from socket import *
import sys

if len(sys.argv) <= 1:
	print 'Usage : "python ProxyServer.py server_ip"\n[server_ip : It is the IP Address Of Proxy Server'
	sys.exit(2)
	
# Create a server socket, bind it to a port and start listening
tcpSerSock = socket(AF_INET, SOCK_STREAM)
tcpSerSock.bind((sys.argv[1], 8888))
tcpSerSock.listen(100)

while 1:
	# Strat receiving data from the client
	print 'Ready to serve...'
	tcpCliSock, addr = tcpSerSock.accept()
	print 'Received a connection from:', addr
	message = tcpCliSock.recv(1024)
	print message
	# Extract the filename from the given message
	print message.split()[1]
	filename = message.split()[1].partition("/")[2]
	print filename
	fileExist = "false"
	filetouse = "/" + filename
	print filetouse
	try:
		# Check wether the file exist in the cache
		f = open(filetouse[1:], "r")                      
		outputdata = f.readlines()                        
		fileExist = "true"
		# ProxyServer finds a cache hit and generates a response message
		tcpCliSock.send("HTTP/1.0 200 OK\r\n")            
		tcpCliSock.send("Content-Type:text/html\r\n")
		for i in range(0, len(outputdata)):               
			tcpCliSock.send(outputdata[i])
			print 'Read from cache'     
	# Error handling for file not found in cache
	except IOError:
		if fileExist == "false": 
			# Create a socket on the proxyserver
			c = socket(AF_INET, SOCK_STREAM)            
			hostn = filename.replace("www.","",1)         
			print hostn                                   
			try:
				# Connect to the socket to port 80
				c.connect((hostn, 80))
				# Create a temporary file on this socket and ask port 80 for the file requested by the client
				fileobj = c.makefile('r', 0)               
				fileobj.write("GET "+"http://" + filename + " HTTP/1.0\n\n")  
				# Read the response into buffer
				buff = fileobj.readlines()
				# Create a new file in the cache for the requested file. Also send the response in the buffer to client socket and the corresponding file in the cache
				tmpFile = open("./" + filename,"wb")  
				for line in buff:                                                     
					tmpFile.write(line);                                               
					tcpCliSock.send(line);
			except:
				print "Illegal request"                                               
		else:
			# HTTP response message for file not found
			tcpCliSock.send("HTTP/1.0 404 sendErrorErrorError\r\n")                             
			tcpCliSock.send("Content-Type:text/html\r\n")
			tcpCliSock.send("\r\n")
	# Close the client and the server sockets    
	tcpCliSock.close() 
tcpSerSock.close()