'''
Copyright 2020, Amazon Web Services Inc.
This code is licensed under MIT license (see LICENSE.txt for details)

Python 3

Provides a buffer object that holds log lines in Elasticsearch _bulk
format. As each line is added, the buffer stores the control line
as well as the log line.
'''


from collections import namedtuple


from es_sink.es_auth import ESAuth, ESNoAuth, ESSigV4Auth, ESHttpAuth
from es_sink.transport_utils import now_pst


class SQSDescriptor():
    '''Description of an SQS queue. Enables generalization of sink targets'''
    def __init__(self, q_url, region):
        '''An SQS queue has a URL and a region'''
        self._sqs_url = q_url
        self._region = region

    @property
    def sqs_url(self):
        '''The target SQS URL'''
        return self. sqs_url

    @property
    def region(self):
        '''The region of the queue'''
        return self._region


# Describes handling of indexes for the ESDescriptor class
# es_v7             Use ES V7 APIs (no _type, mostly)
# es_index:         For API calls that use an index
# es_type:          For ES V6 clusters and calls that use a _type
# timestamped:      For ES API calls, mostly writes, append _YY.MM.DD
#                   to the index name
IndexDescriptor = namedtuple('IndexDescriptor', ['es_index', 'es_type',
                                                 'es_v7', 'timestamped'],
                                              defaults=(None, None, True, True))


class ESDescriptor():
    """Description of an Elasticsearch endpoint."""

    def __init__(self, endpoint, index_descriptor, region=None, auth=None):
        """Describes an ELasticsearch sink.

           This could be refactored to be a little bit better. As of now, it
           supports Amazon ES endpoints as well as vanilla ES endpoints. It also
           supports ES V6 and ES V7 endpoints. These could be mixins.

           endpoint:            The base url to send REST API calls
           region:              For Amazon ES domains, the AWS region. E.g.
                                us-west-2
           indexing_descriptor: An IndexingDescriptor as above, specifying the
            `                   index name, es type, v7 status, and whether to
                                create indices with a timestamped name
           es_auth:             A subclass of the ESAuth class specifying how to
                                handle authentication of requests sent to the
                                Elasticsearch endpoint.
        """
        self._endpoint = endpoint

        if not isinstance(index_descriptor, IndexDescriptor):
            raise TypeError('Wrong type for index_descriptor')
        self._indexing = index_descriptor

        self._auth = auth
        if not auth:
            self._auth = ESNoAuth()

        if not issubclass(type(auth), ESAuth):
            raise ValueError('You must use the a child of the ESAuth class')


        if isinstance(auth, ESSigV4Auth) and not region:
            raise ValueError('You must specify a region to use SigV4Signing')
        self._region = region


    def user_password(self):
        '''Expose a method to retrieve the username/password.'''
        if not self._auth or not isinstance(self._auth, ESHttpAuth):
            raise ValueError('The descriptors authentication is not HTTP')
        return self._auth.auth_creds()

    @property
    def region(self):
        '''The region of the Amazon ES domain'''
        return self._region

    def is_signed(self):
        '''Should requests be signed with AWS SigV4 signing?'''
        return isinstance(self._auth, ESSigV4Auth)

    def is_http_auth(self):
        '''Should requests be signed with AWS SigV4 signing?'''
        return isinstance(self._auth, ESHttpAuth)

    def auth(self):
        '''Return the auth object passed in to init'''
        return self._auth

    def timestamped(self):
        '''Returns true when the index names should carry a timestamp'''
        return self._indexing.timestamped

    def _index_name(self):
        ''' Return es_index-YY.MM.DD. Not timezone-aware '''
        if self.timestamped():
            return "{}-{}".format(self._indexing.es_index,
                                  now_pst().strftime("%Y.%m.%d"))
        return self._indexing.es_index

    def base_url(self):
        ''' Returns the endpoint. Slash-terminated.'''
        if self._endpoint.endswith('/'):
            return self._endpoint
        return '{}/'.format(self._endpoint)

    def base_url_with_index(self):
        '''Returns the endpoint/index, slash terminated. '''
        return '{}{}/'.format(self.base_url(), self._index_name())

    def base_url_6(self):
        ''' Returns the endpoint/index/type. Slash-terminated.
            Set timestamped=True to add the YY.MM.DD to the index
            name.'''
        return '{}{}/{}/'.format(self.base_url(), self._index_name(),
                                 self._indexing.es_type)

    def base_url_7(self):
        ''' Returns the endpoint/index/. Slash-terminated.
            Set timestamped=True to add the YY.MM.DD to the index
            name.'''
        return '{}{}/'.format(self.base_url(), self._index_name())

    def bulk_url(self):
        ''' d - an ESDescriptor. Returns the base url with _bulk.
            This assumes that you do not want index embedded.
            Set timestamped=True to add the YY.MM.DD to the index
            name.'''
        return '{}{}/_bulk'.format(self.base_url(), self._index_name())

    def _es_v7(self):
        return self._indexing.es_v7

    def search_url(self):
        ''' d - an ESDescriptor. Returns the base url with
            <es_index>/<es_type>/_search handles es v7 by removing the
            type. Set timestamped=True to add the YY.MM.DD to the index
            name.'''
        if self._es_v7():
            return '{}{}/_search'.format(self.base_url(),
                                         self._index_name())

        return '{}{}/{}/_search'.format(self.base_url(),
                                        self._index_name(),
                                        self._indexing.es_type)

    ACTION_LINE_6 = '{{"index" : {{ "_index" : "{}", "_type": "{}" }} }}'
    ACTION_LINE_7 = '{{"index" : {{ "_index" : "{}" }} }}'
    def bulk_control_line(self):
        ''' Strictly, this shouldn't go in this class. It's not really
            part of a description. OTOH, all the info is here and it will
            save lots of duplicated code.
            Returns the "control" line for a _bulk request. '''
        if self._es_v7():
            return self.ACTION_LINE_7.format(self._index_name())

        return self.ACTION_LINE_6.format(self._index_name(),
                                         self._indexing.es_type)