Computercraft Snake

term.clear()
segmentx = {2}
segmenty = {2}
score = 0
width, height = term.getSize()
applex = math.random(1, width-1)
appley = math.random(2, 18)
direction = 0
i = 2

function controls()
    keytimer = os.startTimer(0.05)
    event, key = os.pullEvent()
    if event == "key" then
        sleep(0.05)
        if key == 200 and direction ~= 3 then
            direction = 1
        end
        if key == 205 and direction ~= 4 then
            direction = 2
        end
        if key == 208 and direction ~= 1 then
            direction = 3
        end
        if key == 203 and direction ~= 2 then
            direction = 4
        end
    elseif event == "timer" and key == keytimer then
    end
end


--Make the first apple
term.setCursorPos(applex, appley)
print("@")

--Make the first snake part
term.setCursorPos(segmentx[1], segmenty[1])
print("0")

function endgame()

end

while true do
    term.setCursorPos(1, 1)
    term.write("Score: "..score.."  =========================================")
    term.setCursorPos(applex, appley)
    term.write("@")
    term.setCursorPos(1, 19)
    term.write("===================================================")
    controls()
    term.clear()
    posx = segmentx[1]
    posy = segmenty[1]
    if direction == 1 then
        segmenty[1] = segmenty[1]-1
    elseif direction == 2 then
        segmentx[1] = segmentx[1]+1
    elseif direction == 3 then
        segmenty[1] = segmenty[1]+1
    elseif direction == 4 then
        segmentx[1] = segmentx[1]-1
    end
    term.setCursorPos(segmentx[1], segmenty[1])
    term.write("0")
    while i < score + 2 do
             pos2X = segmentx[i]
             pos2Y = segmenty[i]
             segmentx[i] = posx
             segmenty[i] = posy
             posx = pos2X
             posy = pos2Y
             if segmentx[1] == segmentx[i] and segmenty[1] == segmenty[i] then
                 error()
             end
             term.setCursorPos(segmentx[i], segmenty[i])
                if applex == segmentx[i] and appley == segmenty[i] then
                    applex = math.random(1, width-1)
                    appley = math.random(2, 18)
                end
             term.write("0")
             i = i + 1
    end
    i = 2
    if segmentx[1] == applex and segmenty[1] == appley then
        score = score + 1
        applex = math.random(1, width-1)
        appley = math.random(2, 18)
        if direction == 1 then
            table.insert(segmentx, segmentx[score])
            table.insert(segmenty, segmenty[score]+1)
        elseif direction == 2 then
            table.insert(segmentx, segmentx[score]-1)
            table.insert(segmenty, segmenty[score])
        elseif direction == 3 then
            table.insert(segmentx, segmentx[score])
            table.insert(segmenty, segmenty[score]-1)
        elseif direction == 4 then
            table.insert(segmentx, segmentx[score]+1)
            table.insert(segmenty, segmenty[score])
        end
    elseif segmentx[1] > width or segmentx[1] < 1 or segmenty[1] > 18 or segmenty[1] < 2 then
        error()
    end
end