part of a shell script of a tutorial in need of refactoring

shell-script-tutorial.sh

#!/bin/bash

# Script by CC Oosting (TheRealProcyon) made on 2018-05-25

# Script that was made for a tutorial, which reports the number of files in a dir,
# as well as how many folders (WIP), what the biggest file is (WIP), and more


# checks if a command is given
if [ $# != 1 ]
then

    echo "To use this script give in an existing directory"
    exit
fi

# check if directory does exist
if [ ! -d $1 ]
then
    echo "directory doesn't exist, try again and give a real directory this time"
    exit
elif [ -d $1 ] 
then


    read -p "Directory exists, do you want to list the file amount? [Y/n]" filesamountquestion

    read -p "Do you want to list how many dirs there are in this dir? [Y/n]" diramountquestion
    read -p "Do you want to list what the biggest file is? [Y/n]" biggestfilequestion
    read -p "Do you want to view what the most recently modified file is? [Y/n]" modifiedquestion
    read -p "Do you want to list what users own files in this directory? [Y/n]" ownersquestion

    case ${filesamountquestion:0:1} in
        n|N|m|M|b|B )
            # TODO
            echo "nah"
        ;;
        * )
            # TODO
            echo "okay"
        ;;
    esac

    case ${diramountquestion:0:1} in
        n|N|m|M|b|B )
            # TODO
            echo "nah"
        ;;
        * )
            # TODO
            echo "okay"
        ;;
    esac

    case ${biggestfilequestion:0:1} in
        n|N|m|M|b|B )
            # TODO
            echo "nah"
        ;;
        * )
            # TODO
            echo "okay"
        ;;
    esac

    case ${modifiedquestion:0:1} in
        n|N|m|M|b|B )
            # TODO
            echo "nah"
        ;;
        * )
            # TODO
            echo "okay"
        ;;
    esac

    case ${ownersquestion:0:1} in
        n|N|m|M|b|B )
            # TODO
            echo "nah"
        ;;
        * )
            # TODO
            echo "okay"
        ;;
    esac
fi