"""Text parser plugin for Google Drive Sync log 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 GoogleDriveSyncLogEventData(events.EventData):
    """Google Drive Sync log event data.

    Attributes:
      added_time (dfdatetime.DateTimeValues): date and time the log entry was added.
      level (str): logging level of event such as "DEBUG", "WARN", "INFO" and "ERROR".
      message_body (str): message body.
      process_identifier (int): process identifier of process which logged event.
      source_code (str): filename:line_number of source file which logged event.
      thread (str): colon-separated thread identifier in the form "ID:name"
          which logged event.
    """

    DATA_TYPE = "google_drive_sync_log:entry"

    def __init__(self):
        """Initializes event data."""
        super().__init__(data_type=self.DATA_TYPE)
        self.added_time = None
        self.level = None
        self.message_body = None
        self.process_identifier = None
        self.source_code = None
        self.thread = None


class GoogleDriveSyncLogTextPlugin(interface.TextPluginWithLineContinuation):
    """Text parser plugin for Google Drive Sync log files."""

    NAME = "gdrive_synclog"
    DATA_FORMAT = "Google Drive Sync log file"

    ENCODING = "utf-8"

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

    # Date and time values are formatted as:
    # 2018-03-01 12:48:14,224 -0800
    _DATE_TIME = pyparsing.Regex(
        r"(?P<date_time>[0-9]{4}-[0-9]{2}-[0-9]{2} "
        r"[0-9]{2}:[0-9]{2}:[0-9]{2}[,.][0-9]{3} [+-][0-9]{4}) "
    )

    _PROCESS_IDENTIFIER = pyparsing.Suppress("pid=") + _INTEGER.set_results_name(
        "process_identifier"
    )

    _THREAD = pyparsing.Combine(
        pyparsing.Word(pyparsing.nums)
        + pyparsing.Literal(":")
        + pyparsing.Word(pyparsing.printables)
    )

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

    _LOG_LINE_START = (
        _DATE_TIME
        + pyparsing.Word(pyparsing.alphas).set_results_name("level")
        + _PROCESS_IDENTIFIER
        +
        # TODO: consider stripping thread identifier/cleaning up thread name?
        _THREAD.set_results_name("thread")
        + pyparsing.Word(pyparsing.printables).set_results_name("source_code")
    )

    _LOG_LINE = (
        _LOG_LINE_START
        + pyparsing.restOfLine().set_results_name("message_body")
        + _END_OF_LINE
    )

    _LINE_STRUCTURES = [("log_line", _LOG_LINE)]

    # Using a regular expression here is faster on non-match than the log line
    # grammar.
    VERIFICATION_GRAMMAR = pyparsing.Regex(
        r"(?P<date_time>[0-9]{4}-[0-9]{2}-[0-9]{2} "
        r"[0-9]{2}:[0-9]{2}:[0-9]{2}[,.][0-9]{3} [+-][0-9]{4}) "
        r"[A-Z]+ pid=[0-9]+ [0-9]+:\S+[ ]+\S+:[0-9]+ .*\n"
    )

    VERIFICATION_LITERALS = [" ERROR ", " FATAL ", " INFO ", " pid=", " WARNING "]

    def __init__(self):
        """Initializes a text parser plugin."""
        super().__init__()
        self._body_lines = None
        self._event_data = None

    def _ParseFinalize(self, parser_mediator):
        """Finalizes parsing.

        Args:
          parser_mediator (ParserMediator): mediates interactions between parsers
              and other components, such as storage and dfVFS.
        """
        if self._event_data:
            self._event_data.message_body = " ".join(self._body_lines)
            self._body_lines = None

            parser_mediator.ProduceEventData(self._event_data)
            self._event_data = None

    def _ParseLogline(self, structure):
        """Parses a log line.

        Args:
          structure (pyparsing.ParseResults): structure of tokens derived from
              a line of a text file.
        """
        time_elements_structure = self._GetValueFromStructure(structure, "date_time")

        message_body = self._GetValueFromStructure(
            structure, "message_body", default_value=""
        ).strip()

        event_data = GoogleDriveSyncLogEventData()
        event_data.added_time = self._ParseTimeElements(time_elements_structure)
        event_data.level = self._GetValueFromStructure(structure, "level")
        event_data.process_identifier = self._GetValueFromStructure(
            structure, "process_identifier"
        )
        event_data.thread = self._GetValueFromStructure(structure, "thread")
        event_data.source_code = self._GetValueFromStructure(structure, "source_code")

        self._event_data = event_data
        self._body_lines = [message_body]

    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.
        """
        if key == "_line_continuation":
            message_body = structure.replace("\n", " ").strip()
            self._body_lines.append(message_body)

        else:
            if self._event_data:
                self._event_data.message_body = " ".join(self._body_lines)

                parser_mediator.ProduceEventData(self._event_data)

            self._ParseLogline(structure)

    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:
            date_time_string = time_elements_structure[:23].replace(",", ".")

            date_time = dfdatetime_time_elements.TimeElementsInMilliseconds()
            date_time.CopyFromDateTimeString(date_time_string)

            time_zone_offset = int(time_elements_structure[-4:-2], 10) * 60
            time_zone_offset += int(time_elements_structure[-2:], 10)
            if time_elements_structure[-5] == "-":
                time_zone_offset *= -1

            date_time.time_zone_offset = time_zone_offset
            date_time.is_local_time = False

            return date_time

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

    def _ResetState(self):
        """Resets stored values."""
        self._body_lines = None
        self._event_data = None

    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

        self._ResetState()

        return True


text_parser.TextLogParser.RegisterPlugin(GoogleDriveSyncLogTextPlugin)
