nixos-render-docs: add options commonmark converter

the old method of pasting parts of options.json into a markdown document
and hoping for the best no longer works now that options.json contains
more than just docbook. given the infrastructure we have now we can
actually render options.md properly, so we may as well do that.

3 files changed, 399 insertions, 0 deletions

diff --git a/pkgs/tools/nix/nixos-render-docs/src/nixos_render_docs/commonmark.py b/pkgs/tools/nix/nixos-render-docs/src/nixos_render_docs/commonmark.py
new file mode 100644
index 00000000000..4a708b1f92c
--- /dev/null
+++ b/pkgs/tools/nix/nixos-render-docs/src/nixos_render_docs/commonmark.py
@@ -0,0 +1,231 @@
+from collections.abc import Mapping, MutableMapping, Sequence
+from dataclasses import dataclass
+from typing import Any, cast, Optional
+
+from .md import md_escape, md_make_code, Renderer
+
+import markdown_it
+from markdown_it.token import Token
+from markdown_it.utils import OptionsDict
+
+@dataclass(kw_only=True)
+class List:
+    next_idx: Optional[int] = None
+    compact: bool
+    first_item_seen: bool = False
+
+@dataclass
+class Par:
+    indent: str
+    continuing: bool = False
+
+class CommonMarkRenderer(Renderer):
+    __output__ = "commonmark"
+
+    _parstack: list[Par]
+    _link_stack: list[str]
+    _list_stack: list[List]
+
+    def __init__(self, manpage_urls: Mapping[str, str], parser: Optional[markdown_it.MarkdownIt] = None):
+        super().__init__(manpage_urls, parser)
+        self._parstack = [ Par("") ]
+        self._link_stack = []
+        self._list_stack = []
+
+    def _enter_block(self, extra_indent: str) -> None:
+        self._parstack.append(Par(self._parstack[-1].indent + extra_indent))
+    def _leave_block(self) -> None:
+        self._parstack.pop()
+        self._parstack[-1].continuing = True
+    def _break(self) -> str:
+        self._parstack[-1].continuing = True
+        return f"\n{self._parstack[-1].indent}"
+    def _maybe_parbreak(self) -> str:
+        result = f"\n{self._parstack[-1].indent}" * 2 if self._parstack[-1].continuing else ""
+        self._parstack[-1].continuing = True
+        return result
+
+    def _admonition_open(self, kind: str) -> str:
+        pbreak = self._maybe_parbreak()
+        self._enter_block("")
+        return f"{pbreak}**{kind}:** "
+    def _admonition_close(self) -> str:
+        self._leave_block()
+        return ""
+
+    def _indent_raw(self, s: str) -> str:
+        if '\n' not in s:
+            return s
+        return f"\n{self._parstack[-1].indent}".join(s.splitlines())
+
+    def text(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+             env: MutableMapping[str, Any]) -> str:
+        self._parstack[-1].continuing = True
+        return self._indent_raw(md_escape(token.content))
+    def paragraph_open(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                       env: MutableMapping[str, Any]) -> str:
+        return self._maybe_parbreak()
+    def paragraph_close(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                        env: MutableMapping[str, Any]) -> str:
+        return ""
+    def hardbreak(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                  env: MutableMapping[str, Any]) -> str:
+        return f"  {self._break()}"
+    def softbreak(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                  env: MutableMapping[str, Any]) -> str:
+        return self._break()
+    def code_inline(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                    env: MutableMapping[str, Any]) -> str:
+        self._parstack[-1].continuing = True
+        return md_make_code(token.content)
+    def code_block(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                   env: MutableMapping[str, Any]) -> str:
+        return self.fence(token, tokens, i, options, env)
+    def link_open(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                  env: MutableMapping[str, Any]) -> str:
+        self._parstack[-1].continuing = True
+        self._link_stack.append(cast(str, token.attrs['href']))
+        return "["
+    def link_close(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                   env: MutableMapping[str, Any]) -> str:
+        return f"]({md_escape(self._link_stack.pop())})"
+    def list_item_open(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                       env: MutableMapping[str, Any]) -> str:
+        lst = self._list_stack[-1]
+        lbreak = "" if not lst.first_item_seen else self._break() * (1 if lst.compact else 2)
+        lst.first_item_seen = True
+        head = " -"
+        if lst.next_idx is not None:
+            head = f" {lst.next_idx}."
+            lst.next_idx += 1
+        self._enter_block(" " * (len(head) + 1))
+        return f'{lbreak}{head} '
+    def list_item_close(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                        env: MutableMapping[str, Any]) -> str:
+        self._leave_block()
+        return ""
+    def bullet_list_open(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                         env: MutableMapping[str, Any]) -> str:
+        self._list_stack.append(List(compact=bool(token.meta['compact'])))
+        return self._maybe_parbreak()
+    def bullet_list_close(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                          env: MutableMapping[str, Any]) -> str:
+        self._list_stack.pop()
+        return ""
+    def em_open(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                env: MutableMapping[str, Any]) -> str:
+        return "*"
+    def em_close(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                 env: MutableMapping[str, Any]) -> str:
+        return "*"
+    def strong_open(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                    env: MutableMapping[str, Any]) -> str:
+        return "**"
+    def strong_close(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                     env: MutableMapping[str, Any]) -> str:
+        return "**"
