tunnel2

print("Fuel in slot1")
print("Cobblestone in slot 2+ (as much as needed)")
print("bridge length:")
local blength = 1
local step = 0
local cobSlot = 2
blength=tonumber(read())
print("tunnel height(1):")
theight=tonumber(read())

function invCheck(cobSlot)
    if turtle.getItemCount(cobSlot) < 5 then
        print("no cobblestone, searching")
        cobSlot = invSelect()
    end
    return cobSlot
end

function heightCheck(theight)
    if theight == "" then
       theight = 1
    end
    return theight
end

function invSelect()
    local cobSlot = -1

    for i=1,16 do
            if turtle.getItemDetail(i) ~= nil then
                if (turtle.getItemDetail(i).name == "minecraft:cobblestone" and turtle.getItemCount(i) > 5)  then
                    print("cobblestone found in slot".. i )
                    cobSlot = i

                    --i = 16
                    break
                end
            end
    end
    return cobSlot
end

function tmf()
    -- turtle move forward
    while turtle.forward() == false do
        turtle.dig()
        turtle.attack()
    end
end

function tpf()
    --turtle place forward
    --turtle.select(2)
    turtle.place()
end

function tpd()
    --turtle place down
    --turtle.select(2)
    turtle.placeDown()
end

function tmu()
    turtle.digUp()
    turtle.up()
end

function fuelCheck()
    if turtle.getFuelLevel() < 80 then
        if turtle.getItemCount(1) >=1 then
            turtle.select(1)
            turtle.refuel(1)
        else
            print("low on fuel")
            os.shutdown()
        end
    end
end

function row(cobSlot)
    cobSlot = invCheck(cobSlot)
    print("using items from Slot".. cobSlot)
    turtle.select(cobSlot)
    tpd()
    turtle.turnLeft()
    tmf()
    tpd()
    tpf()
    turtle.turnRight()
    turtle.turnRight()
    tmf()
    tmf()
    tpf()
    tpd()
    turtle.turnLeft()
    turtle.turnLeft()
    tmf()
    turtle.turnRight()
end

function rowup(cobslot)
    turtle.turnLeft()
    turtle.dig()
    turtle.turnRight()
    turtle.turnRight()
    turtle.dig()
    turtle.turnLeft()
end

function goback(step)
    turtle.turnRight()
    turtle.turnRight()
    while step > 0 do
        fuelCheck()
        tmf()
        step = step - 1
    end
end

function highRow(theight)
    -- höhenkram
    rowheight = theight
    while rowheight > 1 do
        tmu()
        rowup()
        rowheight = rowheight -1
    end

    while rowheight < theight do
        turtle.down()
        rowheight = rowheight +1
    end

end

theight = heightCheck(theight)
while step < blength do
    fuelCheck()
    tmf()
    row(cobSlot)
    highRow(theight)
    step = step + 1
end

goback(blength)