# Copyright 2016 IBM Corp. All Rights Reserved.
#
# Licensed 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
#
# https://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 os
import uuid

from cloudant import Cloudant
from cloudant.result import Result

class Database:
    db_prefix = os.getenv('DB_PREFIX', '')
    dbname = db_prefix + 'ow_kafka_triggers'
    username = os.environ['CLOUDANT_USER']
    password = os.environ['CLOUDANT_PASS']

    client = Cloudant(username, password, account=username)
    client.connect()

    if dbname in client.all_dbs():
        logging.info('Database exists - connecting to it.')
        database = client[dbname]
    else:
        logging.warn('Database does not exist - creating it.')
        database = client.create_database(dbname)

    def recordTrigger(self, triggerFQN, doc):
        document = dict(doc)
        document['_id'] = triggerFQN

        logging.info('Writing trigger {} to DB'.format(triggerFQN))
        result = self.database.create_document(document)
        logging.info('Successfully wrote trigger {} to DB'.format(triggerFQN))

        return result

    def deleteTrigger(self, triggerFQN):
        document = self.database[triggerFQN]
        if document.exists():
            logging.info('Found trigger to delete from DB: {}'.format(triggerFQN))
            document.delete()
            logging.info('Successfully deleted trigger from DB: {}'.format(triggerFQN))
        else:
            logging.warn('Attempted to delete non-existent trigger from DB: {}'.format(triggerFQN))

    def triggers(self):
        allDocs = []

        logging.info('Fetching all documents from DB')
        for document in Result(self.database.all_docs, include_docs=True):
            allDocs.append(document['doc'])

        logging.info('Successfully retrieved {} documents'.format(len(allDocs)))
        return allDocs

    def migrate(self):
        logging.info('Starting DB migration')

        for trigger in Result(self.database.all_docs, include_docs=True):
            if 'uuid' not in trigger['doc']:
                logging.info('[{}] Does not have a UUID. Generating one...'.format(trigger['id']));

                # this little dance seems odd to me. trigger does not have a .save() method,
                # so I am left to fetch the document this way:
                doc = self.database[trigger['id']]
                doc['uuid'] = str(uuid.uuid4())
                doc.save()

                logging.info('[{}] Now has UUID {}'.format(trigger['id'], doc['uuid']))
            else:
                logging.debug('[{}] Already has UUID'.format(trigger['id']));

        logging.info('Database migration complete')