# Copyright (c) 2019 AT&T Intellectual Property.
# Copyright (c) 2018-2019 Nokia.
#
# 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.

#
# This source code is part of the near-RT RIC (RAN Intelligent Controller)
# platform project (RICP).
#


"""The module provides Shared Data Layer (SDL) database backend interface."""

from typing import (Dict, Set, List, Union)
from abc import ABC, abstractmethod


class DbBackendAbc(ABC):
    """An abstract Shared Data Layer (SDL) class providing database backend interface."""

    @abstractmethod
    def close(self):
        """Close database backend connection."""
        pass

    @abstractmethod
    def set(self, ns: str, data_map: Dict[str, bytes]) -> None:
        """Write key value data mapping to database under a namespace."""
        pass

    @abstractmethod
    def set_if(self, ns: str, key: str, old_data: bytes, new_data: bytes) -> bool:
        """"Write key value to database under a namespace if the old value is expected one."""
        pass

    @abstractmethod
    def set_if_not_exists(self, ns: str, key: str, data: bytes) -> bool:
        """"Write key value to database under a namespace if key doesn't exist."""
        pass

    @abstractmethod
    def get(self, ns: str, keys: List[str]) -> Dict[str, bytes]:
        """"Return values of the keys under a namespace."""
        pass

    @abstractmethod
    def find_keys(self, ns: str, key_prefix: str) -> List[str]:
        """"Return all the keys matching search pattern under a namespace in database."""
        pass

    @abstractmethod
    def find_and_get(self, ns: str, key_prefix: str, atomic: bool) -> Dict[str, bytes]:
        """
        Return all the keys with their values matching search pattern under a namespace in
        database.
        """
        pass

    @abstractmethod
    def remove(self, ns: str, keys: List[str]) -> None:
        """Remove keys and their data from database."""
        pass

    @abstractmethod
    def remove_if(self, ns: str, key: str, data: bytes) -> bool:
        """
           Remove key and its data from database if if the current data value is expected
           one.
        """
        pass

    @abstractmethod
    def add_member(self, ns: str, group: str, members: Set[bytes]) -> None:
        """Add new members to a group under a namespace in database."""
        pass

    @abstractmethod
    def remove_member(self, ns: str, group: str, members: Set[bytes]) -> None:
        """Remove members from a group under a namespace in database."""
        pass

    @abstractmethod
    def remove_group(self, ns: str, group: str) -> None:
        """Remove a group under a namespace in database along with it's members."""
        pass

    @abstractmethod
    def get_members(self, ns: str, group: str) -> Set[bytes]:
        """Get all the members of a group under a namespace in database."""
        pass

    @abstractmethod
    def is_member(self, ns: str, group: str, member: bytes) -> bool:
        """Validate if a given member is in the group under a namespace in database."""
        pass

    @abstractmethod
    def group_size(self, ns: str, group: str) -> int:
        """Return the number of members in a group under a namespace in database."""
        pass


class DbBackendLockAbc(ABC):
    """
    An abstract Shared Data Layer (SDL) class providing database backend lock interface.
    Args:
        ns (str): Namespace under which this lock is targeted.
        name (str): Lock name, identifies the lock key in a database backend.
    """
    def __init__(self, ns: str, name: str) -> None:
        self._ns = ns
        self._lock_name = name
        super().__init__()

    @abstractmethod
    def acquire(self, retry_interval: Union[int, float] = 0.1,
                retry_timeout: Union[int, float] = 10) -> bool:
        """Acquire a database lock."""
        pass

    @abstractmethod
    def release(self) -> None:
        """Release a database lock."""
        pass

    @abstractmethod
    def refresh(self) -> None:
        """Refresh the remaining validity time of the database lock back to a initial value."""
        pass

    @abstractmethod
    def get_validity_time(self) -> Union[int, float]:
        """Return remaining validity time of the lock in seconds."""
        pass