refactor(script): Get variables first then define an operation suffix (#1)

pacman-zfs-snapshot.sh

@@ -5,9 +5,6 @@ while read pkg; do
     pkgs+=("${pkg}")
 done
 
-declare operation
-operation="${1}"
-
 declare conf_file
 conf_file='/etc/pacman-zfs-snapshot.conf'
 
@@ -37,6 +34,20 @@ declare pkg_separator max_zfs_snapshot_name_length
 pkg_separator=':'
 max_zfs_snapshot_name_length='255'
 
+declare operation conf_op_suffix
+operation="${1}"
+case "${operation}" in
+    install)
+        conf_op_suffix="${snap_op_installation_suffix}"
+        ;;
+    remove)
+        conf_op_suffix="${snap_op_remove_suffix}"
+        ;;
+    upgrade)
+        conf_op_suffix="${snap_op_upgrade_suffix}"
+        ;;
+esac
+
 function pprint () {
     local style msg exit_code
     style="${1:?}"