#!/usr/bin/env python
# Parallel Python Software: http://www.parallelpython.com
# Copyright (c) 2005-2012, Vitalii Vanovschi
# All rights reserved.
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#    * Redistributions of source code must retain the above copyright notice,
#      this list of conditions and the following disclaimer.
#    * Redistributions in binary form must reproduce the above copyright
#      notice, this list of conditions and the following disclaimer in the
#      documentation and/or other materials provided with the distribution.
#    * Neither the name of the author nor the names of its contributors
#      may be used to endorse or promote products derived from this software
#      without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
# THE POSSIBILITY OF SUCH DAMAGE.
"""
Parallel Python Software, Network Server

http://www.parallelpython.com - updates, documentation, examples and support
forums
"""

import atexit
import logging
import errno
import getopt
import sys
import socket
import threading
import random
import string
import signal
import time
import os

import pp
import ppauto
import ppcommon
import pptransport

copyright = "Copyright (c) 2005-2012 Vitalii Vanovschi. All rights reserved"
version = "1.6.4"

LISTEN_SOCKET_TIMEOUT = 20

# compatibility with Python 2.6
try:
    import hashlib
    sha_new = hashlib.sha1
except ImportError:
    import sha
    sha_new = sha.new


class _NetworkServer(pp.Server):
    """Network Server Class
    """

    def __init__(self, ncpus="autodetect", interface="0.0.0.0",
                broadcast="255.255.255.255", port=None, secret=None,
                timeout=None, restart=False, proto=2, socket_timeout=3600, pid_file=None):
        pp.Server.__init__(self, ncpus, (), secret, restart,
                proto, socket_timeout)
        if pid_file:
          with open(pid_file, 'w') as pfile:
            print >>pfile, os.getpid()
          atexit.register(os.remove, pid_file)
        self.host = interface
        self.bcast = broadcast
        if port is not None:
            self.port = port
        else:
            self.port = self.default_port
        self.timeout = timeout
        self.ncon = 0
        self.last_con_time = time.time()
        self.ncon_lock = threading.Lock()

        self.logger.debug("Strarting network server interface=%s port=%i"
                % (self.host, self.port))
        if self.timeout is not None:
            self.logger.debug("ppserver will exit in %i seconds if no "\
                    "connections with clients exist" % (self.timeout))
            ppcommon.start_thread("timeout_check",  self.check_timeout)

    def ncon_add(self, val):
        """Keeps track of the number of connections and time of the last one"""
        self.ncon_lock.acquire()
        self.ncon += val
        self.last_con_time = time.time()
        self.ncon_lock.release()

    def check_timeout(self):
        """Checks if timeout happened and shutdowns server if it did"""
        while True:
            if self.ncon == 0:
                idle_time = time.time() - self.last_con_time
                if idle_time < self.timeout:
                    time.sleep(self.timeout - idle_time)
                else:
                    self.logger.debug("exiting ppserver due to timeout (no client"\
                            " connections in last %i sec)", self.timeout)
                    os._exit(0)
            else:
                time.sleep(self.timeout)

    def listen(self):
        """Initiates listenting to incoming connections"""
        try:
            self.ssocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
            # following allows ppserver to restart faster on the same port
            self.ssocket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
            self.ssocket.settimeout(LISTEN_SOCKET_TIMEOUT)
            self.ssocket.bind((self.host, self.port))
            self.ssocket.listen(5)
        except socket.error, e:
            self.logger.error("Cannot create socket for %s:%s, %s", self.host, self.port, e)

        try:
            while 1:
                csocket = None
                # accept connections from outside
                try:
                    (csocket, address) = self.ssocket.accept()
                except socket.timeout:
                    pass
                # don't exit on an interupt due to a signal
                except socket.error as e: 
                    if e.errno == errno.EINTR:
                      pass
                if self._exiting:
                    return                
                # now do something with the clientsocket
                # in this case, we'll pretend this is a threaded server
                if csocket:
                    ppcommon.start_thread("client_socket",  self.crun, (csocket,  ))
        except KeyboardInterrupt:
            pass
        except:
            self.logger.debug("Exception in listen method (possibly expected)", exc_info=True)
        finally:
            self.logger.debug("Closing server socket")
            self.ssocket.close()            

