--------------------------
-- inventory management --
--------------------------
function checkInventory()
  checkTakenInventory()
  if (takenSlots == 16) then
    returnHome()
    dropoff()
  end
end

-------------------------
-- @return:
-- takenSlots[int]
-- takenSlotsArray[Array(int - ordered)]
-------------------------
function checkTakenInventory()
  takenSlots = 0
  takenSlotsArry = {}
  
  for i = 1, 16, 1 do
    turtle.select(i)
    if (turtle.getItemCount <= 1) then
      table.insert(takenSlotsArry, i)
      takenSlots = takenSlots + 1
    end
  end
  
  return takenSlots, takenSlotsArry
end

-------------------------
-- @return:
-- freeSlots[int]
-- freeSlotsArray[Array(int - ordered)]
-------------------------
function checkFreeInventory()
  freeSlots = 0
  freeSlotsArry = {}
  
  for i = 1, 16, 1 do
    turtle.select(i)
    if (turtle.getItemCount == 0) then
      freeSlots = freeSlots + 1
      table.insert(freeSlotsArry, i)
    end
  end

  return freeSlots, freeSlotsArry
end

function dropOff(dropOffLevel)
  if (dropOffLevel == 0) then
    dropOffAll(side, sides)
  elseif(dropOffLevel == 1) then
    dropOffLFA(side, sides)
  elseif(dropOffLevel == 2) then
    dropOffLSF(side, sides)
  else
    debugString = "Drop Off Level was invalid: level "..dropOffLevel
	debugLevel = 1
	debugTerminal(debugString, debugLevel)
  end
end

function dropOffAll(side, sides, actionDelay)
  turtle.select(1) -- We assume there is something in slot 1
  isDroppingOffInventory = true

  if not(turtle.drop(sides[side])) then
    debugString = "Unable to find deposit inventory"
    debugLevel = 1
    debugOutput(debugString, debugLevel)
  else
    for i = 1, 16, 1 do
      turtle.select(i)
      while not(turtle.drop) do
        os.sleep(actionDelay) -- Inventory became full, wait for it to clear
      end
      turtle.drop(sides[side])
    end
    turtle.select(1)
  end

  isDroppingOffInventory = false
end

function dropOffLFA(side, sides, actionDelay) -- A drop off that ignores fuels
  -- Start at slot 1 for everything
  turtle.select(1)

  isDroppingOffInventory = true
  
  if not(turtle.drop(sides[side])) then
    debugString = "Unable to find deposit inventory"
    debugLevel = 1
    debugOutput(debugString, debugLevel)
  else
    for i = 1, 16, 1 do
      turtle.select(i)
      while not(turtle.drop(sides[side])) do
        os.sleep(actionDelay)
      end      
      if not(turtle.refuel()) then
        turtle.drop(sides[side])
      end
    end
  end

  -- Locate all of the fuel to the end of our inventory  
  local t = 16
  local T = 17
  for i = 1, 16, 1 do
	turtle.select(T - i)
    if (turtle.getItemCount() ~= 0) then
	   turtle.transferTo(t)
	   t = t - 1
	end
  end
  
  turtle.select(1)
  
  isDroppingOffInventory = false
end

function dropoffLSF(side, sides) -- drop of Items, leave 1 stack of fuel
  local leftFuel = false
  local fuelSlot = 1
  turtle.select(1) -- We assume there is something in slot 1
  
  isDroppingOffInventory = true

  if not(turtle.drop(sides[side])) then
    debugString = "Unable to find deposit inventory"
    debugLevel = 1
    debugOutput(debugString, debugLevel)
  else
    for i = 1, 16, 1 do
      if ((turtle.refuel()) and not(leftFuel)) then
	    leftFuel = true
	    fuelSlot = i
	  else
	    turtle.drop(sides[side])
	  end
    end
  end
  
  if (fuelSlot ~= 16) then
	turtle.select(fuelSlot)
	turtle.transferTo(16)
  end
  
  turtle.select(1)
  
  isDroppingOffInventory = false
end