Reorganize imports

Signed-off-by: Nikolaos Karaolidis <nick@karaolidis.com>

hosts/common/configs/system/nix-cleanup/cleanup.sh

@@ -0,0 +1,41 @@
+if [[ "${EUID}" -ne 0 ]]; then
+  echo "Please run the script as root."
+  exit 1
+fi
+
+delete_subvolume_recursively() {
+  IFS=$'\n'
+  for i in $(btrfs subvolume list -o "$1" | cut -f 9- -d ' '); do
+    delete_subvolume_recursively "/mnt/btrfs/${i}"
+  done
+  btrfs subvolume delete "$1"
+}
+
+if [[ -e /mnt/btrfs && -n $(mountpoint -q /mnt/btrfs) ]]; then
+  echo "/mnt/btrfs is already mounted. Exiting."
+  exit 1
+fi
+
+if [[ -z "$DEVICE" ]]; then
+  echo "Error: DEVICE variable is not set."
+  exit 1
+fi
+
+mkdir -p /mnt/btrfs
+mount "/dev/mapper/$DEVICE" /mnt/btrfs
+
+if [[ -e /mnt/btrfs/@.bak ]]; then
+  if [[ -n "$(ls -A /mnt/btrfs/@.bak)" ]]; then
+    for i in /mnt/btrfs/@.bak/*; do
+      delete_subvolume_recursively "${i}"
+    done
+  else
+    echo "/mnt/btrfs/@.bak is empty. Nothing to delete."
+  fi
+fi
+
+umount /mnt/btrfs
+rmdir /mnt/btrfs
+
+nix-collect-garbage -d
+nix-store --gc -v

hosts/common/configs/system/nix-cleanup/default.nix

@@ -0,0 +1,17 @@
+{ config, pkgs, ... }:
+{
+  environment.systemPackages = [
+    (pkgs.writeShellApplication {
+      name = "nix-cleanup";
+      runtimeInputs = with pkgs; [
+        coreutils
+        util-linux
+        findutils
+        btrfs-progs
+        nix
+      ];
+      runtimeEnv.DEVICE = config.environment.impermanence.device;
+      text = builtins.readFile ./cleanup.sh;
+    })
+  ];
+}