#!/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 logging
import signal
import json
import sys
import os
import time
import threading
import urllib2
import pprint
from random import randint

from AgentConfig import AgentConfig
from Heartbeat import Heartbeat
from Register import Register
from ActionQueue import ActionQueue
from NetUtil import NetUtil
from Registry import Registry
import ssl
import ProcessHelper
import Constants
import security


logger = logging.getLogger()

AGENT_AUTO_RESTART_EXIT_CODE = 77
HEART_BEAT_RETRY_THRESHOLD = 2

WS_AGENT_CONTEXT_ROOT = '/ws'
SLIDER_PATH_AGENTS = WS_AGENT_CONTEXT_ROOT + '/v1/slider/agents/'
SLIDER_REL_PATH_REGISTER = '/register'
SLIDER_REL_PATH_HEARTBEAT = '/heartbeat'

class State:
  INIT, INSTALLING, INSTALLED, STARTING, STARTED, FAILED = range(6)


class Controller(threading.Thread):
  def __init__(self, config, range=30):
    threading.Thread.__init__(self)
    logger.debug('Initializing Controller RPC thread.')
    self.lock = threading.Lock()
    self.safeMode = True
    self.credential = None
    self.config = config
    self.label = config.getLabel()
    self.hostname = config.get(AgentConfig.SERVER_SECTION, 'hostname')
    self.secured_port = config.get(AgentConfig.SERVER_SECTION, 'secured_port')
    self.server_url = 'https://' + self.hostname + ':' + self.secured_port
    self.registerUrl = self.server_url + SLIDER_PATH_AGENTS + self.label + SLIDER_REL_PATH_REGISTER
    self.heartbeatUrl = self.server_url + SLIDER_PATH_AGENTS + self.label + SLIDER_REL_PATH_HEARTBEAT
    self.netutil = NetUtil()
    self.responseId = -1
    self.repeatRegistration = False
    self.isRegistered = False
    self.cachedconnect = None
    self.range = range
    self.hasMappedComponents = True
    # Event is used for synchronizing heartbeat iterations (to make possible
    # manual wait() interruption between heartbeats )
    self.heartbeat_wait_event = threading.Event()
    # List of callbacks that are called at agent registration
    self.registration_listeners = []
    self.componentExpectedState = State.INIT
    self.componentActualState = State.INIT
    self.statusCommand = None
    self.failureCount = 0
    self.heartBeatRetryCount = 0
    self.autoRestart = False


  def __del__(self):
    logger.info("Server connection disconnected.")
    pass

  def processDebugCommandForRegister(self):
    self.processDebugCommand(Constants.DO_NOT_REGISTER)
    pass

  def processDebugCommandForHeartbeat(self):
    self.processDebugCommand(Constants.DO_NOT_HEARTBEAT)
    pass

  def processDebugCommand(self, command):
    if self.config.isDebugEnabled() and self.config.debugCommand() == command:
      ## Test support - sleep for 10 minutes
      logger.info("Received debug command: "
                  + self.config.debugCommand() + " Sleeping for 10 minutes")
      time.sleep(60*10)
      pass
    pass

  def registerWithServer(self):
    id = -1
    ret = {}

    self.processDebugCommandForRegister()

    while not self.isRegistered:
      try:
        data = json.dumps(self.register.build(
          self.componentActualState,
          self.componentExpectedState,
          self.actionQueue.customServiceOrchestrator.allocated_ports,
          id))
        logger.info("Registering with the server at " + self.registerUrl +
                    " with data " + pprint.pformat(data))
        response = self.sendRequest(self.registerUrl, data)
        ret = json.loads(response)
        exitstatus = 0
        # exitstatus is a code of error which was rised on server side.
        # exitstatus = 0 (OK - Default)
        # exitstatus = 1 (Registration failed because
        #                different version of agent and server)
        if 'exitstatus' in ret.keys():
          exitstatus = int(ret['exitstatus'])
          # log - message, which will be printed to agents  log
        if 'log' in ret.keys():
          log = ret['log']
        if exitstatus == 1:
          logger.error(log)
          self.isRegistered = False
          self.repeatRegistration = False
          return ret
        logger.info("Registered with the server with " + pprint.pformat(ret))
        print("Registered with the server")
        self.responseId = int(ret['responseId'])
        self.isRegistered = True
        if 'statusCommands' in ret.keys():
          logger.info("Got status commands on registration " + pprint.pformat(
            ret['statusCommands']))
          self.addToQueue(ret['statusCommands'])
          pass
        else:
          self.hasMappedComponents = False
        pass
      except ssl.SSLError:
        self.repeatRegistration = False
        self.isRegistered = False
        return
      except Exception, err:
        # try a reconnect only after a certain amount of random time
        delay = randint(0, self.range)
        logger.info("Unable to connect to: " + self.registerUrl, exc_info=True)
        """ Sleeping for {0} seconds and then retrying again """.format(delay)
        time.sleep(delay)
        pass
      pass
    return ret


