"""
 server.py
 
 A simple implementation of a server.

 The server's response protocol is implemented elsewhere
 in a handle_connection(socket) method; see ./sgg.py for an example.

 Tested with python 3 ; see https://docs.python.org/3.5/howto/sockets.html .

Jim Mahoney | cs.marlboro.college | MIT License | April 2018
"""

# python system libraries
import socket, _thread

# server protocol - change this to implement a new protocol
from sgg import handle_connection

def run_server(port=12468, max_connections=3):
    ip = '127.0.0.1'
    # Note: 127.0.0.1 is the 'localhost' address that allows processes 
    # on this machine to connect, which is enough for demos & tests. 
    # To run this server/client across the internet, this will need to be 
    # the machine's network IP address.
    # But under MacOS, the bind() operation may throw error 49's using 
    # real IP addresses; see for example 
    # codefromabove.com/quickies/osx-cant-assign-requested-address-code49 .
    # The IP can be found with socket.gethostbyname_ex(socket.gethostname()) .
    serversocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM) 
    serversocket.bind((ip, port))
    serversocket.listen(max_connections)
    print("sever: listening on {}:{}.".format(ip, port))
    while True:
        print("server: waiting for connection ...")
        (clientsocket, address) = serversocket.accept()
        print("server: connection from {}:{}\n".format(address, clientsocket))
        _thread.start_new_thread(handle_connection, (clientsocket,))

if __name__ == '__main__':
    run_server()