#!/usr/bin/env python3.5
# Copyright 2017 Digital
#
# This file is part of DigiLib.
#
# DigiLib is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# DigiLib is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with DigiLib.  If not, see <http://www.gnu.org/licenses/>.

import atexit
import logging
import logging.handlers
import os
import queue
import select
import socket
import sys
import threading
import time
import traceback

import blinker
import curio
import digilib.misc

lclient = logging.getLogger(__name__+".client")
lserver = logging.getLogger(__name__+".server")
lch = logging.getLogger(__name__+".chandler")
lschat = logging.getLogger(__name__+".server.chat")
lcchat = logging.getLogger(__name__+".client.chat")
lerr = logging.getLogger(__name__+".errhandler")


class ErrorHandler(object):
    """
    This Class provides a easy way to execute a function which is likely to
    raise an exception and log the traceback.
    """
    def __init__(self,logger):
        super().__init__()
        self.logger = logger

    def run(self,func,args=(),kwargs={},text=None,logger=None):
        if not logger:
            logger = self.logger
        if not text:
            print("ErrorHandler:WARNING:no text specified,"
                " this is highly discouraged")
        try:
            func(*args,**kwargs)
        except Exception as exc:
            logger.debug("error occured during "+text,exc_info=exc)

    async def arun(self,func,args=(),kwargs={},text=None,logger=None):
        if not logger:
            logger = self.logger
        if not text:
            print("ErrorHandler:WARNING:no text specified,"
                " this is highly discouraged")
        try:
            await func(*args,**kwargs)
        except Exception as exc:
            logger.debug("error occured during "+text,exc_info=exc)


class ConnHandlerBase(object):
    """
    ConnectionHandlerBase is the base class for all connection handlers.
    It provides basic methodes. Consider inheriting form ConnectionHandler
    instead, as it provides better functionality.
    """
    addr = None
    block_size = 1024
    server = None
    def __init__(self, socket, addr, server):
        super(ConnHandlerBase, self).__init__()
        self.socket = socket
        self.addr = addr
        self.server = server

    async def disconnect(self):
        """
        disconenct explicitely disconnects the client, shuts the socket down
        and closes it.
        """
        try:
            await self.send(bytes())
        except:
            lch.debug("error during disconenct")
        try:
            await self.socket.shutdown(0)
        except:
            lch.debug("error during socket shutdown")
        try:
            await self.socket.close()
        except:
            lch.debug("error closing socket")

    async def handle(self, data):
        """
        This method is called for every message the server receives from the
        client. It should handle the data. Performing asynchronous blocking
        actions is ok, as the client loop does not wait for this method to
        finish. therefore, this method can be called multiple times at once,
        use curio locks if appropriate.
        """
        raise NotImplemented()

    async def recv(self,block_size=block_size):
        """
        This method waits for the client to send something and returns bytes!
        """
        data_received = await self.socket.recv(block_size)
        return data_received

    async def send(self, data, log_msg=None):
        """
        This method sends bytes to the client. Returns False if an exception
        was raised during sending, otherwise True.
        """
        if log_msg:
            lschat.info("server:"+str(log_msg))
        else:
            lschat.info("Server:"+str(data))
        try:
            await self.socket.send(data)
            return True
        except Exception as e:
            lch.error(e, exc_info=True)
            return False


class ConnHandler(ConnHandlerBase):
    """
    More advanced connection handler than ConnectionHandlerBase. For
    instance, sends() takes a string and encodes it, recv() decodes
    the client's and returns a string and welcome_client is called after
    the ConnHandler is initialized (Not after the inheriting class is
    initialized though!)
    """
    def __init__(self, socket, addr, server):
        super(ConnHandler, self).__init__(socket,addr,server)

    async def disconnect(self):
        """
        disconenct() explicitely disconnects the client, performes a proper
        the shutdow on the socket and closes it.
        """
        try:
            await self.send("")
        except:
            lch.debug("error during disconenct")
        try:
            await self.socket.shutdown(0)
        except:
            lch.debug("error during socket shutdown")
        try:
            await self.socket.close()
        except:
            lch.debug("error closing socket")

    async def handle(self, data):
        return

    async def on_welcome(self):
        """
        This method can be used to send a welcome message to the client.
        """
        await self.send("Welcome client, this is the server sending!")

