#!/usr/bin/env python
#
# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements.  See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership.  The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License.  You may obtain a copy of the License at
#
#   http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied.  See the License for the
# specific language governing permissions and limitations
# under the License.
#

import sys
from optparse import OptionParser

from cproton import *


FAILED = 0
CONNECTION_UP = 1
AUTHENTICATING = 2

counter = 0
mailboxes = {}


class Options(object):
    def __init__(self):
        parser = OptionParser(usage="usage: %prog [options] <server-address>")
        parser.add_option("-v", "--verbose",
                          action="store_true", dest="verbose",
                          help="print status messages to stdout")
        # SSL configuration
        parser.add_option("--ssl-cert-file", type="str", metavar="<file>",
                          help="PEM file containing identifying certificate.")
        parser.add_option("--ssl-key-file", type="str", metavar="<file>",
                          help="PEM file containing private key of certificate.")
        parser.add_option("--ssl-key-pw", type="str", metavar='"password"',
                          help="key file password (if key encrypted).")
        parser.add_option("--require-encryption", action="store_true",
                          help="Do not accept connections from clients that do not use encryption.")
        parser.add_option("--ssl-cert-db", type="str", metavar="<dir>",
                          help="database of trusted certificates. Used to authenticate clients.")

        # For client authentication using SSL:
        #parser.add_option("-c", "--ssl-require-client-authentication", action="store_true", help="force client to authenticate itself.")
        #parser.add_option("-t", "--ssl-trusted-CA-file", type="str", metavar="<file>", help="file holding certificates of CAs to advertise")

        opts, self.server = parser.parse_args()   # uses sys.argv[1:]
        self.verbose = opts.verbose

        if opts.ssl_cert_file:
            if not opts.ssl_key_file:
                print("Error: if --ssl-cert-file given, --ssl-key-file must be supplied!");
                sys.exit(-1)
        self.certificate_file = opts.ssl_cert_file
        self.certificate_key_file = opts.ssl_key_file
        self.key_file_password = opts.ssl_key_pw
        self.require_encryption = opts.require_encryption
        self.ca_database = opts.ssl_cert_db

        if self.server:
            addr = self.server[0].rsplit(":", 1)
            self.host = addr[0]
            if len(addr) == 2:
                self.port = addr[1]
            else:
                self.port = "5672"
        else:
            self.host = "0.0.0.0"
            self.port = "5672"


class MailboxServer(object):
    def __init__(self, host, port, require_encryption=False, certificate_file=None,
                 certificate_key_file=None, key_file_password=None,
                 ca_database=None):
        """ Initialize the server to wait on the given address for inbound
        connection requests.
        """
        self.host = host
        self.port = port
        self.certificate_file = certificate_file
        self.certificate_key_file = certificate_key_file
        self.key_file_password = key_file_password
        self.ca_database = ca_database
        self.require_encryption = require_encryption

        self.mailboxes = {}
        self.logging = False
        self.counter = 0


    def setup(self):
        """ Setup and configure the server
        """
        self.log("Server started, listening on %s:%s" % (self.host, self.port))
        self.driver = pn_driver();
        self.listener = pn_listener(self.driver, self.host, self.port, None)
        if self.listener is None:
            print("Error: could not listen on %s:%s" % (self.host, self.port))
            return False
        # if self.certificate_file:
        #     self.log("Setting SSL certificate %s" % self.certificate_file)
        #     if not self.require_encryption:
        #         self.log("Allowing both encrypted AND unencrypted connections!")
        if self.certificate_file:
            if not self.require_encryption:
                self.log("Allowing both encrypted AND unencrypted connections!")
        return True


    def wait(self):
        """ Wait for a network event from the driver
        """
        self.log("Driver sleep...")
        pn_driver_wait(self.driver, -1)
        self.log("...Driver wakeup.")


    def acceptConnectionRequests(self):
        """ Accept connection request coming from remote clients.  Create a
        connector to track each accepted network connection.
        """
        l = pn_driver_listener(self.driver)
        while l:
            self.log("Accepting Connection.")
            cxtr = pn_listener_accept(l)
            pn_connector_set_context(cxtr, AUTHENTICATING)

            # configure SSL
            if self.certificate_file:
                ssl_server = pn_connector_ssl(cxtr)
                assert(ssl_server)
                rc = pn_ssl_set_credentials(ssl_server,
                                            self.certificate_file,
                                            self.certificate_key_file,
                                            self.key_file_password)
                assert(rc == 0)
                if not self.require_encryption:
                    rc = pn_ssl_allow_unsecured_client(ssl_server)
                    assert(rc == 0)