    def crun(self, csocket):
        """Authenticates client and handles its jobs"""
        mysocket = pptransport.CSocketTransport(csocket, self.socket_timeout)
        #send PP version
        mysocket.send(version)
        #generate a random string
        srandom = "".join([random.choice(string.ascii_letters)
                for i in xrange(16)])
        mysocket.send(srandom)
        answer = sha_new(srandom+self.secret).hexdigest()
        clientanswer = mysocket.receive()
        if answer != clientanswer:
            self.logger.warning("Authentication failed, client host=%s, port=%i"
                    % csocket.getpeername())
            mysocket.send("FAILED")
            csocket.close()
            return
        else:
            mysocket.send("OK")

        ctype = mysocket.receive()
        self.logger.debug("Control message received: " + ctype)
        self.ncon_add(1)
        try:
            if ctype == "STAT":
                #reset time at each new connection
                self.get_stats()["local"].time = 0.0
                mysocket.send(str(self.get_ncpus()))
                while 1:
                    mysocket.receive()
                    mysocket.send(str(self.get_stats()["local"].time))
            elif ctype=="EXEC":
                while 1:
                    sfunc = mysocket.creceive()
                    sargs = mysocket.receive()
                    fun = self.insert(sfunc, sargs)
                    sresult = fun(True)
                    mysocket.send(sresult)
        except:
            if self._exiting:
                return
            if pp.SHOW_EXPECTED_EXCEPTIONS:
                self.logger.debug("Exception in crun method (possibly expected)", exc_info=True)
            self.logger.debug("Closing client socket")
            csocket.close()
            self.ncon_add(-1)

    def broadcast(self):
        """Initiaates auto-discovery mechanism"""
        discover = ppauto.Discover(self)
        ppcommon.start_thread("server_broadcast",  discover.run,
                ((self.host, self.port), (self.bcast, self.port)))


def parse_config(file_loc):
    """
    Parses a config file in a very forgiving way.
    """
    # If we don't have configobj installed then let the user know and exit
    try:
        from configobj import ConfigObj
    except ImportError, ie:
        print >> sys.stderr, ("ERROR: You must have config obj installed to use"
                "configuration files. You can still use command line switches.")
        sys.exit(1)

    if not os.access(file_loc, os.F_OK):
        print >> sys.stderr, "ERROR: Can not access %s." % arg
        sys.exit(1)

    # Load the configuration file
    config = ConfigObj(file_loc)
    # try each config item and use the result if it exists. If it doesn't
    # then simply pass and move along
    try:
        args['secret'] = config['general'].get('secret')
    except:
        pass

    try:
        autodiscovery = config['network'].as_bool('autodiscovery')
    except:
        pass

    try:
        args['interface'] = config['network'].get('interface',
                                                  default="0.0.0.0")
    except:
        pass

    try:
        args['broadcast'] = config['network'].get('broadcast')
    except:
        pass

    try:
        args['port'] = config['network'].as_int('port')
    except:
        pass

    try:
        args['loglevel'] = config['general'].as_bool('debug')
    except:
        pass

    try:
        args['ncpus'] = config['general'].as_int('workers')
    except:
        pass

    try:
        args['proto'] = config['general'].as_int('proto')
    except:
        pass

    try:
        args['restart'] = config['general'].as_bool('restart')
    except:
        pass

    try:
        args['timeout'] = config['network'].as_int('timeout')
    except:
        pass

    try:
        args['socket_timeout'] = config['network'].as_int('socket_timeout')
    except:
        pass

