import nfc
import nfc.clf
import nfc.ndef
import nfc.tag
import ndef

# TODO 3 trys for right nfc tag

application_uri = "http://marcelochsendorf.com"
write_try =3
key_to_write = "1337"
last_id = ""
tag_written = 0
reader_con = False


clf = nfc.ContactlessFrontend('usb')




def nfc_connected(tag):
    print("-- CARD SCANNED --")
    global write_try
    global last_id
    global key_to_write
    global application_uri


    if(key_to_write == ""):
	print("-- NO KEY TO WRITE --")
	return
    if(last_id == tag.identifier.encode("hex").upper()):
	print("please scan an other tag")
	return
    #SAFE UUID
    last_id = tag.identifier.encode("hex").upper()
    print last_id
	#TODO ADD TRY
    version = {'Type1Tag': 0x12, 'Type2Tag': 0x12,'Type3Tag': 0x10, 'Type4Tag': 0x30}[tag.type]
    formatted = tag.format(version=version)
    if tag.ndef and formatted:
        print " NDEF"
        print("  readable  = %s" % ("no","yes")[tag.ndef.is_readable])
        print("  writeable = %s" % ("no","yes")[tag.ndef.is_writeable])
        print("  capacity  = %d byte" % tag.ndef.capacity)
        print("  message   = %d byte" % tag.ndef.length)

	obj = {"application":"kaps_data_exporter","key":key_to_write}
	tag.ndef.records = [ndef.SmartposterRecord(str(application_uri),'KAPS'),ndef.TextRecord(str(obj))]
	print "on card:", tag.ndef.message.pretty()
	if(key_to_write in tag.ndef.message.pretty()):
		print("-- KEY WRITTEN TO TAG --")
		key_to_write = ""
		tag_written = 1
#TODO LOG TO DB
    else:
	if(write_try <= 0):
		key_to_write = ""
		print "nfc write limit exeed"
		tag_written = 2
	else:
		write_try = write_try - 1
		print "sorry, no NDEF or not formattable please try again: " + str(write_try)
		tag_written = 3










def nfc_write_aes_key_to_nfc(_key):
    print("--- WRITE AES TO NFC - INSERT A NFC TAG ---")
    global reader_con
    if(reader_con is False):
	print("-- NO READER CONNECTED - CALL INIT")
	return
    global key_to_write
    global tag_written
    tag_written = 0

    key_to_write = _key
    #while(tag_written == 0):
    tag = clf.connect(rdwr={'on-connect': nfc_connected})
    return tag_written


def eject_card():
    print "eject_card"
    # SEND TO CARDDISPENSER


def nfc_init():
    global reader_con

    #clf = nfc.ContactlessFrontend('usb')
    if(clf.open('usb') is True):
	reader_con = True
    else:
	reader_con = false

nfc_init()
nfc_write_aes_key_to_nfc("12354334535")

#init()