"""
rpyc plug-in server (threaded or forking)
"""
import sys
import os
import socket
import time
import threading
import select
import signal
import errno
from rpyc.core import brine, SocketStream, Channel, Connection
from rpyc.utils.logger import Logger
from rpyc.utils.registry import UDPRegistryClient, TCPRegistryClient
from rpyc.utils.authenticators import AuthenticationError


class Server(object):
    def __init__(self, service, hostname = "0.0.0.0", port = 0, backlog = 10, 
            reuse_addr = True, authenticator = None, registrar = None, 
            auto_register = True, protocol_config = {}, logger = None):
        self.active = False
        self._closed = False
        self.service = service
        self.authenticator = authenticator
        self.backlog = backlog
        self.auto_register = auto_register
        self.protocol_config = protocol_config
        self.clients = set()
        if logger is None:
            logger = self._get_logger()
        self.logger = logger
        if registrar is None:
            registrar = UDPRegistryClient(logger = self.logger)
        self.registrar = registrar
        
        self.listener = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        if reuse_addr and sys.platform != "win32":
            # warning: reuseaddr is not what you expect on windows!
            self.listener.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
        
        self.listener.bind((hostname, port))
        self.port = self.listener.getsockname()[1]
    
    def _get_logger(self):
        raise NotImplementedError()
    
    def close(self):
        if self._closed:
            return
        self._closed = True
        self.active = False
        if self.auto_register:
            try:
                self.registrar.unregister(self.port)
            except Exception:
                self.logger.traceback()
        self.listener.close()
        self.logger.info("listener closed")
        for c in set(self.clients):
            try:
                c.shutdown(socket.SHUT_RDWR)
            except:
                pass
            c.close()
        self.clients.clear()
    
    def fileno(self):
        return self.listener.fileno()
    
    def accept(self):
        while True:
            try:
                sock, (h, p) = self.listener.accept()
            except socket.timeout:
                pass
            except socket.error as ex:
                if ex[0] == errno.EINTR:
                    pass
                else:
                    raise EOFError()
            else:
                break
        
        sock.setblocking(True)
        self.logger.info("accepted %s:%s", h, p)
        self.clients.add(sock)
        self._accept_method(sock)
    
    def _accept_method(self, sock):
        """this method should start a thread, fork a child process, or 
        anything else in order to serve the client. once the mechanism has
        been created, it should invoke _authenticate_and_serve_client with 
        `sock` as the argument"""
        raise NotImplementedError
    
    def _serve_client(self, sock, credentials):
        h, p = sock.getpeername()
        self.logger.info("welcome %s:%s", h, p)
        try:
            config = dict(self.protocol_config, credentials = credentials)
            conn = Connection(self.service, Channel(SocketStream(sock)), 
                config = config, _lazy = True)
            conn._init_service()
            conn.serve_all()
        finally:
            self.logger.info("goodbye %s:%s", h, p)
    
    def _bg_register(self):
        interval = self.registrar.REREGISTER_INTERVAL
        self.logger.info("started background auto-register thread "
            "(interval = %s)", interval)
        tnext = 0
        try:
            while self.active:
                t = time.time()
                if t >= tnext: 
                    tnext = t + interval
                    try:
                        self.registrar.register(self.service.get_service_aliases(),
                            self.port)
                    except Exception:
                        self.logger.traceback()
                time.sleep(1)
        finally:
            if not self._closed:
                self.logger.info("background auto-register thread finished")
    
    def start(self):
        """starts the server. use close() to stop"""
        self.listener.listen(self.backlog)
        h, p = self.listener.getsockname()
        self.logger.info("server started on %s:%s", h, p)
        self.active = True
        if self.auto_register:
            t = threading.Thread(target = self._bg_register)
            t.setDaemon(True)
            t.start()
        #if sys.platform == "win32":
        # hack so we can receive Ctrl+C on windows
        self.listener.settimeout(0.5)
        try:
            try:
                while True:
                    self.accept()
            except EOFError:
                pass # server closed by another thread
            except KeyboardInterrupt:
                print()
                self.logger.warn("keyboard interrupt!")
        finally:
            self.logger.info("server has terminated")
            self.close()


class ThreadedServer(Server):
    def _get_logger(self):
        return Logger(self.service.get_service_name(), show_tid = True)
    
    def _accept_method(self, sock):
        t = threading.Thread(target = self._authenticate_and_serve_client, args = (sock,))
        t.setDaemon(True)
        t.start()


class ForkingServer(Server):
    def __init__(self, *args, **kwargs):
        Server.__init__(self, *args, **kwargs)
        # setup sigchld handler
        self._prevhandler = signal.signal(signal.SIGCHLD, self._handle_sigchld)
    
    def close(self):
        Server.close(self)
        signal.signal(signal.SIGCHLD, self._prevhandler)
    
    def _get_logger(self):
        return Logger(self.service.get_service_name(), show_pid = True)
    
    @staticmethod
    def _handle_sigchld(signum, unused):
        try:
            while True:
                os.waitpid(-1, os.WNOHANG)
        except OSError:
            pass
        # re-register signal handler (see man signal(2), under Portability)
        signal.signal(signal.SIGCHLD, self._handle_sigchld)
    
    def _accept_method(self, sock):
        pid = os.fork()
        if pid == 0:
            # child
            try:
                try:
                    self.logger.info("child process created")
                    signal.signal(signal.SIGCHLD, self._prevhandler)
                    self.listener.close()
                    self.clients.clear()
                    self._authenticate_and_serve_client(sock)
                except:
                    self.logger.traceback()
            finally:
                self.logger.info("child terminated")
                os._exit(0)
        else:
            # parent
            sock.close()






