"""Text parser plugin for Apache access log (access.log) files.

Parser based on the two default apache formats, common and combined log format defined
in: https://httpd.apache.org/docs/2.4/logs.html
"""

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 ApacheAccessLogEventData(events.EventData):
    """Apache access log event data.

    Attributes:
      http_request_referer (str): http request referer header information.
      http_request (str): first line of http request.
      http_request_user_agent (str): http request user agent header information.
      http_response_bytes (int): http response bytes size without headers.
      http_response_code (int): http response code from server.
      ip_address (str): IPv4 or IPv6 addresses.
      port_number (int): canonical port of the server serving the request.
      recorded_time (dfdatetime.DateTimeValues): date and time the log entry
          was recorded.
      remote_name (str): remote logname (from identd, if supplied).
      server_name (str): canonical hostname of the server serving the request.
      username (str): username.
    """

    DATA_TYPE = "apache:access_log:entry"

    def __init__(self):
        """Initializes event data."""
        super().__init__(data_type=self.DATA_TYPE)
        self.http_request = None
        self.http_request_referer = None
        self.http_request_user_agent = None
        self.http_response_bytes = None
        self.http_response_code = None
        self.ip_address = None
        self.port_number = None
        self.recorded_time = None
        self.remote_name = None
        self.server_name = None
        self.username = None


class ApacheAccessLogTextPlugin(interface.TextPlugin):
    """Text parser plugin for Apache access log (access.log) files."""

    NAME = "apache_access"
    DATA_FORMAT = "Apache access log (access.log) file"

    _MONTH_DICT = {
        "jan": 1,
        "feb": 2,
        "mar": 3,
        "apr": 4,
        "may": 5,
        "jun": 6,
        "jul": 7,
        "aug": 8,
        "sep": 9,
        "oct": 10,
        "nov": 11,
        "dec": 12,
    }

    _INTEGER = pyparsing.Word(pyparsing.nums).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)
    )

    _THREE_LETTERS = pyparsing.Word(pyparsing.alphas, exact=3)

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

    # Date and time values are formatted as: [18/Sep/2011:19:18:28 -0400]
    _DATE_TIME = pyparsing.Group(
        pyparsing.Suppress("[")
        + _TWO_DIGITS
        + pyparsing.Suppress("/")
        + _THREE_LETTERS
        + pyparsing.Suppress("/")
        + _FOUR_DIGITS
        + pyparsing.Suppress(":")
        + _TWO_DIGITS
        + pyparsing.Suppress(":")
        + _TWO_DIGITS
        + pyparsing.Suppress(":")
        + _TWO_DIGITS
        + _TIME_ZONE_OFFSET
        + pyparsing.Suppress("]")
    ).set_results_name("date_time")

    _HTTP_METHOD = pyparsing.one_of(
        ["CONNECT", "DELETE", "GET", "HEAD", "OPTIONS", "PATCH", "POST", "PUT", "TRACE"]
    )

    _HTTP_VERSION = pyparsing.Combine(
        pyparsing.Literal("HTTP/") + pyparsing.Word(pyparsing.nums + ".")
    )

    _HTTP_REQUEST = (
        pyparsing.Suppress('"')
        + pyparsing.Group(
            _HTTP_METHOD + pyparsing.Regex(r"\S*") + _HTTP_VERSION
        ).set_results_name("http_request")
        + pyparsing.Suppress('"')
    )

    _IP_ADDRESS = (
        pyparsing.pyparsing_common.ipv4_address
        | pyparsing.pyparsing_common.ipv6_address
    )

    _REMOTE_NAME = (
        pyparsing.Word(pyparsing.alphanums) | pyparsing.Literal("-")
    ).set_results_name("remote_name")

    _RESPONSE_BYTES = (pyparsing.Literal("-") | _INTEGER).set_results_name(
        "response_bytes"
    )

    _SERVER_NAME = pyparsing.Word(pyparsing.alphanums + "-" + ".").set_results_name(
        "server_name"
    )

    _USER_AGENT = (
        pyparsing.Suppress('"')
        + pyparsing.CharsNotIn('"').set_results_name("user_agent")
        + pyparsing.Suppress('"')
    )

    _USER_NAME = (
        pyparsing.Word(pyparsing.alphanums + "@" + pyparsing.alphanums + ".")
        | pyparsing.Word(pyparsing.alphanums)
        | pyparsing.Literal("-")
    ).set_results_name("username")

