Computercraft Pong

local args = {...}
term.clear()
--width = 51
--height = 19
local ballXPos = 19
local ballYPos = 9
local lPos = 9
local rPos = 9
local lScore = 0
local rScore = 0
local ballDir = 1
local ballAngle = 1
local waits = 0
local game = true
local monitor = nil
local textSize = 1

if args[1] == nil then
    maxScore = 15
else
    maxScore = args[1]*1
end

if args[2] == "mon" or args[2] == "monitor" then
    textSize = args[3]
    monitor = peripheral.find("monitor")
    if not monitor then
        term.clear()
        term.setCursorPos(1, 1)
        print("No monitor found")
        error()
    end
    monitor.setTextScale(textSize)
end

local drawField = function()
    term.setCursorPos(1, 1)
    term.write("Bryceio Industries: PONG =======================================")
    term.setCursorPos(ballXPos, ballYPos)
    term.write("O")
    for i = (lPos-2),(lPos+2) do
        term.setCursorPos(4, i)
        term.write("|")
    end
    for i = (rPos-2),(rPos+2) do
        term.setCursorPos(36, i)
        term.write("|")
    end
    for i = 2, 18 do
        term.setCursorPos(39, i)
        term.write("||")
    end
    term.setCursorPos(41, 4)
    print("Left:  "..lScore)
    term.setCursorPos(41, 6)
    print("Right: "..rScore)
    term.setCursorPos(41, 9)
    print("Max:   "..maxScore)
    for i = 1, 51 do
        term.setCursorPos(i, 19)
        term.write("=")
    end
end

local controls = function()
    keytimer = os.startTimer(0.4)
    event, key = os.pullEvent()
    if event == "key" then
        sleep(0.2)
        if key == 200 and (lPos > 4)then
            lPos = lPos - 1
        end
        if key == 208 and (lPos < 16) then
            lPos = lPos + 1
        end
    elseif event == "timer" and key == keytimer then
    end
end

local drawFieldMonitor = function()
    monitor.setCursorPos(1, 1)
    monitor.write("Bryceio Industries: PONG =======================================")
    monitor.setCursorPos(ballXPos, ballYPos)
    monitor.write("O")
    for i = (lPos-2),(lPos+2) do
        monitor.setCursorPos(4, i)
        monitor.write("|")
    end
    for i = (rPos-2),(rPos+2) do
        monitor.setCursorPos(36, i)
        monitor.write("|")
    end
    for i = 2, 18 do
        monitor.setCursorPos(39, i)
        monitor.write("||")
    end
    monitor.setCursorPos(41, 4)
    monitor.write("Left:  "..lScore)
    monitor.setCursorPos(41, 6)
    monitor.write("Right: "..rScore)
    monitor.setCursorPos(41, 9)
    monitor.write("Max:   "..maxScore)
    for i = 1, 51 do
        monitor.setCursorPos(i, 19)
        monitor.write("=")
    end
end

while game do
    term.clear()
    drawField()
    if monitor ~= nil then
        drawFieldMonitor()
    end
    controls()
    ballXPos = ballXPos + ballDir
    ballYPos = ballYPos + ballAngle
    if ballYPos > 18 or ballYPos < 2 then
        ballYPos = ballYPos - ballAngle
        ballAngle = ballAngle * -1
    end
    if ballXPos == 4 then
        if ballYPos == lPos-3 then
            ballDir =  1
            ballAngle = -2
            ballXPos = ballXPos + 1
        elseif ballYPos >= lPos-2 and ballYPos <= lPos then
            ballDir = 1
            ballAngle = -1
            ballXPos = ballXPos + 1
        elseif ballYPos <= lPos+2 and ballYPos > lPos then
            ballDir = 1
            ballAngle = 1
            ballXPos = ballXPos + 1
        elseif ballYPos == lPos+3 then
            ballDir = 1
            ballAngle = 2
            ballXPos = ballXPos + 1
        end
    elseif ballXPos == 36 then
        if ballYPos == rPos-3 then
            ballDir =  -1
            ballAngle = -2
            ballXPos = ballXPos - 1
        elseif ballYPos >= rPos-2 and ballYPos <= rPos then
            ballDir = -1
            ballAngle = -1
            ballXPos = ballXPos - 1
        elseif ballYPos <= rPos+2 and ballYPos > rPos then
            ballDir = -1
            ballAngle = 1
            ballXPos = ballXPos - 1
        elseif ballYPos == rPos+3 then
            ballDir = -1
            ballAngle = 2
            ballXPos = ballXPos - 1
        end
    end
    if rPos < ballYPos and waits > 5 then
        rPos = rPos + 1
        waits = 0
    elseif rPos > ballYPos and waits > 5 then
        rPos = rPos - 1
        waits = 0
    elseif waits <= 5 then
        waits = waits + 1
    end
    if ballXPos < 1 then
        ballXPos = 19
        rScore = rScore + 1
        lPos = 9
        rPos = 9
    end
    if ballXPos > 38 then
        ballXPos = 19
        ballYPos = 9
        lScore = lScore + 1
        lPos = 9
        rPos = 9
    end
    if rScore >= maxScore then
        term.setCursorPos(41, 12)
        term.write("Right Wins")
        term.setCursorPos(1, 19)
        game = false
    elseif lScore >= maxScore then
        term.setCursorPos(41, 12)
        term.write("Left Wins")
        term.setCursorPos(1, 19)
        game = false
    end
end