choose-or-die

#!/bin/bash
#
# Code by Leif Högberg <github: leihog>
# Dice ascii art by jgs
#
###

choices=()
choice_numbers=()
assigned_numbers=()

num_dice=0
spots_per_die=0


menu() {
    local menu_choices=()
    local menu_indices=()
    local prompt=
    for c in $1; do
        local ca=(${c//:/ })
        menu_indices+=(${ca[0]})
        menu_choices+=(${ca[1]})
        prompt+=${ca[0]}
    done

    [[ $2 != "" ]] && echo -e "$2"
    echo -n "[$prompt]"

    while true; do
        read -rsn1 input
        for i in ${!menu_indices[@]}; do
            if [[ ${menu_indices[$i]} == $input ]]; then

                echo
                local cmd=${menu_choices[$i]}
                if [[ ${cmd:0:1} == "!" ]]; then
                    ${cmd:1} && return $?
                fi

                $cmd
                echo
                echo -e "$2"
                echo -n "[$prompt]"
                break
            fi
        done
    done
}

trap quit EXIT
quit() {
    echo
    echo "Thank you, come again."
    exit
}

nop() {
    return 0
}

main_prompt() {
    [ ${#choices[@]} -gt 0 ] && echo -n "[a,r,h,q]:" || echo -n "[a,h,q]"
}

collect_choices() {
    echo "When you are done enter a single dot [.]"

    local csize=${#choices[@]}
    local cindex=$((csize + 1))
    while true; do
        echo
        echo -n "Enter a name/description: "
        read input

        [[ $input == "." ]] && break

        choices[$cindex]=$input
        cindex=$((cindex + 1))


        echo
        echo "Possible choices are:"
        for c in "${choices[@]}"; do
            echo "  $c"
        done
    done

    echo
    echo "Possible choices are:"
    for c in "${choices[@]}"; do
        echo "  $c"
    done
}

six_sided_die_with_automatic_assignment() {
    num_dice=0
    spots_per_die=6

    local spots=$spots_per_die
    while true; do
        num_dice=$((num_dice + 1))
        if [[ $(( ($spots - $num_dice + 1) % ${#choices[@]} )) != 0 ]]; then
            spots=$((spots + $spots_per_die)) && continue
        fi

        num_per_choice=$(( $spots / ${#choices[@]} ))
        break
    done

    local min_num=$num_dice
    local max_num=$spots

    echo
    echo Number of choices: ${#choices[@]}
    echo Number of dice: $num_dice
    echo Numbers per choice: $num_per_choice
    echo assigning numbers between $min_num and $max_num
    echo

    local valid_numbers=()
    for ((i=min_num; i<=max_num; i++)); do
        valid_numbers+=($i)
    done

    # shuffle using Knuth-Fisher-Yates shuffle algorithm
    local i rand size tmp
    size=${#valid_numbers[*]}
    for ((i=size; i>0; i--)); do
        rand=$(( RANDOM % (i+1) ))

        tmp=${valid_numbers[i]}
        valid_numbers[i]=${valid_numbers[rand]}
        valid_numbers[rand]=$tmp
    done

    # assign numbers
    local ci=1
    local c_max=${#choices[@]}
    for num in ${valid_numbers[@]}; do
        assigned_numbers[$num]=$ci
        choice_numbers[$ci]="${choice_numbers[$ci]} $num"
        [[ $ci < $c_max ]] && ci=$((ci + 1)) || ci=1
    done

    for i in ${!choice_numbers[@]}; do
        echo "${choices[$i]}: " ${choice_numbers[$i]}
    done
}

roll_dice() {

    echo
    local rand max i total
    max=$(( 32768 / spots_per_die * spots_per_die ))

    total=0
    for (( i=1; i<=num_dice; i++ )); do

        while (( (rand=$RANDOM) >= max )); do :; done
        rand=$(( rand % spots_per_die + 1 ))
        total=$((total + rand))

        [[ $num_dice > 1 ]] && echo "Rolling die #$i: $rand"

    done

    c_index=${assigned_numbers[$total]}
    echo "The result is $total which means that"
    echo "the winner is:" ${choices[$c_index]}
}

show_splash() {
cat <<"Fossa"

        .-------.    ______
       /   o   /|   /\     \
      /_______/o|  /o \  o  \
      | o     | | /   o\_____\
      |   o   |o/ \o   /o    /
      |     o |/   \ o/  o  /
      '-------'     \/____o/

           choose-or-die
          by Leif Högberg

Fossa
}

show_splash

echo "Start by adding choices"
collect_choices

# TODO is there a better way to setup the menu?
echo
menu "a:collect_choices c:!nop" "To continue press [c]. Press [a] to add more choices or ctrl+c to quit."

# algorithm that uses multiple six sided die
echo
echo "Calculating the number of dice to use and assigning numbers"
six_sided_die_with_automatic_assignment

echo
echo "Thats it! We have what we need, the rest is up to lady luck."
echo "Whenever you are ready, press [r] to roll the dice."
menu "r:!roll_dice"