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

    # Defined in https://httpd.apache.org/docs/2.4/logs.html
    # format: "%h %l %u %t \"%r\" %>s %b"
    _COMMON_LOG_FORMAT_LINE = (
        _IP_ADDRESS.set_results_name("ip_address")
        + _REMOTE_NAME
        + _USER_NAME
        + _DATE_TIME
        + _HTTP_REQUEST
        + _INTEGER.set_results_name("response_code")
        + _RESPONSE_BYTES
        + _END_OF_LINE
    )

    # Defined in https://httpd.apache.org/docs/2.4/logs.html
    # format: "%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-agent}i\""
    _COMBINED_LOG_FORMAT_LINE = (
        _IP_ADDRESS.set_results_name("ip_address")
        + _REMOTE_NAME
        + _USER_NAME
        + _DATE_TIME
        + _HTTP_REQUEST
        + _INTEGER.set_results_name("response_code")
        + _RESPONSE_BYTES
        + pyparsing.QuotedString('"').set_results_name("referer")
        + _USER_AGENT
        + _END_OF_LINE
    )

    # "vhost_combined" format as used by Debian and related distributions.
    # "%v:%p %h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-Agent}i\""
    _VHOST_COMBINED_LOG_FORMAT_LINE = (
        _SERVER_NAME
        + pyparsing.Suppress(":")
        + _INTEGER.set_results_name("port_number")
        + _IP_ADDRESS.set_results_name("ip_address")
        + _REMOTE_NAME
        + _USER_NAME
        + _DATE_TIME
        + _HTTP_REQUEST
        + _INTEGER.set_results_name("response_code")
        + _RESPONSE_BYTES
        + pyparsing.QuotedString('"').set_results_name("referer")
        + _USER_AGENT
        + _END_OF_LINE
    )

    _LINE_STRUCTURES = [
        ("combined_log_format", _COMBINED_LOG_FORMAT_LINE),
        ("common_log_format", _COMMON_LOG_FORMAT_LINE),
        ("vhost_combined_log_format", _VHOST_COMBINED_LOG_FORMAT_LINE),
    ]

    VERIFICATION_GRAMMAR = (
        _COMBINED_LOG_FORMAT_LINE
        ^ _COMMON_LOG_FORMAT_LINE
        ^ _VHOST_COMBINED_LOG_FORMAT_LINE
    )

    VERIFICATION_LITERALS = [
        '"CONNECT ',
        '"DELETE ',
        '"GET ',
        '"HEAD ',
        " HTTP/",
        '"OPTIONS ',
        '"PATCH ',
        '"POST ',
        '"PUT ',
        '"TRACE ',
    ]

    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")

        http_request = self._GetValueFromStructure(structure, "http_request")
        if http_request:
            http_request = " ".join(http_request)

        remote_name = self._GetValueFromStructure(structure, "remote_name")
        if remote_name == "-":
            remote_name = None

        username = self._GetValueFromStructure(structure, "username")
        if username == "-":
            username = None

        event_data = ApacheAccessLogEventData()
        event_data.http_request = http_request
        event_data.http_response_bytes = self._GetValueFromStructure(
            structure, "response_bytes"
        )
        event_data.http_response_code = self._GetValueFromStructure(
            structure, "response_code"
        )
        event_data.ip_address = self._GetValueFromStructure(structure, "ip_address")
        event_data.recorded_time = self._ParseTimeElements(time_elements_structure)
        event_data.remote_name = remote_name
        event_data.username = username

        if key in ("combined_log_format", "vhost_combined_log_format"):
            referer = self._GetValueFromStructure(structure, "referer")
            if referer == "-":
                referer = None

            event_data.http_request_referer = referer
            event_data.http_request_user_agent = self._GetValueFromStructure(
                structure, "user_agent"
            )

        if key == "vhost_combined_log_format":
            event_data.port_number = self._GetValueFromStructure(
                structure, "port_number"
            )
            event_data.server_name = self._GetValueFromStructure(
                structure, "server_name"
            )

        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:
            (
                day_of_month,
                month_string,
                year,
                hours,
                minutes,
                seconds,
                time_zone_sign,
                time_zone_hours,
                time_zone_minutes,
            ) = time_elements_structure

            month = self._MONTH_DICT.get(month_string.lower(), 0)

            time_zone_offset = (time_zone_hours * 60) + time_zone_minutes
            if time_zone_sign == "-":
                time_zone_offset *= -1

            time_elements_tuple = (year, month, day_of_month, hours, minutes, seconds)
            return dfdatetime_time_elements.TimeElements(
                time_elements_tuple=time_elements_tuple,
                time_zone_offset=time_zone_offset,
            )

        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 errors.ParseError:
            return False

        return True


text_parser.TextLogParser.RegisterPlugin(ApacheAccessLogTextPlugin)
