import GUI

var x1, x2, y1, y2, xc, yc : int %Declares the coordinate variables for the game
var c, t : int %Declares the counter variables for the game
var p1, p2 : int %Declares the points counter for the game
var velx, vely, facy, facx : int %Declares the velocity variables for the game
var timeprevious, timecurrent, timedifference : int %Declares variables for holding time
var font1 : int %Declares variable for font
var keys : array char of boolean

c := 1 %Counter to see if the game just started
t := 1 %Counter to see who's starting the game
p1 := 0
p2 := 0
velx := 0
vely := 0
facy := 1
facx := 1
font1 := Font.New ("serif:40")
assert font1 > 0

procedure controls1 %Controls for player1
    Input.KeyDown (keys)
    if keys ('a') and x1 >= 0 then
        x1 -= 4
    elsif keys ('d') and x1 + 60 <= maxx then
        x1 += 4
    elsif keys (KEY_SHIFT) then
        vely := 2
        velx := 2
    end if
end controls1

procedure controls2 %Controls for player2
    Input.KeyDown (keys)
    if keys (KEY_LEFT_ARROW) and x2 - 70 >= 0 then
        x2 -= 4
    elsif keys (KEY_RIGHT_ARROW) and x2 <= maxx then
        x2 += 4
    elsif keys (KEY_ENTER) then
        vely := -2
        velx := -2
    end if
end controls2

procedure player1
    if c = 1 then %Intializes the coordinates for player1
        x1 := 20
        y1 := 30
    end if
    drawfillbox (x1, y1, x1 + 60, y1 + 20, blue) %Draws player1
end player1

procedure player2
    if c = 1 then %Intializes the coordinates for player2
        x2 := maxx - 30
        y2 := maxy - 30
    end if
    drawfillbox (x2, y2, x2 - 60, y2 - 20, red) %Draws player2
end player2

procedure ball
    drawfilloval (xc, yc, 20, 20, brown) %Draws the ball
    if yc - 20 >= 0 and yc + 20 <= maxy then
        yc += (vely * facy)
    end if
    if xc - 20 >= 0 and xc + 20 <= maxx then
        xc += (velx * facx)
    end if
end ball

procedure map
    Draw.ThickLine (0, maxy div 2, maxx, maxy div 2, 5, black)
    Draw.ThickLine (0, maxy, maxx, maxy, 5, black)
    Draw.ThickLine (0, 0, maxx, 0, 5, black)
    Draw.ThickLine (0, 0, 0, maxy, 5, black)
    Draw.ThickLine (maxx, 0, maxx, maxy, 5, black)
end map

procedure rules
    if yc + 20 >= maxy then %Sets up the points system
        p1 += 1
        c := 1
    elsif yc - 20 <= 0 then
        p2 += 1
        c := 1
    end if
    if (((xc >= x1 and yc - 20 >= y1) and (xc <= x1 + 60 and yc - 20 <= y1 + 20)) or ((xc >= x2 - 60 and yc + 20 >= y2 - 20) and (xc <= x2 and y2 - 20 <= y2))) and timedifference > 1000 then
        facy *= -1 %If the ball ever collides with the players, it rebounds into the opposite direction
        facx *= -1
        timeprevious := timecurrent %Time is used to prevent the endless facy *= -1 and facx *= -1 if the ball were to ever get "into" the paddles
    elsif (xc + 20 >= maxx) or (xc - 20 <= 0) then %The ball rebounds if it hits the walls
        facx *= -1
    end if
end rules

procedure update %Update procedure
    View.Update
    delay (10)
    cls
end update

procedure game
    setscreen ("offscreenonly") %Buffers the program to prevent lag
    loop
        if c = 1 then
            timeprevious := Time.Elapsed
            xc := 300
            yc := 200
            vely := 0
            velx := 0
        end if
        timecurrent := Time.Elapsed
        timedifference := timecurrent - timeprevious
        map
        controls1
        controls2
        player1
        player2
        ball
        put "Red: ", p1
        put "Blue: ", p2
        update
        c += 1
        rules %Rules is placed after the "c" counter to prevent "c" from increasing over 1 if one of the decisions in Rules are made
    end loop
end game

var button1 : int %Declares variable for Graphic User Interface (GUI) button

%%%%%%%Creates the GUI interface%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
loop
    button1 := GUI.CreateButton (maxx div 2, maxy div 2, 0, "Play", game)
    Font.Draw ("PONG", (maxx div 2) - 50, (maxy div 2) + 50, font1, black)
    exit when GUI.ProcessEvent
    View.Update
end loop

if yc - 20 >= 0 and  yc + 20 <= maxy  then
    yc += (vely * facy)
end if
if xc - 20 >= 0 and xc + 20 <= maxx then
    xc += (velx * facx)
end if