refactor: moved nixos modules to dendrite pattern

modules/nixos/programs/sync/default.nix

@@ -0,0 +1,10 @@
+{config, ...}: let
+  mod = config.flake.nixosModules;
+in {
+  flake.nixosModules.sync = {
+    imports = [
+      mod.sync-service
+      mod.sync-storage
+    ];
+  };
+}

modules/nixos/programs/sync/storage.nix

@@ -0,0 +1,34 @@
+{...}: {
+  flake.nixosModules.sync-storage = {
+    config,
+    lib,
+    ...
+  }: let
+    mountDir = "/mnt/sync";
+    configDir = "/etc/syncthing";
+  in {
+    options = {
+      services.syncthing.impermanence.enable = lib.mkOption {
+        type = lib.types.bool;
+        default = config.services.syncthing.enable && config.storage.impermanence.enable;
+      };
+    };
+
+    config = lib.mkIf config.services.syncthing.enable {
+      storage.datasets.replicate."system/root" = {
+        directories = {
+          "${mountDir}" = lib.mkIf config.services.syncthing.impermanence.enable {
+            enable = true;
+            owner.name = "syncthing";
+            group.name = "syncthing";
+          };
+          "${configDir}" = lib.mkIf config.services.syncthing.impermanence.enable {
+            enable = true;
+            owner.name = "syncthing";
+            group.name = "syncthing";
+          };
+        };
+      };
+    };
+  };
+}

modules/nixos/programs/sync/sync.nix

@@ -0,0 +1,38 @@
+{...}: {
+  flake.nixosModules.sync-service = {
+    config,
+    lib,
+    syncthingConfiguration,
+    ...
+  }: let
+    mountDir = "/mnt/sync";
+    configDir = "/etc/syncthing";
+  in {
+    config = lib.mkMerge [
+      {
+        systemd = lib.mkIf config.services.syncthing.enable {
+          tmpfiles.rules = [
+            "A ${mountDir} -    -        -               - u:syncthing:rwX,g:syncthing:rwX,o::-"
+            "d ${mountDir} 2755 syncthing syncthing -"
+            "d ${config.services.syncthing.dataDir} 775 syncthing syncthing -"
+            "d ${config.services.syncthing.configDir} 755 syncthing syncthing -"
+          ];
+        };
+      }
+      (lib.mkIf config.services.syncthing.enable (lib.mkMerge [
+        {
+          services.syncthing = {
+            user = "syncthing";
+            group = "syncthing";
+            dataDir = "${mountDir}/default";
+            configDir = configDir;
+            overrideDevices = true;
+            overrideFolders = true;
+            configuration = syncthingConfiguration;
+            deviceName = config.networking.hostName;
+          };
+        }
+      ]))
+    ];
+  };
+}