ladder

local tArgs = { ... }

--Check for Valid Args
if (#tArgs < 1) or (#tArgs > 2) then
    print("Usage: ladder <depth> <up?>")
    print("    Make sure that you provide enough fuel to go up and down <depth> + 1")
    print("    Max Depth 64")
    print("    Slot 1: Fuel")
    print("    Slot 2: Wall Blocks")
    print("    Slot 3: Ladder Blocks")
    return
end

local depth=tonumber(tArgs[1])
local dir=0

--Check Depth
if depth>64 then
    depth=64
elseif depth<1 then
    return
end

if (#tArgs > 1) then
    dir=tonumber(tArgs[2])
    if (dir >= 1) then
        dir=1
    else
        dir=-1
    end
end

local function refuel(slot)
    local fuelLevel = turtle.getFuelLevel()
    if fuelLevel == "unlimited" or fuelLevel > 0 then
        return
    end

    local function tryRefuel()
        if turtle.getItemCount(1) > 0 then
            turtle.select(1)
            if turtle.refuel(1) then
                return true
            end
        end
        return false
    end

    if not tryRefuel() then
        print( "Add more fuel to continue." )
        while not tryRefuel() do
            sleep(5)
        end
        print( "Resuming..." )
        turtle.select(slot)
    end
end

local function checkBlock(slot,first,last,block)
    while turtle.getItemCount(slot) == 0 do
        slot = slot + 1
        if slot > last then
            print("Missing: " .. block)
            print("Slots: " .. first .. "-" .. last)
            local line=""
            repeat
                print("Enter 'Y' to continue: ")
                line = io.read()
            until string.lower(line) ~= "y"
            print("Resuming...")
            slot = first --Reset slot to first
        end
    end
    return slot
end

local function checkStorage()
    if turtle.getItemCount(16) > 0 then
        print("Clean inventory...")
        while turtle.getItemCount(16) > 0 do
            sleep(5)
        end
        print( "Resuming..." )
    end
end

--slot  - current slot of blocks (returned)
--inv   - start of inventory slots
--first - start of blocks slots
--last  - end of blocks slots
--block - block name
--dir   - place direction
local function tryBlock(slot,inv,first,last,block,dir)
    slot=checkBlock(slot,first,last,block)
    turtle.select(slot)
    if (dir == 0) then
        turtle.place()
    elseif (dir > 0) then
        turtle.placeUp()
    else
        turtle.placeDown()
    end
    turtle.select(inv)
    return checkBlock(slot,first,last,block)
end

local function tryDig()
    while turtle.detect() do
        if turtle.dig() then
            checkStorage()
            sleep(0.5)
        else
            return false
        end
    end
    return true
end

local function tryDigDown()
    if turtle.digDown() then
        checkStorage()
        return true
    end
    return false
end

local function tryDigUp()
    while turtle.detectUp() do
        if turtle.digUp() then
            checkStorage()
            sleep(0.5)
        else
            return false
        end
    end
    return true
end

local function tryUp(slot)
    refuel(slot)
    while not turtle.up() do
        if turtle.detectUp() then
            if not tryDigUp() then
                return false
            end
        elseif turtle.attackUp() then
            checkStorage()
        else
            sleep( 0.5 )
        end
    end
    return true
end

local function tryDown(slot)
    refuel(slot)
    while not turtle.down() do
        if turtle.detectDown() then
            if not tryDigDown() then
                return false
            end
        elseif turtle.attackDown() then
            checkStorage()
        else
            sleep( 0.5 )
        end
    end
    return true
end

local function tryForward(slot)
    refuel(slot)
    while not turtle.forward() do
        if turtle.detect() then
            if not tryDig() then
                return false
            end
        elseif turtle.attack() then
            checkStorage()
        else
            sleep(0.5)
        end
    end
    return true
end

local i=depth

while i > 0 do
    if (dir < 0) then
        tryDigDown()
        tryDown()
    else
        tryDigUp()
        tryUp()
    end
    tryDig()
    tryBlock(2,4,2,2,"Wall",0)
    i=i-1
end

i=depth
turtle.turnRight()
turtle.turnRight()
tryDig()
tryForward()
turtle.turnRight()
turtle.turnRight()

while i > 0 do
    tryBlock(3,4,3,3,"Ladder",0)
    if (dir > 0) then
        tryDigDown()
        tryDown()
    else
        tryDigUp()
        tryUp()
    end
    i=i-1
end