# SPDX-License-Identifier: GPL-3.0-or-later

import os
import io
import sys
import traceback
import time
import datetime


class Logger:
    LVL_CRITICAL = 50
    LVL_FATAL = LVL_CRITICAL
    LVL_ERROR = 40
    LVL_WARNING = 30
    LVL_WARN = LVL_WARNING
    LVL_INFO = 20
    LVL_DEBUG = 10
    LVL_TRACE = 0

    # the actual logger
    __logger = None

    @staticmethod
    def instance():
        """ return the logger instance

        :returns: the current Logger instance
        :rtype: Logger|None

        """

        return Logger.__logger

    @staticmethod
    def exists():
        """ returns a boolean indicating that a logger was created

        :returns: whether or not a Logger instance exists
        :rtype: bool

        """

        return Logger.__logger is not None

    @staticmethod
    def create_logger(log_file_name, application_name, min_log_level=10,
                      append=False, dual_logger=None):
        """ Initialises the Logger instance and opens it for writing

        :param str|None log_file_name:      Path of the log file to write to.
        :param str application_name:        The name of the current application.
        :param int min_log_level:           Minimum log level to log. Levels equal or higher are logged.
        :param bool append:                 If set to True, the current log file is not deleted.
                                            Default value is False.
        :param function|None dual_logger:   A function that is used for dual logging.

        :return: The new Logger instance
        :rtype: Logger

        """

        if "RETROSPECT_STDOUT_LOGGING" in os.environ and os.environ.get("RETROSPECT_STDOUT_LOGGING") == "1":
            log_file_name = None

        if Logger.__logger is None:
            Logger.__logger = Logger(log_file_name, application_name, min_log_level, append,
                                     dual_logger)
            # Logger.__logger.dualLog("CREATING LOGGER: {0}".format(Logger.__logger.id))
        else:
            Logger.warning("Cannot create a second logger instance!")
            # Logger.__logger.dualLog("EXISTING LOGGER: {0}".format(Logger.__logger.id))
        return Logger.__logger

    def __init__(self, log_file_name, application_name, min_log_level=10,
                 append=False, dual_logger=None):
        """ Initialises the Logger instance and opens it for writing.

        :param str|None log_file_name:      Path of the log file to write to.
        :param str application_name:        The name of the current application.
        :param int min_log_level:           Minimum log level to log. Levels equal or higher are logged.
        :param bool append:                 If set to True, the current log file is not deleted.
                                            Default value is False.
        :param function|None dual_logger:   A function that is used for dual logging.

        """

        self.logFileName = log_file_name
        self.fileMode = "a"
        self.fileFlags = os.O_WRONLY | os.O_APPEND | os.O_CREAT

        self.minLogLevel = min_log_level
        self.dualLog = dual_logger
        self.logDual = dual_logger is not None
        self.logEntryCount = 0
        self.flushInterval = 5 if log_file_name is not None else 1
        self.encoding = 'cp1252'
        self.applicationName = application_name

        self.id = int(time.time())
        self.timeFormat = "%Y%m%d %H:%M:%S"
        self.logFormat = '%s - [%-8s] - %-20s - %-4d - %s\n'

        self.logLevelNames = {
            Logger.LVL_CRITICAL: 'CRITICAL',
            Logger.LVL_ERROR: 'ERROR',
            Logger.LVL_WARNING: 'WARNING',
            Logger.LVL_INFO: 'INFO',
            Logger.LVL_DEBUG: 'DEBUG',
            Logger.LVL_TRACE: 'TRACE'
        }

        if not append:
            self.clean_up_log()

        # now open the file
        self.__open_log()

        # print to the Kodi logfile to tell the user the actual logfile path
        if self.dualLog:
            dual_logger("%s :: Additional logging can be found in '%s'" % (
                self.applicationName, self.logFileName,), 1)
        return

    @staticmethod
    def trace(msg, *args, **kwargs):
        """ Logs an trace message (with loglevel 0)

        The arguments and keyword arguments are used in a string format way
        so and will replace the parameters in the message.

        :param Any msg:       The message to log.
        :param Any args:      List of arguments to fill in the message formatting.
        :param Any kwargs:    Dictionary with keyword arguments.

        """

        # noinspection PyArgumentList
        Logger.__logger.__write(msg, level=Logger.LVL_TRACE, *args, **kwargs)
        return

    @staticmethod
    def debug(msg, *args, **kwargs):
        """Logs an debug message (with loglevel 10)

        The arguments and keyword arguments are used in a string format way
        so and will replace the parameters in the message.

        :param Any msg:       The message to log.
        :param Any args:      List of arguments to fill in the message formatting.
        :param Any kwargs:    Dictionary with keyword arguments.

