function get_term_size() {
    # Get terminal size ('stty' is POSIX and always available).
    # This can't be done reliably across all bash versions in pure bash.
    read -r LINES COLUMNS < <(stty size)

    # Max list items that fit in the scroll area.
    ((max_items=LINES-3))
    return $max_items
}

#CHECK IF ZIP
function checkzip {
    if [[ $1 == *.zip ]]; then
        confirm_question
        if [[ $? -eq 0 ]];
        then
            return 0
        else
            return 1
        fi
    else
        echo "This is not a ZIP file."
        return 1
    fi
}


function checker {
    if [ -f "${list_dir[$selected]}" ];
    then
        checkzip "${list_dir[$selected]}"
        if [[ $? == 0 ]]; then
            push_install "${list_dir[$selected]}"
        else
            filemanager
        fi

    elif [ -d "${list_dir[$selected]}" ];
    then
        cd "${list_dir[$selected]}"
        clear
        start_scroll=0
        stop_scroll=$max_items
        filemanager
    fi
}


get_term_size
start_scroll=0
stop_scroll=$max_items
#FILE NAVIGATING
function filemanager {
    clear

    arr=(*)

    local other=0
    list_dir=("..")
    if [[ ${#arr[@]} -gt $max_items ]]; then
        local d=1
        if [[ $stop_scroll -le ${#arr[@]} ]]; then
            for ((i=$start_scroll; i < stop_scroll; i++)); do
                list_dir[d]+=${arr[i]}
                ((d++))
            done

            if [[ $start_scroll -ne 0 ]]; then
                list_dir[0]="..."
            elif [[ $start_scroll -eq 0 ]]; then
                list_dir[0]='..'
            fi

            if [[ $stop_scroll != ${#arr[@]} ]]; then
                list_dir[d]="..."
            fi
            start_scroll=$stop_scroll
            stop_scroll=$((stop_scroll+max_items))
        else
            stop_scroll=${#arr[@]}
            other=$((stop_scroll-$max_items))
            filemanager
        fi
    else
        list_dir=(".." *)
    fi

    select_option "${list_dir[@]}"
    selected=$?
    if [[ $selected == $d ]]; 
    then
        filemanager
    elif [[ $selected -eq 0 && $start_scroll -ne 0 && $start_scroll -ne $max_items ]]; 
    then
        start_scroll=$(( start_scroll-(max_items*2+other) ))
        stop_scroll=$(( stop_scroll-(max_items*2+other) ))
        if [[ $start_scroll -lt 0 ]]; then
            start_scroll=0
            stop_scroll=$max_items
        fi
        filemanager
    else
        checker
    fi

}