#!/usr/bin/env python

import argparse
import json
import os
import serial
import serial.tools.list_ports
import subprocess
import sys

def screensaver_osx(action):
	"""Perform actions relating to the MacOS X screensaver.

	action='lock'   Lock the screen
	action='unlock' Unlock the screen
	"""
	osascript = """osascript -e 'tell application "ScreenSaverEngine" to %s'"""
	if action == 'lock':
		return subprocess.call(osascript % 'activate', shell=True)
	elif action == 'unlock':
		return subprocess.call(osascript % 'quit', shell=True)
	return False


class RFIDReader:
	def __init__(self, args, security_function):
		self.args = args
		self.serialPort = serial.Serial(self.args.serial_port, 2400)
		self.readStoredCards()
		self.security_function = security_function

	def addCard(self, card):
		self.known_cards[card] = self.args.learn
		self.storeCards()
		print 'Learned %s card: "%s"' % (self.args.learn, card)

	def checkCard(self, card=None):
		if not card:
			card=self.readCard()
		if card in self.known_cards:
			return True
		else:
			return False

	def learnCard(self, card=None):
		if not card:
			card=self.readCard()
		if card not in self.known_cards:
			self.addCard(card)
		else:
			print 'Already know card: "%s"' % card
			
	def learnMode(self):
		while True:
			print '*** (learn: %s) Waiting for card read...' % self.args.learn
			self.learnCard()

	def readData(self):
		while True:
			data = rfid.serialPort.readline()
			if len(data) == 12:
				return data.strip()

	def readCard(self):
		while True:
			first_read = self.readData()
			second_read = self.readData()
			if first_read == second_read:
				return first_read.strip()

	def readMode(self):
		while True:
			print '*** Waiting for card read...'
			card = rfid.readCard()
			if rfid.checkCard(card):
				print '%s card: "%s"' % (self.known_cards[card], card)
				self.security_function(self.known_cards[card])
			else:
				print 'Unknown card: "%s"' % card

	def readStoredCards(self):
		if not self.args.file:
			self.args.file = 'rfid.access'
		if os.path.exists(self.args.file):
			self.known_cards = json.load(open(self.args.file))
		else:
			self.known_cards = {}

	def storeCards(self):
		fd = open(self.args.file, 'w')
		fd.seek(0)
		json.dump(self.known_cards, fd)
		fd.close()


def port_list():
	ports = []
	for port, desc, hwid in sorted(serial.tools.list_ports.comports()):
		ports.append(port)
	return ports


if __name__ == '__main__':
	# Parse the options
	parser = argparse.ArgumentParser(description='Listen for RFID cards')
	parser.add_argument('-s', '--serial-port', help='Serial Port for RFID Reader')
	parser.add_argument('-l', '--learn', nargs='?', default=False, const='lock', choices=['lock', 'unlock'], help='Learn cards and assign them an action')
	parser.add_argument('-lp', '--list-ports', action='store_true', help='List the serial ports available.')
	parser.add_argument('-f', '--file', help='File to store active cards in.')
	args = parser.parse_args()

	# If requested, print the port list and exit
	if args.list_ports:
		print '\n'.join(port_list())
		sys.exit(0)

	# Determine our serial port if it wasn't provided
	if not args.serial_port:
		while True:
			ports = port_list()
			i = 0
			for port in ports:
				print "%d. %s" % (i, port)
				i += 1
			answer = raw_input('Which serial port is your RFID reader? ')
			try:
				if 0 <= int(answer) < i:
					args.serial_port = ports[int(answer)]
					break
			except ValueError:
				continue

	# Main logic
	rfid = RFIDReader(args, screensaver_osx)
	if rfid.args.learn:
		rfid.learnMode()
	else:
		rfid.readMode()