nixos-render-docs: add manual html converter

this converter is currently supposed to be able to reproduce the
docbook-generated html DOMs exactly, though not necessarily the
html *files*. it mirrors many docbook behaviours that seem rather odd,
such as top-level sections in chapters using the same heading depth as
understood by html as their parent chapters do. over time we can
hopefully remove all special casing needed to reproduce docbook
rendering, but for now at least it doesn't hurt *too* much.

pkgs/tools/nix/nixos-render-docs/src/nixos_render_docs/__init__.py

@@ -8,7 +8,6 @@ from pprint import pprint
 from typing import Any, Dict
 
 from .md import Converter
-from . import html
 from . import manual
 from . import options
 from . import parallel

pkgs/tools/nix/nixos-render-docs/src/nixos_render_docs/manual.py

@@ -1,19 +1,23 @@
 import argparse
+import html
 import json
+import re
+import xml.sax.saxutils as xml
 
 from abc import abstractmethod
 from collections.abc import Mapping, Sequence
 from pathlib import Path
 from typing import Any, cast, ClassVar, Generic, get_args, NamedTuple, Optional, Union
-from xml.sax.saxutils import escape, quoteattr
 
 import markdown_it
 from markdown_it.token import Token
 
 from . import md, options
-from .docbook import DocBookRenderer, Heading
-from .manual_structure import check_structure, FragmentType, is_include, TocEntryType
-from .md import Converter
+from .docbook import DocBookRenderer, Heading, make_xml_id
+from .html import HTMLRenderer, UnresolvedXrefError
+from .manual_structure import check_structure, FragmentType, is_include, TocEntry, TocEntryType, XrefTarget
+from .md import Converter, Renderer
+from .utils import Freezeable
 
 class BaseConverter(Converter[md.TR], Generic[md.TR]):
     # per-converter configuration for ns:arg=value arguments to include blocks, following
@@ -31,11 +35,16 @@ class BaseConverter(Converter[md.TR], Generic[md.TR]):
         self._base_paths = [ infile ]
         self._current_type = ['book']
         try:
-            converted = self._render(infile.read_text())
+            tokens = self._parse(infile.read_text())
+            self._postprocess(infile, outfile, tokens)
+            converted = self._renderer.render(tokens)
             outfile.write_text(converted)
         except Exception as e:
             raise RuntimeError(f"failed to render manual {infile}") from e
 
+    def _postprocess(self, infile: Path, outfile: Path, tokens: Sequence[Token]) -> None:
+        pass
+
     def _parse(self, src: str) -> list[Token]:
         tokens = super()._parse(src)
         check_structure(self._current_type[-1], tokens)
@@ -117,12 +126,12 @@ class BaseConverter(Converter[md.TR], Generic[md.TR]):
         except Exception as e:
             raise RuntimeError(f"processing options block in line {token.map[0] + 1}") from e
 
-class ManualDocBookRenderer(DocBookRenderer):
+class RendererMixin(Renderer):
     _toplevel_tag: str
     _revision: str
 
-    def __init__(self, toplevel_tag: str, revision: str, manpage_urls: Mapping[str, str]):
-        super().__init__(manpage_urls)
+    def __init__(self, toplevel_tag: str, revision: str, *args: Any, **kwargs: Any):
+        super().__init__(*args, **kwargs)
         self._toplevel_tag = toplevel_tag
         self._revision = revision
         self.rules |= {
@@ -139,20 +148,39 @@ class ManualDocBookRenderer(DocBookRenderer):
         # generic code is more complicated than it's worth. the checks above have verified
         # that both titles actually exist.
         if self._toplevel_tag == 'book':
-            assert tokens[1].children
-            assert tokens[4].children
-            if (maybe_id := cast(str, tokens[0].attrs.get('id', ""))):
-                maybe_id = "xml:id=" + quoteattr(maybe_id)
-            return (f'<book xmlns="http://docbook.org/ns/docbook"'
-                    f'      xmlns:xlink="http://www.w3.org/1999/xlink"'
-                    f'      {maybe_id} version="5.0">'
-                    f'  <title>{self.renderInline(tokens[1].children)}</title>'
-                    f'  <subtitle>{self.renderInline(tokens[4].children)}</subtitle>'
-                    f'  {super().render(tokens[6:])}'
-                    f'</book>')
+            return self._render_book(tokens)
 
         return super().render(tokens)
 