+    def fence(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+              env: MutableMapping[str, Any]) -> str:
+        code = token.content
+        if code.endswith('\n'):
+            code = code[:-1]
+        pbreak = self._maybe_parbreak()
+        return pbreak + self._indent_raw(md_make_code(code, info=token.info, multiline=True))
+    def blockquote_open(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                        env: MutableMapping[str, Any]) -> str:
+        pbreak = self._maybe_parbreak()
+        self._enter_block("> ")
+        return pbreak + "> "
+    def blockquote_close(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                         env: MutableMapping[str, Any]) -> str:
+        self._leave_block()
+        return ""
+    def note_open(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                  env: MutableMapping[str, Any]) -> str:
+        return self._admonition_open("Note")
+    def note_close(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                   env: MutableMapping[str, Any]) -> str:
+        return self._admonition_close()
+    def caution_open(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                     env: MutableMapping[str, Any]) -> str:
+        return self._admonition_open("Caution")
+    def caution_close(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                      env: MutableMapping[str, Any]) -> str:
+        return self._admonition_close()
+    def important_open(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                       env: MutableMapping[str, Any]) -> str:
+        return self._admonition_open("Important")
+    def important_close(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                        env: MutableMapping[str, Any]) -> str:
+        return self._admonition_close()
+    def tip_open(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                 env: MutableMapping[str, Any]) -> str:
+        return self._admonition_open("Tip")
+    def tip_close(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                  env: MutableMapping[str, Any]) -> str:
+        return self._admonition_close()
+    def warning_open(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                     env: MutableMapping[str, Any]) -> str:
+        return self._admonition_open("Warning")
+    def warning_close(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                      env: MutableMapping[str, Any]) -> str:
+        return self._admonition_close()
+    def dl_open(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                env: MutableMapping[str, Any]) -> str:
+        self._list_stack.append(List(compact=False))
+        return ""
+    def dl_close(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                 env: MutableMapping[str, Any]) -> str:
+        self._list_stack.pop()
+        return ""
+    def dt_open(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                env: MutableMapping[str, Any]) -> str:
+        pbreak = self._maybe_parbreak()
+        self._enter_block("   ")
+        # add an opening zero-width non-joiner to separate *our* emphasis from possible
+        # emphasis in the provided term
+        return f'{pbreak} - *{chr(0x200C)}'
+    def dt_close(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                 env: MutableMapping[str, Any]) -> str:
+        return f"{chr(0x200C)}*"
+    def dd_open(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                env: MutableMapping[str, Any]) -> str:
+        self._parstack[-1].continuing = True
+        return ""
+    def dd_close(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                 env: MutableMapping[str, Any]) -> str:
+        self._leave_block()
+        return ""
+    def myst_role(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                  env: MutableMapping[str, Any]) -> str:
+        self._parstack[-1].continuing = True
+        content = md_make_code(token.content)
+        if token.meta['name'] == 'manpage' and (url := self._manpage_urls.get(token.content)):
+            return f"[{content}]({url})"
+        return content # no roles in regular commonmark
+    def attr_span_begin(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                        env: MutableMapping[str, Any]) -> str:
+        # there's no way we can emit attrspans correctly in all cases. we could use inline
+        # html for ids, but that would not round-trip. same holds for classes. since this
+        # renderer is only used for approximate options export and all of these things are
+        # not allowed in options we can ignore them for now.
+        return ""
+    def attr_span_end(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                      env: MutableMapping[str, Any]) -> str:
+        return ""
+    def heading_open(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                     env: MutableMapping[str, Any]) -> str:
+        return token.markup + " "
+    def heading_close(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                      env: MutableMapping[str, Any]) -> str:
+        return "\n"
+    def ordered_list_open(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                          env: MutableMapping[str, Any]) -> str:
+        self._list_stack.append(
+            List(next_idx = cast(int, token.attrs.get('start', 1)),
+                 compact  = bool(token.meta['compact'])))
+        return self._maybe_parbreak()
+    def ordered_list_close(self, token: Token, tokens: Sequence[Token], i: int, options: OptionsDict,
+                           env: MutableMapping[str, Any]) -> str:
+        self._list_stack.pop()
+        return ""
diff --git a/pkgs/tools/nix/nixos-render-docs/src/nixos_render_docs/options.py b/pkgs/tools/nix/nixos-render-docs/src/nixos_render_docs/options.py
index 39ea8f8c627..d8a24b885f8 100644
--- a/pkgs/tools/nix/nixos-render-docs/src/nixos_render_docs/options.py
+++ b/pkgs/tools/nix/nixos-render-docs/src/nixos_render_docs/options.py
@@ -13,6 +13,7 @@ from xml.sax.saxutils import escape, quoteattr
 import markdown_it
 
