="heading" or <h1>? (HTML5 only)
            self.body.append(self.starttag(node, "p", "", CLASS="topic-title"))
        elif isinstance(node.parent, nodes.sidebar):
            # TODO: use role="heading" or <h1>? (HTML5 only)
            self.body.append(self.starttag(node, "p", "", CLASS="sidebar-title"))
        elif isinstance(node.parent, nodes.Admonition):
            self.body.append(self.starttag(node, "p", "", CLASS="admonition-title"))
        elif isinstance(node.parent, nodes.table):
            self.body.append(self.starttag(node, "caption", ""))
            close_tag = "</caption>\n"
        elif isinstance(node.parent, nodes.document):
            self.body.append(self.starttag(node, "h1", "", CLASS="title"))
            close_tag = "</h1>\n"
            self.in_document_title = len(self.body)
        else:
            assert isinstance(node.parent, nodes.section)
            # Get correct heading and evt. backlink tags
            start_tag, close_tag = self.section_title_tags(node)
            self.body.append(start_tag)
        self.context.append(close_tag)

    def depart_title(self, node):
        self.body.append(self.context.pop())
        if self.in_document_title:
            self.title = self.body[self.in_document_title : -1]
            self.in_document_title = 0
            self.body_pre_docinfo.extend(self.body)
            self.html_title.extend(self.body)
            del self.body[:]

    def visit_title_reference(self, node):
        self.body.append(self.starttag(node, "cite", ""))

    def depart_title_reference(self, node):
        self.body.append("</cite>")

    def visit_topic(self, node):
        self.body.append(self.starttag(node, "div", CLASS="topic"))

    def depart_topic(self, node):
        self.body.append("</div>\n")

    def visit_transition(self, node):
        self.body.append(self.emptytag(node, "hr", CLASS="docutils"))

    def depart_transition(self, node):
        pass

    def visit_version(self, node):
        self.visit_docinfo_item(node, "version", meta=False)

    def depart_version(self, node):
        self.depart_docinfo_item()

    def unimplemented_visit(self, node):
        raise NotImplementedError("visiting unimplemented node type: %s" % node.__class__.__name__)


class SimpleListChecker(nodes.GenericNodeVisitor):

    """
    Raise `nodes.NodeFound` if non-simple list item is encountered.

    Here "simple" means a list item containing nothing other than a single
    paragraph, a simple list, or a paragraph followed by a simple list.

    This version also checks for simple field lists and docinfo.
    """

    def default_visit(self, node):
        raise nodes.NodeFound

    def visit_list_item(self, node):
        children = [child for child in node.children if not isinstance(child, nodes.Invisible)]
        if (
            children
            and isinstance(children[0], nodes.paragraph)
            and (
                isinstance(children[-1], nodes.bullet_list)
                or isinstance(children[-1], nodes.enumerated_list)
                or isinstance(children[-1], nodes.field_list)
            )
        ):
            children.pop()
        if len(children) <= 1:
            return
        else:
            raise nodes.NodeFound

    def pass_node(self, node):
        pass

    def ignore_node(self, node):
        # ignore nodes that are never complex (can contain only inline nodes)
        raise nodes.SkipNode

    # Paragraphs and text
    visit_Text = ignore_node
    visit_paragraph = ignore_node

    # Lists
    visit_bullet_list = pass_node
    visit_enumerated_list = pass_node
    visit_docinfo = pass_node

    # Docinfo nodes:
    visit_author = ignore_node
    visit_authors = visit_list_item
    visit_address = visit_list_item
    visit_contact = pass_node
    visit_copyright = ignore_node
    visit_date = ignore_node
    visit_organization = ignore_node
    visit_status = ignore_node
    visit_version = visit_list_item

    # Definition list:
    visit_definition_list = pass_node
    visit_definition_list_item = pass_node
    visit_term = ignore_node
    visit_classifier = pass_node
    visit_definition = visit_list_item

    # Field list:
    visit_field_list = pass_node
    visit_field = pass_node
    # the field body corresponds to a list item
    visit_field_body = visit_list_item
    visit_field_name = ignore_node

    # Invisible nodes should be ignored.
    visit_comment = ignore_node
    visit_substitution_definition = ignore_node
    visit_target = ignore_node
    visit_pending = ignore_node
