ccStairs

local tArgs = { ... }
local monitor = term.current()
local sizeX,sizeY = monitor.getSize()

-- Logging

local lastMsg = ""
local lastMsgCount = 0
local function logMsg(msg)
    monitor.setCursorPos(1,13)
    monitor.clearLine()
    if lastMsg == msg then
        lastMsgCount = lastMsgCount + 1
        msg = msg .. " " .. lastMsgCount
    else
        lastMsg = msg
        lastMsgCount = 0
        monitor.scroll(1)
    end
    monitor.setCursorPos(1,12)
    monitor.clearLine()
    monitor.write(msg)
    monitor.setCursorPos(1,13)
end
local function msg(msg)
    monitor.setCursorPos(1,13)
    monitor.clearLine()
    monitor.write(msg)
end

-- Turtle Inventory

local function getItemList()
    local itemList = {}
    for slot=1, 16 do
        itemList[slot] = turtle.getItemDetail(slot)
    end
    return itemList
end

local function findEmptySlot(itemList, size)
    for slot=1, size do
        if not itemList[slot] then
            return true, slot
        end
    end
    return false, nil
end

local function isStairs(itemName)
    return string.match(itemName, "_stairs$") ~= nil
end

local function isTorch(itemName)
    return string.match(itemName, "minecraft:torch") ~= nil
end

local function selectStairSlot()
    for slot = 1, 16 do
        local itemDetail = turtle.getItemDetail(slot)
        if itemDetail ~= nil and isStairs(itemDetail.name) then
            turtle.select(slot)
            return true
        end
    end
    return false
end

local function selectTorchSlot()
    for slot = 1, 16 do
        local itemDetail = turtle.getItemDetail(slot)
        if itemDetail ~= nil and isTorch(itemDetail.name) then
            turtle.select(slot)
            return true
        end
    end
    return false
end

local function refuel()
    for slot = 1, 16 do
        local itemDetail = turtle.getItemDetail(slot)
        turtle.select(slot)
        if itemDetail ~= nil and turtle.refuel(1) then
            return true
        end
    end
    return false
end

-- Setup

if #tArgs == 0 then
    logMsg("To start digging a stair type:")
    logMsg("ccstairs <1>")
    logMsg("<1>: the number of floors to dig.")
    return 0
end

local floorsToMine = tArgs[1] + 0

local function startup()
    local startupSuccess = true

    local items = getItemList()
    local freeSlotCount = 0
    local stairsCount = 0
    local torchesCount = 0
    for slot = 1, 16 do
        if not items[slot] then
            freeSlotCount = freeSlotCount + 1
        elseif isStairs(items[slot].name) then
            stairsCount = stairsCount + items[slot].count
        elseif isTorch(items[slot].name) then
            torchesCount = torchesCount + items[slot].count
        end
    end
    local slotsNeeded = 0
    if floorsToMine <= 2 then
        slotsNeeded = floorsToMine * 4
    else
        slotsNeeded = 8 + ((floorsToMine - 2) * 5)
    end
    slotsNeeded = math.ceil(slotsNeeded / 64)

    local fuelNeeded = 0
    if floorsToMine == 1 then
        fuelNeeded = 1
    elseif floorsToMine == 2 then
        fuelNeeded = 3
    else
        fuelNeeded = 3 + ((floorsToMine - 2) * 4)
    end
    logMsg("There is " .. freeSlotCount .. " free slots.")
    logMsg("There is " .. stairsCount .. " stairs.")
    logMsg("There is " .. torchesCount .. " torches.")
    logMsg("There is " .. turtle.getFuelLevel() .. " fuel left.")

    if freeSlotCount < slotsNeeded then
        startupSuccess = false
        logMsg("Not enough free slots ! (".. freeSlotCount .. "/" .. slotsNeeded .. ")")
    end
    if stairsCount < floorsToMine then
        startupSuccess = false
        logMsg("Not enough stairs ! (".. stairsCount .. "/" .. floorsToMine .. ")")
    end
    if floorsToMine > 2 and torchesCount < floorsToMine / 2 then
        startupSuccess = false
        logMsg("Not enough torches ! (".. torchesCount .. "/" .. (floorsToMine / 2) .. ")")
    end

    while turtle.getFuelLevel() < fuelNeeded and refuel() do
    end
    if turtle.getFuelLevel() < fuelNeeded then
        startupSuccess = false
        logMsg("Not enough fuel ! (".. fuelLevel .. "/" .. fuelNeeded .. ")")
    end

    return startupSuccess
end
if not startup() then
    return 0
end

-- Digging

local function move(direction)
    local movement = nil
    if direction == "forward" then
        movement = turtle.forward
    elseif direction == "up" then
        movement = turtle.up
    elseif direction == "down" then
        movement = turtle.down
    else
        error("Error: Bad direction")
    end
    while not movement() do
        -- fuel check
        if turtle.getFuelLevel() < 1 then
            refuel()
        else
            msg("Can't move " .. direction)
        end
    end
end

local function dig(direction)
    local detect = nil
    local dig = nil
    local inspect = nil
    if direction == "forward" then
        detect = turtle.detect
        dig = turtle.dig
        inspect = turtle.inspect
    elseif direction == "up" then
        detect = turtle.detectUp
        dig = turtle.digUp
        inspect = turtle.inspectUp
    elseif direction == "down" then
        detect = turtle.detectDown
        dig = turtle.digDown
        inspect = turtle.inspectDown
    else
        error("Error: Bad direction")
    end
    while detect() do
        if not dig() then
            local block = inspect()
            if block == nil then
                block = {name = "unknown"}
            end
            msg("Can't dig " .. direction .. " " .. block.name)
        end
    end
end

local function placeStair()
    if selectStairSlot() then
        while not turtle.turnRight() do
        end
        while not turtle.turnRight() do
        end
        while not turtle.placeDown() do
        end
        while not turtle.turnRight() do
        end
        while not turtle.turnRight() do
        end
        return true
    end
    return false
end

local function digFirstLevel()
    dig("up")
    dig("forward")
    move("forward")
    dig("up")
    dig("down")
    return placeStair()
end

local function digSecondLevel()
    dig("forward")
    move("forward")
    dig("up")
    dig("down")
    move("down")
    dig("down")
    return placeStair()
end

local function digRemainingLevels(floorNumber)
    move("up")
    dig("forward")
    move("forward")
    dig("up")
    if floorNumber % 2 == 0 then
        if selectTorchSlot() then
            turtle.placeUp()
        end
    end
    dig("down")
    move("down")
    dig("down")
    move("down")
    dig("down")
    return placeStair()
end

for i = 1, floorsToMine do
    if i == 1 then
        digFirstLevel()
    elseif i == 2 then
        digSecondLevel()
    else
        digRemainingLevels(i)
    end
end

monitor.scroll(1)
monitor.setCursorPos(1,13)