                # TODO: client authentication incomplete, for now skip peer verification
                rc = pn_ssl_set_peer_authentication(ssl_server,
                                                    PN_SSL_NO_VERIFY_PEER,
                                                    None)
                assert(rc == 0)

            l = pn_driver_listener(self.driver)


    def processConnections(self):
        """ Check each connector for pending work.
        """
        cxtr = pn_driver_connector(self.driver)
        while cxtr:
            self.log("Process Connector")

            # process any data coming from the network, this will update the
            # engine's view of the state of the remote clients
            pn_connector_process(cxtr)

            state = pn_connector_context(cxtr)
            if state == AUTHENTICATING:
                # connection has not passed SASL authentication yet
                self.authenticateConnector(cxtr)
            elif state == CONNECTION_UP:
                # active connection, service any engine events
                self.serviceConnector(cxtr)
            else:
                print("Error: Unknown Connection state=%s" % state)

            # now generate any outbound network data generated in reponse to
            # any work done by the engine.
            pn_connector_process(cxtr)

            if pn_connector_closed(cxtr):
                self.log("Closing connector")
                pn_connector_free(cxtr)

            cxtr = pn_driver_connector(self.driver)


    def enableLogging(self):
        self.logging = True


    def log(self, msg):
        if self.logging:
            print("%s" % msg)


    def authenticateConnector(self, cxtr):
        """ Authenticate the remote client.  Run the SASL algorithm until it
        passes, fails, or needs more data from the remote.
        """
        self.log("Authenticating...")
        sasl = pn_connector_sasl(cxtr)
        state = pn_sasl_state(sasl)
        while state == PN_SASL_CONF or state == PN_SASL_STEP:
            if state == PN_SASL_CONF:
                self.log("Authenticating-CONF...")
                pn_sasl_mechanisms(sasl, "ANONYMOUS")
                pn_sasl_server(sasl)
            elif state == PN_SASL_STEP:
                self.log("Authenticating-STEP...")
                mech = pn_sasl_remote_mechanisms(sasl)
                if mech == "ANONYMOUS":
                    pn_sasl_done(sasl, PN_SASL_OK)
                else:
                    pn_sasl_done(sasl, PN_SASL_AUTH)
            state = pn_sasl_state(sasl)

        if state == PN_SASL_PASS:
            pn_connector_set_connection(cxtr, pn_connection());
            pn_connector_set_context(cxtr, CONNECTION_UP)
            self.log("Authentication-PASSED")
        elif state == PN_SASL_FAIL:
            pn_connector_set_context(cxtr, FAILED)
            self.log("Authentication-FAILED")
        else:
            self.log("Authentication-PENDING")


    def setupLink(self, link):
        """ Configure a link coming from a client.
        """
        r_tgt = pn_remote_target(link)
        r_src = pn_remote_source(link)

        if pn_is_sender(link):
            self.log("Opening Link to read from mailbox: %s" % r_src)
            if r_src not in self.mailboxes:
                print("Error: mailbox %s does not exist!" % r_src)
                r_src = None  # indicate to remote the mailbox does not exist
        else:
            self.log("Opening Link to write to mailbox: %s" % r_tgt)
            if r_tgt not in self.mailboxes:
                self.mailboxes[r_tgt] = []     # create a new mailbox

        pn_set_target(link, r_tgt)
        pn_set_source(link, r_src)

        if pn_is_sender(link):
            # grant a delivery to the link - it will become "writable" when the
            # driver can accept messages for the sender.
            pn_delivery(link, "server-delivery-%d" % self.counter)
            self.counter += 1
        else:
            # Grant enough credit to the receiver to allow one inbound message
            pn_flow(link, 1)

        pn_link_open(link)


    def serviceConnector(self, cxtr):
        """ Process any pending I/O events on the given connector once it has been
        authenticated.
        """
        self.log("I/O processing start.")

        # get the engine's connection from the driver
        conn = pn_connector_connection(cxtr)

        ## Step 1: setup the engine's connection, and any sessions and links
        ## that may be pending.

        # initialize the connection if it's new
        if pn_connection_state(conn) & PN_LOCAL_UNINIT:
            self.log("Connection Opened.")
            pn_connection_open(conn)

        # open all pending sessions
        ssn = pn_session_head(conn, PN_LOCAL_UNINIT)
        while ssn:
            pn_session_open(ssn)
            self.log("Session Opened.")
            ssn = pn_session_next(ssn, PN_LOCAL_UNINIT)

        # configure and open any pending links
        link = pn_link_head(conn, PN_LOCAL_UNINIT);
        while link:
            self.setupLink(link)
            link = pn_link_next(link, PN_LOCAL_UNINIT);