        """

        # noinspection PyArgumentList
        Logger.__logger.__write(msg, level=Logger.LVL_DEBUG, *args, **kwargs)
        return

    @staticmethod
    def info(msg, *args, **kwargs):
        """Logs an informational message (with loglevel 20)

        The arguments and keyword arguments are used in a string format way
        so and will replace the parameters in the message.

        :param Any msg:       The message to log.
        :param Any args:      List of arguments to fill in the message formatting.
        :param Any kwargs:    Dictionary with keyword arguments.

        """

        # noinspection PyArgumentList
        Logger.__logger.__write(msg, level=Logger.LVL_INFO, *args, **kwargs)
        return

    @staticmethod
    def error(msg, *args, **kwargs):
        """Logs an error message (with loglevel 40)

        The arguments and keyword arguments are used in a string format way
        so and will replace the parameters in the message.

        :param Any msg:       The message to log.
        :param Any args:      List of arguments to fill in the message formatting.
        :param Any kwargs:    Dictionary with keyword arguments.

        """

        # noinspection PyArgumentList
        Logger.__logger.__write(msg, level=Logger.LVL_ERROR, *args, **kwargs)
        return

    @staticmethod
    def warning(msg, *args, **kwargs):
        """Logs an warning message (with loglevel 30)

        The arguments and keyword arguments are used in a string format way
        so and will replace the parameters in the message.

        :param Any msg:       The message to log.
        :param Any args:      List of arguments to fill in the message formatting.
        :param Any kwargs:    Dictionary with keyword arguments.

        """

        # noinspection PyArgumentList
        Logger.__logger.__write(msg, level=Logger.LVL_WARNING, *args, **kwargs)
        return

    @staticmethod
    def critical(msg, *args, **kwargs):
        """Logs an critical message (with loglevel 50)

        The arguments and keyword arguments are used in a string format way
        so and will replace the parameters in the message.

        :param Any msg:       The message to log.
        :param Any args:      List of arguments to fill in the message formatting.
        :param Any kwargs:    Dictionary with keyword arguments.

        """

        # noinspection PyArgumentList
        Logger.__logger.__write(msg, level=Logger.LVL_CRITICAL, *args, **kwargs)
        return

    def close_log(self, log_closing=True):
        """ Close the log file.

        Calling close() on a filehandle also closes the FileDescriptor

        :param log_closing:     Are we actually going to close the log file? A log line
                                is written on closure and the object is disposed of.

        """

        if log_closing:
            self.info("%s :: Flushing and closing logfile.", self.applicationName)
            # Logging for concurrency
            # self.dualLog("CURRENT LOGGER before: {0}".format(Logger.instance() or "none"))
            Logger._Logger__logger = None
            # Logging for concurrency
            # self.dualLog("CURRENT LOGGER after: {0}".format(Logger.instance() or "none"))
            # self.dualLog("CLOSING LOGGER: {0}".format(self.id))

        self.logHandle.flush()
        if self.logHandle is not sys.stdout:
            self.logHandle.close()

    def clean_up_log(self):
        """ Closes an old log file and creates a new one.

        This method renames the current log file to .old.log and creates a
        new log file with the .log filename.

        If the original file was open for writing/appending, the new file
        will also be open for writing/appending

        """

        if self.logFileName is None:
            return

        # create old.log file
        clean_up_message = "{} :: Cleaning up logfile: {}".format(self.applicationName, self.logFileName)
        if self.logDual:
            self.dualLog(clean_up_message, 1)
        else:
            print(clean_up_message)

        try:
            was_open = True
            self.close_log(log_closing=False)
        except:  # NOSONAR
            was_open = False

        (file_name, extension) = os.path.splitext(self.logFileName)
        old_file_name = "%s.old%s" % (file_name, extension)
        if os.path.exists(self.logFileName):
            if os.path.exists(old_file_name):
                os.remove(old_file_name)
            os.rename(self.logFileName, old_file_name)

        if was_open:
            self.__open_log()
        return

    def __str__(self):
        return str(self.id)

    def __repr__(self):
        return str(self.id)

    def __write(self, msg, *args, **kwargs):
        """ Writes the message to the log file taking into account the given arguments and
        keyword arguments.

        The arguments and keyword arguments are used in a string format way
        so and will replace the parameters in the message.

        :param Any msg:       The message to log.
        :param Any args:      List of arguments to fill in the message formatting.
        :param Any kwargs:    Dictionary with keyword arguments.

