from __future__ import (absolute_import, print_function, division)

import traceback
import sys
import socket
import six

from netlib import tcp
from netlib.http.http1 import HTTP1Protocol
from netlib.tcp import NetLibError
from ..exceptions import ProtocolException, ServerException, ClientHandshakeException
from ..protocol import Kill
from ..models import ClientConnection, make_error_response
from .modes import HttpUpstreamProxy, HttpProxy, ReverseProxy, TransparentProxy, Socks5Proxy
from .root_context import RootContext, Log


class DummyServer:
    bound = False

    def __init__(self, config):
        self.config = config

    def start_slave(self, *args):
        pass

    def shutdown(self):
        pass


class ProxyServer(tcp.TCPServer):
    allow_reuse_address = True
    bound = True

    def __init__(self, config):
        """
            Raises ProxyServerError if there's a startup problem.
        """
        self.config = config
        try:
            super(ProxyServer, self).__init__((config.host, config.port))
        except socket.error as e:
            six.reraise(
                ServerException,
                ServerException('Error starting proxy server: ' + repr(e)),
                sys.exc_info()[2]
            )
        self.channel = None

    def start_slave(self, klass, channel):
        slave = klass(channel, self)
        slave.start()

    def set_channel(self, channel):
        self.channel = channel

    def handle_client_connection(self, conn, client_address):
        h = ConnectionHandler(
            conn,
            client_address,
            self.config,
            self.channel
        )
        h.handle()


class ConnectionHandler(object):
    def __init__(self, client_conn, client_address, config, channel):
        self.config = config
        """@type: libmproxy.proxy.config.ProxyConfig"""
        self.client_conn = ClientConnection(
            client_conn,
            client_address,
            None)
        """@type: libmproxy.proxy.connection.ClientConnection"""
        self.channel = channel
        """@type: libmproxy.controller.Channel"""

    def _create_root_layer(self):
        root_context = RootContext(
            self.client_conn,
            self.config,
            self.channel
        )

        mode = self.config.mode
        if mode == "upstream":
            return HttpUpstreamProxy(
                root_context,
                self.config.upstream_server.address
            )
        elif mode == "transparent":
            return TransparentProxy(root_context)
        elif mode == "reverse":
            server_tls = self.config.upstream_server.scheme == "https"
            return ReverseProxy(
                root_context,
                self.config.upstream_server.address,
                server_tls
            )
        elif mode == "socks5":
            return Socks5Proxy(root_context)
        elif mode == "regular":
            return HttpProxy(root_context)
        elif callable(mode):  # pragma: nocover
            return mode(root_context)
        else:  # pragma: nocover
            raise ValueError("Unknown proxy mode: %s" % mode)

    def handle(self):
        self.log("clientconnect", "info")

        root_layer = self._create_root_layer()
        root_layer = self.channel.ask("clientconnect", root_layer)
        if root_layer == Kill:
            def root_layer():
                raise Kill()

        try:
            root_layer()
        except Kill:
            self.log("Connection killed", "info")
        except ProtocolException as e:

            if isinstance(e, ClientHandshakeException):
                self.log(
                    "Client Handshake failed. "
                    "The client may not trust the proxy's certificate for {}.".format(e.server),
                    "error"
                )
                self.log(repr(e), "debug")
            else:
                self.log(repr(e), "error")

                self.log(traceback.format_exc(), "debug")
            # If an error propagates to the topmost level,
            # we send an HTTP error response, which is both
            # understandable by HTTP clients and humans.
            try:
                error_response = make_error_response(502, repr(e))
                self.client_conn.send(HTTP1Protocol().assemble(error_response))
            except NetLibError:
                pass
        except Exception:
            self.log(traceback.format_exc(), "error")
            print(traceback.format_exc(), file=sys.stderr)
            print("mitmproxy has crashed!", file=sys.stderr)
            print("Please lodge a bug report at: https://github.com/mitmproxy/mitmproxy", file=sys.stderr)

        self.log("clientdisconnect", "info")
        self.channel.tell("clientdisconnect", root_layer)
        self.client_conn.finish()

    def log(self, msg, level):
        msg = "{}: {}".format(repr(self.client_conn.address), msg)
        self.channel.tell("log", Log(msg, level))