from socket import *
import sys, traceback, time
from urllib import urlopen
from thread import start_new_thread
from Queue import Queue, Empty

URL = 'http://snake.cs.uni-duesseldorf.de/'
#URL = 'http://127.0.0.1:8000/'

def exchange(path, retry=True):
    global timestamp
    timestamp += 1
    delay = 1
    while True:
        try:
            f = urlopen('%s%x%s' % (URL, timestamp, path))
            data = f.read()
            assert data.startswith('cHs2')
            return data[4:]
        except KeyboardInterrupt:
            raise
        except:
            print '-'*60
            traceback.print_exc()
            print '-'*60
            if not retry:
                break
            if delay > 30:
                print "Giving up, sorry"
                sys.exit(1)
            print 'Retrying in %s seconds...' % delay
            time.sleep(delay)
            delay += 1
timestamp = 0

localport, remotehost, remoteport = sys.argv[1].split(':')
localport = int(localport)
remoteport = int(remoteport)
assert '/' not in remotehost


s = socket(AF_INET, SOCK_STREAM)
s.bind(('', localport))
s.listen(1)
print "Listening from connexion on %s..." % (s.getsockname(),)
t, addr = s.accept()
print "Connected by", addr

f = open('/dev/urandom', 'rb')
key = f.read(8).encode('base64').replace('\n', '').replace('=', '').replace('/', '-')
f.close()
result = exchange('/connect/%s/%s/%d' % (key, remotehost, remoteport))
assert result == ":-) connect\n", "connexion failed:\n%s" % (result,)

def socket_reader():
    try:
        while True:
            inqueue.put(t.recv(140))
    except error:
        inqueue.put('')
        print "Closed socket_reader()"

def socket_writer():
    try:
        while True:
            item = outqueue.get()
            if item is None:
                break
            t.sendall(item)
    except error:
        print "Closed socket_writer()"

inqueue = Queue()
outqueue = Queue()
start_new_thread(socket_reader, ())
start_new_thread(socket_writer, ())

delay = 0.0
try:
    while True:
        try:
            if delay > 0.0:
                data = inqueue.get(timeout=delay)
            else:
                data = inqueue.get(block=False)
            if data == '':
                break   # connexion closed
        except Empty:
            data = ''
        if data:
            data = data.encode('base64').replace('\n', '').replace('=', '')
            data = exchange('/wr/%s/0/%s' % (key, data))
            delay = 0.0
        else:
            data = exchange('/r/%s/0.2' % (key,))
            if not data:
                delay = min(10.0, (delay + 0.1) * 1.5)
                continue
            delay *= 0.1
        data = data.decode('base64')
        if data:
            outqueue.put(data)
finally:
    exchange('/close/%s' % (key,), retry=False)
    outqueue.put(None)