#
#   logactio  -  simple framework for doing configured action on certain
#                log file events
#
#   Copyright 2012 - 2015   David Sommerseth <dazo@eurephia.org>
#
#   This program is free software; you can redistribute it and/or
#   modify it under the terms of the GNU General Public License
#   as published by the Free Software Foundation, version 2
#   of the License.
#
#   This program is distributed in the hope that it will be useful,
#   but WITHOUT ANY WARRANTY; without even the implied warranty of
#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#   GNU General Public License for more details.
#
#   You should have received a copy of the GNU General Public License
#   along with this program; if not, write to the Free Software
#   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
#
#   For the avoidance of doubt the "preferred form" of this code is one which
#   is in an open unpatent encumbered format. Where cryptographic key signing
#   forms part of the process of creating an executable the information
#   including keys needed to generate an equivalently functional executable
#   are deemed to be part of the source code.
#

import sys, smtplib
from email.mime.text import MIMEText
from LogActio import Message, ReporterQueue


class SMTPreporter(ReporterQueue.ReporterQueue):
    """Simple LogActio reporter module, sending alerts via SMTP

    Example configuration to be used in /etc/logactio.cfg

        [Reporter:SMTP]
        module: SMTPreporter
        sender: logactio@example.com
        recipients: john.doe@example.com, jane.doe@example.com
        subject_prefix: LogActio Alert:
        smtp_host: localhost
        smtp_port: 25

    This will send reports to the configured 'recipients' using the given SMTP
    server.
    """

    def __init__(self, config, logger = None):
        if "sender" not in config:
            raise Exception("SMTPreporter is not configured with a sender address")
        if "recipients" not in config:
            raise Exception("SMTPreporter is not configured with any recipients")
        if "smtp_host" not in config:
            raise Exception("SMTPreporter is not configured with SMTP host")

        self.__log = logger and logger or self.__logfnc
        self.__sender = config["sender"]
        self.__recipients = config["recipients"].split(",")
        self.__subjprefix = "subject_prefix" in config and config["subject_prefix"] or None
        self.__smtphost = config["smtp_host"]
        self.__smtpport = "smtp_port" in config and (int(config["smtp_port"])) or 25
        self.__smtpuser = "smtp_username" in config and config["smtp_username"] or None
        self.__smtppass = "smtp_password" in config and config["smtp_password"] or None
        self.__sslmode = "sslmode" in config and config["sslmode"] or None
        self.__idx = 0;

        if (self.__smtpuser and not self.__smtppass) or (not self.__smtpuser and self.__smtppass):
            raise Exception("SMTPreporter must have both smtp_username and smtp_password")

        if self.__sslmode is not None and self.__sslmode != "SSL" and self.__sslmode != "STARTTLS":
            raise Exception("SMTPreporter accepts only SSL or STARTTLS as sslmode values")

        ReporterQueue.ReporterQueue.__init__(self,
                                             "SMTPreporter",
                                             "SMTP Reporter",
                                             self.__processqueue)


    def __logfnc(self, lvl, msg):
        print("%s" % msg)
        sys.stdout.flush()


    def __processqueue(self):
        done = False

        # Process the message queue
        while not done:
            msg = self._QueueGet()

            if( msg.MessageType() == Message.MSG_SHUTDOWN ):
                # Prepare for shutdown
                done = True

            elif( msg.MessageType() == Message.MSG_SEND ):
                m = msg.Message()

                msg = MIMEText(m["body"])
                msg["From"] = self.__sender
                msg["To"] = ",".join(self.__recipients)
                if self.__subjprefix is None:
                    msg["Subject"] = "LogActio Alert: %s" % m["subject"]
                else:
                    msg["Subject"] = "%s %s" % (self.__subjprefix, m["subject"])

                try:
                    self.__log(3, "[SMTPreporter] Connecting to %s:%i" % (self.__smtphost,
                                                                          self.__smtpport))

                    if self.__sslmode == "SSL":
                        smtp.smtplib.SMTP_SSL(self.__smtphost, self.__smtpport)
                    else:
                        smtp = smtplib.SMTP(self.__smtphost, self.__smtpport)
                        if self.__sslmode == "STARTTLS":
                            smtp.starttls()

                    if self.__smtpuser is not None:
                        self.__log(3, "[SMTPreporter] Logging in as %s" % self.__smtpuser)
                        smtp.login(self.__smtpuser, self.__smtppass)

                    smtp.sendmail(self.__sender, self.__recipients, msg.as_string())
                    self.__idx += 1
                    self.__log(1, "[SMTPReporter] {%i} {Rule %s} Logfile: %s, Threshold: %i, Count: %i -- Report sent to: %s" %
                               (self.__idx, m["rulename"], m["logfile"], m["threshold"], m["count"], ", ".join(self.__recipients)))
                    self.__log(2, "[SMTPReporter] {%i} Details: %s" % (self.__idx, str(m["msg"])))
                    smtp.quit()
                except Exception as e:
                    self.__log(0, "** ERROR ** SMTPreporter failed: {%i} %s" % (self.__idx, str(e)))


    def ProcessEvent(self, logfile, rulename, msg, count, threshold):
        # Format the report message
        msg = {"rulename": rulename, "threshold": threshold,
               "count": count, "logfile": logfile, "msg": msg,
               "subject": "Alerts from %s" % logfile,
               "body": """
LogActio have detected %s events in the %s log file since it started running.\n
The following information was extracted:\n
%s
""" % (count, logfile, "\n".join(msg))}

        # Queue the message for sending
        self._QueueMsg(0, msg)


def InitReporter(config, logger = None):
    return SMTPreporter(config, logger)