#!/usr/bin/env python3
# -*- encoding: utf-8 -*-

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#  or more contributor license agreements.  See the NOTICE file
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#  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
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""" memoryhistogramhandler.py """
import json
import traceback
import tornado.gen
import tornado.web

from heron.common.src.python.utils.log import Log
from heron.tools.tracker.src.python import utils
from heron.tools.tracker.src.python.handlers import BaseHandler
from heron.tools.tracker.src.python.handlers.pidhandler import getInstancePid


class MemoryHistogramHandler(BaseHandler):
  """
  URL - /topologies/histo?cluster=<cluster>&topology=<topology> \
        &environ=<environment>&instance=<instance>
  Parameters:
   - cluster - Name of the cluster.
   - role - (optional) Role used to submit the topology.
   - environ - Running environment.
   - topology - Name of topology (Note: Case sensitive. Can only
                include [a-zA-Z0-9-_]+)
   - instance - Instance Id

  Resturns a histogram of top in memory object.
  The response JSON is a dict with following format:
  {
     'command': Full command executed at server.
     'stdout': Text on stdout of executing the command.
     'stderr': <optional> Text on stderr.
  }
  """

  # pylint: disable=attribute-defined-outside-init
  def initialize(self, tracker):
    """ initialize """
    self.tracker = tracker

  @tornado.gen.coroutine
  def get(self):
    """ get method """
    try:
      cluster = self.get_argument_cluster()
      role = self.get_argument_role()
      environ = self.get_argument_environ()
      topology_name = self.get_argument_topology()
      instance = self.get_argument_instance()
      topology_info = self.tracker.get_topology_info(topology_name, cluster, role, environ)
      ret = yield self.getInstanceMemoryHistogram(topology_info, instance)
      self.write_success_response(ret)
    except Exception as e:
      Log.debug(traceback.format_exc())
      self.write_error_response(e)

  # pylint: disable=no-self-use
  @tornado.gen.coroutine
  def getInstanceMemoryHistogram(self, topology_info, instance_id):
    """
    Fetches Instance top memory item as histogram.
    """
    pid_response = yield getInstancePid(topology_info, instance_id)
    try:
      http_client = tornado.httpclient.AsyncHTTPClient()
      pid_json = json.loads(pid_response)
      pid = pid_json['stdout'].strip()
      if pid == '':
        raise Exception('Failed to get pid')
      endpoint = utils.make_shell_endpoint(topology_info, instance_id)
      url = "%s/histo/%s" % (endpoint, pid)
      response = yield http_client.fetch(url)
      Log.debug("HTTP call for url: %s", url)
      raise tornado.gen.Return(response.body)
    except tornado.httpclient.HTTPError as e:
      raise Exception(str(e))