{ lib }:

{ /* Automatically convert an attribute set to command-line options.

     This helps protect against malformed command lines and also to reduce
     boilerplate related to command-line construction for simple use cases.

     Example:
       encodeGNUCommandLine
         { }
         { data = builtins.toJSON { id = 0; };

           X = "PUT";

           retry = 3;

           retry-delay = null;

           url = [ "https://example.com/foo" "https://example.com/bar" ];

           silent = false;

           verbose = true;
         };
       => " -X 'PUT' --data '{\"id\":0}' --retry '3' --url 'https://example.com/foo' --url 'https://example.com/bar' --verbose"
  */
  encodeGNUCommandLine =
    { renderKey ?
        key: if builtins.stringLength key == 1 then "-${key}" else "--${key}"

    , renderOption ?
        key: value:
          if value == null
          then ""
          else " ${renderKey key} ${lib.escapeShellArg value}"

    , renderBool ? key: value: if value then " ${renderKey key}" else ""

    , renderList ? key: value: lib.concatMapStrings (renderOption key) value
    }:
    options:
      let
        render = key: value:
                 if builtins.isBool value
            then renderBool key value
            else if builtins.isList value
            then renderList key value
            else renderOption key value;

      in
        lib.concatStrings (lib.mapAttrsToList render options);
}