docs: Allow to generate man pages for nixvim (#686)

flake.nix

@@ -102,7 +102,11 @@
                 modules = modules pkgs;
               };
             }
-            // (import ./helpers pkgs);
+            // (import ./helpers pkgs)
+            // (import ./man-docs {
+              pkgs = pkgs-unfree;
+              modules = modules pkgs;
+            });
           legacyPackages = rec {
             makeNixvimWithModule = import ./wrappers/standalone.nix pkgs modules;
             makeNixvim = configuration:

man-docs/default.nix

@@ -0,0 +1,50 @@
+{
+  pkgs,
+  modules,
+}: let
+  nixvimPath = toString ./..;
+
+  gitHubDeclaration = user: repo: subpath: {
+    url = "https://github.com/${user}/${repo}/blob/master/${subpath}";
+    name = "<${repo}/${subpath}>";
+  };
+in rec {
+  nixvim-render-docs = pkgs.callPackage ./nixvim-render-docs {};
+
+  man-docs = let
+    eval = pkgs.lib.evalModules {
+      inherit modules;
+    };
+
+    options = pkgs.nixosOptionsDoc {
+      inherit (eval) options;
+      warningsAreErrors = false;
+      transformOptions = opt:
+        opt
+        // {
+          declarations =
+            map (
+              decl:
+                if pkgs.lib.hasPrefix nixvimPath (toString decl)
+                then
+                  gitHubDeclaration "nix-community" "nixvim"
+                  (pkgs.lib.removePrefix "/" (pkgs.lib.removePrefix nixvimPath (toString decl)))
+                else if decl == "lib/modules.nix"
+                then gitHubDeclaration "NixOS" "nixpkgs" decl
+                else decl
+            )
+            opt.declarations;
+        };
+    };
+  in
+    pkgs.runCommand "nixvim-configuration-reference-manpage" {
+      nativeBuildInputs = with pkgs; [installShellFiles nixvim-render-docs];
+    } ''
+      # Generate man-pages
+      mkdir -p $out/share/man/man5
+      nixvim-render-docs -j $NIX_BUILD_CORES options manpage \
+        --revision unstable \
+        ${options.optionsJSON}/share/doc/nixos/options.json \
+        $out/share/man/man5/nixvim.5
+    '';
+}

man-docs/nixvim-render-docs/default.nix

@@ -0,0 +1,31 @@
+{
+  python3,
+  lib,
+  nixos-render-docs,
+}:
+python3.pkgs.buildPythonApplication {
+  pname = "nixvim-render-docs";
+  version = "0.0";
+  format = "pyproject";
+
+  src = lib.cleanSourceWith {
+    filter = name: type:
+      lib.cleanSourceFilter name type
+      && ! (type
+        == "directory"
+        && builtins.elem (baseNameOf name) [
+          ".pytest_cache"
+          ".mypy_cache"
+          "__pycache__"
+        ]);
+    src = ./src;
+  };
+
+  nativeBuildInputs = with python3.pkgs; [
+    setuptools
+  ];
+
+  propagatedBuildInputs = [
+    nixos-render-docs
+  ];
+}

man-docs/nixvim-render-docs/src/nixvim_render_docs/__init__.py

@@ -0,0 +1,113 @@
+# Very laregly inspired by nixos_render_docs, in nixpkgs at:
+# `pkgs/tools/nix/nixos-render-docs/src/nixos_render_docs`
+
+import argparse
+import sys
+import traceback
+import json
+
+import nixos_render_docs
+from nixos_render_docs import parallel
+from nixos_render_docs import options as nx_options
+from nixos_render_docs.manpage import man_escape
+from nixos_render_docs.md import md_escape
+
+
+class NixvimManpageConverter(nx_options.ManpageConverter):
+    def __init__(self, revision, *, _options_by_id=None):
+        super().__init__(revision, _options_by_id=_options_by_id)
+
+    def finalize(self):
+        result = []
+
+        result += [
+            r'''.TH "NIXVIM" "5" "01/01/1980" "Nixvim" "Nixvim Reference Pages"''',
+            r""".\" disable hyphenation""",
+            r""".nh""",
+            r""".\" disable justification (adjust text to left margin only)""",
+            r""".ad l""",
+            r""".\" enable line breaks after slashes""",
+            r""".cflags 4 /""",
+            r'''.SH "NAME"''',
+            self._render("nixvim options specification"),
+            r'''.SH "DESCRIPTION"''',
+            r""".PP""",
+            self._render(
+                "This page lists all the options that can be used in nixvim. "
+                "Nixvim can either be used as a Home-Manager module, an NixOS module or a standalone package. "
+                "Please refer to the installation instructions for more details."
+            ),
+            r'''.SH "OPTIONS"''',
+            r""".PP""",
+            self._render("You can use the following options in a nixvim module."),
+        ]
+
+        for name, opt in self._sorted_options():
+            result += [
+                ".PP",
+                f"\\fB{man_escape(name)}\\fR",
+                ".RS 4",
+            ]
+            result += opt.lines
+            if links := opt.links:
+                result.append(self.__option_block_separator__)
+                md_links = ""
+                for i in range(0, len(links)):
+                    md_links += "\n" if i > 0 else ""
+                    if links[i].startswith("#opt-"):
+                        md_links += f"{i+1}. see the {{option}}`{self._options_by_id[links[i]]}` option"
+                    else:
+                        md_links += f"{i+1}. " + md_escape(links[i])
+                result.append(self._render(md_links))
+
+            result.append(".RE")
+
+        result += [
+            r'''.SH "AUTHORS"''',
+            r""".PP""",
+            r"""nixvim maintainers""",
+        ]
+
+        return "\n".join(result)
+
+
+def run_manpage_options(args):
+    md = NixvimManpageConverter(revision=args.revision)
+
+    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 run_options(args):
+    if args.format == "manpage":
+        run_manpage_options(args)
+    else:
+        raise RuntimeError("format not hooked up", args)
+
+
+def main():
+    parser = argparse.ArgumentParser(description="render nixos manual bits")
+    parser.add_argument("-j", "--jobs", type=int, default=None)
+
+    commands = parser.add_subparsers(dest="command", required=True)
+    options = commands.add_parser("options")
+
+    formats = options.add_subparsers(dest="format", required=True)
+    manpage = formats.add_parser("manpage")
+    manpage.add_argument("--revision", required=True)
+    manpage.add_argument("infile")
+    manpage.add_argument("outfile")
+
+    args = parser.parse_args()
+    try:
+        parallel.pool_processes = args.jobs
+        if args.command == "options":
+            run_options(args)
+        else:
+            raise RuntimeError("command not hooked up", args)
+    except Exception as e:
+        traceback.print_exc()
+        nixos_render_docs.pretty_print_exc(e)
+        sys.exit(1)

man-docs/nixvim-render-docs/src/pyproject.toml

@@ -0,0 +1,14 @@
+[project]
+name = "nixvim-render-docs"
+version = "0.0"
+description = "Renderer for Nixvim option docs"
+classifiers = [
+	"Programming Language :: Python :: 3",
+	"Operating System :: OS Independent",
+]
+
+[project.scripts]
+nixvim-render-docs = "nixvim_render_docs:main"
+
+[build-system]
+requires = ["setuptools"]