#!/bin/bash
option=x
#sudo apt-get install bc
areaOfSquare ()
{
printf "Please enter the length of a side of the square:\n"
read side

area=$((side**2))
printf "The area of the square is: $area\n"
}

areaOfRectangle ()
{
printf "Please enter the length of the rectangle:\n"
read length

printf "Please enter the width of the rectangle:\n"
read width

area=$(($length * $width))
printf "The area of the rectangle is: $area\n"
}

areaOfCircle ()
{
printf "Please enter the radius of the circle:\n"
read radius

area=$( echo "scale=6; $radius * $radius * 3.14159" | bc )
printf "The area of the circle is: $area\n"
}

areaOfCylinder ()
{
printf "Please enter the radius of the top of the cylinder:\n"
read radius

printf "Please enter the height of the cylinder:\n"
read height

areaCircle=$( echo "scale=6; $radius * $radius * 3.14159" | bc )

areaCylinder=$(echo "scale=6; $areaCircle * $height" | bc)

printf "The area of the cylinder is: $areaCylinder\n"
}

printf "Use one of the following options:\n"
printf "s:  to calculate the area of a square\n"
printf "r:  to calculate the area of a rectangle\n"
printf "c:  to calculate the area of a circle\n"
printf "cy: to calculate the area of a cylinder\n"

until [ "$option" = "s" -o "$option" = "r" -o "$option" = "c" -o "$option" = "cy" ]
do
    printf "Please enter your option:\n"
    read option

    # if [ "$option" != "s" -o "$option" != "r" -o "$option" != "c" -o "$option" != "cy" ]
        # then
            # printf "You have entered an incorrect option.\n"
    # fi

done

case "$option" in
    s)  areaOfSquare
        ;;
    r)  areaOfRectangle
        ;;
    c)  areaOfCircle
        ;;
    cy) areaOfCylinder
        ;;

esac