lib: pkgs:
# Future improvements:
#   - extra documentation from anyOf types, they can have `enumDescriptions` that are valuable
with lib;
let
  packageJson = "${pkgs.rust-analyzer.src}/editors/code/package.json";

  options = (trivial.importJSON packageJson).contributes.configuration.properties;

  packageJsonTxt = strings.splitString "\n" (builtins.readFile packageJson);
  vscodeStart = lists.findFirstIndex (
    x: x == "        \"configuration\": {"
  ) (throw "no configuration") packageJsonTxt;
  vscodeEnd =
    lists.findFirstIndex (strings.hasInfix "generated-start") (throw "no generated start")
      packageJsonTxt;
  vscodeOptions = lists.sublist vscodeStart (vscodeEnd - vscodeStart) packageJsonTxt;

  vscodeOptionNames = builtins.map (
    x: strings.removeSuffix "\": {" (strings.removePrefix "                \"" x)
  ) (lists.filter (strings.hasPrefix "                \"rust-analyzer.") vscodeOptions);

  rustAnalyzerOptions = builtins.removeAttrs options (
    vscodeOptionNames
    ++ [
      "\$generated-start"
      "\$generated-end"
    ]
  );

  nullType = mkOptionType {
    name = "nullType";
    description = "null";
    descriptionClass = "noun";
    merge = mergeEqualOption;
    check = e: e == null;
  };

  mkRustAnalyzerType =
    opt:
    {
      type,
      enum ? null,
      minimum ? null,
      maximum ? null,
      items ? null,
      anyOf ? null,
      uniqueItems ? null,
      # unused, but for exhaustivness
      enumDescriptions ? null,
    }@def:
    if enum != null then
      types.enum enum
    else if anyOf != null then
      types.oneOf (builtins.map (mkRustAnalyzerType opt) anyOf)
    else if builtins.isList type then
      if builtins.length type == 2 && builtins.head type == "null" then
        types.nullOr (mkRustAnalyzerType opt (def // { type = builtins.elemAt type 1; }))
      else
        types.oneOf (builtins.map (t: mkRustAnalyzerType opt (def // { type = t; })) type)
    else if type == "boolean" then
      types.bool
    else if type == "object" then
      types.attrsOf types.anything
    else if type == "string" then
      types.str
    else if type == "null" then
      nullType
    else if type == "array" then
      types.listOf (
        mkRustAnalyzerType "${opt}-items" (
          if items == null then throw "null items with array type (in ${opt})" else items
        )
      )
    else if type == "number" then
      if minimum != null && maximum != null then
        types.numbers.between minimum maximum
      else if minimum != null then
        types.addCheck types.number (x: x >= minimum)
      else if maximum != null then
        types.addCheck types.number (x: x <= maximum)
      else
        types.number
    else if type == "integer" then
      if minimum != null && maximum != null then
        types.ints.between minimum maximum
      else if minimum != null then
        types.addCheck types.int (x: x >= minimum)
      else if maximum != null then
        types.addCheck types.int (x: x <= maximum)
      else
        types.int
    else
      throw "unhandled type `${builtins.toJSON type}` (in ${opt})";

  mkRustAnalyzerOption =
    opt:
    {
      default,
      markdownDescription,
      type ? null,
      anyOf ? null,
      # Enum types
      enum ? null,
      enumDescriptions ? null,
      # Int types
      minimum ? null,
      maximum ? null,
      # List types
      items ? null,
      uniqueItems ? false,
    }:
    mkOption {
      type = types.nullOr (
        mkRustAnalyzerType opt {
          inherit
            type
            enum
            minimum
            maximum
            items
            anyOf
            uniqueItems
            ;
        }
      );
      default = null;
      description =
        if enum != null then
          let
            valueDesc = builtins.map ({ fst, snd }: ''- ${fst}: ${snd}'') (
              lists.zipLists enum enumDescriptions
            );
          in
          ''
            ${markdownDescription}

            Values:
            ${builtins.concatStringsSep "\n" valueDesc}

            ```nix
            ${generators.toPretty { } default}
            ```
          ''
        else
          ''
            ${markdownDescription}

            default:
            ```nix
            ${generators.toPretty { } default}
            ```
          '';
    };

  nixOptions = builtins.mapAttrs mkRustAnalyzerOption rustAnalyzerOptions;

  nestOpt =
    opt: value:
    let
      parts = strings.splitString "." opt;
    in
    builtins.foldl' (current: segment: { ${segment} = current; }) value (lists.reverseList parts);

  nestedNixOptions = attrsets.mapAttrsToList nestOpt nixOptions;
in
(builtins.foldl' attrsets.recursiveUpdate { } nestedNixOptions).rust-analyzer