Filler

local ms = require("movescript")
local component = require("component")
local robot = require("robot")
local ic = component.inventory_controller

local BLOCK_NAME = "minecraft:dirt"
local BLOCK_DATA = 0

--[[
Select an item, given its name and damage value.
item_name - string: The id string for an item.
item_data - number: The damage value, or variation of an item. Defaults to zero.
return - boolean: True if at least one slot contains the item. That slot is now
selected.
--]]
local function selectItemByName(item_name, item_data)
    for i=1,16 do
        local stack = ic.getStackInInternalSlot(i)
        if (stack ~= nil and stack.name == item_name and stack.damage == item_data) then
            robot.select(i)
            return true
        end
    end
    return false
end

--[[
Select an item, similar to selectItemByName, but if the item cannot be found,
the user will be prompted to add it to the robot's inventory and press enter to
continue.
item_name - string: The id string for an item.
item_data - number: The damage value, or variation of an item. Defaults to zero.
return - nil: If set to be continuous, then if the item cannot be found, then
the program will exit. If not, it will loop until the item is provided by the
user.
--]]
local function selectSafely(item_name, item_data)
    local success = selectItemByName(item_name, item_data)
    while not success do
        print("Cannot find "..item_name.." in inventory. Please add some, and press enter.")
        io.read()
        success = selectItemByName(item_name, item_data)
    end
end

local function fillSpot()
    local displacement = 0
    local success, data = robot.detectDown()
    while ((not success) or (data == "replaceable")) do
        ms.execute("d_D")
        success, data = robot.detectDown()
        displacement = displacement + 1
    end
    for i = 1, displacement do
        ms.execute("U")
        selectSafely(BLOCK_NAME, BLOCK_DATA)
        robot.placeDown()
    end
end

local function fillArea(length, width)
    for row = 1, length do
        ms.execute("d_F")

        if (row % 2) == 1 then robot.turnRight() else robot.turnLeft() end

        for col = 1, width - 1 do
            fillSpot()
            ms.execute("d_F")
        end

        fillSpot()
        if (row % 2) == 1 then robot.turnLeft() else robot.turnRight() end
    end
end

local function mainMenu()
    print("[1] Use " .. BLOCK_NAME .. ":" .. BLOCK_DATA .. " as default.")
    print("[2] Define your own block to use.")
    choice = tonumber(io.read())
    if choice == 2 then
        print("What is the name of the block?")
        BLOCK_NAME = io.read()
        print("What is the data value?")
        BLOCK_DATA = tonumber(io.read())
    end

    print("What is the length of the area to fill? (How far forward)")
    length = tonumber(io.read())
    print("What is the width of the area to fill? (How far to the right)")
    width = tonumber(io.read())

    fillArea(length, width)
end

mainMenu()