#!/usr/bin/python


class BaseOrderedLogParser:
    """
    This parser is to be inherited from. It goes through log entries
    until it finds an entry it hasn't gone through, in which case it
    parses until the end of the entries.
    """

    def execute(self):
        self.retrieve_status()
        self.parser_init()

        context_manager = self.get_context_manager()

        with context_manager(*self.context_manager_args) as file:
            self.aggregators_init(file)
            line = file.readline()
            new_flag = False

            while (line):
                # Only check for a new line if we're not at new entries yet
                if not new_flag:
                    new_flag = self.new_flag_condition(line)

                # Ignore old entries and only consider new ones
                if new_flag:
                    break_condition = self.parse_line(line)

                    if not break_condition:
                        break

                line = file.readline()

            self.aggregators_deinit(file)

        self.update_status()
        self.parser_deinit()

    def get_context_manager(self):
        """
        Hook to customize the context manager. Defaults to the file context
        manager. The context manager file should have a readline() method
        that reads the next "line".
        """
        return open

    def parser_init(self):
        """
        Extra hook that runs after the status has been retrieved but before
        the parser starts going through the file
        """
        pass

    def aggregators_deinit(self, file):
        """
        Hook that runs right before the context manager closes the file.
        """
        pass

    def update_status(self):
        """
        Updates the saved status of the parser
        """
        pass

    def parser_deinit(self):
        """
        Extra hook that runs after the parser updated the saved status
        """
        pass