startup

sizeX = 7
sizeY = 14
g = peripheral.wrap("left")
local function valueX()
    local h = fs.open("x", "r")
    local X = h.readAll()
    h.close()
    print(X)
    return X
end

local function valueY()
    local h = fs.open("y", "r")
    local Y = h.readAll()
    h.close()
    return Y
end

local function saveX(x)
    local h = fs.open("x","w")
    h.write(x)
    h.close()
end

local function saveY(y)
    local h = fs.open("y","w")
    h.write(y)
    h.close()
end

local function saveDir(dir)
    local h = fs.open("dir","w")
    h.write(dir)
    h.close()
end

local function check()
    if turtle.detectDown() == true then
        turtle.digDown()
        turtle.select(1)
        turtle.placeDown()
    end
end

function setDir(d)
    local h = fs.open("dir","r")
    local curDir = tonumber(h.readAll())
    print(curDir)
    h.close()
    local diff = (curDir - d)
    if diff < 0 then
        for i=1,math.abs(diff) do
            turtle.turnRight()
            curDir = curDir + 1
            if curDir >= 5 then
                curDir = 1
            end
        end
    elseif diff > 0 then
        for i=1,math.abs(diff) do
            turtle.turnLeft()
            curDir = curDir - 1
            if curDir <= 0 then
                curDir = 4
            end
        end
    else
        return true
    end
    saveDir(curDir)
    if curDir - d == 0 then
        return true
    else
        return false
    end
end

local function Home()
    local thisX = tonumber(valueX())
    local thisY = tonumber(valueY())
    local newY = thisY
    local newX = thisX
    if thisX > 0 then
        setDir(2)
        for i=1,thisX do
            turtle.forward()
            newX = newX-1
        end
        saveX(newX)
    end

    if thisY > 0 then
        setDir(3)
        for i=1,thisY do
            turtle.forward()
            newY = newY-1
        end
        saveY(newY)
    end

    if newY == 0 and newX == 0 then
        return true
    else
        return false
    end
end

if Home() then
    setDir(1)

    while true do
        for x=0,sizeX do
            for y=0,sizeY do
                turtle.forward()
                saveY(y)
                check()
            end
            if (valueX() % 2) == 0 then
                turtle.turnLeft()
                turtle.forward()
                turtle.turnLeft()
                saveDir(3)
            else
                turtle.turnRight()
                turtle.forward()
                turtle.turnRight()
                saveDir(1)
            end
            saveX(x)
        end
        Home()
        setDir(1)
        sleep(10)
    end

end