labwc: Add module for Labwc (#6807)

Add a module for labwc compositor.
Add myself as labwc module maintainer

modules/services/window-managers/labwc/function.nix

@@ -0,0 +1,146 @@
+{ lib, ... }:
+
+let
+  # Escape XML special characters (e.g., <, >, &, etc.)
+  escape = lib.escapeXML;
+
+  # Indent each non-empty line of the given text by `level` using two spaces per level.
+  indent =
+    level: text:
+    let
+      indentation = lib.concatStrings (lib.genList (_: "  ") level); # Two spaces per level
+      lines = lib.splitString "\n" text; # Split text into lines
+      indentedLines = map (line: if line == "" then "" else "${indentation}${line}") lines;
+    in
+    lib.concatStringsSep "\n" indentedLines;
+
+  # Generate a <menu> or <item> or <separator> XML entry based on a menu item definition
+  generateMenu =
+    item:
+    if item ? separator then
+      let
+        labelAttr = if item.separator ? label then " label=\"${escape item.separator.label}\"" else "";
+      in
+      "<separator${labelAttr} />"
+
+    else if item ? menuId then
+      let
+        idAttr = " id=\"${escape item.menuId}\"";
+        labelAttr = if item ? label then " label=\"${escape item.label}\"" else "";
+        children = if item ? items then lib.concatMapStringsSep "\n" generateMenu item.items else "";
+      in
+      "<menu${idAttr}${labelAttr}>\n${indent 1 children}\n</menu>"
+
+    else
+      let
+        labelAttr = " label=\"${escape item.label}\"";
+        action = item.action;
+        nameAttr = " name=\"${escape action.name}\"";
+        toAttr = if action ? to then " to=\"${escape action.to}\"" else "";
+        commandAttr = if action ? command then " command=\"${escape action.command}\"" else "";
+      in
+      "<item${labelAttr}>\n  <action${nameAttr}${toAttr}${commandAttr} />\n</item>";
+
+  # Get keys in a preferred order
+  orderedKeys =
+    name: keys:
+    let
+      # Define key orderings for known structures
+      tagOrder = {
+        font = [ "@place" ];
+        keyboard = [ "default" ];
+        mouse = [ "default" ];
+        action = [ "@name" ];
+        mousebind = [ "@button" ];
+      };
+      preferred = lib.attrByPath [ name ] [ ] tagOrder;
+      cmp =
+        a: b:
+        let
+          ia = lib.lists.findFirstIndex (x: x == a) (-1) preferred;
+          ib = lib.lists.findFirstIndex (x: x == b) (-1) preferred;
+        in
+        if ia == -1 && ib == -1 then
+          builtins.lessThan a b
+        else if ia == -1 then
+          false
+        else if ib == -1 then
+          true
+        else
+          builtins.lessThan ia ib;
+    in
+    builtins.sort cmp keys;
+
+  generateRc =
+    name: value:
+    # If the value is an attribute set (i.e., a record / dictionary)
+    if builtins.isAttrs value then
+      let
+        # keys = builtins.attrNames value;
+        keys = orderedKeys name (builtins.attrNames value);
+
+        attrKeys = builtins.filter (k: lib.hasPrefix "@" k) keys;
+        childKeys = builtins.filter (k: !(lib.hasPrefix "@" k)) keys;
+
+        # Generate string of XML attributes from keys like "@id" → id="value"
+        attrs = lib.concatStrings (
+          map (
+            k:
+            let
+              attrName = builtins.substring 1 999 k; # Remove "@" prefix
+              attrValue = value.${k};
+            in
+            " ${attrName}=\"${escape (builtins.toString attrValue)}\""
+          ) attrKeys
+        );
+
+        # Recursively convert children to XML, with increased indentation
+        children = lib.concatStringsSep "\n" (map (k: generateRc k value.${k}) childKeys);
+      in
+
+      if children == "" then
+        # Only attributes — use self-closing tag with attributes
+        "<${name}${attrs} />"
+
+      else
+        # Attributes and/or children — use full open/close tag
+        "<${name}${attrs}>\n${indent 1 children}\n</${name}>"
+
+    # If the value is a boolean `true`, render as self-closing tag
+    else if builtins.isBool value && value then
+      "<${name} />"
+
+    # If the value is a list, emit the same tag name for each item
+    else if builtins.isList value then
+      # Reuse the same tag name for each list item
+      lib.concatStringsSep "\n" (map (v: generateRc name v) value)
+
+    # All other primitive values: wrap in start/end tag
+    else
+      "<${name}>${escape (builtins.toString value)}</${name}>";
+
+  generateXML = name: config: extraConfig: ''
+    <?xml version="1.0" encoding="UTF-8"?>
+    <!-- ### This file was generated with Nix. Don't modify this file directly. -->
+    <${name}>
+    ${indent 1 (
+      lib.concatStringsSep "\n" (
+        (
+          if name == "openbox_menu" then
+            map generateMenu
+          else if name == "labwc_config" then
+            lib.mapAttrsToList generateRc
+          else
+            builtins.throw "error ${name} is neither openbox_menu nor labwc_config"
+        )
+          config
+      )
+    )}
+    ${indent 1 extraConfig}
+    </${name}>
+  '';
+
+in
+{
+  generateXML = generateXML;
+}