#!/usr/bin/env bash

            declare -i f=75 s=13 r=2000 t=0 c=1 n=0 l=0
            declare -ir w=$(tput cols) h=$(tput lines)
            declare -i x=$((w/2)) y=$((h/2))

            declare -ar v=( [00]="\x82" [01]="\x8c" [03]="\x90"    ####
                            [10]="\x98" [11]="\x80" [12]="\x90"    #  Normal UTF-8 box characters.
                            [21]="\x94" [22]="\x82" [23]="\x98"    #  (These are the default for they are supported almost everywhere.)
                            [30]="\x94" [32]="\x8c" [33]="\x80" )  ####

           #declare -ar v=( [00]="\x83" [01]="\x8f" [03]="\x93"    ####
           #                [10]="\x9b" [11]="\x81" [12]="\x93"    #  Heavy UTF-8 box characters.
           #                [21]="\x97" [22]="\x83" [23]="\x9b"    #  (Uncomment only if your terminal supports it)
           #                [30]="\x97" [32]="\x8f" [33]="\x81" )  ####

            OPTIND=1
            while getopts "f:s:r:h" arg; do
            case $arg in
                    f) ((f=($OPTARG>19 && $OPTARG<101)?$OPTARG:$f));;
                    s) ((s=($OPTARG>4 && $OPTARG<16 )?$OPTARG:$s));;
                    r) ((r=($OPTARG>0)?$OPTARG:$r));;
                    h) echo -e "Usage: pipes [OPTION]..."
                            echo -e "Animated pipes terminal screensaver.\n"
                            echo -e " -f [20-100]\tframerate (D=75)."
                            echo -e " -s [5-15]\tprobability of a straight fitting (D=13)."
                            echo -e " -r LIMIT\treset after x characters (D=2000)."
                            echo -e " -h\t\thelp (this screen).\n"
                            exit 0;;
                    esac
            done

    tput smcup
    tput reset
    tput civis

    trap "tput rmcup; tput reset; exit" SIGINT

    while true; do
                    # New position:
                    (($l%2)) && ((x+=($l==1)?1:-1))
                    ((!($l%2))) && ((y+=($l==2)?1:-1))

                    # Loop on edges (change color on loop):
                    ((c=($x>$w || $x<0 || $y>$h || $y<0)?($RANDOM%7):$c))
                    ((x=($x>$w)?0:(($x<0)?$w:$x)))
                    ((y=($y>$h)?0:(($y<0)?$h:$y)))

                    # New random direction:
                    ((n=$RANDOM%$s-1))
                    ((n=($n>1||$n==0)?$l:$l+$n))
                    ((n=($n<0)?3:$n%4))

                    # Print:
                    tput cup $y $x
                    printf "\033[1;3${c}m\xe2\x94${v[$l$n]}"
                    (($t>$r)) && tput reset && tput civis && t=0 || ((t++))
                    l=$n
                    sleep $(echo "scale=5;1/$f"|bc)
    done