#!/bin/zsh

tput civis
stty -echo

size_x=30
size_y=20
tps=6
paddle=2

spt=$((1000000000 / $tps))
last_tick=0

left_score=0
right_score=0

scramble_speed () {
    ball_rx=$((0.66 + $RANDOM % 6 / 6.0))
    ball_ry=$((0.66 + $RANDOM % 6 / 6.0))
}

reset_game () {
    clear

    ball_x=$(($size_x / 2))
    ball_y=$(($size_y / 2))
    ball_vx=$(($RANDOM % 2 * 2 - 1))
    ball_vy=$(($RANDOM % 2 * 2 - 1))
    scramble_speed

    left_y=$(($size_y / 2))
    left_vy=0

    right_y=$(($size_y / 2))
    right_vy=0
}

render_game () {
    #clear

    [ -z $ball_fy ] || tput cup $(($ball_fy / 2)) $ball_fx
    printf " "

    y=$((($left_y - $paddle) / 2 - 1))
    [ $y -ge 0 ] && tput cup $y 0
    printf " "
    tput cup $((($left_y + $paddle) / 2 + 1)) 0
    printf " "

    y=$((($right_y - $paddle) / 2 - 1))
    [ $y -ge 0 ] && tput cup $y $(($size_x - 1))
    printf " "
    tput cup $((($right_y + $paddle) / 2 + 1)) $(($size_x - 1))
    printf " "

    tput cup $(($size_y / 2)) $(($size_x / 2 - 3))
    printf $left_score
    tput cup $(($size_y / 2)) $(($size_x / 2 + 2))
    printf $right_score

    ball_fx=$(printf $ball_x | sed -E 's/\..*//')
    ball_fy=$(printf $ball_y | sed -E 's/\..*//')
    tput cup $(($ball_fy / 2)) $ball_fx
    if [[ $(($ball_y % 2)) -le 0.6 ]]; then
        #char="º"
        char="▀"
        #printf "º"
    elif [[ $(($ball_y % 1)) -le 1.3 ]]; then
        #char="∘"
        char="▪"
        #printf "∘"
    else
        #char="ₒ"
        char="▄"
        #printf "ₒ"
    fi
    printf $char
    #tput cup $size_y 0
    #printf $char

    #tput cup 0 0
    #printf " $ball_y $ball_x "

    for y in {-$paddle..$paddle}; do
        tput cup $((($left_y - $y) / 2)) 0
        printf "▌"
        tput cup $((($right_y - $y) / 2)) $(($size_x - 1))
        printf "▐"
    done
}

reset_game
render_game

while true; do
    key=""
    read -t 0.1 -k 1 key
    if [ "$key" != "" ]; then
        if [ "$key" = "w" ]; then; left_vy=-2
        elif [ "$key" = "s" ]; then; left_vy=2
        elif [ "$key" = "k" ]; then; right_vy=-2
        elif [ "$key" = "j" ]; then; right_vy=2
        fi
    fi

    tick=$(($(date +%N) / $spt))
    if [ $tick != $last_tick ]; then
        last_tick=$tick
        ball_x=$(($ball_x + $ball_vx * $ball_rx))
        ball_y=$(($ball_y + $ball_vy * $ball_ry))
        left_y=$(($left_y + $left_vy))
        right_y=$(($right_y + $right_vy))
        left_vy=0
        right_vy=0

        if [[ $ball_y -lt 0 ]]; then; ball_vy=1; ball_y=0; fi
        if [[ $ball_y -gt $(($size_y - 1)) ]]; then; ball_vy=-1; ball_y=$(($size_y - 1)); fi
        if [[ $left_y -lt $paddle ]]; then; left_y=$paddle; fi
        if [[ $left_y -ge $(($size_y - $paddle - 1)) ]]; then; left_y=$(($size_y - $paddle - 1)); fi
        if [[ $right_y -lt $paddle ]]; then; right_y=$paddle; fi
        if [[ $right_y -ge $(($size_y - $paddle - 1)) ]]; then; right_y=$(($size_y - $paddle - 1)); fi

        if [[ $ball_x -le 2 ]] then
            if [[ $ball_y -ge $(($left_y - $paddle - 1)) ]] && [[ $ball_y -le $(($left_y + $paddle + 1)) ]]; then
                 ball_vx=1
                 scramble_speed
             else
                 right_score=$(($right_score + 1))
                 reset_game
             fi
        fi

        if [[ $ball_x -ge $(($size_x - 2)) ]]; then
            if [[ $ball_y -ge $(($right_y - $paddle - 1)) ]] && [[ $ball_y -le $(($right_y + $paddle + 1)) ]]; then
                 ball_vx=-1
                 scramble_speed
             else
                 left_score=$(($right_score + 1))
                 reset_game
             fi
        fi

        render_game
    fi
done