local xPos,yPos = 15,6
local mouseX,mouseY = 15,2
local monitor = peripheral.wrap("top")
or error("Unable to wrap monitor!",0)

local function closest(x,y)
	local nearX,nearY = x,y
	local nearestDistance = math.huge

	for xOffset = -1,1 do
		for yOffset = -1,1 do
			if (xOffset==0 or yOffset==0) and yOffset~=xOffset then
				local dx = x+xOffset-xPos
				local dy = y+yOffset-yPos
				local distance = math.sqrt(dx^2+dy^2)

				if distance < nearestDistance then
					nearX = x + xOffset
					nearY = y + yOffset
				end
			end
		end
	end

	return nearX,nearY
end

local function draw()
	monitor.clear()

	monitor.setCursorPos(mouseX,mouseY)
	monitor.write("X")

	monitor.setCursorPos(closest(mouseX,mouseY))
	monitor.write("o")

	monitor.setCursorPos(xPos,yPos)
	monitor.write("T")
end

local updateRate = 1/5
local update = os.startTimer(updateRate)
while true do
	local ev,p1,p2,p3,p4,p5 = os.pullEvent()

	if ev == "timer" and p1 == update then
		-- time to draw
		update = os.startTimer(updateRate)
		draw()
	elseif ev == "monitor_touch" then
		-- p1 = side of monitor
		mouseX = p2
		mouseY = p3
	end
end