 from . import parallel
+from .commonmark import CommonMarkRenderer
 from .docbook import DocBookRenderer, make_xml_id
 from .manpage import ManpageRenderer, man_escape
 from .md import Converter, md_escape, md_make_code
@@ -422,6 +423,59 @@ class ManpageConverter(BaseConverter):
 
         return "\n".join(result)
 
+class OptionsCommonMarkRenderer(OptionDocsRestrictions, CommonMarkRenderer):
+    pass
+
+class CommonMarkConverter(BaseConverter):
+    __renderer__ = OptionsCommonMarkRenderer
+    __option_block_separator__ = ""
+
+    def _parallel_render_prepare(self) -> Any:
+        return (self._manpage_urls, self._revision, self._markdown_by_default)
+    @classmethod
+    def _parallel_render_init_worker(cls, a: Any) -> CommonMarkConverter:
+        return cls(*a)
+
+    def _render_code(self, option: dict[str, Any], key: str) -> list[str]:
+        # NOTE this duplicates the old direct-paste behavior, even if it is somewhat
+        # incorrect, since users rely on it.
+        if lit := option_is(option, key, 'literalDocBook'):
+            return [ f"*{key.capitalize()}:* {lit['text']}" ]
+        else:
+            return super()._render_code(option, key)
+
+    def _render_description(self, desc: str | dict[str, Any]) -> list[str]:
+        # NOTE this duplicates the old direct-paste behavior, even if it is somewhat
+        # incorrect, since users rely on it.
+        if isinstance(desc, str) and not self._markdown_by_default:
+            return [ desc ]
+        else:
+            return super()._render_description(desc)
+
+    def _related_packages_header(self) -> list[str]:
+        return [ "*Related packages:*" ]
+
+    def _decl_def_header(self, header: str) -> list[str]:
+        return [ f"*{header}:*" ]
+
+    def _decl_def_entry(self, href: Optional[str], name: str) -> list[str]:
+        if href is not None:
+            return [ f" - [{md_escape(name)}]({href})" ]
+        return [ f" - {md_escape(name)}" ]
+
+    def _decl_def_footer(self) -> list[str]:
+        return []
+
+    def finalize(self) -> str:
+        result = []
+
+        for (name, opt) in self._sorted_options():
+            result.append(f"## {md_escape(name)}\n")
+            result += opt.lines
+            result.append("\n\n")
+
+        return "\n".join(result)
+
 def _build_cli_db(p: argparse.ArgumentParser) -> None:
     p.add_argument('--manpage-urls', required=True)
     p.add_argument('--revision', required=True)
@@ -437,6 +491,13 @@ def _build_cli_manpage(p: argparse.ArgumentParser) -> None:
     p.add_argument("infile")
     p.add_argument("outfile")
 
