selfhostblocks/docs/default.nix

# Taken nearly verbatim from https://github.com/nix-community/home-manager/pull/4673
# Read these docs online at https://shb.skarabox.com.
{
  pkgs,
  buildPackages,
  lib,
  nmdsrc,
  stdenv,
  documentation-highlighter,
  nixos-render-docs,

  release,
  allModules,

  version ? builtins.readFile ../VERSION,
  substituteVersionIn,

  modules,
}:

let
  shbPath = toString ./..;

  gitHubDeclaration =
    user: repo: subpath:
    let
      urlRef = "main";
      end = if subpath == "" then "" else "/" + subpath;
    in
    {
      url = "https://github.com/${user}/${repo}/blob/${urlRef}${end}";
      name = "<${repo}${end}>";
    };

  ghRoot = (gitHubDeclaration "ibizaman" "selfhostblocks" "").url;

  buildOptionsDocs =
    {
      modules,
      filterOptionPath ? null,
    }:
    args:
    let
      config = {
        _module.check = false;
        _module.args = { };
        system.stateVersion = "22.11";
      };

      utils = import "${pkgs.path}/nixos/lib/utils.nix" {
        inherit config lib;
        pkgs = null;
      };

      eval = lib.evalModules {
        inherit modules;

        specialArgs = {
          inherit utils;
        };
      };

      options = lib.setAttrByPath filterOptionPath (lib.getAttrFromPath filterOptionPath eval.options);
    in
    buildPackages.nixosOptionsDoc (
      {
        inherit options;

        transformOptions =
          opt:
          opt
          // {
            # Clean up declaration sites to not refer to the Home Manager
            # source tree.
            declarations = map (
              decl:
              gitHubDeclaration "ibizaman" "selfhostblocks" (
                lib.removePrefix "/" (lib.removePrefix shbPath (toString decl))
              )
            ) opt.declarations;
          };
      }
      // builtins.removeAttrs args [ "includeModuleSystemOptions" ]
    );

  scrubbedModule = {
    _module.args.pkgs = lib.mkForce (nmd.scrubDerivations "pkgs" pkgs);
    _module.check = false;
  };

  allOptionsDocs =
    paths:
    (buildOptionsDocs
      {
        modules = paths ++ allModules ++ [ scrubbedModule ];
        filterOptionPath = [ "shb" ];
      }
      {
        variablelistId = "selfhostblocks-options";
      }
    ).optionsJSON;

  individualModuleOptionsDocs =
    filterOptionPath: paths:
    (buildOptionsDocs
      {
        modules = paths ++ [ scrubbedModule ];
        inherit filterOptionPath;
      }
      {
        variablelistId = "selfhostblocks-options";
      }
    ).optionsJSON;

  nmd = import nmdsrc {
    inherit lib;
    # The DocBook output of `nixos-render-docs` doesn't have the change
    # `nmd` uses to work around the broken stylesheets in
    # `docbook-xsl-ns`, so we restore the patched version here.
    pkgs = pkgs // {
      docbook-xsl-ns = pkgs.docbook-xsl-ns.override { withManOptDedupPatch = true; };
    };
  };

  outputPath = "share/doc/selfhostblocks";

  manpage-urls = pkgs.writeText "manpage-urls.json" ''{}'';
in
stdenv.mkDerivation {
  name = "self-host-blocks-manual";

  nativeBuildInputs = [ nixos-render-docs ];

  # We include the parent so we get the documentation inside the root
  # modules/ and demo/ folders.
  src = ./..;

  buildPhase = ''
    cd docs

    mkdir -p demo
    cp -t . -r ../demo
    cp -t . -r ../modules

    mkdir -p out/media
    mkdir -p out/highlightjs
    mkdir -p out/static

    cp -t out/highlightjs \
      ${documentation-highlighter}/highlight.pack.js \
      ${documentation-highlighter}/LICENSE \
      ${documentation-highlighter}/mono-blue.css \
      ${documentation-highlighter}/loader.js

    cp -t out/static \
      ${nmdsrc}/static/style.css \
      ${nmdsrc}/static/highlightjs/tomorrow-night.min.css \
      ${nmdsrc}/static/highlightjs/highlight.min.js \
      ${nmdsrc}/static/highlightjs/highlight.load.js

  ''
  + lib.concatStringsSep "\n" (
    map (m: ''
      substituteInPlace ${m} --replace '@VERSION@' ${version}
    '') substituteVersionIn
  )
  + ''
    substituteInPlace ./options.md \
      --replace \
        '@OPTIONS_JSON@' \
        ${
          allOptionsDocs [
            (pkgs.path + "/nixos/modules/services/misc/forgejo.nix")
          ]
        }/share/doc/nixos/options.json
  ''
  + lib.concatStringsSep "\n" (
    lib.mapAttrsToList (
      name: cfg':
      let
        cfg = if builtins.isAttrs cfg' then cfg' else { module = cfg'; };
        module = if builtins.isList cfg.module then cfg.module else [ cfg.module ];
        optionRoot =
          cfg.optionRoot or [
            "shb"
            (lib.last (lib.splitString "/" name))
          ];
      in
      ''
        substituteInPlace ./modules/${name}/docs/default.md \
          --replace-fail \
            '@OPTIONS_JSON@' \
            ${individualModuleOptionsDocs optionRoot module}/share/doc/nixos/options.json
      ''
    ) modules
  )
  + ''
    find . -name "*.md" -print0 | \
      while IFS= read -r -d ''' f; do
        substituteInPlace "''${f}" \
          --replace-quiet \
            '@REPO@' \
            "${ghRoot}" 2>/dev/null
      done

    nixos-render-docs manual html \
      --manpage-urls ${manpage-urls} \
      --redirects ./redirects.json \
      --media-dir media \
      --revision ${lib.trivial.revisionWithDefault release} \
      --stylesheet static/style.css \
      --stylesheet static/tomorrow-night.min.css \
      --script static/highlight.min.js \
      --script static/highlight.load.js \
      --toc-depth 1 \
      --section-toc-depth 1 \
      manual.md \
      out/index.html
  '';

  installPhase = ''
    dest="$out/${outputPath}"
    mkdir -p "$(dirname "$dest")"
    mv out "$dest"
    mkdir -p $out/nix-support/
    echo "doc manual $dest index.html" >> $out/nix-support/hydra-build-products
  '';
}