1 files changed, 77 insertions, 0 deletions
diff --git a/sys/fs/layout.nix b/sys/fs/layout.nix
new file mode 100644
index 0000000..999492d
--- /dev/null
+++ b/sys/fs/layout.nix
@@ -0,0 +1,77 @@
+{ lib, config, ... }:
+with lib; let
+  cfg = config.local;
+in {
+  options.local.fs.layout = with lib.types; {
+    sysHddBtrfs = mkOption {
+      default = null;
+
+      type = nullOr (submodule {
+        options = {
+          sys = {
+            device = mkOption {
+              type = str;
+            };
+
+            ssd = mkOption {
+              type = bool;
+            };
+
+            root = mkOption {
+              type = str;
+            };
+
+            toplevel = mkOption {
+              type = str;
+            };
+          };
+
+          hdd = {
+            device = mkOption {
+              type = str;
+            };
+
+            home = mkOption {
+              type = str;
+            };
+          };
+        };
+      });
+    };
+  };
+
+  config = {
+    local.fs.btrfs = let
+      sysHddBtrfs = layout: {
+        "/" = {
+          inherit (layout.sys) device ssd;
+          subvol = layout.sys.root;
+        };
+
+        "/toplevel" = {
+          inherit (layout.sys) device ssd;
+          subvol = layout.sys.toplevel;
+        };
+
+        "/hdd" = {
+          inherit (layout.hdd) device;
+          subvol = "/";
+          ssd = false;
+        };
+
+        "/home" = {
+          inherit (layout.hdd) device;
+          subvol = layout.hdd.home;
+          ssd = false;
+          snapper = "home";
+        };
+      };
+
+      inherit (cfg.fs) layout;
+
+      layoutMaps = [ sysHddBtrfs ];
+      layoutOpts = [ layout.sysHddBtrfs ];
+      valid = filter ({ snd, ... }: snd != null) (zipLists layoutMaps layoutOpts);
+    in optionalAttrs (valid != []) ((head valid).fst (head valid).snd);
+  };
+}