  def addToQueue(self, commands):
    """Add to the queue for running the commands """
    """ Put the required actions into the Queue """
    if not commands:
      logger.debug("No commands from the server : " + pprint.pformat(commands))
    else:
      """Only add to the queue if not empty list """
      self.actionQueue.put(commands)
    pass

  # For testing purposes
  DEBUG_HEARTBEAT_RETRIES = 0
  DEBUG_SUCCESSFULL_HEARTBEATS = 0
  DEBUG_STOP_HEARTBEATING = False
  MAX_FAILURE_COUNT_TO_STOP = 2

  def shouldStopAgent(self):
    '''
    If component has failed after start then stop the agent
    '''
    if (self.componentActualState == State.FAILED) \
      and (self.componentExpectedState == State.STARTED) \
      and (self.failureCount >= Controller.MAX_FAILURE_COUNT_TO_STOP):
      return True
    else:
      return False
    pass

  def heartbeatWithServer(self):
    self.DEBUG_HEARTBEAT_RETRIES = 0
    self.DEBUG_SUCCESSFULL_HEARTBEATS = 0
    retry = False
    certVerifFailed = False

    self.processDebugCommandForHeartbeat()

    while not self.DEBUG_STOP_HEARTBEATING:

      if self.shouldStopAgent():
        logger.info("Component instance has stopped, stopping the agent ...")
        ProcessHelper.stopAgent()

      commandResult = {}
      try:
        if not retry:
          data = json.dumps(
            self.heartbeat.build(commandResult,
                                 self.responseId, self.hasMappedComponents))
          self.updateStateBasedOnResult(commandResult)
          logger.debug("Sending request: " + data)
          pass
        else:
          self.DEBUG_HEARTBEAT_RETRIES += 1
        response = self.sendRequest(self.heartbeatUrl, data)
        response = json.loads(response)

        logger.debug('Got server response: ' + pprint.pformat(response))

        serverId = int(response['responseId'])

        restartEnabled = False
        if 'restartEnabled' in response:
          restartEnabled = response['restartEnabled']
          if restartEnabled:
            logger.info("Component auto-restart is enabled.")

        if 'hasMappedComponents' in response.keys():
          self.hasMappedComponents = response['hasMappedComponents'] != False

        if 'registrationCommand' in response.keys():
          # check if the registration command is None. If none skip
          if response['registrationCommand'] is not None:
            logger.info(
              "RegistrationCommand received - repeat agent registration")
            self.isRegistered = False
            self.repeatRegistration = True
            return

        if serverId != self.responseId + 1:
          logger.error("Error in responseId sequence expected " + str(self.responseId + 1)
                       + " but got " + str(serverId) + " - restarting")
          self.restartAgent()
        else:
          self.responseId = serverId

        if 'executionCommands' in response.keys():
          self.updateStateBasedOnCommand(response['executionCommands'])
          self.addToQueue(response['executionCommands'])
          pass
        if 'statusCommands' in response.keys() and len(response['statusCommands']) > 0:
          self.addToQueue(response['statusCommands'])
          pass
        if "true" == response['restartAgent']:
          logger.error("Got restartAgent command")
          self.restartAgent()
        else:
          logger.info("No commands sent from the Server.")
          pass

        # Add a start command
        if self.componentActualState == State.FAILED and \
                self.componentExpectedState == State.STARTED and restartEnabled:
          stored_command = self.actionQueue.customServiceOrchestrator.stored_command
          if len(stored_command) > 0:
            auto_start_command = self.create_start_command(stored_command)
            if auto_start_command:
              logger.info("Automatically adding a start command.")
              logger.debug("Auto start command: " + pprint.pformat(auto_start_command))
              self.updateStateBasedOnCommand([auto_start_command], False)
              self.addToQueue([auto_start_command])
          pass

