add sway displays

lib/modules/display.nix

@@ -10,7 +10,7 @@ let
   displayHyprlandSetting = display:
     "monitor = " + specificDisplay display +
     ", " + resToString display.resolution +
-    ", " + display.position +
+    ", " + positionToHyprlandString display.position +
     ", " + toString display.scaling;
 
   swaybgJob = displays:
@@ -35,6 +35,23 @@ let
     then display.name
     else "desc:" + display.description;
 
+  positionToHyprlandString = { x, y }:
+    if (x == "" || y == "") then "auto" else x + "x" + y;
+
+  renderDisplaysForSway = displays:
+    listToAttrs (map displaySwaySetting displays);
+
+  displaySwaySetting = display: {
+    name = display.name;
+    value = let res = display.resolution; in
+      {
+        mode = mkIf (resIsSet res)
+          "${toString res.x}x${toString res.y}@${toString res.freq}Hz";
+        bg = display.wallpaper + " fill";
+        scale = toString display.scaling;
+      };
+  };
+
   resolutionType = types.submodule ({ x, y, freq, ... }:
     {
       options = {
@@ -74,9 +91,11 @@ let
           type = resolutionType;
           default = { };
         };
-        position = mkOption {
-          description = "XxY";
-          default = "auto";
+        position.x = mkOption {
+          default = "";
+        };
+        position.y = mkOption {
+          default = "";
         };
         wallpaper = mkOption {
           description = "path to wallpaper";
@@ -85,10 +104,14 @@ let
       };
     });
 
+  resIsSet = res:
+    !(res.x == 0 || res.y == 0 || res.freq == 0);
+
   resToString = res:
-    if res.x == 0 || res.y == 0 || res.freq == 0
+    if resIsSet res
     then "preferred"
     else "${toString res.x}x${toString res.y}@${toString res.freq}";
+
 in
 {
   options.displays =
@@ -107,6 +130,8 @@ in
           (renderDisplaysForHyprland cfg.displays);
 
         systemd.user.services.swaybg = swaybgJob cfg.displays;
+        wayland.windowManager.sway.config.output = mkIf (cfg.displays != [ ])
+          (renderDisplaysForSway cfg.displays);
       }
     ];
   };