+    @abstractmethod
+    def _render_book(self, tokens: Sequence[Token]) -> str:
+        raise NotImplementedError()
+
+    @abstractmethod
+    def _included_thing(self, tag: str, token: Token, tokens: Sequence[Token], i: int) -> str:
+        raise NotImplementedError()
+
+    @abstractmethod
+    def included_options(self, token: Token, tokens: Sequence[Token], i: int) -> str:
+        raise NotImplementedError()
+
+class ManualDocBookRenderer(RendererMixin, DocBookRenderer):
+    def __init__(self, toplevel_tag: str, revision: str, manpage_urls: Mapping[str, str]):
+        super().__init__(toplevel_tag, revision, manpage_urls)
+
+    def _render_book(self, tokens: Sequence[Token]) -> str:
+        assert tokens[1].children
+        assert tokens[4].children
+        if (maybe_id := cast(str, tokens[0].attrs.get('id', ""))):
+            maybe_id = "xml:id=" + xml.quoteattr(maybe_id)
+        return (f'<book xmlns="http://docbook.org/ns/docbook"'
+                f'      xmlns:xlink="http://www.w3.org/1999/xlink"'
+                f'      {maybe_id} version="5.0">'
+                f'  <title>{self.renderInline(tokens[1].children)}</title>'
+                f'  <subtitle>{self.renderInline(tokens[4].children)}</subtitle>'
+                f'  {super(DocBookRenderer, self).render(tokens[6:])}'
+                f'</book>')
+
     def _heading_tag(self, token: Token, tokens: Sequence[Token], i: int) -> tuple[str, dict[str, str]]:
         (tag, attrs) = super()._heading_tag(token, tokens, i)
         # render() has already verified that we don't have supernumerary headings and since the
@@ -192,10 +220,10 @@ class ManualDocBookRenderer(DocBookRenderer):
     def paragraph_close(self, token: Token, tokens: Sequence[Token], i: int) -> str:
         return "\n" + super().paragraph_close(token, tokens, i)
     def code_block(self, token: Token, tokens: Sequence[Token], i: int) -> str:
-        return f"<programlisting>\n{escape(token.content)}</programlisting>"
+        return f"<programlisting>\n{xml.escape(token.content)}</programlisting>"
     def fence(self, token: Token, tokens: Sequence[Token], i: int) -> str:
-        info = f" language={quoteattr(token.info)}" if token.info != "" else ""
-        return f"<programlisting{info}>\n{escape(token.content)}</programlisting>"
+        info = f" language={xml.quoteattr(token.info)}" if token.info != "" else ""
+        return f"<programlisting{info}>\n{xml.escape(token.content)}</programlisting>"
 
 class DocBookConverter(BaseConverter[ManualDocBookRenderer]):
     INCLUDE_ARGS_NS = "docbook"
@@ -205,6 +233,366 @@ class DocBookConverter(BaseConverter[ManualDocBookRenderer]):
         self._renderer = ManualDocBookRenderer('book', revision, manpage_urls)
 
