#CMPS 128 - Homework 2
#Josep Valls - 4/24/2008
#jvallsva - 1139975
#Time client
import socket
import struct
import time,datetime
import sys
#Defaults, for testing purposes
pip='127.0.0.1'
pport=1235
preqs=8
pdelay=500
#Parameters read from the given arguments
pip=sys.argv[1]
pport=int(sys.argv[2])
preqs=int(sys.argv[3])
pdelay=int(sys.argv[4])
#Variable initialization
askew=0.0
adelay=0.0
#Object initialization
dgramSock=socket.socket(socket.AF_INET,socket.SOCK_DGRAM)
dgramSock.settimeout(3)
#Main program procedure
for req in range(preqs):
	#Prepare and send the request to the server
	print 'Sending request:',req+1
	tsent=time.clock()
	dgramSock.sendto(struct.pack('!I',0x1234deed),(pip,pport))
	#Receive the response
        resp=[]
	try:
                resp=struct.unpack('!III',dgramSock.recv(12))
               	if resp[0]!=0xbeef5678:
        		print 'magic number error',"%#x" % resp[0]
        	else:
                        #Time metrics
                        stime=datetime.datetime.fromtimestamp(resp[1])
                        askew=askew+time.time()-resp[1]-resp[2]*0.000001
                        delay=time.clock()-tsent
                        adelay=adelay+delay
                        print 'Server time:',stime,resp[2],'lag:',delay
        except:
                print 'timeout'
	time.sleep(pdelay/1000.0)
#Metrics and final math	
askew=askew/preqs
adelay=adelay/preqs
askew=askew+adelay
print '\nClock skew:',askew,'Average lag:',adelay
#Program termination
dgramSock.close()