help im dum

menuselect() {
    local -n ref_choice=$1
    local -a arr=( "${@:2}" )
    local ht=$MENUHT
    local ct=${#arr[@]}
    if [[ "$ht" == '' ]]; then
        ht=$(($TERM_HEIGHT - 10))
    fi
    if [[ $ht -gt $ct ]]; then
        ht=$ct
    fi
    for i in $(seq $(($ht - 1))); do
        echo -en "${arr[$i]}\e[${#arr[$i]}D\e[B"
    done
    echo -en "\e[${ht}A\e[47m\e[30m${arr[0]}\e[0m"`
        `"\e[${#arr[0]}D"
    local n=0
    local scroll=0
    local key
    local str
    local m
    local scroll_up
    readv scroll_up << 'EOT'
        if [[ $amt -gt $n ]]; then amt=$n; fi
        m=$(($n - $amt))
        if [[ $n -le 0 ]]; then :
        elif [[ $m -ge $scroll ]]; then
            echo -en "${arr[$n]}\e[${#arr[$n]}D"`
                `"\e[${amt}A\e[47m\e[30m${arr[$m]}\e[0m"`
                `"\e[${#arr[$m]}D"
            n=$m
        else
            for i in $(seq $scroll $(($scroll + $ht - 1))); do
                printf "%${#arr[$i]}s" ''
                echo -en "\e[${#arr[$i]}D\e[B"
            done
            echo -en "\e[${ht}A"
            scramt=$amt
            if [[ $(($scroll - $scramt)) -lt 0 ]]; then
                scramt=$scroll
            fi
            for i in $(seq $(($scroll - $scramt)) $(($scroll + $ht - 1 - $scramt))); do
                printf "%${#arr[$(($i+$scramt))]}s" ''
                echo -en "\e[${#arr[$(($i+$scramt))]}D"`
                    `"${arr[$i]}\e[${#arr[$i]}D\e[B"
            done
            scroll=$(($scroll - $scramt))
            n=$m
            echo -en "\e[$(($ht-$m+$scroll))A\e[47m\e[30m${arr[$n]}\e[0m\e[${#arr[$n]}D"
        fi
EOT
    local scroll_down
    readv scroll_down << 'EOT'
        if [[ $amt -gt $(($ct - $n - 1)) ]]; then
            amt=$(($ct - $n - 1))
        fi
        m=$(($n + $amt))
        if [[ $n -ge $(($ct - 1)) ]]; then :
        elif [[ $m -lt $(($scroll + $ht)) ]]; then
            echo -en "${arr[$n]}\e[${#arr[$n]}D"`
                `"\e[${amt}B\e[47m\e[30m${arr[$m]}\e[0m"`
                `"\e[${#arr[$m]}D"
            n=$m
        else
            echo -en "\e[$(($n-$scroll))A"
            for i in $(seq $scroll $(($scroll + $ht - 1))); do
                printf "%${#arr[$i]}s" ''
                echo -en "\e[${#arr[$i]}D\e[B"
            done
            echo -en "\e[${ht}A"
            scramt=$amt
            if [[ $(($scroll + $scramt)) -gt $(($ct - $ht)) ]]; then
                scramt=$(($ct - $ht - $scroll))
            fi
            for i in $(seq $(($scroll + $scramt)) $(($scroll + $ht - 1 + $scramt))); do
                printf "%${#arr[$(($i-$scramt))]}s" ''
                echo -en "\e[${#arr[$(($i-$scramt))]}D"`
                    `"${arr[$i]}\e[${#arr[$i]}D\e[B"
            done
            scroll=$(($scroll + $scramt))
            n=$m
            echo -en "\e[$(($ht-$m+$scroll))A\e[47m\e[30m${arr[$n]}\e[0m\e[${#arr[$n]}D"
        fi
EOT
    local amt
    while key=$(getkey); do case ${key} in
    '^[[A')
        amt=1
        eval "$scroll_up"
        ;;
    '^[[B')
        amt=1
        eval "$scroll_down"
        ;;
    '^[[5~')
        if [[ $n == $scroll ]]; then
            amt=$ht
        else
            amt=$(($n - $scroll))
        fi
        eval "$scroll_up"
        ;;
    '^[[6~')
        amt=$(($ht - $n + $scroll))
        if [[ $(($scroll + $ht)) -lt $ct ]]; then
            eval "$scroll_down"
        else
            local times=$amt
            for j in $(seq $times); do
                amt=1
                eval "$scroll_down"
            done
        fi
        ;;
    '')
        ref_choice=$n
        return 0
        ;;
    esac; done
    return 1
}