 
+class HTMLParameters(NamedTuple):
+    generator: str
+    stylesheets: Sequence[str]
+    scripts: Sequence[str]
+    toc_depth: int
+    chunk_toc_depth: int
+
+class ManualHTMLRenderer(RendererMixin, HTMLRenderer):
+    _base_path: Path
+    _html_params: HTMLParameters
+
+    def __init__(self, toplevel_tag: str, revision: str, html_params: HTMLParameters,
+                 manpage_urls: Mapping[str, str], xref_targets: dict[str, XrefTarget],
+                 base_path: Path):
+        super().__init__(toplevel_tag, revision, manpage_urls, xref_targets)
+        self._base_path, self._html_params = base_path, html_params
+
+    def _push(self, tag: str, hlevel_offset: int) -> Any:
+        result = (self._toplevel_tag, self._headings, self._attrspans, self._hlevel_offset)
+        self._hlevel_offset += hlevel_offset
+        self._toplevel_tag, self._headings, self._attrspans = tag, [], []
+        return result
+
+    def _pop(self, state: Any) -> None:
+        (self._toplevel_tag, self._headings, self._attrspans, self._hlevel_offset) = state
+
+    def _render_book(self, tokens: Sequence[Token]) -> str:
+        assert tokens[4].children
+        title_id = cast(str, tokens[0].attrs.get('id', ""))
+        title = self._xref_targets[title_id].title
+        # subtitles don't have IDs, so we can't use xrefs to get them
+        subtitle = self.renderInline(tokens[4].children)
+
+        toc = TocEntry.of(tokens[0])
+        return "\n".join([
+            self._file_header(toc),
+            ' <div class="book">',
+            '  <div class="titlepage">',
+            '   <div>',
+            f'   <div><h1 class="title"><a id="{html.escape(title_id, True)}"></a>{title}</h1></div>',
+            f'   <div><h2 class="subtitle">{subtitle}</h2></div>',
+            '   </div>',
+            "   <hr />",
+            '  </div>',
+            self._build_toc(tokens, 0),
+            super(HTMLRenderer, self).render(tokens[6:]),
+            ' </div>',
+            self._file_footer(toc),
+        ])
+
+    def _file_header(self, toc: TocEntry) -> str:
+        prev_link, up_link, next_link = "", "", ""
+        prev_a, next_a, parent_title = "", "", "&nbsp;"
+        home = toc.root
+        if toc.prev:
+            prev_link = f'<link rel="prev" href="{toc.prev.target.href()}" title="{toc.prev.target.title}" />'
+            prev_a = f'<a accesskey="p" href="{toc.prev.target.href()}">Prev</a>'
+        if toc.parent:
+            up_link = (
+                f'<link rel="up" href="{toc.parent.target.href()}" '
+                f'title="{toc.parent.target.title}" />'
+            )
+            if (part := toc.parent) and part.kind != 'book':
+                assert part.target.title
+                parent_title = part.target.title
+        if toc.next:
+            next_link = f'<link rel="next" href="{toc.next.target.href()}" title="{toc.next.target.title}" />'
+            next_a = f'<a accesskey="n" href="{toc.next.target.href()}">Next</a>'
+        return "\n".join([
+            '<?xml version="1.0" encoding="utf-8" standalone="no"?>',
+            '<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"',
+            '  "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">',
+            '<html xmlns="http://www.w3.org/1999/xhtml">',
+            ' <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />',
+            f' <title>{toc.target.title}</title>',
+            "".join((f'<link rel="stylesheet" type="text/css" href="{html.escape(style, True)}" />'
+                     for style in self._html_params.stylesheets)),
+            "".join((f'<script src="{html.escape(script, True)}" type="text/javascript"></script>'
+                     for script in self._html_params.scripts)),
+            f' <meta name="generator" content="{html.escape(self._html_params.generator, True)}" />',
+            f' <link rel="home" href="{home.target.href()}" title="{home.target.title}" />',
+            f' {up_link}{prev_link}{next_link}',
+            ' </head>',
+            ' <body>',
+            '  <div class="navheader">',
+            '   <table width="100%" summary="Navigation header">',
+            '    <tr>',
+            f'    <th colspan="3" align="center">{toc.target.title}</th>',
+            '    </tr>',
+            '    <tr>',
+            f'    <td width="20%" align="left">{prev_a}&nbsp;</td>',
+            f'    <th width="60%" align="center">{parent_title}</th>',
+            f'    <td width="20%" align="right">&nbsp;{next_a}</td>',
+            '    </tr>',
+            '   </table>',
+            '   <hr />',
+            '  </div>',
+        ])
+
+    def _file_footer(self, toc: TocEntry) -> str:
+        # prev, next = self._get_prev_and_next()
+        prev_a, up_a, home_a, next_a = "", "&nbsp;", "&nbsp;", ""
+        prev_text, up_text, next_text = "", "", ""
+        home = toc.root
+        if toc.prev:
+            prev_a = f'<a accesskey="p" href="{toc.prev.target.href()}">Prev</a>'
+            assert toc.prev.target.title
+            prev_text = toc.prev.target.title
+        if toc.parent:
+            home_a = f'<a accesskey="h" href="{home.target.href()}">Home</a>'
+            if toc.parent != home:
+                up_a = f'<a accesskey="u" href="{toc.parent.target.href()}">Up</a>'
+        if toc.next:
+            next_a = f'<a accesskey="n" href="{toc.next.target.href()}">Next</a>'
+            assert toc.next.target.title
+            next_text = toc.next.target.title
+        return "\n".join([
+            '  <div class="navfooter">',
+            '   <hr />',
+            '   <table width="100%" summary="Navigation footer">',
+            '    <tr>',
+            f'    <td width="40%" align="left">{prev_a}&nbsp;</td>',
+            f'    <td width="20%" align="center">{up_a}</td>',
