snowfall-lib/snowfall-lib/attrs/default.nix

{ core-inputs
, user-inputs
, snowfall-lib
, snowfall-config
}:

let
  inherit (core-inputs.nixpkgs.lib)
    assertMsg
    mapAttrsToList
    mapAttrs
    flatten
    foldl
    recursiveUpdate
    mergeAttrs
    isDerivation;
in
{
  attrs = {
    ## Map and flatten an attribute set into a list.
    ## Example Usage:
    ## ```nix
    ## map-concat-attrs-to-list (name: value: [name value]) { x = 1; y = 2; }
    ## ```
    ## Result:
    ## ```nix
    ## [ "x" 1 "y" 2 ]
    ## ```
    #@ (a -> b -> [c]) -> Attrs -> [c]
    map-concat-attrs-to-list = f: attrs:
      flatten (mapAttrsToList f attrs);

    ## Recursively merge a list of attribute sets.
    ## Example Usage:
    ## ```nix
    ## merge-deep [{ x = 1; } { x = 2; }]
    ## ```
    ## Result:
    ## ```nix
    ## { x = 2; }
    ## ```
    #@ [Attrs] -> Attrs
    merge-deep = foldl recursiveUpdate { };

    ## Merge the root of a list of attribute sets.
    ## Example Usage:
    ## ```nix
    ## merge-shallow [{ x = 1; } { x = 2; }]
    ## ```
    ## Result:
    ## ```nix
    ## { x = 2; }
    ## ```
    #@ [Attrs] -> Attrs
    merge-shallow = foldl mergeAttrs { };

    ## Merge shallow for packages, but allow one deeper layer of attribute sets.
    ## Example Usage:
    ## ```nix
    ## merge-shallow-packages [ { inherit (pkgs) vim; some.value = true; } { some.value = false; } ]
    ## ```
    ## Result:
    ## ```nix
    ## { vim = ...; some.value = false; }
    ## ```
    #@ [Attrs] -> Attrs
    merge-shallow-packages = items:
      foldl
        (result: item:
          result // (mapAttrs
            (name: value:
              if isDerivation value then
                value
              else if builtins.isAttrs value then
                (result.${name} or { }) // value
              else
                value
            )
            item)
        )
        { }
        items;
  };
}