#!/usr/bin/python

#
#	gpg-mailgate
#
#	This file is part of the gpg-mailgate source code.
#
#	gpg-mailgate 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, either version 3 of the License, or
#	(at your option) any later version.
#
#	gpg-mailgate source code 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 gpg-mailgate source code. If not, see <http://www.gnu.org/licenses/>.
#

from configparser import RawConfigParser
import GnuPG
import sqlalchemy
from sqlalchemy.sql import select, delete, update, and_
import smtplib
import markdown
import syslog
import os
from email.mime.text import MIMEText
from email.mime.multipart import MIMEMultipart

# Environment variable name we read to retrieve configuration path.  This is to
# enable non-root users to set up and run GPG Mailgate and to make the software
# testable.
CONFIG_PATH_ENV = "GPG_MAILGATE_CONFIG"

def appendLog(msg):
	print(msg)
	if 'logging' in cfg and 'file' in cfg['logging']:
		if cfg['logging'].get('file') == "syslog":
			syslog.syslog(syslog.LOG_INFO | syslog.LOG_MAIL, msg)
		else:
			logfile = open(cfg['logging']['file'], 'a')
			logfile.write(msg + "\n")
			logfile.close()

def load_file(name):
    f = open(name)
    data = f.read()
    f.close()
    return data

def authenticate_maybe(smtp):
	if  'smtp' in cfg and 'enabled' in cfg['smtp'] and cfg['smtp']['enabled'] == 'true':
		smtp.connect(cfg['smtp']['host'],cfg['smtp']['port'])
		smtp.ehlo()
		if cfg['smtp']['startls'] == 'true':
			smtp.starttls()
		smtp.ehlo()
		smtp.login(cfg['smtp']['username'], cfg['smtp']['password'])

def send_msg( mailsubject, messagefile, recipients = None ):
	mailbody = load_file( cfg['cron']['mail_templates'] + "/" + messagefile)
	msg = MIMEMultipart("alternative")

	msg["From"] = cfg['cron']['notification_email']
	msg["To"] = recipients
	msg["Subject"] = mailsubject
	
	msg.attach(MIMEText(mailbody, 'plain'))
	msg.attach(MIMEText(markdown.markdown(mailbody), 'html'))
	
	if 'relay' in cfg and 'host' in cfg['relay'] and 'enc_port' in cfg['relay']:
		relay = (cfg['relay']['host'], int(cfg['relay']['enc_port']))
		smtp = smtplib.SMTP(relay[0], relay[1])
		authenticate_maybe(smtp)
		smtp.sendmail( cfg['cron']['notification_email'], recipients, msg.as_string() )
	else:
		appendLog("Could not send mail due to wrong configuration")

def setup_db_connection(url):
	engine = sqlalchemy.create_engine(url)
	return (engine, engine.connect())

def define_db_schema():
	meta = sqlalchemy.MetaData()

	gpgmw_keys = sqlalchemy.Table('gpgmw_keys', meta,
								  sqlalchemy.Column('id', sqlalchemy.Integer, primary_key=True),
								  sqlalchemy.Column('email', sqlalchemy.String(256)),
								  sqlalchemy.Column('publickey', sqlalchemy.Text),
								  sqlalchemy.Column('confirm', sqlalchemy.String(32)),
								  sqlalchemy.Column('status', sqlalchemy.Integer),
								  sqlalchemy.Column('time', sqlalchemy.DateTime))

	return (gpgmw_keys)


# Read configuration from /etc/gpg-mailgate.conf
_cfg = RawConfigParser()
_cfg.read(os.getenv(CONFIG_PATH_ENV, '/etc/gpg-mailgate.conf'))
cfg = dict()
for sect in _cfg.sections():
	cfg[sect] = dict()
	for (name, value) in _cfg.items(sect):
		cfg[sect][name] = value

if 'database' in cfg and 'enabled' in cfg['database'] and cfg['database']['enabled'] == 'yes' and 'url' in cfg['database']:
	(engine, conn) = setup_db_connection(cfg["database"]["url"])
	(gpgmw_keys) = define_db_schema()

	selq = select(gpgmw_keys.c.publickey, gpgmw_keys.c.id, gpgmw_keys.c.email)\
	  .where(and_(gpgmw_keys.c.status == 0, gpgmw_keys.c.confirm == ""))\
	  .limit(100)
	result_set = conn.execute(selq)

	for row in result_set:
		# delete any other public keys associated with this confirmed email address
		delq = delete(gpgmw_keys).where(and_(gpgmw_keys.c.email == row[2], gpgmw_keys.c.id != row[1]))
		conn.execute(delq)
		GnuPG.delete_key(cfg['gpg']['keyhome'], row[2])
		appendLog('Deleted key for <' + row[2] + '> via import request')

		if row[0].strip(): # we have this so that user can submit blank key to remove any encryption
			if GnuPG.confirm_key(row[0], row[2]):
				GnuPG.add_key(cfg['gpg']['keyhome'], row[0]) # import the key to gpg
				modq = gpgmw_keys.update().where(gpgmw_keys.c.id == row[1]).values(status = 1)
				conn.execute(modq) # mark key as accepted
				appendLog('Imported key from <' + row[2] + '>')
				if 'send_email' in cfg['cron'] and cfg['cron']['send_email'] == 'yes':
					send_msg( "PGP key registration successful", "registrationSuccess.md", row[2] )
			else:
				delq = delete(gpgmw_keys).where(gpgmw_keys.c.id == row[1])
				conn.execute(delq) # delete key
				appendLog('Import confirmation failed for <' + row[2] + '>')
				if 'send_email' in cfg['cron'] and cfg['cron']['send_email'] == 'yes':
					send_msg( "PGP key registration failed", "registrationError.md", row[2] )
		else:
			# delete key so we don't continue processing it
			delq = delete(gpgmw_keys).where(gpgmw_keys.c.id == row[1])
			conn.execute(delq)
			if 'send_email' in cfg['cron'] and cfg['cron']['send_email'] == 'yes':
				send_msg( "PGP key deleted", "keyDeleted.md", row[2])

	# delete keys
	stat2q = select(gpgmw_keys.c.email, gpgmw_keys.c.id).where(gpgmw_keys.c.status == 2).limit(100)
	stat2_result_set = conn.execute(stat2q)

	for row in stat2_result_set:
		GnuPG.delete_key(cfg['gpg']['keyhome'], row[0])
		delq = delete(gpgmw_keys).where(gpgmw_keys.c.id == row[1])
		conn.execute(delq)
		appendLog('Deleted key for <' + row[0] + '>')
else:
	print("Warning: doing nothing since database settings are not configured!")