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# Copyright (c) 2023 The Regents of the University of California
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met: redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer;
# redistributions in binary form must reproduce the above copyright
# notice, this list of conditions and the following disclaimer in the
# documentation and/or other materials provided with the distribution;
# neither the name of the copyright holders nor the names of its
# contributors may be used to endorse or promote products derived from
# this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
from abc import ABC, abstractmethod
from typing import Dict, List
class Client(ABC):
def __init__(self):
self.__undo_stack = []
self.__redo_stack = []
self.__undo_limit = 10
@abstractmethod
def find_resource(self, query: Dict) -> Dict:
raise NotImplementedError
@abstractmethod
def get_versions(self, query: Dict) -> List[Dict]:
raise NotImplementedError
@abstractmethod
def update_resource(self, query: Dict) -> Dict:
raise NotImplementedError
@abstractmethod
def check_resource_exists(self, query: Dict) -> Dict:
raise NotImplementedError
@abstractmethod
def insert_resource(self, query: Dict) -> Dict:
raise NotImplementedError
@abstractmethod
def delete_resource(self, query: Dict) -> Dict:
raise NotImplementedError
@abstractmethod
def save_session(self) -> Dict:
raise NotImplementedError
def undo_operation(self) -> Dict:
"""
This function undoes the last operation performed on the database.
"""
if len(self.__undo_stack) == 0:
return {"status": "Nothing to undo"}
operation = self.__undo_stack.pop()
print(operation)
if operation["operation"] == "insert":
self.delete_resource(operation["resource"])
elif operation["operation"] == "delete":
self.insert_resource(operation["resource"])
elif operation["operation"] == "update":
self.update_resource(operation["resource"])
temp = operation["resource"]["resource"]
operation["resource"]["resource"] = operation["resource"][
"original_resource"
]
operation["resource"]["original_resource"] = temp
else:
raise Exception("Invalid Operation")
self.__redo_stack.append(operation)
return {"status": "Undone"}
def redo_operation(self) -> Dict:
"""
This function redoes the last operation performed on the database.
"""
if len(self.__redo_stack) == 0:
return {"status": "No operations to redo"}
operation = self.__redo_stack.pop()
print(operation)
if operation["operation"] == "insert":
self.insert_resource(operation["resource"])
elif operation["operation"] == "delete":
self.delete_resource(operation["resource"])
elif operation["operation"] == "update":
self.update_resource(operation["resource"])
temp = operation["resource"]["resource"]
operation["resource"]["resource"] = operation["resource"][
"original_resource"
]
operation["resource"]["original_resource"] = temp
else:
raise Exception("Invalid Operation")
self.__undo_stack.append(operation)
return {"status": "Redone"}
def _add_to_stack(self, operation: Dict) -> Dict:
if len(self.__undo_stack) == self.__undo_limit:
self.__undo_stack.pop(0)
self.__undo_stack.append(operation)
self.__redo_stack.clear()
return {"status": "Added to stack"}
def get_revision_status(self) -> Dict:
"""
This function saves the status of revision operations to a dictionary.
The revision operations whose statuses are saved are undo and redo.
If the stack of a given revision operation is empty, the status of
that operation is set to 1 else the status is set to 0.
:return: A dictionary containing the status of revision operations.
"""
return {
"undo": 1 if len(self.__undo_stack) == 0 else 0,
"redo": 1 if len(self.__redo_stack) == 0 else 0,
}