# Copyright 2022-2023 ETSI TeraFlowSDN - TFS OSG (https://tfs.etsi.org/)
#
# 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
#
#      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.

import sqlalchemy
from typing import Any, List
from sqlalchemy.orm import Session, sessionmaker, declarative_base
from sqlalchemy.sql import text
from sqlalchemy_cockroachdb import run_transaction

_Base = declarative_base()

def create_performance_enhancers(db_engine : sqlalchemy.engine.Engine) -> None:
    def index_storing(
        index_name : str, table_name : str, index_fields : List[str], storing_fields : List[str]
    ) -> Any:
        str_index_fields = ','.join(['"{:s}"'.format(index_field) for index_field in index_fields])
        str_storing_fields = ','.join(['"{:s}"'.format(storing_field) for storing_field in storing_fields])
        INDEX_STORING = 'CREATE INDEX IF NOT EXISTS {:s} ON "{:s}" ({:s}) STORING ({:s});'
        return text(INDEX_STORING.format(index_name, table_name, str_index_fields, str_storing_fields))

    statements = [
        index_storing('configrule_device_uuid_rec_idx', 'configrule', ['device_uuid'], [
            'service_uuid', 'slice_uuid', 'position', 'kind', 'action', 'data', 'created_at', 'updated_at'
        ]),
        index_storing('configrule_service_uuid_rec_idx', 'configrule', ['service_uuid'], [
            'device_uuid', 'slice_uuid', 'position', 'kind', 'action', 'data', 'created_at', 'updated_at'
        ]),
        index_storing('configrule_slice_uuid_rec_idx', 'configrule', ['slice_uuid'], [
            'device_uuid', 'service_uuid', 'position', 'kind', 'action', 'data', 'created_at', 'updated_at'
        ]),
        index_storing('connection_service_uuid_rec_idx', 'connection', ['service_uuid'], [
            'settings', 'created_at', 'updated_at'
        ]),
        index_storing('constraint_service_uuid_rec_idx', 'constraint', ['service_uuid'], [
            'slice_uuid', 'position', 'kind', 'data', 'created_at', 'updated_at'
        ]),
        index_storing('constraint_slice_uuid_rec_idx', 'constraint', ['slice_uuid'], [
            'service_uuid', 'position', 'kind', 'data', 'created_at', 'updated_at'
        ]),
        index_storing('endpoint_device_uuid_rec_idx', 'endpoint', ['device_uuid'], [
            'topology_uuid', 'name', 'endpoint_type', 'kpi_sample_types', 'created_at', 'updated_at'
        ]),
        index_storing('service_context_uuid_rec_idx', 'service', ['context_uuid'], [
            'service_name', 'service_type', 'service_status', 'created_at', 'updated_at'
        ]),
        index_storing('slice_context_uuid_rec_idx', 'slice', ['context_uuid'], [
            'slice_name', 'slice_status', 'slice_owner_uuid', 'slice_owner_string', 'created_at', 'updated_at'
        ]),

        index_storing('topology_context_uuid_rec_idx', 'topology', ['context_uuid'], [
            'topology_name', 'created_at', 'updated_at'
        ]),
    ]
    def callback(session : Session) -> bool:
        for stmt in statements: session.execute(stmt)
    run_transaction(sessionmaker(bind=db_engine), callback)

def rebuild_database(db_engine : sqlalchemy.engine.Engine, drop_if_exists : bool = False):
    if drop_if_exists: _Base.metadata.drop_all(db_engine)
    _Base.metadata.create_all(db_engine)
    create_performance_enhancers(db_engine)
