# MIT License
#
# Copyright (c) 2016-2022 Mark Qvist / unsigned.io
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.

from .Interface import Interface
import socketserver
import threading
import socket
import time
import sys
import os
import RNS

class HDLC():
    FLAG              = 0x7E
    ESC               = 0x7D
    ESC_MASK          = 0x20

    @staticmethod
    def escape(data):
        data = data.replace(bytes([HDLC.ESC]), bytes([HDLC.ESC, HDLC.ESC^HDLC.ESC_MASK]))
        data = data.replace(bytes([HDLC.FLAG]), bytes([HDLC.ESC, HDLC.FLAG^HDLC.ESC_MASK]))
        return data

class ThreadingTCPServer(socketserver.ThreadingMixIn, socketserver.TCPServer):
    pass

class LocalClientInterface(Interface):
    RECONNECT_WAIT = 3

    def __init__(self, owner, name, target_port = None, connected_socket=None):
        self.rxb = 0
        self.txb = 0

        # TODO: Remove at some point
        self.rxptime = 0
        
        self.HW_MTU = 1064

        self.online  = False
        
        self.IN               = True
        self.OUT              = False
        self.socket           = None
        self.parent_interface = None
        self.reconnecting     = False
        self.never_connected  = True
        self.detached         = False
        self.name             = name
        self.mode             = RNS.Interfaces.Interface.Interface.MODE_FULL

        if connected_socket != None:
            self.receives    = True
            self.target_ip   = None
            self.target_port = None
            self.socket      = connected_socket

            self.is_connected_to_shared_instance = False

        elif target_port != None:
            self.receives    = True
            self.target_ip   = "127.0.0.1"
            self.target_port = target_port
            self.connect()

        self.owner   = owner
        self.bitrate = 1000*1000*1000
        self.online  = True
        self.writing = False

        self.announce_rate_target  = None
        self.announce_rate_grace   = None
        self.announce_rate_penalty = None

        if connected_socket == None:
            thread = threading.Thread(target=self.read_loop)
            thread.setDaemon(True)
            thread.start()

    def connect(self):
        self.socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        self.socket.connect((self.target_ip, self.target_port))

        self.online = True
        self.is_connected_to_shared_instance = True
        self.never_connected = False

        return True


    def reconnect(self):
        if self.is_connected_to_shared_instance:
            if not self.reconnecting:
                self.reconnecting = True
                attempts = 0

                while not self.online:
                    time.sleep(LocalClientInterface.RECONNECT_WAIT)
                    attempts += 1

                    try:
                        self.connect()

                    except Exception as e:
                        RNS.log("Connection attempt for "+str(self)+" failed: "+str(e), RNS.LOG_DEBUG)

                if not self.never_connected:
                    RNS.log("Reconnected TCP socket for "+str(self)+".", RNS.LOG_INFO)

                self.reconnecting = False
                thread = threading.Thread(target=self.read_loop)
                thread.setDaemon(True)
                thread.start()
                RNS.Transport.shared_connection_reappeared()
        
        else:
            RNS.log("Attempt to reconnect on a non-initiator shared local interface. This should not happen.", RNS.LOG_ERROR)
            raise IOError("Attempt to reconnect on a non-initiator local interface")


    def processIncoming(self, data):
        self.rxb += len(data)
        if hasattr(self, "parent_interface") and self.parent_interface != None:
            self.parent_interface.rxb += len(data)
        
        # TODO: Remove at some point
        processing_start = time.time()
        
        self.owner.inbound(data, self)

        # TODO: Remove at some point
        duration = time.time() - processing_start
        self.rxptime += duration

    def processOutgoing(self, data):
        if self.online:
            try:
                self.writing = True
                data = bytes([HDLC.FLAG])+HDLC.escape(data)+bytes([HDLC.FLAG])
                self.socket.sendall(data)
                self.writing = False
                self.txb += len(data)
                if hasattr(self, "parent_interface") and self.parent_interface != None:
                    self.parent_interface.txb += len(data)

            except Exception as e:
                RNS.log("Exception occurred while transmitting via "+str(self)+", tearing down interface", RNS.LOG_ERROR)
                RNS.log("The contained exception was: "+str(e), RNS.LOG_ERROR)
                self.teardown()


    def read_loop(self):
        try:
            in_frame = False
            escape = False
            data_buffer = b""

