# Modalità "rotate"
# Variabili e funzioni di supporto
# a modalità rotate

# Fai un backup compresso del db file
# Assegna il nome del file di backup
# alla variabile attesa come primo
# argomento.
bkcomp_dbfile(){
  local COMPBK_NAME="${SHIFT_FILE}.bk$(date +%F_%T).gz"

  gzip -c9 "$SHIFT_FILE" > "$COMPBK_NAME" 2>/dev/null ||\
  echoerr "Failed to backup shifts file ${SHIFT_FILE}."

  chgrp "$OPGROUP" "$COMPBK_NAME" &>/dev/null ||\
  echoerr "Failed to change group ownership of backed up shifts file $COMPBK_NAME to $OPGROUP."
  chmod g=wr,o= "$COMPBK_NAME" &>/dev/null ||\
  echoerr "Failed to change mode of backed up shifts file $COMPBK_NAME."

  eval $1="$COMPBK_NAME"

  return 0
}

# Chiede conferma della rotazione.
ask_rotate(){
  echo -e "\n\e[0;33mWarning\e[0m: rotation of shifts file clears current shifts records."
  echo "This operation can only be reverted manually."
  echo "Proceed at your own risk."
  echo -n 'Enter "YES" to proceed, anything else to abort: '
  
  local ANSWER 
  read ANSWER
  
  [ "$ANSWER" == "YES" ] ||\
  { echo -e "\nRotation aborted. You don't make me spin. :("; exit 0; }
}

# Ruota il file dei turni
rotate_dbfile(){
  # Check esistenza
  check_dbfile exist ||\
  echoerr "There's nothing to rotate: $SHIFT_FILE does not exist."
  
  # Conferma
  ask_rotate  

  # Backup
  local SHIFT_FILE_COMPBK
  bkcomp_dbfile SHIFT_FILE_COMPBK

  # Init nuovo file turni
  initialize_dbfile

  # Notifica
  echo -e "\n\e[0;32mRotation successful!\e[0m I feel dizzy. O.o"
  echo "Old shifts file backed up as ${SHIFT_FILE_COMPBK}."
}