#!/usr/bin/env python3

# Copyright (C) 1994-2021 Altair Engineering, Inc.
# For more information, contact Altair at www.altair.com.
#
# This file is part of both the OpenPBS software ("OpenPBS")
# and the PBS Professional ("PBS Pro") software.
#
# Open Source License Information:
#
# OpenPBS is free software. You can redistribute it and/or modify it under
# the terms of the GNU Affero General Public License as published by the
# Free Software Foundation, either version 3 of the License, or (at your
# option) any later version.
#
# OpenPBS 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 Affero General Public
# License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
# Commercial License Information:
#
# PBS Pro is commercially licensed software that shares a common core with
# the OpenPBS software.  For a copy of the commercial license terms and
# conditions, go to: (http://www.pbspro.com/agreement.html) or contact the
# Altair Legal Department.
#
# Altair's dual-license business model allows companies, individuals, and
# organizations to create proprietary derivative works of OpenPBS and
# distribute them - whether embedded or bundled with other software -
# under a commercial license agreement.
#
# Use of Altair's trademarks, including but not limited to "PBS™",
# "OpenPBS®", "PBS Professional®", and "PBS Pro™" and Altair's logos is
# subject to Altair's trademark licensing policies.

import sys
import time
import sqlite3
import subprocess
import socket
import json
import os
import atexit
import re
from signal import SIGTERM


#
# CLASS Daemon
#
class Daemon(object):
    """
    Deamon class
    """

    sleeptime = 5

    def __init__(self, pidfile, debug):
        self.pidfile = pidfile
        self.debug = debug

    def daemonize(self):
        """
        Daemonize me
        """

        try:
            pid = os.fork()
            if pid > 0:
                sys.exit(0)
        except Exception as err:
            printf("fork failed: %s" % err)
            sys.exit(1)

        os.chdir("/")
        os.setsid()
        os.umask(0)

        atexit.register(self.delPID)
        pid = str(os.getpid())
        open(self.pidfile, 'w+').write("%s\n" % pid)

    def delPID(self):
        """
        Delete PID file
        """

        try:
            os.remove(self.pidfile)
        except OSError:
            pass

    def status(self):
        """
        Check status of daemon
        """

        try:
            f = open(self.pidfile, 'r')
            pid = int(f.read().strip())
            f.close()
        except IOError:
            return None

        try:
            os.kill(pid, 0)
        except Exception:
            self.delPID()
            return None

        return pid

    def start(self):
        """
        Daemonize and start main process: run()
        """

        pid = self.status()

        if pid:
            print("Daemon already running with pid %d" % pid)
            sys.exit(1)

        if not self.debug:
            if self.daemonize():
                sys.exit(1)

        try:
            self.run()
        except Exception as err:
            if self.debug:
                print("run() failed: %s" % err)
            return(1)

        return(0)

    def stop(self):
        """
        Stop process
        """

        try:
            f = open(self.pidfile, 'r')
            pid = int(f.read().strip())
            f.close()
        except IOError:
            pid = None

        if not pid:
            return(0)

        try:
            while True:
                os.kill(pid, SIGTERM)
                time.sleep(0.1)
        except OSError as err:
            err = str(err)
            if err.find("No such process") > 0:
                if os.path.exists(self.pidfile):
                    self.delPID()
            else:
                return(1)

        return(0)

    def restart(self):
        """
        Restart process - stop and start again
        """

        if self.stop() == 0:
            return self.start()

        return 1

    def run(self):
        """
        Main loop
        """

        while True:
            time.sleep(self.sleeptime)


