# Copyright (c) 2014 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

# This file defines helper functions for putting entries into elasticsearch.

"""Utils for sending metadata to elasticsearch

Elasticsearch is a key-value store NOSQL database.
Source is here: https://github.com/elasticsearch/elasticsearch
We will be using es to store our metadata.

For example, if we wanted to store the following metadata:

metadata = {
    'host_id': 1
    'job_id': 20
    'time_start': 100000
    'time_recorded': 100006
}

The following call will send metadata to the default es server.
    es_utils.ESMetadata().post(index, metadata)
We can also specify which port and host to use.

Using for testing: Sometimes, when we choose a single index
to put entries into, we want to clear that index of all
entries before running our tests. Use clear_index function.
(see es_utils_functionaltest.py for an example)

This file also contains methods for sending queries to es. Currently,
the query (json dict) we send to es is quite complicated (but flexible).
We've included several methods that composes queries that would be useful.
These methods are all named create_*_query()

For example, the below query returns job_id, host_id, and job_start
for all job_ids in [0, 99999] and host_id matching 10.

range_eq_query = {
    'fields': ['job_id', 'host_id', 'job_start'],
    'query': {
        'filtered': {
            'query': {
                'match': {
                    'host_id': 10,
                }
            }
            'filter': {
                'range': {
                    'job_id': {
                        'gte': 0,
                        'lte': 99999,
                    }
                }
            }
        }
    }
}

To send a query once it is created, call execute_query() to send it to the
intended elasticsearch server.

"""

import datetime
import json
import logging
import socket
import time

import common

try:
    import elasticsearch
except ImportError:
    logging.debug('import elasticsearch failed,'
                  'no metadata will be reported.')
    import elasticsearch_mock as elasticsearch

from autotest_lib.client.common_lib import global_config


# Server and ports for elasticsearch (for metadata use only)
METADATA_ES_SERVER = global_config.global_config.get_config_value(
        'CROS', 'ES_HOST', default='localhost')
ES_PORT = global_config.global_config.get_config_value(
        'CROS', 'ES_PORT', type=int, default=9200)
ES_UDP_PORT = global_config.global_config.get_config_value(
        'CROS', 'ES_UDP_PORT', type=int, default=9700)
ES_DEFAULT_INDEX = global_config.global_config.get_config_value(
        'CROS', 'ES_DEFAULT_INDEX', default='default')
ES_USE_HTTP = global_config.global_config.get_config_value(
        'CROS', 'ES_USE_HTTP', type=bool, default=False)

# 3 Seconds before connection to esdb timeout.
DEFAULT_TIMEOUT = 3

# Index is determined solely by autotest instance.
INDEX_METADATA = global_config.global_config.get_config_value(
        'SERVER', 'hostname', type=str, default='localhost')


class EsUtilException(Exception):
    """Exception raised when functions here fail. """
    pass

def create_udp_message_from_metadata(index, type_str, metadata):
    """Outputs a json encoded string to send via udp to es server.

    @param index: index in elasticsearch to insert data to
    @param type_str: sets the _type field in elasticsearch db.
    @param metadata: dictionary object containing metadata
    @returns: string representing udp message.

    Format of the string follows bulk udp api for es.
    """
    metadata_message = json.dumps(metadata, separators=(', ', ' : '))
    message_header = json.dumps(
            {'index': {'_index': index, '_type': type_str}},
            separators=(', ', ' : '))
    # Add new line, then the metadata message, then another new line.
    return '%s\n%s\n' % (message_header, metadata_message)


class ESMetadata(object):
    """Class handling es connection for posting metadata. """

    def __init__(self, host=METADATA_ES_SERVER, port=ES_PORT,
                 timeout=DEFAULT_TIMEOUT):
        """Initialize ESMetadata object.

        @param host: elasticsearch host
        @param port: elasticsearch port
        @param timeout: how long to wait while connecting to es.
        """
        self.host = host
        self.port = port
        self.timeout = timeout


    def _send_data(self, type_str, index, metadata, use_http):
        """Sends data to insert into elasticsearch.

        @param type_str: sets the _type field in elasticsearch db.
        @param index: index in elasticsearch to insert data to.
        @param metadata: dictionary object containing metadata
        @param use_http: whether to use http. udp is very little overhead
          (around 3 ms) compared to using http (tcp) takes ~ 500 ms
          for the first connection and 50-100ms for subsequent connections.
        """
        if not use_http:
            try:
                message = create_udp_message_from_metadata(index, type_str,
                                                           metadata)
                sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
                result = sock.sendto(message, (self.host, ES_UDP_PORT))
            except socket.error as e:
                logging.warn(e)
        else:
            self.es = elasticsearch.Elasticsearch(host=self.host,
                                                  port=self.port,
                                                  timeout=self.timeout)
            self.es.index(index=index, doc_type=type_str, body=metadata)


    def post(self, type_str, metadata=None, index=INDEX_METADATA,
             use_http=ES_USE_HTTP, **kwargs):
        """Wraps call of send_data, inserts entry into elasticsearch.

        @param type_str: sets the _type field in elasticsearch db.
        @param index: index in elasticsearch to insert data to.
        @param metadata: dictionary object containing metadata
        @param use_http: will use udp to send data when this is False.
        @param kwargs: additional metadata fields
        """
        if not metadata:
            return
        # Create a copy to avoid issues from mutable types.
        metadata_copy = metadata.copy()
        # kwargs could be extra metadata, append to metadata.
        metadata_copy.update(kwargs)
        # metadata should not contain anything with key '_type'
        if '_type' in metadata_copy:
            type_str = metadata_copy['_type']
            del metadata_copy['_type']
        try:
            self._send_data(type_str, index, metadata_copy, use_http)
        except elasticsearch.ElasticsearchException as e:
            logging.error(e)


def create_range_eq_query_multiple(fields_returned,
                                   equality_constraints,
                                   range_constraints,
                                   size,
                                   sort_specs):
    """Creates a dict. representing multple range and/or equality queries.

