turtle

--new changes entirely untested
local x,y,z = -164,64,193
local inventory = {}
local facing = 1
local selected = 1

--comment this out to not print anything
local function debugprint(msg)
  print(msg)
end

--[[

USEFUL FUNCTIONS SECTION

--]]

local function turnTo(dir)
  if dir ~= facing then
    debugprint("turning from "..facing.." to "..dir)
    if math.abs(facing-dir) == 2 then
      turtle.turnRight()
      turtle.turnRight()
    elseif facing == dir-1 or (facing == 3 and dir == 0) then
      turtle.turnRight()
    else
      turtle.turnLeft()
    end
  end
  facing = dir
end

local function decend()
  local dug = false
  if turtle.detectDown() then
    if not turtle.digDown() then
      debugprint("was not able to dig down")
      return false, false, false
    end
    dug = true
  end
  if not turtle.down() then
    debugprint("error moving down")
    return false, dug, turtle.attackDown()
  end
  y = y - 1
  return true, dug, false
end

local function accend()
  local dug = false
  if turtle.detectUp() then
    if not turtle.digUp() then
      debugprint("was not able to dig up")
      return false, false, false
    end
    dug = true
  end
  if not turtle.up() then
    debugprint("was not able to move up")
    return false, dug, turtle.attackUp()
  end
  y = y + 1
  return true, dug, false
end

local function move(dir)
  turnTo(dir)
  local dug = false
  if turtle.detect() then
    if not turtle.dig() then
      debugprint("was not able to dig")
      return false, false, false
    end
    dug = true
  end
  if not turtle.forward() then
    debugprint("error moving forward")
    return false, dug, turtle.attack()
  end
  if dir == 0 then z = z + 1
  elseif dir == 1 then x = x - 1
  elseif dir == 2 then z = z - 1
  elseif dir == 3 then x = x + 1
  end
  return true, dug, false
end

local function detectInventoryChange()
  for i=1,16 do
    turtle.select(i)
    local amount = turtle.getItemCount(i)
    if amount ~= 0 and inventory[i].amount == 0 then
      debugprint("found previously unknown item in slot "..i)
      for j=1,16 do
        if i~=j then
          if turtle.compareTo(j) then
            debugprint("unknown item is "..inventory[j].name.." from slot "..j)
            inventory[i] = {["name"] = inventory[j].name, ["amount"] = amount}
            return inventory[i].name, i, amount
          end
        end
      end
      inventory[i] = {["name"] = "unknown", ["amount"] = amount}
      return inventory[i].name, i, amount
    elseif amount == 0 and inventory[i].amount == 0 then
      --both slots empty, nothing changed
    elseif amount > inventory[i].amount then
      debugprint("found "..(amount - inventory[i].amount).." "..inventory[i].name.." in slot "..i)
      inventory[i].amount = amount
      return inventory[i].name, i, (amount - inventory[i].amount)
    elseif amounts < inventory[i].amount then
      debugprint("WARNING: "..inventory[i].name.." in slot "..i.." decreased by "..(inventory[i].amount - inventoryBackup[i].amount))
      inventory[i].amount = amount
    end
  end
end

local function tryMove(moveFunction, ...)
  local continue = true
  while continue do
    local moved, dug, attacked = moveFunction(...)
    if moved then return true, dug, attacked end
    if dug then detectInventoryChange() end
    elseif attacked then detectInventoryChange() end
    continue = dug or attacked
  end
  print("FATAL ERROR: cannot move")
  error("cannot move, aborting")
  return false, false, false
end

local function checkFuel()
  local fuel = turtle.getFuelLevel()
  if fuel == "unlimited" then return true end
  if fuel < 10 then
    debugprint("Low on fuel, refueling")
    turtle.select(1)
    if not turtle.refuel(10) then
      debugprint("ERROR: coult not refuel")
      if fuel == 0 then
        print("FATAL ERROR: cannot refuel")
        error("FATAL ERROR: cannot refuel")
      else
        debugprint("ERROR: cannot refuel")
      end
      return false
    end
    return true
  end
  return false
end

--[[

PROGRAMS START HERE

--]]

local function stairs()
  local goingUp = false
  local yAdj = 0
  while true do
    if not checkFuel() then return end
    tryMove(move, facing)
    if goingUp then
      if yAdj == 0 and not turtle.detectDown() then
        turtle.select(2)
        turtle.placeDown()
      end
      tryMove(accend)
      if y == 64+yAdj then
        if yAdj == 3 then
          break
       else
          yAdj = yAdj + 1
          tryMove(accend)
          tryMove(move, (facing+3)%4)
          turnTo((facing+3)%4)
          goingUp = false
        end
      end
    else
      tryMove(decend)
      if yAdj == 0 and not turtle.detectDown() then
        turtle.select(2)
        turtle.placeDown()
      end
      if y == 10+yAdj then
        goingUp = true
        tryMove(move, (facing+3)%4)
        turnTo((facing+3)%4)
        tryMove(accend)
      end
    end
  end
end

function test()
  for i=1,10 do
    tryMove(move, facing)
  end
end