        ## Step 2: Now drain all the pending deliveries from the connection's
        ## work queue and process them

        delivery = pn_work_head(conn)
        while delivery:
            self.log("Process delivery %s." % pn_delivery_tag(delivery))

            if pn_readable(delivery):   # inbound data available
                self.processReceive(delivery)
            elif pn_writable(delivery): # can send a message
                self.sendMessage(delivery)

            if pn_updated(delivery):
                # check to see if the remote has accepted message we sent
                self.log("remote disposition for %s: %s " % (str(pn_delivery_tag(delivery)),
                                                             str(pn_remote_disposition(delivery))))
                if pn_remote_disposition(delivery):
                    # once we know the remote has seen the message, we can
                    # release the delivery.
                    pn_settle(delivery)

            delivery = pn_work_next(delivery)

        ## Step 3: Clean up any links or sessions that have been closed by the
        ## remote.  If the connection has been closed remotely, clean that up
        ## also.

        # teardown any terminating links
        link = pn_link_head(conn, PN_LOCAL_ACTIVE | PN_REMOTE_CLOSED)
        while link:
            pn_link_close(link)
            self.log("Link Closed")
            link = pn_link_next(link, PN_LOCAL_ACTIVE | PN_REMOTE_CLOSED)

        # teardown any terminating sessions
        ssn = pn_session_head(conn, PN_LOCAL_ACTIVE | PN_REMOTE_CLOSED)
        while ssn:
            pn_session_close(ssn)
            self.log("Session Closed")
            ssn = pn_session_next(ssn, PN_LOCAL_ACTIVE | PN_REMOTE_CLOSED)

        # teardown the connection if it's terminating
        if pn_connection_state(conn) == (PN_LOCAL_ACTIVE | PN_REMOTE_CLOSED):
            self.log("Connection Closed")
            pn_connection_close(conn)


    def processReceive(self, delivery):
        """ A delivery has indicated that message data is available.  Read the
        message data, process it, then accept the message.
        """
        link = pn_link(delivery)
        mbox = pn_remote_target(link)
        rc, msg = pn_recv(link, 1024);
        self.log("Msg Received %d" % rc);
        while rc >= 0:
            if mbox not in self.mailboxes:
                print("Error: cannot sent to mailbox %s - dropping message." % mbox)
            else:
                self.mailboxes[mbox].append(msg)
                self.log("Mailbox %s contains: %s" % (mbox, str(self.mailboxes[mbox])))
            rc, msg = pn_recv(link, 1024);

        # now that we hit the end of the message, update the
        # disposition to let the remote know we accepted it.
        self.log("Msg Accepted.");
        pn_disposition(delivery, PN_ACCEPTED)

        # since we no longer have any more work to do on this delivery, finish
        # it and move to the next.
        pn_settle(delivery)
        pn_advance(link)

        # if more credit is needed, grant it
        if pn_credit(link) == 0:
            pn_flow(link, 1)


    def sendMessage(self, delivery):
        """ A delivery has indicated that the link is able to accept a
        message.  Send a message over the link, but do not settle it until the
        remote accepts it (and updates the delivery's disposition).
        """
        link = pn_link(delivery)
        mbox = pn_remote_source(link)
        self.log("Request for Mailbox=%s" % str(mbox))
        if mbox in self.mailboxes and self.mailboxes[mbox]:
            msg = self.mailboxes[mbox].pop(0)
            self.log("Fetching message %s" % str(msg))
        else:
            print("Warning: mailbox %s is empty, sending empty message." % mbox)
            msg = ""
        sent = pn_send(link, msg)
        assert(sent == len(msg))
        self.log("Msg Sent %d" % sent);

        # if the link can accept more ???RAFI, is that correct????, grant
        # another delivery
        if pn_advance(link):
            pn_delivery(link, "server-delivery-%d" % self.counter)
            self.counter += 1

        # do not settle the delivery now - wait until the remote sets the disposition.


##################################################
##################################################
##################################################


def main():
    options = Options()

    server = MailboxServer(options.host, options.port,
                           options.require_encryption,
                           options.certificate_file,
                           options.certificate_key_file,
                           options.key_file_password,
                           options.ca_database)
    if (options.verbose):
        server.enableLogging()

    if not server.setup():
        return -1;

    while True:
        # wait for a driver event
        server.wait()

        # accept all pending connection requests
        server.acceptConnectionRequests()

        # process all connectors with pending events
        server.processConnections()


if __name__ == "__main__":
        sys.exit(main())