+            f'    <td width="40%" align="right">&nbsp;{next_a}</td>',
+            '    </tr>',
+            '    <tr>',
+            f'     <td width="40%" align="left" valign="top">{prev_text}&nbsp;</td>',
+            f'     <td width="20%" align="center">{home_a}</td>',
+            f'     <td width="40%" align="right" valign="top">&nbsp;{next_text}</td>',
+            '    </tr>',
+            '   </table>',
+            '  </div>',
+            ' </body>',
+            '</html>',
+        ])
+
+    def _heading_tag(self, token: Token, tokens: Sequence[Token], i: int) -> str:
+        if token.tag == 'h1':
+            return self._toplevel_tag
+        return super()._heading_tag(token, tokens, i)
+    def _build_toc(self, tokens: Sequence[Token], i: int) -> str:
+        toc = TocEntry.of(tokens[i])
+        if toc.kind == 'section':
+            return ""
+        def walk_and_emit(toc: TocEntry, depth: int) -> list[str]:
+            if depth <= 0:
+                return []
+            result = []
+            for child in toc.children:
+                result.append(
+                    f'<dt>'
+                    f' <span class="{html.escape(child.kind, True)}">'
+                    f'  <a href="{child.target.href()}">{child.target.toc_html}</a>'
+                    f' </span>'
+                    f'</dt>'
+                )
+                # we want to look straight through parts because docbook-xsl does too, but it
+                # also makes for more uesful top-level tocs.
+                next_level = walk_and_emit(child, depth - (0 if child.kind == 'part' else 1))
+                if next_level:
+                    result.append(f'<dd><dl>{"".join(next_level)}</dl></dd>')
+            return result
+        toc_depth = (
+            self._html_params.chunk_toc_depth
+            if toc.starts_new_chunk and toc.kind != 'book'
+            else self._html_params.toc_depth
+        )
+        if not (items := walk_and_emit(toc, toc_depth)):
+            return ""
+        return (
+            f'<div class="toc">'
+            f' <p><strong>Table of Contents</strong></p>'
+            f' <dl class="toc">'
+            f'  {"".join(items)}'
+            f' </dl>'
+            f'</div>'
+        )
+
+    def _make_hN(self, level: int) -> tuple[str, str]:
+        # for some reason chapters don't increase the hN nesting count in docbook xslts. duplicate
+        # this for consistency.
+        if self._toplevel_tag == 'chapter':
+            level -= 1
+        # TODO docbook compat. these are never useful for us, but not having them breaks manual
+        # compare workflows while docbook is still allowed.
+        style = ""
+        if level + self._hlevel_offset < 3 \
+           and (self._toplevel_tag == 'section' or (self._toplevel_tag == 'chapter' and level > 0)):
+            style = "clear: both"
+        tag, hstyle = super()._make_hN(max(1, level))
+        return tag, style
+
+    def _included_thing(self, tag: str, token: Token, tokens: Sequence[Token], i: int) -> str:
+        outer, inner = [], []
+        # since books have no non-include content the toplevel book wrapper will not count
+        # towards nesting depth. other types will have at least a title+id heading which
+        # *does* count towards the nesting depth. chapters give a -1 to included sections
+        # mirroring the special handing in _make_hN. sigh.
+        hoffset = (
+            0 if not self._headings
+            else self._headings[-1].level - 1 if self._toplevel_tag == 'chapter'
+            else self._headings[-1].level
+        )
+        outer.append(self._maybe_close_partintro())
+        into = token.meta['include-args'].get('into-file')
+        fragments = token.meta['included']
+        state = self._push(tag, hoffset)
+        if into:
+            toc = TocEntry.of(fragments[0][0][0])
+            inner.append(self._file_header(toc))
+            # we do not set _hlevel_offset=0 because docbook doesn't either.
+        else:
+            inner = outer
+        for included, path in fragments:
+            try:
+                inner.append(self.render(included))
+            except Exception as e:
+                raise RuntimeError(f"rendering {path}") from e
+        if into:
+            inner.append(self._file_footer(toc))
+            (self._base_path / into).write_text("".join(inner))
+        self._pop(state)
+        return "".join(outer)
+
+    def included_options(self, token: Token, tokens: Sequence[Token], i: int) -> str:
+        conv = options.HTMLConverter(self._manpage_urls, self._revision, False,
+                                     token.meta['list-id'], token.meta['id-prefix'],
+                                     self._xref_targets)
+        conv.add_options(token.meta['source'])
+        return conv.finalize()
+
+def _to_base26(n: int) -> str:
+    return (_to_base26(n // 26) if n > 26 else "") + chr(ord("A") + n % 26)
+
+class HTMLConverter(BaseConverter[ManualHTMLRenderer]):
+    INCLUDE_ARGS_NS = "html"
+    INCLUDE_FRAGMENT_ALLOWED_ARGS = { 'into-file' }
+
+    _revision: str
+    _html_params: HTMLParameters
+    _manpage_urls: Mapping[str, str]
+    _xref_targets: dict[str, XrefTarget]
+    _redirection_targets: set[str]
+    _appendix_count: int = 0
+
+    def _next_appendix_id(self) -> str:
+        self._appendix_count += 1
+        return _to_base26(self._appendix_count - 1)
+
+    def __init__(self, revision: str, html_params: HTMLParameters, manpage_urls: Mapping[str, str]):
+        super().__init__()
+        self._revision, self._html_params, self._manpage_urls = revision, html_params, manpage_urls
+        self._xref_targets = {}
+        self._redirection_targets = set()
+        # renderer not set on purpose since it has a dependency on the output path!
