#
# 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.

from typing import Any

from sqlalchemy import MetaData
from sqlalchemy.ext.declarative import declarative_base

from airflow.configuration import conf

SQL_ALCHEMY_SCHEMA = conf.get("core", "SQL_ALCHEMY_SCHEMA")

metadata = (
    None if not SQL_ALCHEMY_SCHEMA or SQL_ALCHEMY_SCHEMA.isspace() else MetaData(schema=SQL_ALCHEMY_SCHEMA)
)
Base = declarative_base(metadata=metadata)  # type: Any

ID_LEN = 250


# used for typing
class Operator:
    """Class just used for Typing"""


def get_id_collation_args():
    """Get SQLAlchemy args to use for COLLATION"""
    collation = conf.get('core', 'sql_engine_collation_for_ids', fallback=None)
    if collation:
        return {'collation': collation}
    else:
        # Automatically use utf8mb3_bin collation for mysql
        # This is backwards-compatible. All our IDS are ASCII anyway so even if
        # we migrate from previously installed database with different collation and we end up mixture of
        # COLLATIONS, it's not a problem whatsoever (and we keep it small enough so that our indexes
        # for MYSQL will not exceed the maximum index size.
        #
        # See https://github.com/apache/airflow/pull/17603#issuecomment-901121618.
        #
        # We cannot use session/dialect as at this point we are trying to determine the right connection
        # parameters, so we use the connection
        conn = conf.get('core', 'sql_alchemy_conn', fallback='')
        if conn.startswith('mysql') or conn.startswith("mariadb"):
            return {'collation': 'utf8mb3_bin'}
        return {}


COLLATION_ARGS = get_id_collation_args()