home-manager/modules/lib/generators.nix

{ lib }:

{
  toHyprconf =
    {
      attrs,
      indentLevel ? 0,
      importantPrefixes ? [ "$" ],
    }:
    let
      inherit (lib)
        all
        concatMapStringsSep
        concatStrings
        concatStringsSep
        filterAttrs
        foldl
        generators
        hasPrefix
        isAttrs
        isList
        mapAttrsToList
        replicate
        ;

      initialIndent = concatStrings (replicate indentLevel "  ");

      toHyprconf' =
        indent: attrs:
        let
          sections = filterAttrs (n: v: isAttrs v || (isList v && all isAttrs v)) attrs;

          mkSection =
            n: attrs:
            if lib.isList attrs then
              (concatMapStringsSep "\n" (a: mkSection n a) attrs)
            else
              ''
                ${indent}${n} {
                ${toHyprconf' "  ${indent}" attrs}${indent}}
              '';

          mkFields = generators.toKeyValue {
            listsAsDuplicateKeys = true;
            inherit indent;
          };

          allFields = filterAttrs (n: v: !(isAttrs v || (isList v && all isAttrs v))) attrs;

          isImportantField =
            n: _: foldl (acc: prev: if hasPrefix prev n then true else acc) false importantPrefixes;

          importantFields = filterAttrs isImportantField allFields;

          fields = builtins.removeAttrs allFields (mapAttrsToList (n: _: n) importantFields);
        in
        mkFields importantFields
        + concatStringsSep "\n" (mapAttrsToList mkSection sections)
        + mkFields fields;
    in
    toHyprconf' initialIndent attrs;

  toKDL =
    { }:
    let
      inherit (lib)
        concatStringsSep
        splitString
        mapAttrsToList
        any
        ;
      inherit (builtins) typeOf replaceStrings elem;

      # ListOf String -> String
      indentStrings =
        let
          # Although the input of this function is a list of strings,
          # the strings themselves *will* contain newlines, so you need
          # to normalize the list by joining and resplitting them.
          unlines = lib.splitString "\n";
          lines = lib.concatStringsSep "\n";
          indentAll = lines: concatStringsSep "\n" (map (x: "	" + x) lines);
        in
        stringsWithNewlines: indentAll (unlines (lines stringsWithNewlines));

      # String -> String
      sanitizeString = replaceStrings [ "\n" ''"'' ] [ "\\n" ''\"'' ];

      # OneOf [Int Float String Bool Null] -> String
      literalValueToString =
        element:
        lib.throwIfNot
          (elem (typeOf element) [
            "int"
            "float"
            "string"
            "bool"
            "null"
          ])
          "Cannot convert value of type ${typeOf element} to KDL literal."
          (
            if typeOf element == "null" then
              "null"
            else if element == false then
              "false"
            else if element == true then
              "true"
            else if typeOf element == "string" then
              ''"${sanitizeString element}"''
            else
              toString element
          );

      # Attrset Conversion
      # String -> AttrsOf Anything -> String
      convertAttrsToKDL =
        name: attrs:
        let
          optArgs = map literalValueToString (attrs._args or [ ]);
          optProps = lib.mapAttrsToList (name: value: "${name}=${literalValueToString value}") (
            attrs._props or { }
          );

          orderedChildren = lib.pipe (attrs._children or [ ]) [
            (map (child: mapAttrsToList convertAttributeToKDL child))
            lib.flatten
          ];
          unorderedChildren = lib.pipe attrs [
            (lib.filterAttrs (
              name: _:
              !(elem name [
                "_args"
                "_props"
                "_children"
              ])
            ))
            (mapAttrsToList convertAttributeToKDL)
          ];
          children = orderedChildren ++ unorderedChildren;
          optChildren = lib.optional (children != [ ]) ''
            {
            ${indentStrings children}
            }'';

        in
        lib.concatStringsSep " " ([ name ] ++ optArgs ++ optProps ++ optChildren);

      # List Conversion
      # String -> ListOf (OneOf [Int Float String Bool Null])  -> String
      convertListOfFlatAttrsToKDL =
        name: list:
        let
          flatElements = map literalValueToString list;
        in
        "${name} ${concatStringsSep " " flatElements}";

      # String -> ListOf Anything -> String
      convertListOfNonFlatAttrsToKDL = name: list: ''
        ${name} {
        ${indentStrings (map (x: convertAttributeToKDL "-" x) list)}
        }'';