    async def recv(self,block_size=None):
        """
        This method waits for the client to send something, decodes it and
        returns a string.
        """
        if block_size == None:
            block_size = self.block_size
        data_received = await self.socket.recv(block_size)
        data_decoded = data_received.decode("utf-8")
        return data_decoded

    async def send(self, data, log_msg=False):
        """
        This method takes a string, encodes it and sends it to the client.
        Returns False if an exception was raised during sending, otherwise True.
        """
        if log_msg:
            lschat.info("server:"+log_msg)
        else:
            lschat.info("Server:"+data)
        data_encoded = bytes(data, "utf-8")
        try:
            await self.socket.send(data_encoded)
            return True
        except Exception as e:
            lch.error(e, exc_info=True)
            return False


class ConnHandlerEcho(ConnHandler):
    """
    A Conn handler which sends everything it receives to every other client
    connected to the server
    """
    def __init__(self, socket, addr, server):
        super(ConnHandlerEcho, self).__init__(socket, addr, server)

    def handle(self, data):
        for h in self.server.connection_handler:
            if not h is self:
                h.send(data)

class Server(object):
    """
    Server opens either an unix or an inet connection. For every new client
    a new ClientHandler object is created.
    _string_ **host** and _int_ **port** are the filename, hostname or ip
    address and the port respectively on which the connection will be opened.
    If you make an AF_UNIX socket, port is ignored so simply pass None.
    _object_ **handler_class** is the class (not an object of the class) used
    for making connection handlers.
    _dict_ **handler_kwargs** is a dict which will be passed as keyword
    argumetns to the __init__ function of handler_class when creating a new
    connection handler. Default is an emtpy dict.
    _string_ **af_family** specifies the AF_FAMILY socket type, valid options
    are: "AF_INET" for a inet socket and "AF_UNIX" for a unix (file) socket.
    Default is "AF_INET".
    _bool_ **log_ip** specifies wether the ip address of the server/client is logged.
    Default is False.
    _int_ **max_allowed_clients** specifies the maximum amount of clients
    connected to the server at once. Default is 5 (for now. this will change
    in the future).
    """
    # set to true when the server shuts down, for instance after a
    # fatal exception
    exit_event = False
    def __init__(
                self,
                host,
                port,
                handler_class,
                handler_kwargs={},
                af_family="AF_INET",
                log_ip=False,
                max_allowed_clients=5,
            ):
        super(Server, self).__init__()
        self.host = host
        self.port = port
        self.handler_class = handler_class
        self.handler_kwargs = handler_kwargs
        self.af_family = af_family
        self.log_ip = log_ip
        self.max_allowed_clients = max_allowed_clients
        # the error handler used by, for instance server.shutdown
        self.safe_handle = ErrorHandler(lserver)
        # don't make the socket yet, we don't need right now. will be created
        # when the start method is called
        self.socket = None
        # create a task group for handlers, so we can easily cancel/terminate
        # them all at once
        self.handle_tasks = curio.TaskGroup(name="tg_handle_clients")
        # list of all active connection handlers
        self.connection_handler = []
        # register our cleanup method to be executed when the program exits.
        # the cleanup function unregisters itself, so it won't get executed
        # twice when the user called it befor the program exites
        atexit.register(self.shutdown)

    def make_socket(self):
        """
        factory method for sockets.
        this method makes a normal socket and wraps it in a curi.io.Socket wrapper
        """
        lserver.debug("making a {} socket".format(self.af_family))
        if self.af_family == "AF_INET":
            s = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
        elif self.af_family == "AF_UNIX":
            s = socket.socket(socket.AF_UNIX,socket.SOCK_STREAM)
        else:
            raise ValueError(
                "AF_FAMILY '{}' not supported!".format(
                    self.af_family
                )
            )
        s = curio.io.Socket(s)
        return s

    def make_handler(self, conn, addr):
        """
        factory method for handlers.
        this method creates a handler object from self.handler_class and self.handler_kwargs
        """
        return self.handler_class(conn, addr, self, **self.handler_kwargs)