#
# CLASS sender
#
class PBS_mail_sender(Daemon):
    """
    Email sender class
    """

    pidfile = "/var/spool/pbs/pbs_mail.pid"
    sqlite_db = "/var/spool/pbs/mail.sqlite"
    tb_name_emails = "pbs_emails"
    tb_name_timestamps = "pbs_users_timestamp"
    gathering_period = 1800
    mailer_cycle_sleep = 60
    sendmail = "/usr/sbin/sendmail"
    add_servername = True
    send_begin_immediately = False

    def __init__(self, debug):
        config = {}
        try:
            config_file = "pbs_mail.json"
            paths = []

            abspath = os.path.dirname(os.path.abspath(__file__))
            paths.append(os.path.join(abspath, config_file))
            paths.append(os.path.join(abspath, '..', 'etc', config_file))
            paths.append(os.path.join('/etc', config_file))
            paths.append(os.path.join('/opt', 'pbs', 'etc', config_file))

            for path in paths:
                if os.path.isfile(path):
                    config_file = path
                    break

            f = open(os.path.join(path, config_file),)
            config = json.load(f)
            f.close()

            self.pidfile = config["pidfile"]
            self.sqlite_db = config["sqlite_db"]
            self.gathering_period = config["gathering_period"]
            self.mailer_cycle_sleep = config["mailer_cycle_sleep"]
            self.sendmail = config["sendmail"]
            self.add_servername = config["add_servername"]
            self.send_begin_immediately = \
                config["send_begin_immediately"]

        except Exception as err:
            print("Failed to load configuration: %s" % err)
            sys.exit(1)

        super(PBS_mail_sender, self).__init__(self.pidfile, debug)

    def db_delete_emails(self, c):
        """
        Delete 'emails_to_delete' from sqllite db
        """

        for rowid in self.emails_to_delete:
            c.execute("DELETE FROM '%s' WHERE rowid == %d" % (
                self.tb_name_emails,
                rowid))
        self.emails_to_delete = []

    def send_mail(self, email_to, email_from, subject, body):
        """
        Real email sending
        """

        p = subprocess.Popen([self.sendmail, '-f ' + email_from, email_to],
                             stdout=subprocess.PIPE,
                             stdin=subprocess.PIPE,
                             stderr=subprocess.STDOUT)

        email_input = "To: %s\n" % email_to
        email_input += "Subject: %s\n\n" % subject
        email_input += body
        p.communicate(input=str.encode(email_input))

    def run(self):
        """
        Main
        """

        while True:
            now = int(time.time())

            try:
                conn = sqlite3.connect(self.sqlite_db)

                def regexp(expr, item):
                    reg = re.compile(expr)
                    return reg.search(item) is not None
                conn.create_function("REGEXP", 2, regexp)

                c = conn.cursor()
                req = "SELECT name FROM sqlite_master \
                      WHERE type='table' AND name='%s'" % \
                      self.tb_name_emails
                c.execute(req)
                if c.fetchone() is None:
                    conn.commit()
                    conn.close()
                    time.sleep(self.mailer_cycle_sleep)
                    continue
            except Exception as err:
                print(str(err))
                conn.commit()
                conn.close()
                time.sleep(self.mailer_cycle_sleep)
                continue

            emails_to_send = {}
            self.emails_to_delete = []
            threshold = now - self.gathering_period

            if self.send_begin_immediately:
                req = "SELECT rowid, date, email_to, email_from, subject, body \
                      FROM '%s' \
                      WHERE body REGEXP \
                      '.*Begun execution.*|\
.*Reservation period starting.*'" % self.tb_name_emails
                for email in c.execute(req):
                    (rowid,
                        timestamp,
                        email_to,
                        email_from,
                        subject,
                        body) = email

                    if email_to not in emails_to_send.keys():
                        emails_to_send[email_to] = []

                    emails_to_send[email_to].append([email_from,
                                                    subject,
                                                    body])
                    self.emails_to_delete.append(rowid)

            self.db_delete_emails(c)

            req = "SELECT name FROM sqlite_master \
                  WHERE type='table' AND name='%s'" % \
                  self.tb_name_timestamps
            c.execute(req)
            if c.fetchone() is None:
                req = "CREATE TABLE %s \
                      (date integer, recipient text UNIQUE)" % \
                      self.tb_name_timestamps
                c.execute(req)

