collectitems

local function tryMove()
  while turtle.getFuelLevel() == 0 do
    for i = 1, 16 do
      turtle.select(i)
      if turtle.refuel(1) then
        break
      end
    end
    turtle.select(1)
  end
end

local function up()
  tryMove()
  while not turtle.up() do
    turtle.digUp()
  end
end

local function down()
  tryMove()
  while not turtle.down() do
    turtle.digDown()
  end
end

local function forward()
  tryMove()
  while not turtle.forward() do
    turtle.dig()
  end
end

local dir = 0
local dx = 0
local dy = 0
local lastx = 0
local lasty = 0
local x = 0
local y = 0
local height = 0

local function searchItems()

end

local function returnHome()

end

local function invHasItems()
  for i = 1, 16 do
    if turtle.getItemCount() ~= 0 then
      return true
    end
  end
  return false
end

local function dropItems()
  local empty = true
  for i = 1, 16 do
    turtle.select(i)
    turtle.drop()
    if turtle.getItemCount() ~= 0 then
      empty = false
    end
  end
  return empty
end

local function emptyInventory()
  turtle.turnRight()
  turtle.turnRight()
  local empty = false
  while not empty do
    empty = dropItems()
    if not empty then
      tryMove()
      turtle.up()
      height = height + 1
  end
end

local function resumeSearch()

end

while true do
  while searchItems() do end
  returnHome()
  emptyInventory()
  resumeSearch()
end