    def setup(self):
        """
        creates a scoket, opens the connection and starts listening for
        clients. this method does not block, it returns after starting to
        listen.
        """
        lserver.info("setting up server")
        self.socket = self.make_socket()
        if self.af_family == "AF_INET":
            self.socket.bind((self.host, self.port))
        elif self.af_family == "AF_UNIX":
            if os.path.exists(self.host):
                lserver.debug("file already exists")
                lserver.debug("attempting to remove it")
                os.remove(self.host)
            self.socket.bind(self.host)
        self.socket.listen(self.max_allowed_clients)

    def shutdown(self):
        """
        this method can be called synchronous and calls the asynchronous
        shutdown method.
        """
        curio.run(self.async_shutdown)

    async def async_shutdown(self):
        """
        This method properly shuts down the sockets and closes them.
        it unregisters itself from atexit, so it doesn't get executed twice
        when it was manually called before to program exits.
        """
        atexit.unregister(self.shutdown)
        lserver.info("shutting down server")
        await self.safe_handle.arun(
            self.handle_tasks.cancel_remaining,text="handler cancel")
        try:
            await curio.ignore_after(0.01,self.handle_tasks.join)
        except Exception as exc:
            lserver.error("error joining tasks:",exc_info=exc)
        # check if there is actually a socket. if the shutdown method is
        # executed before the start method, there is no socket.
        if self.socket:
            await self.safe_handle.arun(self.socket.shutdown,
                args=[socket.SHUT_RDWR,],text="socket shutdown")
            await self.safe_handle.arun(self.socket.close,text="socket close")

    def start(self):
        """
        this method starts the server. it is blocking.
        """
        self.setup()
        curio.run(self.run)

    async def run(self):
        """
        this method is the main loop of the Server. it waits for new client
        connections and creates a handle task for each of them. it does not
        receive or send anything.
        """
        lserver.debug("entering main loop")
        while ( not self.exit_event ):
            lserver.debug("waiting for client to connect")
            # wait for a client to connect
            conn,addr = await self.socket.accept()
            if self.log_ip:
                lserver.info(
                    "new client connection, {}:{}!".format(*addr))
            else:
                lserver.info("a new client connected, let's handle it")
            handler = self.make_handler(conn, addr)
            # self.register_conn(conn, addr)
            # self.register_handler(handler, conn)
            await self.handle_tasks.spawn(self.handle_client(conn,handler))

    async def handle_client(self,socket,handler):
        """
        This method waits for the client to send something and calls the
        ClientHandler's handle method. there is a handle_client method running for each client connected.
        """
        if hasattr(handler,"on_welcome"):
            await handler.on_welcome()
        while True:
            try:
                if self.log_ip:
                    lserver.debug("waiting for {} to send something"
                        .format(socket.getsockname()))
                else:
                    lserver.debug("waiting for the client to send something")
                # wait for the client to send something
                data = await handler.recv()
                # if there is no data the client disconnected. this is a
                # tcp protocoll specification.
                if not data:
                    if self.log_ip:
                        lserver.info("the connection to {} was closed"
                            .format(socket.getsockname()))
                    else:
                        lserver.info("the connection to the client was closed")
                    await handler.disconnect()
                    # break out of the loop. don't return because we need to
                    # do cleanup
                    break
                else:
                    # don't strip the data of its whitespaces, since they may
                    # be important.
                    lschat.info("Client:"+data.rstrip())
                    await handler.handle(data)
            except Exception as e:
                    lserver.error(e, exc_info=True)
                    # let's sleep a bit, in case something is broken and the
                    # loop throws an exception every time
                    await curio.sleep(0.01)
        # if a task exits and hasn't been joined, curio prints a warning.
        # we don't want the warning, so let's join the current task for 0
        # seconds. instead of task.join() we use task.wait(). the only
        # difference is that wait doesn't throw a exception if the task was
        # stopped or crashed
        cur_task = await curio.current_task()
        await curio.ignore_after(0.01,cur_task.wait)

