#!/usr/bin/env bash


add_question() {
    question="|"
    until [[ ${#question} -eq 0 ]]; do
        read -p "Enter the question. (leave blank to end): " question
        if [[ ${#question} -eq 0 ]]; then
            continue
        fi
        while [[ $question == *"|"* ]]; do
            echo "Question cannot contain '|'. Please try again."
            read -p "Enter the question (without '|' character): " question
        done
        question="${question^}"

        answers=()
        read -p "Enter the answer (or press Enter to proceed to correct answer): " answer
        while [[ -n $answer ]]; do
            answers+=("$answer")
            if [[ "${answer^^}" =~ ^(T(R(U(E)?)?)?|F(A(L(S(E)?)?)?)?)$ ]]; then
                break
            fi
            read -p "Next answer? (press Enter to proceed): " answer
        done

        if [[ ${#answers[@]} -gt 1 ]]; then
            choices=()
            for ((i=1; i<=${#answers[@]}; i++)); do
                letter=$(printf "%s" $((i)) | tr '1-9' 'A-J')
                choices+=("${letter}: ${answers[$((i-1))]}")
            done

            choicesStr="${choices[0]}"
            for ((i=1; i<${#choices[@]}; i++)); do
                choicesStr+="|${choices[$i]}"
            done

            echo "Enter the correct choice:"
            read -p "${choicesStr//|/$'\n'}: " correct
            correct="${correct^}"
            while [[ ! $correct =~ ^[A-${letter}]$ ]]; do
                echo "Invalid choice. Please try again."
                read -p "Enter the correct choice (${choicesStr}): " correct
            done
            correctChoice="${correct:0:1}"
        elif [[ ${#answers[@]} -eq 1 ]]; then
            choice=${answers[0]}
            if [[ "${choice^^}" =~ ^[T][R][U][E]?$ ]]; then
                correctChoice="T"
            elif [[ "$choice" =~ ^[F][A][L][S][E]?$ ]]; then
                correctChoice="F"
            else
                echo "Invalid choice. Assuming 'T' (True) as the correct answer."
                correctChoice="T"
            fi
        else
            echo "No answers provided. Skipping the question."
            return
        fi

        question="${question}|${correctChoice:0:1}|${choicesStr}"
        question="${question%|}"
        echo "${question}" >> "$0"
        echo "Question added successfully!"
    done
    exit 0
}


shuffle_choices() {
    if [[ ${#answers[@]} -lt 2 ]]; then
        return
    fi
    local letter=({A..Z})
    local length="${#answers[@]}"
    local newAnswer
    local shuffledChoices
    mapfile -t shuffledChoices < <(shuf -e "${answers[@]#*: }")
    for i in "${!answers[@]}" ; do
    if [[ "${answers[$i]:0:1}" == "${answer}" ]]; then
        newAnswer="${answers[$i]}"
    fi
done
    for i in "${!shuffledChoices[@]}" ; do
        shuffledChoices[$i]="${letter[$i]}: ${shuffledChoices[$i]}"
        if [[ "${shuffledChoices[$i]#*:}" == "${newAnswer#*:}" ]]; then
            answer="${letter[$i]}"
        fi
    done
    answers=("${shuffledChoices[@]}")
}


if [[ $# -gt 1 ]]; then
    echo "Only 1 argument supported, -a or --question."
    exit 0
fi

if [[ $# -eq 1 ]]; then
    if [[ "${1}" == "-a" ]] || [[ "${1}" == "--add-question" ]]; then
        add_question
    else
        echo "Only 1 argument supported, -a or --question."
        exit 0
    fi
fi


startPosition="$(grep -n '^exit 0$' "${0}")"
startPosition="${startPosition%%:*}"
((startPosition++))
mapfile -t data < <(tail -n +${startPosition} "$0" | grep -v "^#" | grep -v "^$" | shuf)
right=0
wrong=0
                                                                                                                                                                
echo "Total questions: ${#data[@]}"
if [[ ${#data[@]} -eq 0 ]]; then
    echo "To add questions use the -a or --add-questions flag."
fi

for i in "${data[@]}" ; do
    question="${i%%|*}"
    i="${i#*|}"
    answer="${i%%|*}"
    answer="${answer^}"
    i="${i#*|}"
    unset answers
    while [[ ${#i} -gt 1 ]]; do
        answers+=("${i%%|*}")
        i="${i#*|}"
        if [[ "${i%%|*}" == "${i}" ]]; then
            answers+=("${i}")
            break
        fi
    done
    shuffle_choices
    echo
    echo "${question}"
    for i in "${answers[@]}" ; do
        echo "${i}"
    done
    read -r choice
    choice="${choice:0:1}"
    choice="${choice^}"
    if [[ "${choice}" == "${answer}" ]]; then
        echo "Correct!"
        ((right++))
    else
        echo -n "Wrong, the answer is: "
        for i in "${answers[@]}" ; do
            if [[ "${answer}" == "${i:0:1}" ]]; then
                echo "$i"
            fi
        done
        ((wrong++))
    fi
    if [[ "${answer}" == "F" ]] || [[ "${answer}" == "T" ]]; then
        answer="${answer/F/False}"
        answer="${answer/T/True}"
        echo "${answer}"
    fi
    read -rp "Press enter to continue"
done


# Results
echo
echo "Out of ${#data[@]} questions, you got ${right} correct."
if [[ ${#wrong} -gt 0 ]]; then
    echo "You missed ${wrong} questions."
fi
if command -v bc &> /dev/null ; then
    grade=$(echo "scale=2; $right * 100 / ${#data[@]}" | bc)
    echo "On a 100 based grading scale, this gives you a score of $grade."
fi


exit 0