feh: add themes option (#6074)

- added themes option
- added themes test
- updated broken man page links

modules/programs/feh.nix

@@ -8,6 +8,12 @@ let
 
   bindingsOf = t: with types; attrsOf (nullOr (either t (listOf t)));
 
+  renderThemes = options:
+    let
+      render =
+        mapAttrsToList (theme: options: "${theme} ${escapeShellArgs options}");
+    in concatStringsSep "\n" (render options);
+
   renderBindings = bindings:
     let
       enabled = filterAttrs (n: v: v != null) bindings;
@@ -41,7 +47,7 @@ in {
         Override feh's default mouse button mapping. If you want to disable an
         action, set its value to null. If you want to bind multiple buttons to
         an action, set its value to a list.
-        See <https://man.finalrewind.org/1/feh/#x425554544f4e53> for
+        See <https://man.finalrewind.org/1/feh/#BUTTONS_CONFIG_SYNTAX> for
         default bindings and available commands.
       '';
     };
@@ -58,10 +64,37 @@ in {
         Override feh's default keybindings. If you want to disable a keybinding
         set its value to null. If you want to bind multiple keys to an action,
         set its value to a list.
-        See <https://man.finalrewind.org/1/feh/#x4b455953> for
+        See <https://man.finalrewind.org/1/feh/#KEYS_CONFIG_SYNTAX> for
         default bindings and available commands.
       '';
     };
+
+    themes = mkOption {
+      default = { };
+      type = with types; attrsOf (listOf str);
+      example = {
+        feh = [ "--image-bg" "black" ];
+        webcam = [ "--multiwindow" "--reload" "20" ];
+        present = [ "--full-screen" "--sort" "name" "--hide-pointer" ];
+        booth = [ "--full-screen" "--hide-pointer" "--slideshow-delay" "20" ];
+        imagemap = [
+          "-rVq"
+          "--thumb-width"
+          "40"
+          "--thumb-height"
+          "30"
+          "--index-info"
+          "%n\\n%wx%h"
+        ];
+        example = [ "--info" "foo bar" ];
+      };
+      description = ''
+        Define themes for feh.
+        See <https://man.finalrewind.org/1/feh/#THEMES_CONFIG_SYNTAX> for
+        important guidelines and limitations related to theme configuration.
+      '';
+    };
+
   };
 
   config = mkIf cfg.enable {
@@ -79,5 +112,8 @@ in {
     xdg.configFile."feh/keys" = mkIf (cfg.keybindings != { }) {
       text = renderBindings cfg.keybindings + "\n";
     };
+
+    xdg.configFile."feh/themes" =
+      mkIf (cfg.themes != { }) { text = renderThemes cfg.themes + "\n"; };
   };
 }