"""Text parser plugin for System Center Configuration Manager (SCCM) logs."""

import re

from dfdatetime import time_elements as dfdatetime_time_elements

import pyparsing

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


class SCCMLogEventData(events.EventData):
    """SCCM log event data.

    Attributes:
      component (str): component.
      text (str): text.
      written_time (dfdatetime.DateTimeValues): date and time the entry was
          written.
    """

    DATA_TYPE = "sccm_log:entry"

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


class SCCMTextPlugin(interface.TextPlugin):
    """Text parser plugin for System Center Configuration Manager (SCCM) logs."""

    NAME = "sccm"
    DATA_FORMAT = "System Center Configuration Manager (SCCM) client log file"

    ENCODING = "utf-8"

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

    _TWO_OR_THREE_DIGITS = pyparsing.Word(
        pyparsing.nums, min=2, max=3
    ).set_parse_action(lambda tokens: int(tokens[0], 10))

    _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 formatted as: date="M-D-YYYY"
    _DATE = (
        pyparsing.Suppress('" date="')
        + _ONE_OR_TWO_DIGITS
        + pyparsing.Suppress("-")
        + _ONE_OR_TWO_DIGITS
        + pyparsing.Suppress("-")
        + _FOUR_DIGITS
    )

    _TIME_ZONE_OFFSET = pyparsing.Group(
        pyparsing.Word("+-", exact=1) + _TWO_OR_THREE_DIGITS
    )

    # Time formatted as: time="h:mm:ss.###or time="h:mm:ss.###[+-]##"
    _TIME = (
        pyparsing.Suppress('time="')
        + _ONE_OR_TWO_DIGITS
        + pyparsing.Suppress(":")
        + _TWO_DIGITS
        + pyparsing.Suppress(":")
        + _TWO_DIGITS
        + pyparsing.Suppress(".")
        + pyparsing.Regex(r"\d{3,7}")
        + pyparsing.Optional(_TIME_ZONE_OFFSET)
    )

    _DATE_TIME = (_TIME + _DATE).set_results_name("date_time")

    _LOG_MESSAGE_START = pyparsing.Suppress("<![LOG[")

    # Using a regular expression look ahead here is faster than pyparsing.SkipTo()
    _LOG_MESSAGE_TEXT = pyparsing.Regex(r".*?(?=(]LOG]!><))", re.DOTALL)

    _LOG_MESSAGE_END = pyparsing.Suppress("]LOG]!><")

    _LOG_MESSAGE = (
        _LOG_MESSAGE_START
        + _LOG_MESSAGE_TEXT.set_results_name("text")
        + _LOG_MESSAGE_END
    )

    _COMPONENT = pyparsing.Suppress('" component="') + pyparsing.Word(
        pyparsing.alphanums
    ).set_results_name("component")

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

    _LOG_LINE = (
        _LOG_MESSAGE
        + _DATE_TIME
        + _COMPONENT
        + pyparsing.Regex(r".*?(?=(<!\[LOG\[))", re.DOTALL)
    )

    _LAST_LOG_LINE = (
        _LOG_MESSAGE + _DATE_TIME + _COMPONENT + pyparsing.restOfLine() + _END_OF_LINE
    )

    _LINE_STRUCTURES = [("log_line", _LOG_LINE), ("last_log_line", _LAST_LOG_LINE)]

    # Because logs files can lead with a partial event, we can't assume that
    # the first character (post-BOM) in the file is the beginning of our match,
    # so we look for match anywhere in lines.

    VERIFICATION_GRAMMAR = (
        pyparsing.Regex(r".*<!\[LOG\[.*]LOG]!><", re.DOTALL) + _DATE_TIME + _COMPONENT
    )

    VERIFICATION_LITERALS = ["<![LOG[", ']LOG]!><time="']

    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 = SCCMLogEventData()
        event_data.component = self._GetValueFromStructure(structure, "component")
        event_data.text = self._GetValueFromStructure(structure, "text")
        event_data.written_time = self._ParseTimeElements(time_elements_structure)

        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.
        """
        # 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 exist.

        try:
            if len(time_elements_structure) == 8:
                (
                    hours,
                    minutes,
                    seconds,
                    fraction_of_second,
                    utc_offset_minutes,
                    month,
                    day_of_month,
                    year,
                ) = time_elements_structure

                time_zone_offset = utc_offset_minutes[1]
                if utc_offset_minutes[0] == "-":
                    time_zone_offset *= -1

            else:
                (
                    hours,
                    minutes,
                    seconds,
                    fraction_of_second,
                    month,
                    day_of_month,
                    year,
                ) = time_elements_structure

                time_zone_offset = None

            if len(fraction_of_second) == 3:
                milliseconds = int(fraction_of_second, 10)
                time_elements_tuple = (
                    year,
                    month,
                    day_of_month,
                    hours,
                    minutes,
                    seconds,
                    milliseconds,
                )
                date_time = dfdatetime_time_elements.TimeElementsInMilliseconds(
                    time_elements_tuple=time_elements_tuple,
                    time_zone_offset=time_zone_offset,
                )

            else:
                # TODO: improve precision support, but for now ignore the 100ns
                # precision.
                microseconds = int(fraction_of_second[:6], 10)
                time_elements_tuple = (
                    year,
                    month,
                    day_of_month,
                    hours,
                    minutes,
                    seconds,
                    microseconds,
                )
                date_time = dfdatetime_time_elements.TimeElementsInMicroseconds(
                    time_elements_tuple=time_elements_tuple,
                    time_zone_offset=time_zone_offset,
                )

            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 parser.

        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 errors.ParseError:
            return False

        return True


text_parser.TextLogParser.RegisterPlugin(SCCMTextPlugin)