    Example input:
        create_range_eq_query_multiple(
                fields_returned = ['time_recorded', 'hostname',
                                   'status', 'dbg_str'],
                equality_constraints = [
                    ('_type', 'host_history'),
                    ('hostname', '172.22.169.106'),
                ],
                range_constraints = [
                    ('time_recorded', 1405628341.904379, 1405700341.904379)
                ],
                size=20,
                sort_specs=[
                    'hostname',
                    {'time_recorded': 'asc'},
                ]
        )

    Output:
    {
        'fields': ['time_recorded', 'hostname', 'status', 'dbg_str'],
        'query': {
            'bool': {
                'minimum_should_match': 3,
                'should': [
                    {
                        'term':  {
                            '_type': 'host_history'
                        }
                    },

                    {
                        'term': {
                            'hostname': '172.22.169.106'
                        }
                    },

                    {
                        'range': {
                            'time_recorded': {
                                'gte': 1405628341.904379,
                                'lte': 1405700341.904379
                            }
                        }
                    }
                ]
            },
        },
        'size': 20
        'sort': [
            'hostname',
            { 'time_recorded': 'asc'},
        ]
    }

    @param fields_returned: list of fields that we should return when
                            the query is executed
    @param equality_constraints: list of tuples of (field, value) pairs
        representing what each field should equal to in the query.
        e.g. [ ('field1', 1), ('field2', 'value') ]
    @param range_constraints: list of tuples of (field, low, high) pairs
        representing what each field should be between (inclusive).
        e.g. [ ('field1', 2, 10), ('field2', -1, 20) ]
        If you want one side to be unbounded, you can use None.
        e.g. [ ('field1', 2, None) ] means value of field1 >= 2.
    @param size: max number of entries to return.
    @param sort_specs: A list of fields to sort on, tiebreakers will be
        broken by the next field(s).
    @param returns: dictionary object that represents query to es.
                    This will return None if there are no equality constraints
                    and no range constraints.
    """
    if not equality_constraints and not range_constraints:
        raise EsUtilException('No range or equality constraints specified...')

    # Creates list of range dictionaries to put in the 'should' list.
    range_list = []
    if range_constraints:
        for key, low, high in range_constraints:
            if low == None and high == None:
                continue
            temp_dict = {}
            if low != None:
                temp_dict['gte'] = _to_epoch_time(low)
            if high != None:
                temp_dict['lte'] = _to_epoch_time(high)
            range_list.append( {'range': {key: temp_dict}})

    # Creates the list of term dictionaries to put in the 'should' list.
    eq_list = [{'term': {k: v}} for k, v in equality_constraints if k]
    num_constraints = len(equality_constraints) + len(range_constraints)
    return {
        'fields': fields_returned,
        'query': {
            'bool': {
                'should': eq_list + range_list,
                'minimum_should_match': num_constraints,
            }
        },
        'size': size,
        'sort': sort_specs if sort_specs else [],
    }


def _to_epoch_time(value):
    """Converts value to epoch time if it is a datetime object.

    This function should only be called in create_range_eq_query_multiple.

    @param value: anything
    @param returns: epoch time if value is datetime.datetime,
                    otherwise returns the value.
    """
    if isinstance(value, datetime.datetime):
        # This looks kinda hacky, timetuple() only goes to the
        # level of seconds. So I need to add on the decimal part.
        return time.mktime(value.timetuple()) + 0.000001*value.microsecond
    return value


def execute_query(query, index, host, port, timeout=3):
    """Makes a query on the given index.

    @param query: query dictionary (see create_range_query)
    @param index: index within db to query
    @param host: host running es
    @param port: port running es
    @param timeout: seconds to wait before es retries if conn. fails.
                    default is 3 seconds.
    @returns: dictionary of the results, or None if index does not exist.

    Example output:
    {
      "took" : 5,
      "timed_out" : false,
      "_shards" : {
        "total" : 16,
        "successful" : 16,
        "failed" : 0
      },
      "hits" : {
        "total" : 4,
        "max_score" : 1.0,
        "hits" : [ {
          "_index" : "graphite_metrics2",
          "_type" : "metric",
          "_id" : "rtntrjgdsafdsfdsfdsfdsfdssssssss",
          "_score" : 1.0,
          "_source":{"target_type": "timer",
                     "host_id": 1,
                     "job_id": 22,
                     "time_start": 400}
        }, {
          "_index" : "graphite_metrics2",
          "_type" : "metric",
          "_id" : "dfgfddddddddddddddddddddddhhh",
          "_score" : 1.0,
          "_source":{"target_type": "timer",
                     "host_id": 2,
                     "job_id": 23,
                     "time_start": 405}
        }, {
          "_index" : "graphite_metrics2",
          "_type" : "metric",
          "_id" : "erwerwerwewtrewgfednvfngfngfrhfd",
          "_score" : 1.0,
          "_source":{"target_type": "timer",
                     "host_id": 3,
                     "job_id": 24,
                     "time_start": 4098}
        }, {
          "_index" : "graphite_metrics2",
          "_type" : "metric",
          "_id" : "dfherjgwetfrsupbretowegoegheorgsa",
          "_score" : 1.0,
          "_source":{"target_type": "timer",
                     "host_id": 22,
                     "job_id": 25,
                     "time_start": 4200}
        } ]
      }
    }

    """
    es = elasticsearch.Elasticsearch(host=host, port=port, timeout=timeout)
    if not es.indices.exists(index=index):
        return None
    return es.search(index=index, body=query)