refactor(script): Trim package name if it doesn't fit full-length (#1)

pacman-zfs-snapshot.sh

@@ -180,6 +180,24 @@ function find_max_dataset_name_length () {
     fi
 }
 
+function trim_single_remaining_package_name () {
+    local pkg_name
+    pkg_name="${shorter_pkg_list}"
+    case 1 in
+        # Trim to 1 to 3 characters, no trailing ellipsis (...)
+        $(( 1<=pkgs_list_max_length && pkgs_list_max_length<=3 )))
+            pkg_name="${pkg_name::${pkgs_list_max_length}}"
+            ;;
+        # Show as many pkg name characters as we can while also
+        # fitting an ellipsis into the name (...) to indicate
+        # that we've cut the pkg name off at the end.
+        $(( pkgs_list_max_length>=4 )))
+            pkg_name="${pkg_name::$(( pkgs_list_max_length - 3 ))}"'...'
+            ;;
+    esac
+    shorter_pkg_list="${pkg_name}"
+}
+
 function trim_pkg_list_oneline () {
     local available_pkg_list_length
     available_pkg_list_length="$((${max_zfs_snapshot_name_length} - ${max_dataset_name_length}))"
@@ -190,6 +208,12 @@ function trim_pkg_list_oneline () {
     fi
 
     local shorter_pkg_list
+    if [[ "${pkgs_list_max_length}" -le '0' ]]; then
+        # User wants zero characters of pkg names in snapshot name,
+        # no need to even find an appropriate pkg name string. Just
+        # set to empty string and we're done here.
+        shorter_pkg_list=''
+    else
         shorter_pkg_list="${unabridged_pkg_list_oneline}"
         while [[ "${#shorter_pkg_list}" -gt "${pkgs_list_max_length}" ]]; do
             shorter_pkg_list="${shorter_pkg_list%${pkg_separator}*}"
@@ -199,9 +223,10 @@ function trim_pkg_list_oneline () {
             fi
         done
         if [[ "${#shorter_pkg_list}" -gt "${pkgs_list_max_length}" ]]; then
-        # If this is still too long we empty the package list
+            trim_single_remaining_package_name
-        shorter_pkg_list=''
         fi
+    fi
+
     trimmed_pkg_list_oneline="${shorter_pkg_list}"
 }