+
+    def convert(self, infile: Path, outfile: Path) -> None:
+        self._renderer = ManualHTMLRenderer('book', self._revision, self._html_params,
+                                            self._manpage_urls, self._xref_targets, outfile.parent)
+        super().convert(infile, outfile)
+
+    def _parse(self, src: str) -> list[Token]:
+        tokens = super()._parse(src)
+        for token in tokens:
+            if not token.type.startswith('included_') \
+               or not (into := token.meta['include-args'].get('into-file')):
+                continue
+            assert token.map
+            if len(token.meta['included']) == 0:
+                raise RuntimeError(f"redirection target {into} in line {token.map[0] + 1} is empty!")
+            # we use blender-style //path to denote paths relative to the origin file
+            # (usually index.html). this makes everything a lot easier and clearer.
+            if not into.startswith("//") or '/' in into[2:]:
+                raise RuntimeError(f"html:into-file must be a relative-to-origin //filename", into)
+            into = token.meta['include-args']['into-file'] = into[2:]
+            if into in self._redirection_targets:
+                raise RuntimeError(f"redirection target {into} in line {token.map[0] + 1} is already in use")
+            self._redirection_targets.add(into)
+        return tokens
+
+    # xref | (id, type, heading inlines, file, starts new file)
+    def _collect_ids(self, tokens: Sequence[Token], target_file: str, typ: str, file_changed: bool
+                     ) -> list[XrefTarget | tuple[str, str, Token, str, bool]]:
+        result: list[XrefTarget | tuple[str, str, Token, str, bool]] = []
+        # collect all IDs and their xref substitutions. headings are deferred until everything
+        # has been parsed so we can resolve links in headings. if that's even used anywhere.
+        for (i, bt) in enumerate(tokens):
+            if bt.type == 'heading_open' and (id := cast(str, bt.attrs.get('id', ''))):
+                result.append((id, typ if bt.tag == 'h1' else 'section', tokens[i + 1], target_file,
+                               i == 0 and file_changed))
+            elif bt.type == 'included_options':
+                id_prefix = bt.meta['id-prefix']
+                for opt in bt.meta['source'].keys():
+                    id = make_xml_id(f"{id_prefix}{opt}")
+                    name = html.escape(opt)
+                    result.append(XrefTarget(id, f'<code class="option">{name}</code>', name, None, target_file))
+            elif bt.type.startswith('included_'):
+                sub_file = bt.meta['include-args'].get('into-file', target_file)
+                subtyp = bt.type.removeprefix('included_').removesuffix('s')
+                for si, (sub, _path) in enumerate(bt.meta['included']):
+                    result += self._collect_ids(sub, sub_file, subtyp, si == 0 and sub_file != target_file)
+            elif bt.type == 'inline':
+                assert bt.children
+                result += self._collect_ids(bt.children, target_file, typ, False)
+            elif id := cast(str, bt.attrs.get('id', '')):
+                # anchors and examples have no titles we could use, but we'll have to put
+                # *something* here to communicate that there's no title.
+                result.append(XrefTarget(id, "???", None, None, target_file))
+        return result
+
+    def _render_xref(self, id: str, typ: str, inlines: Token, path: str, drop_fragment: bool) -> XrefTarget:
+        assert inlines.children
+        title_html = self._renderer.renderInline(inlines.children)
+        if typ == 'appendix':
+            # NOTE the docbook compat is strong here
+            n = self._next_appendix_id()
+            prefix = f"Appendix\u00A0{n}.\u00A0"
+            # HACK for docbook compat: prefix the title inlines with appendix id if
+            # necessary. the alternative is to mess with titlepage rendering in headings,
+            # which seems just a lot worse than this
+            prefix_tokens = [Token(type='text', tag='', nesting=0, content=prefix)]
+            inlines.children = prefix_tokens + list(inlines.children)
+            title = prefix + title_html
+            toc_html = f"{n}. {title_html}"
+            title_html = f"Appendix&nbsp;{n}"
+        else:
+            toc_html, title = title_html, title_html
+            title_html = (
+                f"<em>{title_html}</em>"
+                if typ == 'chapter'
+                else title_html if typ in [ 'book', 'part' ]
+                else f'the section called “{title_html}”'
+            )
+        return XrefTarget(id, title_html, toc_html, re.sub('<.*?>', '', title), path, drop_fragment)
+
+    def _postprocess(self, infile: Path, outfile: Path, tokens: Sequence[Token]) -> None:
+        xref_queue = self._collect_ids(tokens, outfile.name, 'book', True)
+
+        failed = False
+        deferred = []
+        while xref_queue:
+            for item in xref_queue:
+                try:
+                    target = item if isinstance(item, XrefTarget) else self._render_xref(*item)
+                except UnresolvedXrefError as e:
+                    if failed:
+                        raise
+                    deferred.append(item)
+                    continue
+
+                if target.id in self._xref_targets:
+                    raise RuntimeError(f"found duplicate id #{target.id}")
+                self._xref_targets[target.id] = target
+            if len(deferred) == len(xref_queue):
+                failed = True # do another round and report the first error
+            xref_queue = deferred
+
+        TocEntry.collect_and_link(self._xref_targets, tokens)
+
+
 
