LavaCast

local tArgs = { ... }

if #tArgs ~= 1 then
    print( "Usage: cast <length>" )
    return
end

local j = 2
local i = 0

-- Initial Fueling
turtle.refuel(1)

-- variable to tell main function when to stop
local o = 1

-- Function to get the fuel level of the robot as a number
fcount = function()
        return turtle.getFuelLevel()
end

--Finds an inventory slot with a block that is not slot 1
findSlot = function()
    while turtle.getItemCount(j) == 0 do
        if j < 16 then
            j = j+1
        else
            print("Out of blocks")
        end
    end
    turtle.select(j)
end

-- Move forward, Fuel Check and Refuel function
forwardCheck = function()
        turtle.forward()

        if fcount() < 1 then
                turtle.select(1)
                print ("Attempting to eat my fuel...")
                if turtle.getItemCount(1) < 1 then
                    print ("I am out of fuel...")
                    o = 0
                end
                turtle.refuel(1)
                findSlot()
        end
end

buildBridge = function(length)
    while i < length do
        placeBlocks()
    end
    turtle.turnRight()
    turtle.turnRight()
    for x=1,length do
        turtle.forward()
    end
end

placeBlocks = function()
    if not turtle.detectUp() then
        findSlot()
        turtle.placeUp()
    end
    turtle.turnLeft()
    if not turtle.detect() then
        findSlot()
        turtle.place()
    end
    turtle.turnRight()
    turtle.turnRight()
    if not turtle.detect() then
        findSlot()
        turtle.place()
    end
    turtle.turnLeft()
    forwardCheck()
    i = i + 1
    turtle.turnRight()
    if not turtle.detect() then
        findSlot()
        turtle.place()
    end
    turtle.turnRight()
    if not turtle.detect() then
        findSlot()
        turtle.place()
    end
    turtle.turnRight()
    if not turtle.detect() then
        findSlot()
        turtle.place()
    end
    turtle.turnRight()
    forwardCheck()
    i = i + 1
    turtle.turnRight()
    if not turtle.detect() then
        findSlot()
        turtle.place()
    end
    turtle.turnRight()
    turtle.turnRight()
    if not turtle.detect() then
        findSlot()
        turtle.place()
    end
    turtle.turnRight()
    forwardCheck()
    i = i + 1
end

buildBridge(tonumber(tArgs[1]))