+def _build_cli_commonmark(p: argparse.ArgumentParser) -> None:
+    p.add_argument('--manpage-urls', required=True)
+    p.add_argument('--revision', required=True)
+    p.add_argument('--markdown-by-default', default=False, action='store_true')
+    p.add_argument("infile")
+    p.add_argument("outfile")
+
 def _run_cli_db(args: argparse.Namespace) -> None:
     with open(args.manpage_urls, 'r') as manpage_urls:
         md = DocBookConverter(
@@ -464,15 +525,30 @@ def _run_cli_manpage(args: argparse.Namespace) -> None:
     with open(args.outfile, 'w') as f:
         f.write(md.finalize())
 
+def _run_cli_commonmark(args: argparse.Namespace) -> None:
+    with open(args.manpage_urls, 'r') as manpage_urls:
+        md = CommonMarkConverter(
+            json.load(manpage_urls),
+            revision = args.revision,
+            markdown_by_default = args.markdown_by_default)
+
+        with open(args.infile, 'r') as f:
+            md.add_options(json.load(f))
+        with open(args.outfile, 'w') as f:
+            f.write(md.finalize())
+
 def build_cli(p: argparse.ArgumentParser) -> None:
     formats = p.add_subparsers(dest='format', required=True)
     _build_cli_db(formats.add_parser('docbook'))
     _build_cli_manpage(formats.add_parser('manpage'))
+    _build_cli_commonmark(formats.add_parser('commonmark'))
 
 def run_cli(args: argparse.Namespace) -> None:
     if args.format == 'docbook':
         _run_cli_db(args)
     elif args.format == 'manpage':
         _run_cli_manpage(args)
+    elif args.format == 'commonmark':
+        _run_cli_commonmark(args)
     else:
         raise RuntimeError('format not hooked up', args)
diff --git a/pkgs/tools/nix/nixos-render-docs/src/tests/test_commonmark.py b/pkgs/tools/nix/nixos-render-docs/src/tests/test_commonmark.py
new file mode 100644
index 00000000000..5e0d63eb672
--- /dev/null
+++ b/pkgs/tools/nix/nixos-render-docs/src/tests/test_commonmark.py
@@ -0,0 +1,92 @@
+import nixos_render_docs
+
+from sample_md import sample1
+
+from typing import Mapping, Optional
+
+import markdown_it
+
+class Converter(nixos_render_docs.md.Converter):
+    __renderer__ = nixos_render_docs.commonmark.CommonMarkRenderer
+
+# NOTE: in these tests we represent trailing spaces by ` ` and replace them with real space later,
+# since a number of editors will strip trailing whitespace on save and that would break the tests.
+
+def test_indented_fence() -> None:
+    c = Converter({})
+    s = """\
+>  - ```foo
+>    thing
+>      
+>    rest
+>    ```\
+""".replace(' ', ' ')
+    assert c._render(s) == s
+
+def test_full() -> None:
+    c = Converter({ 'man(1)': 'http://example.org' })
+    assert c._render(sample1) == f"""\
+**Warning:** foo
+
+**Note:** nested
+
+[
+multiline
+](link)
+
+[` man(1) `](http://example.org) reference
+
+some nested anchors
+
+*emph* **strong** *nesting emph **and strong** and ` code `*
+
+ - wide bullet
+
+ - list
+
+ 1. wide ordered
+
+ 2. list
+
+ - narrow bullet
+ - list
+
+ 1. narrow ordered
+ 2. list
+
+> quotes
+> 
+> > with *nesting*
+> > 
+> > ```
+> > nested code block
+> > ```
+> 
+>  - and lists
+>  - ```
+>    containing code
+>    ```
+> 
+> and more quote
+
+ 100. list starting at 100
+ 101. goes on
+
+ - *‌deflist‌*
+   
+   > with a quote
+   > and stuff
+   
+   ```
+   code block
+   ```
+   
+   ```
+   fenced block
+   ```
+   
+   text
+
+ - *‌more stuff in same deflist‌*
+   
+   foo""".replace(' ', ' ')