#!/usr/bin/env python

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# Licensed to the Apache Software Foundation (ASF) under one
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# 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
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import os
import optparse
import sys
from optparse       import IndentedHelpFormatter
from time           import time, strftime, gmtime, sleep
from threading      import Lock, Condition, Thread
from qpid.messaging import Connection
import qpid.messaging.exceptions

home = os.environ.get("QPID_TOOLS_HOME", os.path.normpath("/usr/share/qpid-tools"))
sys.path.append(os.path.join(home, "python"))

from qpidtoollibs.broker import EventHelper


class Printer(object):
  """
  This class serializes printed lines so that events coming from different
  threads don't overlap each other.
  """
  def __init__(self):
    self.lock = Lock()

  def pr(self, text):
    self.lock.acquire()
    try:
      print text
    finally:
      self.lock.release()
    sys.stdout.flush()
  

class EventReceiver(Thread):
  """
  One instance of this class is created for each broker that is being monitored.
  This class does not use the "reconnect" option because it needs to report as
  events when the connection is established and when it's lost.
  """
  def __init__(self, printer, url, options):
    Thread.__init__(self)
    self.printer   = printer
    self.url       = url
    self.options   = options
    self.running   = True
    self.helper    = EventHelper()

  def cancel(self):
    self.running = False

  def run(self):
    isOpen = False
    while self.running:
      try:
        conn = Connection.establish(self.url, **self.options)
        isOpen = True
        self.printer.pr(strftime("%c", gmtime(time())) + " NOTIC qpid-printevents:brokerConnected broker=%s" % self.url)

        sess = conn.session()
        rx = sess.receiver(self.helper.eventAddress())

        while self.running:
          try:
            msg = rx.fetch(1)
            event = self.helper.event(msg)
            self.printer.pr(event.__repr__())
            sess.acknowledge()
          except qpid.messaging.exceptions.Empty:
            pass
        
      except Exception, e:
        if isOpen:
          self.printer.pr(strftime("%c", gmtime(time())) + " NOTIC qpid-printevents:brokerDisconnected broker=%s" % self.url)
        isOpen = False
        sleep(1)


class JHelpFormatter(IndentedHelpFormatter):
    """
    Format usage and description without stripping newlines from usage strings
    """
    def format_usage(self, usage):
        return usage

    def format_description(self, description):
        if description:
            return description + "\n"
        else:
            return ""

_usage = "%prog [options] [broker-addr]..."

_description = \
"""
Collect and print events from one or more Qpid message brokers.

If no broker-addr is supplied, %prog connects to 'localhost:5672'.

[broker-addr] syntax:

          [username/password@] hostname
          ip-address [:<port>]

Examples:

$ %prog localhost:5672
$ %prog 10.1.1.7:10000
$ %prog guest/guest@broker-host:10000
"""

def main(argv=None):
  p = optparse.OptionParser(usage=_usage, description=_description, formatter=JHelpFormatter())
  p.add_option("--heartbeats", action="store_true", default=False, help="Use heartbeats.")
  p.add_option("--sasl-mechanism", action="store", type="string", metavar="<mech>", help="SASL mechanism for authentication (e.g. EXTERNAL, ANONYMOUS, PLAIN, CRAM-MD, DIGEST-MD5, GSSAPI). SASL automatically picks the most secure available mechanism - use this option to override.")
  p.add_option("--ssl-certificate", action="store", type="string", metavar="<cert>", help="Client SSL certificate (PEM Format)")
  p.add_option("--ssl-key", action="store", type="string", metavar="<key>", help="Client SSL private key (PEM Format)")
  p.add_option("--ha-admin", action="store_true", help="Allow connection to a HA backup broker.")

  options, arguments = p.parse_args(args=argv)
  if len(arguments) == 0:
    arguments.append("localhost")

  brokers   = []
  conn_options = {}
  props = {}
  printer   = Printer()

  if options.sasl_mechanism:
    conn_options['sasl_mechanisms'] = options.sasl_mechanism
  if options.ssl_certificate:
    conn_options['ssl_certfile'] = options.ssl_certificate
  if options.ssl_key:
    if not options.ssl_certificate:
      p.error("missing '--ssl-certificate' (required by '--ssl-key')")
    conn_options['ssl_keyfile'] = options.ssl_key
  if options.ha_admin:
    props['qpid.ha-admin'] = 1
  if options.heartbeats:
    props['heartbeat'] = 5

  if len(props) > 0:
    conn_options['client_properties'] = props

  try:
    try:
      for host in arguments:
        er = EventReceiver(printer, host, conn_options)
        brokers.append(er)
        er.start()

      while (True):
        sleep(10)

    except KeyboardInterrupt:
        print
        return 0

    except Exception, e:
        print "Failed: %s - %s" % (e.__class__.__name__, e)
        return 1
  finally:
    for b in brokers:
      b.cancel()
    for b in brokers:
      b.join()

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