            while True:
                data_in = self.socket.recv(4096)
                if len(data_in) > 0:
                    pointer = 0
                    while pointer < len(data_in):
                        byte = data_in[pointer]
                        pointer += 1
                        if (in_frame and byte == HDLC.FLAG):
                            in_frame = False
                            self.processIncoming(data_buffer)
                        elif (byte == HDLC.FLAG):
                            in_frame = True
                            data_buffer = b""
                        elif (in_frame and len(data_buffer) < self.HW_MTU):
                            if (byte == HDLC.ESC):
                                escape = True
                            else:
                                if (escape):
                                    if (byte == HDLC.FLAG ^ HDLC.ESC_MASK):
                                        byte = HDLC.FLAG
                                    if (byte == HDLC.ESC  ^ HDLC.ESC_MASK):
                                        byte = HDLC.ESC
                                    escape = False
                                data_buffer = data_buffer+bytes([byte])
                else:
                    self.online = False
                    if self.is_connected_to_shared_instance and not self.detached:
                        RNS.log("Socket for "+str(self)+" was closed, attempting to reconnect...", RNS.LOG_WARNING)
                        RNS.Transport.shared_connection_disappeared()
                        self.reconnect()
                    else:
                        self.teardown(nowarning=True)

                    break

                
        except Exception as e:
            self.online = False
            RNS.log("An interface error occurred, the contained exception was: "+str(e), RNS.LOG_ERROR)
            RNS.log("Tearing down "+str(self), RNS.LOG_ERROR)
            self.teardown()

    def detach(self):
        if self.socket != None:
            if hasattr(self.socket, "close"):
                if callable(self.socket.close):
                    RNS.log("Detaching "+str(self), RNS.LOG_DEBUG)
                    self.detached = True
                    
                    try:
                        self.socket.shutdown(socket.SHUT_RDWR)
                    except Exception as e:
                        RNS.log("Error while shutting down socket for "+str(self)+": "+str(e))

                    try:
                        self.socket.close()
                    except Exception as e:
                        RNS.log("Error while closing socket for "+str(self)+": "+str(e))

                    self.socket = None

    def teardown(self, nowarning=False):
        self.online = False
        self.OUT = False
        self.IN = False

        if self in RNS.Transport.interfaces:
            RNS.Transport.interfaces.remove(self)

        if self in RNS.Transport.local_client_interfaces:
            RNS.Transport.local_client_interfaces.remove(self)
            if hasattr(self, "parent_interface") and self.parent_interface != None:
                self.parent_interface.clients -= 1

        if nowarning == False:
            RNS.log("The interface "+str(self)+" experienced an unrecoverable error and is being torn down. Restart Reticulum to attempt to open this interface again.", RNS.LOG_ERROR)
            if RNS.Reticulum.panic_on_interface_error:
                RNS.panic()

        if self.is_connected_to_shared_instance:
            if nowarning == False:
                RNS.log("Permanently lost connection to local shared RNS instance. Exiting now.", RNS.LOG_CRITICAL)
    
            RNS.exit()


    def __str__(self):
        return "LocalInterface["+str(self.target_port)+"]"


class LocalServerInterface(Interface):

    def __init__(self, owner, bindport=None):
        self.rxb = 0
        self.txb = 0
        self.online = False
        self.clients = 0
        
        self.IN  = True
        self.OUT = False
        self.name = "Reticulum"
        self.mode = RNS.Interfaces.Interface.Interface.MODE_FULL

        if (bindport != None):
            self.receives = True
            self.bind_ip = "127.0.0.1"
            self.bind_port = bindport

            def handlerFactory(callback):
                def createHandler(*args, **keys):
                    return LocalInterfaceHandler(callback, *args, **keys)
                return createHandler

            self.owner = owner
            self.is_local_shared_instance = True

            address = (self.bind_ip, self.bind_port)

            ThreadingTCPServer.allow_reuse_address = True
            self.server = ThreadingTCPServer(address, handlerFactory(self.incoming_connection))

            thread = threading.Thread(target=self.server.serve_forever)
            thread.setDaemon(True)
            thread.start()

            self.announce_rate_target  = None
            self.announce_rate_grace   = None
            self.announce_rate_penalty = None

            self.bitrate = 1000*1000*1000
            self.online = True



    def incoming_connection(self, handler):
        interface_name = str(str(handler.client_address[1]))
        spawned_interface = LocalClientInterface(self.owner, name=interface_name, connected_socket=handler.request)
        spawned_interface.OUT = self.OUT
        spawned_interface.IN  = self.IN
        spawned_interface.target_ip = handler.client_address[0]
        spawned_interface.target_port = str(handler.client_address[1])
        spawned_interface.parent_interface = self
        spawned_interface.bitrate = self.bitrate
        RNS.log("Accepting new connection to shared instance: "+str(spawned_interface), RNS.LOG_EXTREME)
        RNS.Transport.interfaces.append(spawned_interface)
        RNS.Transport.local_client_interfaces.append(spawned_interface)
        self.clients += 1
        spawned_interface.read_loop()

    def processOutgoing(self, data):
        pass

    def __str__(self):
        return "Shared Instance["+str(self.bind_port)+"]"

class LocalInterfaceHandler(socketserver.BaseRequestHandler):
    def __init__(self, callback, *args, **keys):
        self.callback = callback
        socketserver.BaseRequestHandler.__init__(self, *args, **keys)

    def handle(self):
        self.callback(handler=self)