function initialize
{
        num_ques=0              # Number of questions asked so far
        num_correct=0           # Number answered correctly so far
        cd ${QUIZDIR:=/usr/games/lib/quiz} || exit 2
}

function choose_subj
{
        subjects=$(\ls)
        PS3="Choose a subject for the quiz from the following:  "
        select Subject in $subjects
        do
                if [[ -z "$Subject" ]]
                then
                        echo "No subject chosen.  Bye." >&2
                        exit 1
                fi
                echo $Subject
                return 0
        done
}

function exchange
{
        temp_value=${questions[$1]}
        questions[$1]=${questions[$2]}
        questions[$2]=$temp_value
}

function scramble
{
        set -A questions $(\ls)
        quescount=${#questions[*]}      # Number of elements
        ((index=quescount-1))
        while [[ $index > 0 ]]
        do
                ((target=RANDOM % index))
                exchange $target $index
                ((index=index-1))
        done
}

function ask
{
        exec 3<$1
        read -u3 ques || exit 2
        read -u3 num_opts || exit 2

        index=0
        choices=""
        while [[ $index < $num_opts ]]
        do
                read -u3 next_choice || exit 2
                choices="$choices:$next_choice"
                ((index=index+1))
        done

        read -u3 correct_answer || exit 2
        exec 3<&-
       
        SaveIFS="$IFS"
        IFS=":"
        choices=${choices#:}
        set $choices

         echo "You may press the Interrupt Key at any time to quit."
         PS3=$ques"  "      # Make $ques the prompt for select, but...
                            # ...add some spaces for legibility.
        select answer
                do
                IFS="$SaveIFS"
                if [[ -z "$answer" ]]
                then
                        echo  Not a valid choice. Please choose again.
                elif [[ "$answer" = "$correct_answer" ]]
                then
                        echo Correct!
                        return 1
                else
                        echo No, the answer is $correct_answer.
                        return 0
                fi
        done
}

function summarize
{
        if [[ $num_ques == 0 ]]
        then
                echo "You did not answer any questions"
                exit 0
        fi

        ((percent=num_correct*100/num_ques))
        print "You answered $num_correct questions correctly, out of \
$num_ques total questions."
        print "Your score is $percent percent."
}

# Main program
initialize
trap 'summarize ; exit 0' INT

subject=$(choose_subj)
[[ $? -eq 0 ]] || exit 2

cd $subject || exit 2

echo	        # Skip a line
scramble

for ques in ${questions[*]}
do
        ask $ques
        result=$?
        ((num_ques=num_ques+1))
        if [[ $result == 1 ]]
        then
                ((num_correct=num_correct+1))
        fi
        echo            # skip a line between questions
	sleep ${QUIZDELAY:=1}
done

summarize
exit 0