            recipients = {}

            req = "SELECT DISTINCT email_to FROM '%s'" % self.tb_name_emails
            for email_to, in c.execute(req):
                recipients[email_to] = 1

            req = "SELECT date, recipient FROM '%s'" % self.tb_name_timestamps
            for timestamp, email_to in c.execute(req):
                recipients[email_to] = timestamp

            for i in recipients.keys():
                req = "SELECT rowid, date, email_to, email_from, subject, body \
                      FROM '%s' WHERE email_to = '%s'" % (
                      self.tb_name_emails,
                      i)
                for email in c.execute(req):
                    (rowid,
                        timestamp,
                        email_to,
                        email_from,
                        subject,
                        body) = email

                    is_time = recipients[email_to] < \
                        now - self.gathering_period
                    is_present = email_to in emails_to_send.keys()
                    if is_time or is_present:
                        if email_to not in emails_to_send.keys():
                            emails_to_send[email_to] = []

                        emails_to_send[email_to].append([
                            email_from,
                            subject,
                            body])
                        self.emails_to_delete.append(rowid)

            self.db_delete_emails(c)

            for email_to in emails_to_send.keys():
                req = "SELECT recipient FROM '%s' \
                      WHERE recipient='%s'" % (
                      self.tb_name_timestamps,
                      email_to)
                c.execute(req)
                if c.fetchone() is None:
                    req = "INSERT INTO %s VALUES (%d, '%s')" % (
                          self.tb_name_timestamps,
                          now,
                          email_to)
                else:
                    req = "UPDATE '%s' SET date = %d \
                          WHERE recipient = '%s'" % (
                          self.tb_name_timestamps,
                          now,
                          email_to)
                c.execute(req)

            conn.commit()
            conn.close()

            for email_to in emails_to_send.keys():
                email_from = ""
                email_body = ""
                subject = "PBS report"
                subjects = []

                for email in emails_to_send[email_to]:
                    email_from = email[0]
                    if self.add_servername:
                        email_body += email[1] \
                                      + "@" \
                                      + socket.gethostname()\
                                      + "\n\t"
                    else:
                        email_body += email[1] + "\n\t"
                    email_body += email[2].replace("\n", "\n\t") + "\n\n"
                    subjects.append(email[1])

                if len(subjects) == 1:
                    subject = subjects[0]
                else:
                    is_job = False
                    is_resv = False
                    for s in subjects:
                        if s.startswith("PBS JOB"):
                            is_job = True
                        if s.startswith("PBS RESERVATION"):
                            is_resv = True
                    subject = "PBS "
                    if is_job:
                        subject += "JOB"
                    if is_job and is_resv:
                        subject += "|"
                    if is_resv:
                        subject += "RESERVATION"
                    subject += " squashed report"
                    email_body = "This e-mail is a squashed report of " \
                                 + str(len(subjects)) \
                                 + " e-mails from PBS.\n\n" \
                                 + email_body
                self.send_mail(email_to, email_from, subject, email_body)

            time.sleep(self.mailer_cycle_sleep)


if __name__ == "__main__":
    debug = False
    if "--debug" in sys.argv or "-d" in sys.argv:
        debug = True

    sender = PBS_mail_sender(debug)

    if len(sys.argv) > 1:
        if 'restart' in sys.argv:
            if sender.stop() != 0 or sender.start() != 0:
                print("Restarting failed")

        elif 'stop' in sys.argv:
            if sender.stop() > 0:
                print("Stopping failed")

        elif 'start' in sys.argv:
            if sender.start() > 0:
                print("Starting failed")

        else:
            print("Unknown deamon command: %s" % " ".join(sys.argv))
            print("usage: %s start|stop|restart [-d|--debug]" % sys.argv[0])
            sys.exit(1)

        sys.exit(0)

    else:
        print("usage: %s start|stop|restart [-d|--debug]" % sys.argv[0])
        sys.exit(1)