      # String -> ListOf Anything  -> String
      convertListToKDL =
        name: list:
        let
          elementsAreFlat =
            !any (
              el:
              elem (typeOf el) [
                "list"
                "set"
              ]
            ) list;
        in
        if elementsAreFlat then
          convertListOfFlatAttrsToKDL name list
        else
          convertListOfNonFlatAttrsToKDL name list;

      # Combined Conversion
      # String -> Anything  -> String
      convertAttributeToKDL =
        name: value:
        let
          vType = typeOf value;
        in
        if
          elem vType [
            "int"
            "float"
            "bool"
            "null"
            "string"
          ]
        then
          "${name} ${literalValueToString value}"
        else if vType == "set" then
          convertAttrsToKDL name value
        else if vType == "list" then
          convertListToKDL name value
        else
          throw ''
            Cannot convert type `(${typeOf value})` to KDL:
              ${name} = ${toString value}
          '';
    in
    attrs: ''
      ${concatStringsSep "\n" (mapAttrsToList convertAttributeToKDL attrs)}
    '';

  toSCFG =
    { }:
    let
      inherit (lib) concatStringsSep mapAttrsToList any;
      inherit (builtins) typeOf replaceStrings elem;

      # ListOf String -> String
      indentStrings =
        let
          # Although the input of this function is a list of strings,
          # the strings themselves *will* contain newlines, so you need
          # to normalize the list by joining and resplitting them.
          unlines = lib.splitString "\n";
          lines = lib.concatStringsSep "\n";
          indentAll = lines: concatStringsSep "\n" (map (x: "	" + x) lines);
        in
        stringsWithNewlines: indentAll (unlines (lines stringsWithNewlines));

      # String -> Bool
      specialChars =
        s:
        any (
          char:
          elem char (
            reserved
            ++ [
              " "
              "'"
              "{"
              "}"
            ]
          )
        ) (lib.stringToCharacters s);

      # String -> String
      sanitizeString = replaceStrings reserved [
        ''\"''
        "\\\\"
        "\\r"
        "\\n"
        "\\t"
      ];

      reserved = [
        ''"''
        "\\"
        "\r"
        "\n"
        "	"
      ];

      # OneOf [Int Float String Bool] -> String
      literalValueToString =
        element:
        lib.throwIfNot
          (elem (typeOf element) [
            "int"
            "float"
            "string"
            "bool"
          ])
          "Cannot convert value of type ${typeOf element} to SCFG literal."
          (
            if element == false then
              "false"
            else if element == true then
              "true"
            else if typeOf element == "string" then
              if element == "" || specialChars element then ''"${sanitizeString element}"'' else element
            else
              toString element
          );

      # Bool -> ListOf (OneOf [Int Float String Bool]) -> String
      toOptParamsString =
        cond: list:
        lib.optionalString (cond) (
          lib.pipe list [
            (map literalValueToString)
            (concatStringsSep " ")
            (s: " " + s)
          ]
        );

      # Attrset Conversion
      # String -> AttrsOf Anything -> String
      convertAttrsToSCFG =
        name: attrs:
        let
          optParamsString = toOptParamsString (attrs ? "_params") attrs._params;
        in
        ''
          ${name}${optParamsString} {
          ${indentStrings (convertToAttrsSCFG' attrs)}
          }'';

      # Attrset Conversion
      # AttrsOf Anything -> ListOf String
      convertToAttrsSCFG' =
        attrs:
        mapAttrsToList convertAttributeToSCFG (
          lib.filterAttrs (name: val: !isNull val && name != "_params") attrs
        );

      # List Conversion
      # String -> ListOf (OneOf [Int Float String Bool]) -> String
      convertListOfFlatAttrsToSCFG =
        name: list:
        let
          optParamsString = toOptParamsString (list != [ ]) list;
        in
        "${name}${optParamsString}";

      # Combined Conversion
      # String -> Anything  -> String
      convertAttributeToSCFG =
        name: value:
        lib.throwIf (name == "") "Directive must not be empty" (
          let
            vType = typeOf value;
          in
          if
            elem vType [
              "int"
              "float"
              "bool"
              "string"
            ]
          then
            "${name} ${literalValueToString value}"
          else if vType == "set" then
            convertAttrsToSCFG name value
          else if vType == "list" then
            convertListOfFlatAttrsToSCFG name value
          else
            throw ''
              Cannot convert type `(${typeOf value})` to SCFG:
                ${name} = ${toString value}
            ''
        );
    in
    attrs:
    lib.optionalString (attrs != { }) ''
      ${concatStringsSep "\n" (convertToAttrsSCFG' attrs)}
    '';
}