#!/usr/bin/env python

# -*- coding: UTF-8 -*-

#

# Copyright 2017 University of Westminster. All Rights Reserved.

#

# 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.

# ==============================================================================

"""It is an interface for serialising python objects and optionally compressing them.

"""

from typing import TypeVar, Any

import pickle

import bz2

import sys

import os

import logging

from Configs.CONSTANTS import CONSTANTS

OsStatResult = TypeVar('stat_result')

__author__ = "Mohsen Mesgarpour"

__copyright__ = "Copyright 2016, https://github.com/mesgarpour"

__credits__ = ["Mohsen Mesgarpour"]

__license__ = "GPL"

__version__ = "1.1"

__maintainer__ = "Mohsen Mesgarpour"

__email__ = "mohsen.mesgarpour@gmail.com"

__status__ = "Release"

class PickleSerialised:

    def __init__(self):

        """Initialise the objects and constants."""

        self.__logger = logging.getLogger(CONSTANTS.app_name)

        self.__logger.debug(__name__)

        self.__path = None

    def set(self,

            path: str,

            title: str,

            ext: str):

        """Set the python serialiser configuration settings.

        :param path: the directory path of the serialised file.

        :param title: the title of the output file.

        :param ext: the extension of the output file.

        """

        self.__logger.debug("Set the pickle file.")

        self.__path = os.path.join(path, title + "." + ext)

        self.__logger.debug(self.__path)

    def exists(self) -> bool:

        """Check if the serialised object exists.

        :return: indicates if the file exists.

        """

        self.__logger.debug("Check if the pickle file exists.")

        return os.path.isfile(self.__path)

    def save(self,

             objects: Any):

        """Serialise the object (Pickle protocol=4), without compression.

        :param objects: the object to be saved.

        """

        self.__logger.debug("Save the Pickle file.")

        try:

            with open(self.__path, 'wb') as f:

                pickle.dump(objects, f, protocol=4)

        except (OSError, IOError) as e:

            self.__logger.error(__name__ + " - Can not open the file: \n" + self.__path + "\n")

            print(e)

            sys.exit()

        except Exception as e:

            self.__logger.error(__name__ + " - Unable to save data to: \n" + self.__path + "\n")

            print(e)

            sys.exit()

        file_stats = os.stat(self.__path)

        self.__logger.info("Pickle Size: " + str(file_stats.st_size) + ".")

    def save_bz2(self,

                 objects: Any):

        """Serialise the object (Pickle protocol=4), then compress (BZ2 compression).

        :param objects: the object to be saved.

        """

        self.__logger.debug("Save the Pickle file and compress.")

        try:

            with bz2.BZ2File(self.__path, 'wb') as f:

                pickle.dump(objects, f, protocol=4)

        except (OSError, IOError) as e:

            self.__logger.error(__name__ + " - Can not open the file: \n" + self.__path + "\n")

            print(e)

            sys.exit()

        except Exception as e:

            self.__logger.error(__name__ + " - Unable to save data to: \n" + self.__path + "\n")

            print(e)

            sys.exit()

        file_stats = os.stat(self.__path)

        self.__logger.info("Pickle Size: " + str(file_stats.st_size) + ".")

    def load(self) -> Any:

        """Load a serialised object, that was not compressed.

        :return: the loaded python object.

        """

        self.__logger.debug("Load a Pickle file.")

        try:

            with open(self.__path, 'rb') as f:

                objects = pickle.load(f)

        except (OSError, IOError) as e:

            self.__logger.error(__name__ + " - Can not open the file: \n" + self.__path + "\n")

            print(e)

            sys.exit()

        except Exception as e:

            self.__logger.error(__name__ + " - Unable to load data from: \n" + self.__path + "\n")

            print(e)

            sys.exit()

        return objects

    def load_bz2(self) -> Any:

        """Load a serialised object, that was compressed (BZ2 compression).

        :return: the loaded python object.

        """

        self.__logger.debug("Save a compressed Pickle file.")

        try:

            with bz2.BZ2File(self.__path, 'rb') as f:

                objects = pickle.load(f)

        except (OSError, IOError) as e:

            self.__logger.error(__name__ + " - Can not open the file: \n" + self.__path + "\n")

            print(e)

            sys.exit()

        except Exception as e:

            self.__logger.error(__name__ + " - Unable to load data from \n" + self.__path + "\n")

            print(e)

            sys.exit()

        return objects

    def size(self) -> OsStatResult:

        """Check the size of the saved file.

        :return: showing stat information of the file.

        """

        return os.stat(self.__path)