class Client(threading.Thread):
    """docstring for Client"""
    status = "uninitialized"
    exit_event = False
    def __init__(
                self,
                host,
                port=None,
                af_family="AF_INET",
                handle_data_func=None,
                error_handler=None,
                block_size=1024,
            ):
        super().__init__()
        self.name = "Client"
        self.host = host
        self.port = port
        self.af_family = af_family
        self.block_size = block_size
        self.handle_data_func = handle_data_func
        self.error_handler = error_handler
        self.socket = None
        self.status = "disconnected"

    def connect(self):
        self.status = "connecting"
        self.socket = self.make_socket()
        lclient.info("connecting to socket '{}' of type {}"
            .format(self.host,self.af_family))
        try:
            if self.af_family == "AF_INET":
                self.socket.connect((self.host, self.port))
            elif self.af_family == "AF_UNIX":
                self.socket.connect(self.host)
            self.status = "connected"
            lclient.info("connected")
            return True
        except Exception as e:
            lclient.debug(e, exc_info=True)
            if type(e) is ConnectionRefusedError:
                lclient.info(
                    "failed to connect to socket '{}'".format(self.host))
                self.disconnect()
                return False
    def disconnect(self):
        lclient.info("disconnecting from socket '{}'".format(self.host))
        self.status = "disconnected"
        if self.socket:
            try:
                self.socket.shutdown(socket.SHUT_RDWR)
            except Exception as e:
                lclient.error(e)
            try:
                self.socket.close()
            except Exception as e:
                lclient.error("error occured while closing the socket, " +
                    "maybe it is already closed",exc_info=e)
        del self.socket
        self.socket = None
    def handle_data(self, data_received):
        data_decoded = data_received.decode("utf-8")
        lcchat.info("Server: "+data_decoded)
        if self.handle_data_func:
            try:
                self.handle_data_func(data_decoded)
            except Exception as e:
                lclient.error(e, exc_info=True)
    def is_running(self):
        return (self in threading.enumerate())
    def make_socket(self):
        lclient.info("creating a {} socket".format(self.af_family))
        if self.af_family == "AF_INET":
            s = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
        elif self.af_family == "AF_UNIX":
            s = socket.socket(socket.AF_UNIX,socket.SOCK_STREAM)
        else:
            raise ValueError(
                "AF_FAMILY '{}' not supported!".format(
                    self.af_family
                )
            )
        return s
    def main_loop(self):
        lclient.debug("starting main loop")
        while ( not self.exit_event ):
            if not self.status in ["connected"]:
                time.sleep(0.1)
                continue
            # print(0)
            read_confirmed, write_confirmed, exc_confirmed \
            = select.select(
                [self.socket],
                [],
                [self.socket],
                1
            )
            if self.socket in exc_confirmed:
                lclient.warning("socket is expected to corrupt, exiting")
                self.disconnect()
               # self.stop()
                break
            elif self.socket in read_confirmed:
                try:
                    data_received = self.read_from_socket()
                    if data_received == b'':
                        lclient.info("connection is broken, closing socket exiting")
                        self.disconnect()
                        # self.stop()
                        # break
                    else:
                        try:
                            self.handle_data(data_received)
                        except Exception as e:
                            lserver.error(
                                "Error while handling data",
                                exc_info=e
                            )
                except Exception as e:
                    lclient.error(e, exc_info=True)
                    if type(e) is OSError:
                        lclient.warn("connection broken, exiting")
                        self.disconnect()
                        # self.stop()
                        # break
                    else:
                        raise
            else:
                time.sleep(0.1)
    def read_from_socket(self):
        data_received = self.socket.recv(self.block_size)
        return data_received
    def run(self):
        # self.connect()
        if self.error_handler:
            self.error_handler(self.main_loop)
        else:
            self.main_loop()
    def send(self, msg):
        msg = msg.rstrip()
        msg_encoded = bytes(msg+"\r\n", "utf-8")
        try:
            lcchat.info("Client: "+msg)
            self.socket.send(msg_encoded)
        except Exception as e:
            lclient.error(e, exc_info=True)
            self.status = "shutdown"
    def setup(self):
        pass
    def stop(self,reason=None):
        self.disconnect()
        self.exit_event = True
        if reason:
            print(reason)