 def _build_cli_db(p: argparse.ArgumentParser) -> None:
     p.add_argument('--manpage-urls', required=True)
@@ -212,17 +600,40 @@ def _build_cli_db(p: argparse.ArgumentParser) -> None:
     p.add_argument('infile', type=Path)
     p.add_argument('outfile', type=Path)
 
+def _build_cli_html(p: argparse.ArgumentParser) -> None:
+    p.add_argument('--manpage-urls', required=True)
+    p.add_argument('--revision', required=True)
+    p.add_argument('--generator', default='nixos-render-docs')
+    p.add_argument('--stylesheet', default=[], action='append')
+    p.add_argument('--script', default=[], action='append')
+    p.add_argument('--toc-depth', default=1, type=int)
+    p.add_argument('--chunk-toc-depth', default=1, type=int)
+    p.add_argument('infile', type=Path)
+    p.add_argument('outfile', type=Path)
+
 def _run_cli_db(args: argparse.Namespace) -> None:
     with open(args.manpage_urls, 'r') as manpage_urls:
         md = DocBookConverter(json.load(manpage_urls), args.revision)
         md.convert(args.infile, args.outfile)
 
+def _run_cli_html(args: argparse.Namespace) -> None:
+    with open(args.manpage_urls, 'r') as manpage_urls:
+        md = HTMLConverter(
+            args.revision,
+            HTMLParameters(args.generator, args.stylesheet, args.script, args.toc_depth,
+                           args.chunk_toc_depth),
+            json.load(manpage_urls))
+        md.convert(args.infile, args.outfile)
+
 def build_cli(p: argparse.ArgumentParser) -> None:
     formats = p.add_subparsers(dest='format', required=True)
     _build_cli_db(formats.add_parser('docbook'))
+    _build_cli_html(formats.add_parser('html'))
 
 def run_cli(args: argparse.Namespace) -> None:
     if args.format == 'docbook':
         _run_cli_db(args)
+    elif args.format == 'html':
+        _run_cli_html(args)
     else:
         raise RuntimeError('format not hooked up', args)