Refactor code to make linter runs succeed

This commit refactors the codebase in order to make the shellcheck
workflow pass.

duplicati/duplicati-backup.sh

@@ -27,6 +27,59 @@ while getopts ":f:h:u:p:m:b:" opt; do
   esac
 done
 
+TMP_FILENAME="duplicati_db-$(date +"%Y%m%d").bak"
+TMP_FILEPATH="$SCRIPT_ABS_LOCATION"
+
+log "Compressing and encrypting the Duplicati Databases"
+sudo tar --absolute-names -czf - "$SOURCE_DIR" | openssl enc -aes-256-cbc -pbkdf2 -pass "pass:$BACKUP_ENCR_PASSPHRASE" > "$TMP_FILEPATH/$TMP_FILENAME" || {
+    log "Error: Failed to create encrypted archive."
+    exit 1
+}
+
+log "Fetching number of backups in destination folder"
+EXISTING_BACKUPS=$(ssh -p 23 -i "$SSH_KEY" "$SSH_USERNAME@$SSH_DESTINATION" "ls '$BACKUP_FOLDER'" | wc -l) || {
+    log "Error: Failed to count existing backups."
+    exit 1
+}
+
+if (( $EXISTING_BACKUPS > $MAX_BACKUPS )); then
+  log "Removing old backups in order to save space"
+  ssh "$SSH_USERNAME@$SSH_DESTINATION" -p 23 -i "$SSH_KEY" "ls -t $BACKUP_FOLDER | tail -n +$((MAX_BACKUPS+1)) | xargs rm" || { log "Error: Failed to remove old backups."; ex
+it 1; }
+fi
+
+log "Transferring archive to SSH Destination"
+scp -v -P 23 -i "$SSH_KEY" "$TMP_FILEPATH/$TMP_FILENAME" "$SSH_USERNAME@$SSH_DESTINATION:$BACKUP_FOLDER$TMP_FILENAME" || {
+    log "Error: Failed to transfer the encrypted archive."
+    exit 1
+}
+
+log "Cleaning up temporary files"
+rm "$TMP_FILEPATH/$TMP_FILENAME" || {
+    log "Error: Failed to remove the temporary file."
+    exit 1
+}
+
+log "Backup completed successfully."
+
+SOURCE_DIR="/mnt/data/duplicati"
+
+# Set default values for parameters
+MAX_BACKUPS=7
+
+# Override default values with command-line arguments
+while getopts ":f:h:u:p:m:b:" opt; do
+  case $opt in
+    f) SOURCE_DIR="$OPTARG";;
+    h) SSH_DESTINATION="$OPTARG";;
+    u) SSH_USERNAME="$OPTARG";;
+    p) SSH_KEY="$OPTARG";;
+    m) MAX_BACKUPS="$OPTARG";;
+    b) BACKUP_FOLDER="$OPTARG";;
+    \?) echo "Invalid option: -$OPTARG"; exit 1;;
+  esac
+done
+
 # Create a temporary file for the encrypted archive
 TMP_FILENAME="duplicati_db-$(date +"%Y%m%d").bak"
 TMP_FILEPATH="$SCRIPT_ABS_LOCATION"