class AsyncClient(object):
    """docstring for Client"""
    block_size = 1024
    status = "uninitialized"
    exit_event = False
    def __init__(
                self,
                host,
                port=None,
                af_family="AF_INET",
                handle_data_func=None,
                error_handler=None,
                block_size=1024,
            ):
        super().__init__()
        self.host = host
        self.port = port
        self.af_family = af_family
        self.block_size = block_size
        self.handle_data_func = handle_data_func
        self.error_handler = error_handler
        self.socket = None
        self.status = "disconnected"

    def connect(self):
        self.status = "connecting"
        self.socket = self.make_socket()
        lclient.info("connecting to socket '{}' of type {}".format(
                self.host,self.af_family))
        try:
            if self.af_family == "AF_INET":
                self.socket.connect((self.host, self.port))
            elif self.af_family == "AF_UNIX":
                self.socket.connect(self.host)
            self.is_connected = True
            self.status = "connected"
            lclient.info("connected")
            return True
        except Exception as e:
            lclient.debug(e, exc_info=True)
            if type(e) is ConnectionRefusedError:
                lclient.info("failed to connect to socket '{}'".format(self.host))
                self.disconnect()
                return False

    def disconnect(self):
        lclient.info("disconnecting from socket '{}'".format(self.host))
        self.is_connected = False
        self.status = "disconnected"
        if self.socket:
            try:
                self.socket.shutdown(socket.SHUT_RDWR)
            except Exception as e:
                lclient.error(e)
            try:
                self.socket.close()
            except Exception as e:
                lclient.error("error occured while closing the socket, " +
                    "maybe it is already closed",exc_info=e)
        del self.socket
        self.socket = None

    def handle_data(self, data_received):
        data_decoded = data_received.decode("utf-8")
        lcchat.info("Server: "+data_decoded)
        if self.handle_data_func:
            try:
                self.handle_data_func(data_decoded)
            except Exception as e:
                lclient.error(e, exc_info=True)

    def is_running(self):
        return (self in threading.enumerate())

    def make_socket(self):
        lclient.info("creating a {} socket".format(self.af_family))
        if self.af_family == "AF_INET":
            s = trio.socket.socket(socket.AF_INET,socket.SOCK_STREAM)
        elif self.af_family == "AF_UNIX":
            s = trio.socket.socket(socket.AF_UNIX,socket.SOCK_STREAM)
        else:
            raise ValueError(
                "AF_FAMILY '{}' not supported!".format(
                    self.af_family
                )
            )
        return s

    async def read_from_socket(self):
        data_received = await self.socket.recv(self.block_size)
        return data_received

    async def recv(self):
        data_received = await self.socket.recv(self.block_size)
        data_decoded = data_received.decode("utf-8")
        return data_decoded

    async def run(self):
        lclient.debug("starting main loop")
        while ( not self.exit_event ):
            if not self.status in ["connected"]:
                time.sleep(0.1)
                continue
            # if self.socket in exc_confirmed:
            #     self.is_connected = False
            #     lclient.warning("socket is expected to corrupt, exiting")
            #     self.disconnect()
            #    # self.stop()
            #     break
            # elif self.socket in read_confirmed:
            try:
                data = await self.read_from_socket()
                if not data:
                    lclient.info("connection closed")
                    self.disconnect()
                else:
                    self.handle_data(data)
            except Exception as e:
                lclient.error(e, exc_info=True)
                if type(e) is OSError:
                    self.is_connected = False
                    lclient.warn("connection broken, exiting")
                    self.disconnect()
                else:
                    raise

    async def start(self,connect=False):
        if connect:
            self.connect()
        if self.error_handler:
            self.error_handler(self.run)
        else:
            self.run()

    def send(self, msg):
        msg = msg.rstrip()
        msg_encoded = bytes(msg+"\r\n", "utf-8")
        try:
            lcchat.info("Client: "+msg)
            self.socket.send(msg_encoded)
        except Exception as e:
            self.is_connected = False
            lclient.error(e, exc_info=True)
            self.disconnect()
            # self.exit_event = True
            # self.status = "shutdown"

    def setup(self):
        pass

    def stop(self,reason=None):
        self.disconnect()
        self.exit_event = True
        if reason:
            print(reason)




























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