"""Text parser plugin for Sophos anti-virus logs (SAV.txt) files."""

import pyparsing

from dfdatetime import time_elements as dfdatetime_time_elements

from plaso.containers import events
from plaso.lib import errors
from plaso.parsers import text_parser
from plaso.parsers.text_plugins import interface


class SophosAVLogEventData(events.EventData):
    """Sophos anti-virus log event data.

    Attributes:
      added_time (dfdatetime.DateTimeValues): date and time the log entry
          was added.
      text (str): Sophos anti-virus log message.
    """

    DATA_TYPE = "sophos:av:log"

    def __init__(self):
        """Initializes event data."""
        super().__init__(data_type=self.DATA_TYPE)
        self.added_time = None
        self.text = None


class SophosAVLogTextPlugin(interface.TextPlugin):
    """Text parser plugin for Sophos anti-virus logs (SAV.txt) files."""

    NAME = "sophos_av"
    DATA_FORMAT = "Sophos anti-virus log file (SAV.txt) file"

    ENCODING = "utf-16-le"

    _TWO_DIGITS = pyparsing.Word(pyparsing.nums, exact=2).set_parse_action(
        lambda tokens: int(tokens[0], 10)
    )

    _FOUR_DIGITS = pyparsing.Word(pyparsing.nums, exact=4).set_parse_action(
        lambda tokens: int(tokens[0], 10)
    )

    # Date and time values are formatted as: YYYYMMDD hhmmss
    # For example: 20100720 183814
    _DATE_TIME = pyparsing.Group(
        _FOUR_DIGITS
        + _TWO_DIGITS
        + _TWO_DIGITS
        + _TWO_DIGITS
        + _TWO_DIGITS
        + _TWO_DIGITS
    )

    _END_OF_LINE = pyparsing.Suppress(pyparsing.LineEnd())

    _LOG_LINE = (
        _DATE_TIME.set_results_name("date_time")
        + pyparsing.restOfLine().set_results_name("text")
        + _END_OF_LINE
    )

    _LINE_STRUCTURES = [("log_line", _LOG_LINE)]

    VERIFICATION_GRAMMAR = _LOG_LINE

    def _ParseRecord(self, parser_mediator, key, structure):
        """Parses a pyparsing structure.

        Args:
          parser_mediator (ParserMediator): mediates interactions between parsers
              and other components, such as storage and dfVFS.
          key (str): name of the parsed structure.
          structure (pyparsing.ParseResults): tokens from a parsed log line.

        Raises:
          ParseError: if the structure cannot be parsed.
        """
        time_elements_structure = self._GetValueFromStructure(structure, "date_time")

        event_data = SophosAVLogEventData()
        event_data.added_time = self._ParseTimeElements(time_elements_structure)
        event_data.text = self._GetStringValueFromStructure(structure, "text")

        parser_mediator.ProduceEventData(event_data)

    def _ParseTimeElements(self, time_elements_structure):
        """Parses date and time elements of a log line.

        Args:
          time_elements_structure (pyparsing.ParseResults): date and time elements
              of a log line.

        Returns:
          dfdatetime.TimeElements: date and time value.

        Raises:
          ParseError: if a valid date and time value cannot be derived from
              the time elements.
        """
        try:
            # Ensure time_elements_tuple is not a pyparsing.ParseResults otherwise
            # copy.deepcopy() of the dfDateTime object will fail on Python 3.8 with:
            # "TypeError: 'str' object is not callable" due to pyparsing.ParseResults
            # overriding __getattr__ with a function that returns an empty string
            # when named token does not exists.

            year, month, day_of_month, hours, minutes, seconds = time_elements_structure

            time_elements_tuple = (year, month, day_of_month, hours, minutes, seconds)

            date_time = dfdatetime_time_elements.TimeElements(
                time_elements_tuple=time_elements_tuple
            )

            # TODO: check if date and time values are local time or in UTC.
            date_time.is_local_time = True

            return date_time

        except (IndexError, TypeError, ValueError) as exception:
            raise errors.ParseError(
                f"Unable to parse time elements with error: {exception!s}"
            )

    def CheckRequiredFormat(self, parser_mediator, text_reader):
        """Check if the log record has the minimal structure required by the plugin.

        Args:
          parser_mediator (ParserMediator): mediates interactions between parsers
              and other components, such as storage and dfVFS.
          text_reader (EncodedTextReader): text reader.

        Returns:
          bool: True if this is the correct plugin, False otherwise.
        """
        try:
            structure = self._VerifyString(text_reader.lines)
        except errors.ParseError:
            return False

        time_elements_structure = self._GetValueFromStructure(structure, "date_time")

        try:
            self._ParseTimeElements(time_elements_structure)
        except ValueError:
            return False

        return True


text_parser.TextLogParser.RegisterPlugin(SophosAVLogTextPlugin)