        """

        try:
            formatted_message = ""
            log_level = kwargs["level"]

            # determine if write is needed:
            if log_level < self.minLogLevel:
                return

            # convert possible tupple to string:
            msg = str(msg)

            # Fill the message with it's content
            if len(args) > 0:
                msg = msg % args

            # get frame information
            (source_file, source_line_number) = self.__find_caller()

            # get time information
            timestamp = datetime.datetime.today().strftime(self.timeFormat)

            # check for exception info, if present, add to end of string:
            # noinspection PyArgumentList
            msg = self.__process_exc_info(msg, **kwargs)

            # now split lines and write everyline into the logfile:
            lines = msg.splitlines()
            line_count = len(lines)

            # check if multiline
            if line_count > 1:
                for i in range(0, line_count):
                    # for line in lines:
                    line = lines[i]
                    if len(line) <= 0:
                        continue

                    # if last line:
                    if i == line_count - 1:
                        line = '+ %s' % (line, )
                    elif i > 0:
                        line = '| %s' % (line,)

                    formatted_message = self.logFormat % (
                        timestamp,
                        self.logLevelNames.get(log_level),
                        source_file,
                        source_line_number,
                        line)
                    self.logHandle.write(formatted_message)
            else:
                formatted_message = self.logFormat % (
                    timestamp,
                    self.logLevelNames.get(log_level),
                    source_file,
                    source_line_number,
                    msg)
                self.logHandle.write(formatted_message)

            # Finally close the filehandle
            self.logEntryCount += 1
            if self.logEntryCount % self.flushInterval == 0:
                self.logEntryCount = 0
                self.logHandle.flush()
            return
        except:  # NOSONAR
            if not self.logDual:
                traceback.print_exc()
                return

            self.dualLog("Retrospect Logger :: Error logging in Logger.py:")
            self.dualLog("---------------------------")
            self.dualLog(traceback.format_exc())
            self.dualLog("---------------------------")
            self.dualLog(repr(msg))
            self.dualLog(repr(args))
            # noinspection PyUnboundLocalVariable
            self.dualLog(repr(formatted_message))
            self.dualLog("---------------------------")

    def __find_caller(self):
        """Find the stack frame of the caller.

        Find the stack frame of the caller so that we can note the source
        file name, line number and function name.

        :return: the source file and line number of the caller
        :rtype: tuple[str, int]

        """
        return_value = ("Unknown", 0)

        # get the current frame and descent down until the correct one is found
        # noinspection PyProtectedMember,PyUnresolvedReferences
        current_frame = sys._getframe(3)  # could be _getframe(#) and (3)
        while hasattr(current_frame, "f_code"):
            co = current_frame.f_code
            source_file = os.path.normcase(co.co_filename)
            method_name = co.co_name
            # if current_frame belongs to this logger.py, equals <string> or equals a private log
            # method (_log or __Log) continue searching.
            if source_file == "<string>" \
                    or source_file in os.path.normcase(__file__) \
                    or "stopwatch.py" in source_file \
                    or method_name in ("_Log", "__Log", "_log", "__log"):
                current_frame = current_frame.f_back
                continue
            else:
                # get the source_path and source_file
                (source_path, source_file) = os.path.split(source_file)
                return_value = (source_file, current_frame.f_lineno)
                break

        return return_value

    def __open_log(self):
        """ Opens the log file for appending.

        This method opens a logfile for writing. If one already exists, it will
        be appended. If it does not exist, a new one is created.

        Problem:
        If we would use open(self.logFileName, "a") we would get an invalid
        filedescriptor error in Linux!

        Possible fixes:
        1 - Modding the flags to only have os.O_CREATE if the file does not exists
            works, but then the file is appended at position 0 instead of the end!

        2 - Using a custom filedescriptor. This works, but now the file just keeps
            getting overwritten.

        3 - OR: why not do a manual append: first read the complete file into a
            string. Then do an open(self.logFileName, "w"), write the previous
            content and then just continue!

        Finally: stick to the basic open(file, mode) and changes modes depending on
        the available files.

        """

        if self.logFileName is None:
            self.logHandle = sys.stdout
            return

        if os.path.exists(self.logFileName):
            # the file already exists. Now to prevent errors in Linux
            # we will open a file in Read + (Read and Update) mode
            # and set the pointer to the end.
            self.logHandle = io.open(self.logFileName, "r+", encoding='utf-8')
            self.logHandle.seek(0, 2)
            self.__write("XOT Logger :: Appending Existing logFile", level=Logger.LVL_INFO)
        else:
            log_dir = os.path.dirname(self.logFileName)
            if not os.path.isdir(log_dir):
                os.makedirs(log_dir)
            # no file exists, so just create a new one for writing
            self.logHandle = io.open(self.logFileName, "w", encoding='utf-8')

        return

    def __process_exc_info(self, msg, **kwargs):
        """ Adds the Exception Traceback if the exc_info keyword parameter is specified.

        :param Any msg:       The message to log.
        :param Any kwargs:    Dictionary with keyword arguments.

        :return: The new updated message string
        :rtype: str

        """

        if "exc_info" in kwargs:
            if self.logDual:
                self.dualLog(traceback.format_exc())
            msg = "%s\n%s" % (msg, traceback.format_exc())

        return msg