        # Add a status command
        if (self.componentActualState != State.STARTING and \
                self.componentExpectedState == State.STARTED) and \
            not self.statusCommand == None:
          self.addToQueue([self.statusCommand])

        if retry:
          print("Reconnected to the server")
          logger.info("Reconnected to the server")
        retry = False
        certVerifFailed = False
        self.DEBUG_SUCCESSFULL_HEARTBEATS += 1
        self.DEBUG_HEARTBEAT_RETRIES = 0
        self.heartbeat_wait_event.clear()
      except ssl.SSLError:
        self.repeatRegistration = False
        self.isRegistered = False
        return
      except Exception, err:
        #randomize the heartbeat
        delay = randint(0, self.range)
        time.sleep(delay)
        if "code" in err:
          logger.error(err.code)
        else:
          logger.error(
            "Unable to connect to: " + self.heartbeatUrl + " due to " + str(
              err))
          logger.debug("Details: " + str(err), exc_info=True)
          if not retry:
            print("Connection to the server was lost. Reconnecting...")
          if 'certificate verify failed' in str(err) and not certVerifFailed:
            print(
              "Server certificate verify failed. Did you regenerate server certificate?")
            certVerifFailed = True
        self.heartBeatRetryCount += 1
        logger.error(
          "Heartbeat retry count = %d" % (self.heartBeatRetryCount))
        # Re-read zk registry in case AM was restarted and came up with new 
        # host/port, but do this only after heartbeat retry attempts crosses
        # threshold
        if self.heartBeatRetryCount > HEART_BEAT_RETRY_THRESHOLD:
          self.isRegistered = False
          self.repeatRegistration = True
          self.heartBeatRetryCount = 0
          self.cachedconnect = None # Previous connection is broken now
          zk_quorum = self.config.get(AgentConfig.SERVER_SECTION, Constants.ZK_QUORUM)
          zk_reg_path = self.config.get(AgentConfig.SERVER_SECTION, Constants.ZK_REG_PATH)
          registry = Registry(zk_quorum, zk_reg_path)
          amHost, amSecuredPort = registry.readAMHostPort()
          logger.info("Read from ZK registry: AM host = %s, AM secured port = %s" % (amHost, amSecuredPort))
          self.hostname = amHost
          self.secured_port = amSecuredPort
          self.config.set(AgentConfig.SERVER_SECTION, "hostname", self.hostname)
          self.config.set(AgentConfig.SERVER_SECTION, "secured_port", self.secured_port)
          self.server_url = 'https://' + self.hostname + ':' + self.secured_port
          self.registerUrl = self.server_url + SLIDER_PATH_AGENTS + self.label + SLIDER_REL_PATH_REGISTER
          self.heartbeatUrl = self.server_url + SLIDER_PATH_AGENTS + self.label + SLIDER_REL_PATH_HEARTBEAT
          return
        self.cachedconnect = None # Previous connection is broken now
        retry = True
      # Sleep for some time
      timeout = self.netutil.HEARTBEAT_IDDLE_INTERVAL_SEC \
                - self.netutil.MINIMUM_INTERVAL_BETWEEN_HEARTBEATS
      self.heartbeat_wait_event.wait(timeout=timeout)
      # Sleep a bit more to allow STATUS_COMMAND results to be collected
      # and sent in one heartbeat. Also avoid server overload with heartbeats
      time.sleep(self.netutil.MINIMUM_INTERVAL_BETWEEN_HEARTBEATS)
    pass
    logger.info("Controller stopped heart-beating.")


  def create_start_command(self, stored_command):
    taskId = int(stored_command['taskId'])
    taskId = taskId + 1
    stored_command['taskId'] = taskId
    stored_command['commandId'] = "{0}-1".format(taskId)
    stored_command[Constants.AUTO_GENERATED] = True
    return stored_command
    pass


  def updateStateBasedOnCommand(self, commands, createStatus=True):
    for command in commands:
      if command["roleCommand"] == "START":
        self.componentExpectedState = State.STARTED
        self.componentActualState = State.STARTING
        self.failureCount = 0
        if createStatus:
          self.statusCommand = self.createStatusCommand(command)

      if command["roleCommand"] == "INSTALL":
        self.componentExpectedState = State.INSTALLED
        self.componentActualState = State.INSTALLING
        self.failureCount = 0
      break;


