#!/bin/bash

LINES=$(tput lines)
COLUMNS=$(tput cols)

declare -A snowflakes
declare -A lastflakes

clear

function move_flake() {
    i="$1"

    if [ "${snowflakes[$i]}" = "" ] || [ "${snowflakes[$i]}" = "$LINES" ]; then
        snowflakes[$i]=0
    else
        if [ "${lastflakes[$i]}" != "" ]; then
            printf "\033[%s;%sH \033[0;0H " "${lastflakes[$i]}" "$i"
        fi
    fi

    printf "\033[%s;%sH❄\033[0;0H" "${snowflakes[$i]}" "$i"

    lastflakes[$i]=${snowflakes[$i]}
    snowflakes[$i]=$((${snowflakes[$i]}+1))
}

while :
do
    i=$((RANDOM % COLUMNS))

    move_flake $i

    for x in "${!lastflakes[@]}"
    do
        move_flake "$x"
    done

    sleep 0.1
done