function depo()
    turtle.digUp()
    chestslot = find("minecraft:chest")
    if chestslot == false then print("out of chests!!!") end
    turtle.select(chestslot)
    turtle.placeUp()
    for slot = 1,16 do
        turtle.select(slot)
        item = turtle.getItemDetail(slot)
        if item then
            if item.name == "minecraft:chest" then
            elseif item.name == "minecraft:coal" then
                turtle.refuel()
                turtle.dropUp()
            else
                turtle.dropUp()
            end
        end
    end
end

function findslot(name,skipg)
    skipg = skipg or false
    if name == "minecraft:coal_ore" then
        name = "minecraft:coal"
    end

    if name == "minecraft:redstone_ore" then
        name = "minecraft:redstone"
    end

    if name == "minecraft:lapis_ore" then
        name = "minecraft:lapis_lazuli"
    end

    if name == "minecraft:emerald_ore" then
        name = "minecraft:emerald"
    end

    if name == "minecraft:diamond_ore" then
        name = "minecraft:diamond"
    end

    if name == "minecraft:stone" then
        name = "minecraft:cobblestone"
    end
    if name == "minecraft:cobweb" then
        name = "minecraft:string"
    end
    if name == "minecraft:gravel" then
        return 1
    end

    if name then
        firstempty = false
        for i = 1,16 do
            slotitem = turtle.getItemDetail(i)
            if slotitem then
                if name == slotitem.name then
                    if slotitem.count < 64 then
                        return i
                    end
                end
            else
                if not firstempty then firstempty = i end
            end
        end
        if firstempty then return firstempty end
        return false
    end
    return 1
end


function tablelength(T)
    local count = 0
    for _ in pairs(T) do count = count + 1 end
    return count
  end

 -- vvv fuel limit removed, replace true with turtle.getFuelLevel() < 200

function refuel()
    print(turtle.getFuelLevel())
    if  true then
        found = find("minecraft:coal")
        if found then
            turtle.select(found)
            turtle.refuel()
        end
    end
end


intebajs = {'minecraft:diamond', 'minecraft:iron_ore', 'minecraft:gold_ore', 'minecraft:emerald', 'minecraft:obsidian', 'minecraft:coal'}

function in_list (tab, val)
    for index, value in ipairs(tab) do
        if value == val then
            return true
        end
    end

    return false
end

function throw_shit()
    for i = 1,16 do
        sname = turtle.getItemDetail(i)
        if sname then
            if not in_list(intebajs,sname.name) then turtle.dropDown() end
        end
    end
end

function find(name)
    for i = 1,16 do
        sname = turtle.getItemDetail(i)
        if sname then
            sname = sname.name
            if name == sname then
                return i
            end
        end
    end
    return false
end

function findnextslot()
    for i = 1,16 do
        if turtle.getItemCount(i) ~= 0 then return i
        end
    end
end


function mine()
    itemsuc,item = turtle.inspectUp()
    if itemsuc then
            --print(item["name"])
            slot = findslot(item["name"])
        if slot then
            turtle.select(slot)
            turtle.digUp()
        else
            depo()
        end
    end
    itemsuc,item = turtle.inspectDown()
    if itemsuc then
        slot = findslot(item["name"])
        if slot then
            turtle.select(slot)
            turtle.digDown()
        else
            depo()
            turtle.digDown()
        end
    end
    itemsuc,item = turtle.inspect()
    --print(item)
    if itemsuc then
        slot = findslot(item["name"])
        if slot then
            turtle.select(slot)
            turtle.dig()
        else
            depo()
            turtle.dig()
        end
    end

    suc = turtle.forward()
    return suc
end

xl = 2
yl = 4
de = 3

function walk (len)
    x = 0
    while x < len do
        if mine() then x = x + 1 end
    end
end
for zw = 0,de do
    for xw = 1,xl do
        refuel()
        for yw = 1,yl-1 do
            walk(1)
        end
        turtle.turnRight()
        walk(1)
        turtle.turnRight()
        for yw = 1,yl-1 do
            walk(1)
        end
        if xw ~= xl then
            turtle.turnLeft()
            walk(1)
            turtle.turnLeft()
        else
            if zw ~= de then
                turtle.digUp()
                turtle.digDown()
                turtle.down()
                turtle.digDown()
                turtle.down()
                turtle.digDown()
                turtle.down()
                turtle.turnRight()
            end
        end
    end
end