monitor breakout

-- Global Constants
local speaker = peripheral.wrap("left")
term.redirect(peripheral.wrap("top"))
local width, height = term.getSize()
local paddleWidth = 6
local keyDelay = 0.1
local delay = 0.15
local brickRows = 3

local backgroundColor = colors.black
local textColor       = colors.white
local paddleColor     = colors.white
local scoreLineColor  = colors.lightGray
local brickColor      = colors.magenta
local ballColor       = colors.white

-- Global variables
local paddle
local score
local bricks
local ballx
local bally
local ballvx
local ballvy
local gameOver

function restart()
  paddle = math.floor((width - paddleWidth) / 2)

  score  = 0

  ballx  = math.floor( width / 2)
  bally  = height - 8

  ballvx = 1
  ballvy = 1

  gameOver = false

  -- Fill in the brick array, which is a
  -- 2D array that records if the brick still
  -- exists at each location.
  bricks = {}
  for x = 1, width do
    bricks[x] = {}
    for y = 2, brickRows + 1 do
      bricks[x][y] = true
    end
  end

end



-- Draws the initial screen, then from there
-- things are changed character by character.
function initialDraw()
  term.setBackgroundColor(backgroundColor)
  term.clear()

  --Draw paddle
  term.setBackgroundColor(paddleColor)
  for i=0, paddleWidth  do
    term.setCursorPos(paddle+i, height)
    term.write(" ")
  end

  --draw score line
  term.setBackgroundColor(scoreLineColor)
  for i = 1, width do
    term.setCursorPos(i, 1)
    term.write(" ")
  end
  term.setTextColor(textColor)
  term.setCursorPos(1,1)
  term.write(score)

  --draw the bricks. Since it's the initial draw
  --we don't have to check if the bricks exist
  term.setBackgroundColor(brickColor)
  for x = 1, width do
    for y = 2, brickRows + 1 do
      term.setCursorPos(x,y)
      term.write(" ")
    end
  end

  -- draw the ball
  term.setBackgroundColor(ballColor)
  term.setCursorPos(math.floor(ballx), math.floor(bally))
  term.write(" ")

end


function drawScore()
  term.setBackgroundColor(backgroundColor)
  term.setTextColor(textColor)
  term.clear()
  centertext("Final Score: "..score, height/2)
  centertext("Press top half to restart", (height/2)+1)
end


function moveBall()
  -- First we need to check to see if the
  -- ball hits a brick. We have 2 cases, either the
  -- brick is directly above the ball, or the brick
  -- is directly in the path of the ball (for
  -- diagonal collisions)

  local breakBrickX, breakBrickY

  -- brick above ball
  if bricks[ballx][bally - 1] == true then
    breakBrickX = ballx
    breakBrickY = bally - 1
    bounce(1)

  -- brick in path of ball
  elseif bricks[ballx+ballvx][bally+ballvy] == true then
    breakBrickX = ballx + ballvx
    breakBrickY = bally + ballvy
    bounce(1)

    bounce(2)

  end

  if breakBrickX ~= nil and breakBrickY ~= nil then
    bricks[breakBrickX][breakBrickY] = false

    -- draw a blank space over the broken brick
    term.setBackgroundColor(backgroundColor)
    term.setCursorPos(breakBrickX, breakBrickY)
    term.write(" ")

    -- print new score. Since score only gets
    -- bigger, we don't need to worry about
    -- redrawing the whole score line
    score = score + 1
    term.setBackgroundColor(scoreLineColor)
    term.setTextColor(textColor)
    term.setCursorPos(1,1)
    term.write(score)
  end

  local oldx = ballx
  local oldy = bally
  ballx = ballx + ballvx
  bally = bally + ballvy


  -- ball hits the paddle
  if bally == height - 1
      and ballx >= paddle
      and ballx <= paddle + paddleWidth then
    bounce(1)

  end

  -- ball hits top wall
  if bally == 2 then
    bounce(1)

  end

  -- ball hits right wall
  if ballx >= width then
    bounce(2)

  end

  -- ball hits left wall
  if ballx <= 1 then
    bounce(2)

  end

  --Now draw the new position of the ball
  term.setBackgroundColor(backgroundColor)
  term.setCursorPos(oldx, oldy)
  term.write(" ")
  term.setBackgroundColor(ballColor)
  term.setCursorPos(math.floor(ballx),math.floor(bally))
  term.write(" ")
end



function bounce(dir)
  if dir == 1 then
speaker.playSound("create:fwoomp",.5,2)
    ballvy = -ballvy
  end
  if dir == 2 then
speaker.playSound("create:fwoomp",.5,2)
    ballvx = -ballvx
  end
end


-- direction of -1 is left and 1 is right
-- drawing is done by removing a character from
-- one end of the paddle and drawing a new
-- character at the other end.
function movePaddle( direction )

  local removeX, addX

  -- calculate the new paddle position and also
  -- find the positions of the chars that need to
  -- be added and removed
  if direction == 1
      and paddle + paddleWidth <  width then
    removeX = paddle
    addX    = paddle + paddleWidth + 1
    paddle  = paddle + 1

  elseif direction == -1
      and paddle > 1 then
    removeX = paddle + paddleWidth
    addX    = paddle - 1
    paddle  = paddle - 1
  else
    return
  end

  -- Draw the new paddle
  term.setBackgroundColor(backgroundColor)
  term.setCursorPos(removeX, height)
  term.write(" ")

  term.setBackgroundColor(paddleColor)
  term.setCursorPos(addX, height)
  term.write(" ")
end


function centertext(text, height)
  term.setCursorPos((width/2)-(string.len(text)/2), height)
  term.write(text)
end



-- Main Game Loop
restart()
initialDraw()

-- every delay seconds a timer goes off which
-- moves the ball
local timerID = os.startTimer(delay)

while true do

  event, value, x, y = os.pullEvent()

  if event == "monitor_touch" then

    if y <= 10 then
      restart()
      initialDraw()
    end

    if x == 0 and y == 0 then
      term.setBackgroundColor(colors.black)
      term.setTextColor(colors.white)
      term.clear()
      term.setCursorPos(1,1)
      return
    end

    if x >= 20

        or value == keys.d then
            speaker.playSound("quark:ambient.clock",.3)
      movePaddle(1)
    end

    if x <= 20
        or value == keys.a then
            speaker.playSound("quark:ambient.clock",.3)
      movePaddle(-1)
    end
  end

  if event == "timer" and timerID == value then
    moveBall()
    timerID = os.startTimer(delay)
  end

  if bally > height then
    drawScore()
  end

end