pass = 0
cols = 1
rows = 1

function turnLeft()
    turtle.digDown()
    turtle.turnLeft()
    turtle.forward()
    turtle.turnLeft()
end

function turnRight()
    turtle.digDown()
    turtle.turnRight()
    turtle.forward()
    turtle.turnRight()
end

function turnLeftDown()
    turtle.turnLeft()
    turtle.turnLeft()
    turtle.digDown()
    turtle.down()
    turtle.digDown()
    turtle.forward()
end

function turnRightDown()
    turtle.turnRight()
    turtle.turnRight()
    turtle.digDown()
    turtle.down()
    turtle.digDown()
    turtle.forward()
end

function forward()
    turtle.digDown()
    turtle.forward()
end

function inventoryCheck()
    local usedSlots = 0

    for i = 1, 16 do
        if turtle.getItemCount(i) > 0 then
            usedSlots = usedSlots + 1
        end
    end

    if usedSlots == 16 then return false end

    return true
end

function quary()
    while inventoryCheck() do
        if turtle.getFuelLevel() < 15 then
            turtle.refuel(1)
        end

        if pass % 2 == 0 then
            if cols == 8 and rows % 2 > 0 and rows < 8 then
                turnRight()

                rows = rows + 1
                cols = 1
            elseif cols == 8 and rows % 2 == 0 and rows < 8 then
                turnLeft()

                rows = rows + 1
                cols = 1
            elseif cols == 8 and rows == 8 then
                turnRightDown()

                rows = 1
                cols = 1
                pass = pass + 1
            else
                forward()

                cols = cols + 1
            end
        elseif pass % 2 > 0 then
            if cols == 8 and rows % 2 > 0 and rows < 8 then
                turnLeft()

                rows = rows + 1
                cols = 1
            elseif cols == 8 and rows % 2 == 0 and rows < 8 then
                turnRight()

                rows = rows + 1
                cols = 1
            elseif cols == 8 and rows == 8 then
                turnLeftDown()

                rows = 1
                cols = 1
                pass = pass + 1
            else
                forward()

                cols = cols + 1
            end
        end
    end
end

function unLoad()
    local oldPass = pass
    local oldCols = cols
    local oldRows = rows

    if turtle.getFuelLevel() < 15 then
        turtle.refuel(3)
    end

    -- Go to chest

    while pass ~= 0 do
        turtle.up()
        pass = pass - 1
    end

    turtle.up()

    if oldPass % 2 == oldRows % 2 then
        turtle.turnLeft()
    else
        turtle.turnRight()
    end

    while rows ~= 1 do
        turtle.forward()
        rows = rows - 1
    end

    turtle.turnLeft()

    while cols ~= 1 do
        turtle.forward()
        cols = cols - 1
    end

    -- End go to chest
    -- Empty invetory into chest

    for i = 2, 16 do
        turtle.select(i)
        turtle.drop()
    end

    turtle.select(1)

    -- End empty invetory into chest
    -- Go back

    turtle.turnLeft()
    turtle.turnLeft()

    while cols ~= oldCols do
        turtle.forward()
        cols = cols + 1
    end

    turtle.turnRight()

    while rows ~= oldRows do
        turtle.forward()
        rows = rows + 1
    end

    while pass ~= oldPass do
        turtle.down()
        pass = pass + 1
    end

    if oldPass % 2 == oldRows % 2 then
        turtle.turnLeft()
    else
        turtle.turnRight()
    end
    -- End go back
end

function process()
    while true do
        quary()
        unLoad()
    end
end

process()