startup

function refuel()
  count = turtle.getItemCount(16)
  print("Got "..tostring(count).." coal blocks")
  if count < 64 then
    toGet = 64 - count
    print("Getting "..tostring(toGet).." coal blocks")
    turtle.select(16)
    turtle.suck(toGet)
  end
  if turtle.getFuelLevel() < 1000 then
    print("Low on fuel --> refueling")
    turtle.select(16)
    turtle.refuel(64)
    refuel()
  end
end

refuel()
print("Initial refil finished")
rednet.open("left")
h = fs.open("inventory","r")
inventory = textutils.unserialize(h.readAll())
h.close()

inventoryState = {}
for i=1,15 do
  inventoryState[i] = (turtle.getItemCount(i) > 0)
end

while true do
  event,id,msg = os.pullEvent()
  if event == "turtle_inventory" then
    for i=1,15 do
      if (turtle.getItemCount(i) > 0) ~= inventoryState[i] then
        inventoryState[i] = not inventoryState[i]
        newDestination = i
      end
    end
    rednet.send(5,"received","nexus_portal")
    id,msg=rednet.receive("nexus_portal")
    inventory[newDestination] = msg
    fs.delete("inventory")
    h = fs.open("inventory","w")
    h.write(textutils.serialize(inventory))
    h.close()
  elseif event == "rednet_message" and msg ~= "drawbridges" then
    msg = textutils.unserialize(msg)
    print("Looking for "..msg[2])
    local i = 1
    while inventory[i] ~= msg[2] and i < 16 do
      print("Not in slot "..tostring(i))
      i = i + 1
    end
    if i < 16 then
      selection = i
      print(msg[2].." is in slot "..tostring(selection))
      if msg[1] == "select" then
        refuel()
        print("Selecting "..msg[2].." in slot "..tostring(selection))
        turtle.select(selection)
        turtle.back()
        while turtle.up() do break end
        turtle.forward()
        turtle.dropUp()
        rednet.broadcast("drawbridges","nexus_portal")
        sleep(5)
        rednet.broadcast("drawbridges","nexus_portal")
        turtle.suckUp()
        turtle.back()
        while turtle.detect() do
          turtle.down()
        end
        turtle.forward()
      elseif msg[1] == "remove" then
        print("Removing "..msg[2].." in slot "..tostring(selection))
        turtle.select(selection)
        turtle.turnRight()
        turtle.drop()
        turtle.turnLeft()
        table.remove(inventory,selection)
        fs.delete("inventory")
        h = fs.open("inventory","w")
        h.write(textutils.serialize(inventory))
        h.close()
      end
    end
  end
end