encode and decode str with base64

base64.bash

#!/bin/bash

INPUT=false
ACTION=""
CODE=""

while getopts 'iD:E:h' flag; do
  case "${flag}" in
    i) INPUT=true ;;
    D) ACTION="D" && CODE="$OPTARG" ;;
    E) ACTION="E" && CODE="$OPTARG" ;;
    h) printf "available option \n\tD<STR> - decode str\n\tE<STR> - encode str\n\ti - decode/encode by reading input separately" && exit 0 ;;
    *) error "Unexpected option ${flag} run -h for more information" ;;
  esac
done

# INPUT SECTION

if $INPUT; then
    while true; do
        printf "\nInput str[e<STR>|d<STR>|q]: \n"
        read str
        if [[ $str == "q" ]]; then
            exit
        fi

        first="${str:0:1}"
        real_str="${str#?}"

        if [[ $first == "d" ]]; then
            echo "$real_str" | base64 -D 
        else 
            echo "$real_str" | base64
        fi
    done
fi

# NORMAL SECTION

if [[ $CODE == "" ]]; then 
    echo "more information at -h"
    exit 1
fi

if [[ $ACTION == "D" ]]; then
    echo "$CODE" | base64 -D 
else 
    echo "$CODE" | base64
fi