DEFINE BALL_RADIUS 2
DEFINE PADDLE_WIDTH 2
DEFINE PADDLE_HEIGHT 30
DEFINE PADDLE_MOVEMENT_STEP 6
// lower rotary encoder
DEFINE RE_CW 24
DEFINE RE_CCW 25

VAR $ball_pos_x = $_RANDOM_INT%100 + 5
VAR $ball_pos_y = $_RANDOM_INT%100 + 5
VAR $ball_velocity_x = $_RANDOM_INT%2 + 2
VAR $ball_velocity_y = $_RANDOM_INT%2 + 2
VAR $paddle_pos = 64
VAR $active_key = 0
VAR $score = 0

VAR $paddle_upper_limit = PADDLE_HEIGHT/2
VAR $paddle_lower_limit = 127-PADDLE_HEIGHT/2

FUNCTION update_paddle_position()
    IF $active_key == RE_CW THEN
        $paddle_pos = $paddle_pos + PADDLE_MOVEMENT_STEP
        IF $paddle_pos > $paddle_lower_limit THEN
            $paddle_pos = $paddle_lower_limit
        END_IF
    END_IF

    IF $active_key == RE_CCW THEN
        $paddle_pos = $paddle_pos - PADDLE_MOVEMENT_STEP
        IF $paddle_pos < $paddle_upper_limit THEN
            $paddle_pos = $paddle_upper_limit
        END_IF
    END_IF
END_FUNCTION

FUNCTION draw_court()
    OLED_LINE 0 0 127 0
    OLED_LINE 0 127 127 127
    OLED_LINE 127 0 127 127
END_FUNCTION

FUNCTION draw_paddle()
    VAR $paddle_top_y = $paddle_pos - PADDLE_HEIGHT/2
    VAR $paddle_bottom_y = $paddle_pos + PADDLE_HEIGHT/2
    OLED_RECT 0 $paddle_top_y PADDLE_WIDTH $paddle_bottom_y 1
END_FUNCTION

FUNCTION draw_ball()
    VAR $drawx = $ball_pos_x
    VAR $drawy = $ball_pos_y

    IF $drawx >= 127-BALL_RADIUS || $drawx <= BALL_RADIUS THEN
        RETURN
    END_IF
    IF $drawy >= 127-BALL_RADIUS || $drawy <= BALL_RADIUS THEN
        RETURN
    END_IF

    OLED_CIRCLE $drawx $drawy BALL_RADIUS 1
END_FUNCTION

FUNCTION draw_gameover()
    SWC_FILL 255 0 0
    OLED_CLEAR
    draw_paddle()
    draw_court()
    draw_ball()
    
    OLED_CURSOR 20 40
    OLED_PRINT GAME OVER
    OLED_CURSOR 20 60
    OLED_PRINT Score: $score
    OLED_CURSOR 20 80
    OLED_PRINT Anykey to quit
    OLED_UPDATE
    
    BCLR
    WHILE TRUE
        IF $_BLOCKING_READKEY <= 20 THEN
            SWC_RESET 99
            HALT
        END_IF
    END_WHILE
END_FUNCTION

FUNCTION speed_up_ball()
    IF $ball_velocity_x >= 0 THEN
        $ball_velocity_x = $ball_velocity_x + ($_RANDOM_INT % 2)
    ELSE IF $ball_velocity_x < 0 THEN
        $ball_velocity_x = $ball_velocity_x - ($_RANDOM_INT % 2)
    END_IF

    IF $ball_velocity_y >= 0 THEN
        $ball_velocity_y = $ball_velocity_y + ($_RANDOM_INT % 2)
    ELSE IF $ball_velocity_y < 0 THEN
        $ball_velocity_y = $ball_velocity_y - ($_RANDOM_INT % 2)
    END_IF
END_FUNCTION

FUNCTION update_ball_pos()
    $ball_pos_x = $ball_pos_x + $ball_velocity_x
    $ball_pos_y = $ball_pos_y + $ball_velocity_y

    // upper and lower wall
    IF ($ball_pos_y >= 127 - BALL_RADIUS*2) || ($ball_pos_y <= BALL_RADIUS*2) THEN
        $ball_velocity_y = $ball_velocity_y * -1
    END_IF

    // right wall
    IF $ball_pos_x >= 127 - BALL_RADIUS*2 THEN
        $ball_velocity_x = $ball_velocity_x * -1
    END_IF

    // paddle collision
    IF $ball_pos_x <= BALL_RADIUS*2 THEN
        VAR $paddle_top = $paddle_pos - PADDLE_HEIGHT/2
        VAR $paddle_bottom = $paddle_pos + PADDLE_HEIGHT/2
        IF $ball_pos_y >= $paddle_top && $ball_pos_y <= $paddle_bottom THEN
            $ball_velocity_x = $ball_velocity_x * -1
            $score = $score + 1
            speed_up_ball()
            SWC_FILL $_RANDOM_INT%255 $_RANDOM_INT%255 $_RANDOM_INT%255
        ELSE
            $ball_velocity_x = 0
            $ball_velocity_y = 0
            draw_gameover()
        END_IF
    END_IF
END_FUNCTION

SWC_FILL 0 255 0

WHILE TRUE
    $active_key = $_READKEY
    update_paddle_position()
    update_ball_pos()
    OLED_CLEAR
    draw_paddle()
    draw_court()
    draw_ball()
    OLED_UPDATE
    DELAY 20
END_WHILE