  def updateStateBasedOnResult(self, commandResult):
    if len(commandResult) > 0:
      if "commandStatus" in commandResult:
        if commandResult["commandStatus"] == ActionQueue.COMPLETED_STATUS:
          self.componentActualState = self.componentExpectedState
          self.logStates()
          pass
        pass

        if commandResult["commandStatus"] == ActionQueue.FAILED_STATUS:
          self.componentActualState = State.FAILED
          self.failureCount += 1
          self.logStates()
          pass

      if "healthStatus" in commandResult:
        if commandResult["healthStatus"] == "INSTALLED":
          # Mark it FAILED as its a failure remedied by auto-start or container restart
          self.componentActualState = State.FAILED
          self.failureCount += 1
          self.logStates()
        if (commandResult["healthStatus"] == "STARTED") and (self.componentActualState != State.STARTED):
          self.componentActualState = State.STARTED
          self.failureCount = 0
          self.logStates()
          pass
        pass
      pass

  def logStates(self):
    logger.info("Component states (result): Expected: " + str(self.componentExpectedState) + \
                " and Actual: " + str(self.componentActualState))
    pass

  def createStatusCommand(self, command):
    statusCommand = {}
    statusCommand["clusterName"] = command["clusterName"]
    statusCommand["commandParams"] = command["commandParams"]
    statusCommand["commandType"] = "STATUS_COMMAND"
    statusCommand["roleCommand"] = "STATUS"
    statusCommand["componentName"] = command["role"]
    statusCommand["configurations"] = {}
    statusCommand["configurations"]["global"] = command["configurations"]["global"]
    statusCommand["hostLevelParams"] = command["hostLevelParams"]
    statusCommand["serviceName"] = command["serviceName"]
    statusCommand["taskId"] = "status"
    statusCommand[Constants.AUTO_GENERATED] = True
    logger.info("Status command: " + pprint.pformat(statusCommand))
    return statusCommand
    pass


  def run(self):
    self.actionQueue = ActionQueue(self.config, controller=self)
    self.actionQueue.start()
    self.register = Register(self.config)
    self.heartbeat = Heartbeat(self.actionQueue, self.config)

    opener = urllib2.build_opener()
    urllib2.install_opener(opener)

    while True:
      self.repeatRegistration = False
      self.registerAndHeartbeat()
      if not self.repeatRegistration:
        break
    logger.info("Controller stopped.")
    pass

  def registerAndHeartbeat(self):
    registerResponse = self.registerWithServer()
    message = registerResponse['response']
    logger.info("Response from server = " + message)
    if self.isRegistered:
      # Process callbacks
      for callback in self.registration_listeners:
        callback()
      time.sleep(self.netutil.HEARTBEAT_IDDLE_INTERVAL_SEC)
      self.heartbeatWithServer()
    logger.info("Controller stopped heartbeating.")

  def restartAgent(self):
    os._exit(AGENT_AUTO_RESTART_EXIT_CODE)
    pass

  def sendRequest(self, url, data):
    response = None
    try:
        if self.cachedconnect is None: # Lazy initialization
            self.cachedconnect = security.CachedHTTPSConnection(self.config)
        req = urllib2.Request(url, data, {'Content-Type': 'application/json'})
        response = self.cachedconnect.request(req)
        return response
    except Exception:
        exc_type, exc_value, exc_traceback = sys.exc_info()
        logger.error("Exception raised", exc_info=(exc_type, exc_value, exc_traceback))
        if response is None:
            err_msg = 'Request failed! Data: ' + str(data)
            logger.warn(err_msg)
            return {'exitstatus': 1, 'log': err_msg}
        else:
            err_msg = ('Response parsing failed! Request data: ' + str(data)
                       + '; Response: ' + str(response))
            logger.warn(err_msg)
            return {'exitstatus': 1, 'log': err_msg}


def main(argv=None):
  # Allow Ctrl-C
  signal.signal(signal.SIGINT, signal.SIG_DFL)

  logger.setLevel(logging.INFO)
  formatter = logging.Formatter("%(asctime)s %(filename)s:%(lineno)d - \
    %(message)s")
  stream_handler = logging.StreamHandler()
  stream_handler.setFormatter(formatter)
  logger.addHandler(stream_handler)

  logger.info('Starting Server RPC Thread: %s' % ' '.join(sys.argv))

  config = AgentConfig()
  collector = Controller(config)
  collector.start()
  collector.run()


if __name__ == '__main__':
  main()