ceiling.lua

if not turtle then
    printError("Requires a Turtle")
    return
end

local tArgs = { ... }
if #tArgs ~= 3 then
    local programName = arg[0] or fs.getName(shell.getRunningProgram())
    print("Usage: " .. programName .. " <width> <length> <item to place>")
    return
end

local width = tonumber(tArgs[1])
local length = tonumber(tArgs[2])
local targetItem = tArgs[3]

local function refuel(amount)
    local fuelLevel = turtle.getFuelLevel()
    if fuelLevel == "unlimited" then
        return true
    end

    turtle.select(16)
    while turtle.getItemCount(16) > 0 and turtle.getFuelLevel() < amount do
        if not turtle.refuel(1) then
            return false
        end
    end

    if turtle.getFuelLevel() < amount then
        return false
    else
        return true
    end
end

local function waitForFuel(amount)
    if not refuel(amount) then
        print("Please put fuel in slot 16")
        while not refuel(amount) do
            sleep(0.5)
        end
        print("Received sufficient fuel. Continuing...")
    end
end

local function selectItem(name)
    for i=15, 1, -1 do
        itemDetail = turtle.getItemDetail(i)
        if itemDetail and itemDetail.name == name then
            turtle.select(i)
            return true
        end
    end
    return false
end

local function countItem(name)
    num = 0
    for i=1, 15 do
        itemDetail = turtle.getItemDetail(i)
        if itemDetail and itemDetail.name == name then
            num = num + itemDetail.count
        end
    end
    return num
end

local function waitForItem(name, amount)
    if countItem(name) < amount then
        print("Please provide more " .. name)
        while countItem(name) < amount do
            sleep(0.5)
        end
        print("Received sufficient " .. name .. ". Continuing...")
    end
    selectItem(name)
end

local function waitForDrop()
    if turtle.getItemCount() > 0 and not turtle.drop() then
        print("Please make room for turtle to drop")
        while turtle.getItemCount() > 0 and not turtle.drop() do
            sleep(0.5)
        end
        print("Turtle successfully dropped. Continuing...")
    end
end

local function waitForDropDown()
    if turtle.getItemCount() > 0 and not turtle.dropDown() then
        print("Please make room for turtle to drop")
        while turtle.getItemCount() > 0 and not turtle.dropDown() do
            sleep(0.5)
        end
        print("Turtle successfully dropped. Continuing...")
    end
end

local function getBlock()
    local hasBlock, data = turtle.inspect()
    if hasBlock then
        return data.name
    else
        return "minecraft:air"
    end
end

local function getBlockDown()
    local hasBlock, data = turtle.inspectDown()
    if hasBlock then
        return data.name
    else
        return "minecraft:air"
    end
end

local function getBlockUp()
    local hasBlock, data = turtle.inspectUp()
    if hasBlock then
        return data.name
    else
        return "minecraft:air"
    end
end

local function tryForward()
    waitForFuel(1)
    if not turtle.forward() then
        exit()
    end
end

local function tryMakeCeiling()
    if turtle.detectUp() then
        turtle.digUp()
    end
    waitForItem(targetItem, 1)
    turtle.placeUp()
end

waitForFuel(2*width*length)
waitForItem(targetItem, width*length)

for i=1, width do
    for j=1, length-1 do
        tryMakeCeiling()
        tryForward()
    end
    tryMakeCeiling()
    if i < width then
        if i % 2 == 1 then
            turtle.turnRight()
            tryForward()
            turtle.turnRight()
        else
            turtle.turnLeft()
            tryForward()
            turtle.turnLeft()
        end
    end
end