"""Text parser plugin for bash history files."""

import pyparsing

from dfdatetime import posix_time as dfdatetime_posix_time

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


class BashHistoryEventData(events.EventData):
    """Bash history log event data.

    Attributes:
      command (str): command that was executed.
      written_time (dfdatetime.DateTimeValues): date and time the entry was
          written.
    """

    DATA_TYPE = "bash:history:entry"

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


class BashHistoryTextPlugin(interface.TextPluginWithLineContinuation):
    """Text parser plugin for bash history files."""

    NAME = "bash_history"

    DATA_FORMAT = "Bash history file"

    ENCODING = "utf-8"

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

    _TIMESTAMP_LINE = pyparsing.Regex(r"#(?P<timestamp>[1-9][0-9]{8,9})\n")

    _COMMAND_LINE = pyparsing.restOfLine().set_results_name("command") + _END_OF_LINE

    _LINE_STRUCTURES = [("timestamp_line", _TIMESTAMP_LINE)]

    # A desynchronized bash history file will start with the command line
    # instead of the timestamp.
    VERIFICATION_GRAMMAR = (_TIMESTAMP_LINE + _COMMAND_LINE) ^ (
        _COMMAND_LINE + _TIMESTAMP_LINE + _COMMAND_LINE
    )

    def __init__(self):
        """Initializes a text parser plugin."""
        super().__init__()
        self._command_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.command = " ".join(self._command_lines)
            self._command_lines = []

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

    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":
            # A desynchronized bash history file will start with the command line
            # instead of the timestamp.
            if not self._event_data:
                self._event_data = BashHistoryEventData()

            command = structure.replace("\n", " ").strip()
            self._command_lines.append(command)

        else:
            if self._event_data:
                self._event_data.command = " ".join(self._command_lines)

                parser_mediator.ProduceEventData(self._event_data)

            timestamp = self._GetDecimalValueFromStructure(structure, "timestamp")

            self._event_data = BashHistoryEventData()
            self._event_data.written_time = dfdatetime_posix_time.PosixTime(
                timestamp=timestamp
            )
            self._command_lines = []

    def _ResetState(self):
        """Resets stored values."""
        self._command_lines = []
        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:
            self._VerifyString(text_reader.lines)
        except errors.ParseError:
            return False

        self._ResetState()

        return True


text_parser.TextLogParser.RegisterPlugin(BashHistoryTextPlugin)
