# 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.

import os
import uuid

from parquet_flask.utils.singleton import Singleton


class Config(metaclass=Singleton):
    master_spark_url = 'master_spark_url'
    parquet_metadata_tbl = 'parquet_metadata_tbl'
    spark_app_name = 'spark_app_name'
    spark_config_dict = 'spark_config_dict'
    parquet_file_name = 'parquet_file_name'
    aws_region = 'aws_region'
    aws_access_key_id = 'aws_access_key_id'
    aws_secret_access_key = 'aws_secret_access_key'
    aws_session_token = 'aws_session_token'
    in_situ_schema = 'in_situ_schema'
    spark_ram_size = 'spark_ram_size'
    missing_depth_value = 'missing_depth_value'
    authentication_type = 'authentication_type'
    authentication_key = 'authentication_key'
    es_url = 'es_url'
    es_index = 'es_index'
    es_port = 'es_port'

    def __init__(self, validate_env: bool = True):
        self.__keys = [
            Config.es_url,
            Config.master_spark_url,
            Config.spark_app_name,
            # Config.spark_config_dict,
            Config.parquet_file_name,
            Config.in_situ_schema,
            Config.authentication_type,
            Config.authentication_key,
            Config.parquet_metadata_tbl,
        ]
        self.__optional_keys = [
            Config.spark_ram_size,
            Config.aws_access_key_id,
            Config.aws_secret_access_key,
            Config.aws_session_token,
        ]
        if validate_env:
            self.__validate()
        app_name_postfix = self.get_value('HOSTNAME', str(uuid.uuid4()))
        self.__spark_app_name = f'{self.get_value(Config.spark_app_name)}___{app_name_postfix}'

    def get_spark_app_name(self):
        return self.__spark_app_name

    def __validate(self):
        missing_mandatory_keys = [k for k in self.__keys if k not in os.environ]
        if len(missing_mandatory_keys) > 0:
            raise RuntimeError('missing configuration values in environment values: {}'.format(missing_mandatory_keys))
        return

    def get_value(self, key, default_val=None):
        if key in os.environ:
            return os.environ[key]
        return default_val