add first wp

flake.nix

@@ -0,0 +1,17 @@
+{
+  description = "A very basic flake";
+
+  outputs =
+    _:
+    let
+      lib = import ./lib;
+    in
+    {
+      wallpapers = lib.toWallpkgs ./wallpapers [
+        "png"
+        "jpg"
+        "jpeg"
+        "gif"
+      ];
+    };
+}

lib/default.nix

@@ -0,0 +1,99 @@
+# Credits: https://github.com/NotAShelf/wallpkgs
+#
+# This is the wallpkgs... un-extended library. It appends a few useful functions
+# based on their nixpkgs.lib variants, without any reliance on nixpkgs' own lib.
+# Idea is that we do not need to pull an input for nixpkgs library alone, since
+# wallpapers here are no longer packages. If implementing a new function, please
+# remember to keep it lib-free. If it *must* rely on lib, then implement the
+# function or functions you need as well as the main function.
+let
+  splitString =
+    separator: str:
+    let
+      # "Nix doesn't have for loops it's a functional programming language!"
+      # You know what it has now? For loops. Nerd.
+      loop =
+        str: acc: currentPos: currentSegment:
+        if currentPos == builtins.stringLength str then
+          # end of string: add the current segment (even if it's empty)
+          acc ++ [ currentSegment ]
+        else
+          let
+            char = builtins.substring currentPos 1 str;
+          in
+          if char == separator then
+            # separator; add the current segment (even if it's empty) to acc
+            # and start a new segment for the next part
+            loop str (acc ++ [ currentSegment ]) (currentPos + 1) ""
+          else
+            loop str acc (currentPos + 1) (currentSegment + char);
+    in
+    loop str [ ] 0 "";
+
+  filterAttrs =
+    f: attrs:
+    let
+      names = builtins.attrNames attrs;
+      filteredNames = builtins.filter (name: f name (attrs.${name})) names;
+    in
+    builtins.listToAttrs (
+      map (name: {
+        name = name;
+        value = attrs.${name};
+      }) filteredNames
+    );
+
+  genAttrs =
+    names: f:
+    builtins.listToAttrs (
+      map (name: {
+        name = name;
+        value = f name;
+      }) names
+    );
+
+  # TODO: This needs to be extensible, possibly in order to allow additional directories.
+  # In theory, we should only need to handle path*s* instead of a path, and search multiple
+  # paths by extension instead of just once, right?
+  toWallpkgs =
+    path: extensions:
+    let
+      fileExts = extensions;
+    in
+    builtins.listToAttrs (
+      map
+        (
+          n:
+          let
+            filesByExtension = builtins.filter builtins.pathExists (map (ext: path + /${n}.${ext}) fileExts);
+            file =
+              if filesByExtension == [ ] then
+                builtins.throw "Either ${n} is not a file or it does not have the ${builtins.concatStringsSep ", " fileExts} extensions."
+              else
+                builtins.head filesByExtension;
+          in
+          {
+            name = n;
+            value = {
+              path = file;
+              tags = splitString "-" n;
+              hash = builtins.hashFile "md5" file; # in theory, md5 is the fastest option because it produces a 128-bit hash instead of >= 160
+            };
+          }
+        )
+        (
+          map (n: builtins.head (splitString "." n)) (
+            builtins.attrNames (filterAttrs (n: _: n != "README.md") (builtins.readDir path))
+          )
+        )
+    );
+in
+{
+  # Partial re-implementations of functions from Nixpkgs.
+  # They may not work as intended, as the implementation is *completely* different. If this is
+  # the case while contributing, please create an issue!
+  inherit splitString filterAttrs genAttrs;
+
+  # Main function to create the final collection of wallpapers from a given directory.
+  inherit toWallpkgs;
+}