MC Bank Withdraw

--[[
    CC-Bank
    Copyright © 2012  Yingtong Li

    CC-Bank is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    CC-Bank is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with CC-Bank.  If not, see <http://www.gnu.org/licenses/>.
--]]

local modemSide = "right"
local clientId = 0
local version = "CC-Bank-0.2.0-Compatible"

local function serve()
	rednet.open(modemSide)
	local senderId, message = rednet.receive()

	if senderId == clientId then
		if string.len(message) >= string.len(version) then
			if string.sub(message, 1, string.len(version)) == version then
				local bits = textutils.unserialize(string.sub(message, string.len(version) + 1))
				local command = bits[1]
				local amount = tonumber(bits[2])

				if command == "WITHDRAW" then
					local slot = 1
					turtle.select(slot)
					for i = 1, amount, 1 do
						while turtle.getItemCount(slot) <= 0 do
							if slot < 16 then
								slot = slot + 1
								turtle.select(slot)
							else
								rednet.send(senderId, "-")
								return
							end
						end

						turtle.drop(1)
					end
					rednet.send(senderId, "+")
				elseif command == "DEPOSIT" then
					-- Depositing cannot be implemented until turtle.suck() takes a number
					rednet.send(senderId, "-")
				end
			end
			rednet.send(senderId, "-")
		end
	end
end

while true do
	serve()
end