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

"""
    common elasticsearch database setup
    also adds defaults for most methods
"""

from ponymailconfig import PonymailConfig
import sys
import logging
import certifi

try:
    from elasticsearch import Elasticsearch, helpers
    from elasticsearch import VERSION as ES_VERSION
    from elasticsearch import ConnectionError as ES_ConnectionError
except ImportError as e:
    sys.exit("Sorry, you need to install the elasticsearch module from pip first. (%s)" % str(e))

class Elastic:
    def __init__(self, dbname=None):
        # Fetch config
        config = PonymailConfig()
        self.dbname = dbname or config.get("elasticsearch", "dbname")
        ssl = config.get("elasticsearch", "ssl", fallback="false").lower() == 'true'
        uri = config.get("elasticsearch", "uri", fallback="")
        auth = None
        if config.has_option('elasticsearch', 'user'):
            auth = (config.get('elasticsearch','user'), config.get('elasticsearch','password'))


        # elasticsearch logs lots of warnings on retries/connection failure
        logging.getLogger("elasticsearch").setLevel(logging.ERROR)

#         # add debug
#         trace = logging.getLogger("elasticsearch.trace")
#         trace.setLevel(logging.DEBUG)
#         # create console handler
#         consoleHandler = logging.StreamHandler()
#         trace.addHandler(consoleHandler)

        self.es = Elasticsearch([
            {
                'host': config.get("elasticsearch", "hostname"),
                'port': int(config.get("elasticsearch", "port")),
                'use_ssl': ssl,
                'url_prefix': uri,
                'auth': auth,
                'ca_certs': certifi.where()
            }],
            max_retries=5,
            retry_on_timeout=True
            )
        self.dbVersion = None
        # Mimic ES hierarchy: es.indices.xyz()
        self.indices=_indices_wrap(self)

    def libraryVersion(self):
        return ES_VERSION
    def libraryMajor(self):
        return ES_VERSION[0]

    def engineVersion(self):
        if not self.dbVersion:
            try:
                self.dbVersion = self.info()['version']['number']
            except ES_ConnectionError:
                # default if cannot connect; allows retry
                return '0.0.0'
        return self.dbVersion
    def engineMajor(self):
        return int(self.engineVersion().split('.')[0])

    def getdbname(self):
        return self.dbname

    def search(self, doc_type='mbox', **kwargs):
        return self.es.search(
            index=self.dbname,
            doc_type=doc_type,
            **kwargs
        )

    def index(self, **kwargs):
        return self.es.index(
            index=self.dbname,
            **kwargs
        )

    def update(self, **kwargs):
        return self.es.update(
            index=self.dbname,
            **kwargs
        )

    def scan(self, doc_type='mbox', scroll='3m', size = 100, **kwargs):
        return self.es.search(
            index=self.dbname,
            doc_type=doc_type,
            search_type = 'scan',
            size = size,
            scroll = scroll,
            **kwargs
        )
    
    def scan_and_scroll(self, doc_type='mbox', scroll='3m', size = 100, **kwargs):
        """ Run a backwards compatible scan/scroll, passing an iterator
            that returns one page of hits per iteration. This
            incorporates es.scroll for continuous iteration, and thus the
            scroll() does NOT need to be called at all by the calling
            process. """
        results = self.es.search(
            index=self.dbname,
            doc_type=doc_type,
            size = size,
            scroll = scroll,
            **kwargs
        )
        if results['hits'].get('hits', []): # Might not be there in 2.x?
            yield results
        
        # While we have hits waiting, scroll...
        scroll_size = results['hits']['total']
        while (scroll_size > 0):
            results = self.scroll(scroll_id = results['_scroll_id'], scroll = scroll)
            scroll_size = len(results['hits']['hits']) # If >0, try another scroll next.
            yield results
            
    def get(self, **kwargs):
        return self.es.get(index=self.dbname, **kwargs)

    def scroll(self, **kwargs):
        return self.es.scroll(**kwargs)

    def info(self, **kwargs):
        return self.es.info(**kwargs)

    def bulk(self, actions, **kwargs):
        return helpers.bulk(self.es, actions, **kwargs)

    def clear_scroll(self, *args, **kwargs):
        """
            Call this to release the scroll id and its resources

            It looks like the Python library already releases the SID
            if the caller scrolls to the end of the results, so only need to call this
            when terminating scrolling early.
        """
        return self.es.clear_scroll(*args, **kwargs)

class _indices_wrap(object):
    """
        Wrapper for the ES indices methods we use
    """
    def __init__(self, parent):
        self.es = parent.es

    def exists(self, *args, **kwargs):
        return self.es.indices.exists(*args, **kwargs)

if __name__ == '__main__':
    es = Elastic()
    print("Versions: Library: %d %s Engine: %d (%s)" % (es.libraryMajor(), es.libraryVersion(), es.engineMajor(), es.engineVersion()))
    try:
        print(es.indices.exists(index='ponymail'))
        print(es.indices.exists('test'))
    except ES_ConnectionError as e:
        print(type(e))