    try:
        args['pid_file'] = config['general'].get('pid_file')
    except:
        pass
    # Return a tuple of the args dict and autodiscovery variable
    return args, autodiscovery


def print_usage():
    """Prints help"""
    print "Parallel Python Network Server (pp-" + version + ")"
    print "Usage: ppserver.py [-hdar] [-f format] [-n proto]"\
            " [-c config_path] [-i interface] [-b broadcast]"\
            " [-p port] [-w nworkers] [-s secret] [-t seconds]"\
            " [-k seconds] [-P pid_file]"
    print
    print "Options: "
    print "-h                 : this help message"
    print "-d                 : set log level to debug"
    print "-f format          : log format"
    print "-a                 : enable auto-discovery service"
    print "-r                 : restart worker process after each"\
            " task completion"
    print "-n proto           : protocol number for pickle module"
    print "-c path            : path to config file"
    print "-i interface       : interface to listen"
    print "-b broadcast       : broadcast address for auto-discovery service"
    print "-p port            : port to listen"
    print "-w nworkers        : number of workers to start"
    print "-s secret          : secret for authentication"
    print "-t seconds         : timeout to exit if no connections with "\
            "clients exist"
    print "-k seconds         : socket timeout in seconds"
    print "-P pid_file        : file to write PID to"
    print
    print "To print server stats send SIGUSR1 to its main process (unix only). "
    print 
    print "Due to the security concerns always use a non-trivial secret key."
    print "Secret key set by -s switch will override secret key assigned by"
    print "pp_secret variable in .pythonrc.py"
    print
    print "Please visit http://www.parallelpython.com for extended up-to-date"
    print "documentation, examples and support forums"


def create_network_server(argv):
    try:
        opts, args = getopt.getopt(argv, "hdarn:c:b:i:p:w:s:t:f:k:P:", ["help"])
    except getopt.GetoptError:
        print_usage()
        raise

    args = {}
    autodiscovery = False

    log_level = logging.WARNING
    log_format = "%(asctime)s - %(name)s - %(levelname)s - %(message)s"

    for opt, arg in opts:
        if opt in ("-h", "--help"):
            print_usage()
            sys.exit()
        elif opt == "-c":
            args, autodiscovery = parse_config(arg)
        elif opt == "-d":
            log_level = logging.DEBUG
            pp.SHOW_EXPECTED_EXCEPTIONS = True
        elif opt == "-f":
            log_format = arg
        elif opt == "-i":
            args["interface"] = arg
        elif opt == "-s":
            args["secret"] = arg
        elif opt == "-p":
            args["port"] = int(arg)
        elif opt == "-w":
            args["ncpus"] = int(arg)
        elif opt == "-a":
            autodiscovery = True
        elif opt == "-r":
            args["restart"] = True
        elif opt == "-b":
            args["broadcast"] = arg
        elif opt == "-n":
            args["proto"] = int(arg)
        elif opt == "-t":
            args["timeout"] = int(arg)
        elif opt == "-k":
            args["socket_timeout"] = int(arg)
        elif opt == "-P":
            args["pid_file"] = arg

    log_handler = logging.StreamHandler()
    log_handler.setFormatter(logging.Formatter(log_format))
    logging.getLogger("pp").setLevel(log_level)
    logging.getLogger("pp").addHandler(log_handler)

    server = _NetworkServer(**args)
    if autodiscovery:
        server.broadcast()
    return server    
    
def signal_handler(signum, stack):
    """Prints server stats when SIGUSR1 is received (unix only). """
    server.print_stats()

if __name__ == "__main__":
    server = create_network_server(sys.argv[1:])
    if hasattr(signal, "SIGUSR1"):
      signal.signal(signal.SIGUSR1, signal_handler)
    server.listen()
    #have to destroy it here explicitly otherwise an exception
    #comes out in Python 2.4
    del server
    

# Parallel Python Software: http://www.parallelpython.com
