#!/usr/bin/env python

import psycopg, pwd, grp, smtplib, os
from email.MIMEText import MIMEText
import Settings, PasswordTools

class InvalidDomain(Exception):
  """This exception is raised if an invalid domain is used."""
  def __init__(self, domain):
    self.domain = domain
  
  def __str__(self):
    return repr("Invalid domain %s" % (self.domain))

class NoSysuserForDomain(Exception):
  """This exception is raised if no system user is associated with a domain."""
  def __init__(self, domain):
    self.domain = domain

  def __str__(self):
    return repr("No system user for domain %s" % (self.domain))

class InvalidPopUser(Exception):
  """This exception is raised if an invalid POP3/IMAP user has been specified."""
  def __init__(self, domain, username):
    self.domain = domain
    self.username = username

  def __str__(self):
    return "Invalid POP3/IMAP user %s in domain %s." % (self.username, self.domain)

class Domain:
  """A Domain representation object with service methods."""
  def __init__(self, domain):
    self.cnx = psycopg.connect("user=%(dbuser)s password=%(dbpassword)s dbname=%(dbname)s" % Settings.dbsettings)
    self.domain = domain
    self.validate_domain()

  def validate_domain(self):
    """This function validates whether the given domain is allowed.
    That means that the domain needs to be registered in the database.
  
    If the domain is invalid InvalidDomain is raised."""
    cr = self.cnx.cursor()

    cr.execute("SELECT * FROM domain WHERE domainname=%(name)s" %
               {'name': psycopg.QuotedString(self.domain)})
    self.cnx.commit()

    result = cr.fetchall()
    if (not result):
      raise InvalidDomain(self)

  def __str__(self):
    return str(self.domain)

  def getSysuser(self):
    """Gets the system user id of the domain."""
    cr = self.cnx.cursor()

    cr.execute("""SELECT sysuser.name FROM domain, sysuser 
                  WHERE domain.domainname=%(name)s
		  AND domain.sysuserid=sysuser.sysuserid""" %
		  {'name': psycopg.QuotedString(self.domain)})
    self.cnx.commit()

    result = cr.fetchall()
    if (not result):
      raise NoSysuserForDomain(self)
    # return row 0, field 0
    return result[0][0]

  def getNextPopUser(self):
    """Gets the user id of the next available POP3/IMAP-user for the domain."""
    cr = self.cnx.cursor()

    sysuser = self.getSysuser()

    cr.execute("""SELECT max(id) FROM mailpasswd WHERE 
                  id LIKE %(username)s""" %
		  {'username': psycopg.QuotedString(sysuser+'%')})
    self.cnx.commit()

    result = cr.fetchall()
    if (not result):
      return sysuser + "p1"

    maxpopuser = result[0][0]
    if (not maxpopuser):
      return sysuser + "p1"

    num = int(maxpopuser[len(sysuser)+1:])+1
    return "%sp%d" % (sysuser, num)

  def makePopUser(self, password):
    """Creates a new POP3/IMAP-user for the domain using the given password."""
    cr = self.cnx.cursor()

    sysuser = self.getSysuser()
    popaccount = self.getNextPopUser()
    crypted = PasswordTools.md5_crypt_password(password)
    uid = pwd.getpwnam(sysuser)[2]
    gid = grp.getgrnam(Settings.popgroup)[2]
    homedir = Settings.pophome + popaccount

    os.mkdir(homedir, 0755)
    os.system("maildirmake \"%s/Maildir\"" % (homedir))
    os.system("chown -R %s.%s %s" % ( sysuser, Settings.popgroup, homedir ))

    cr = self.cnx.cursor()
    cr.execute("""INSERT INTO mailpasswd (id, crypt, clear, uid, gid, home)
             VALUES (%(id)s, %(crypt)s, %(clear)s, %(uid)d, %(gid)d, %(home)s)""" % {
	      'id': psycopg.QuotedString(popaccount),
	      'crypt': psycopg.QuotedString(crypted),
	      'clear': psycopg.QuotedString(password),
	      'uid': uid, 'gid': gid, 
	      'home': psycopg.QuotedString(homedir)})
    self.cnx.commit()

    text = """A new POP3/IMAP account has been created
Domain:   %(domain)s
User:     %(user)s
Password: %(password)s""" % {'domain': self.domain,
	       'user': popaccount,
	       'password': password}
    themail = MIMEText(text)
    themail['Subject'] = "A new POP3/IMAP account has been created"
    themail['From'] = Settings.mailsender
    themail['To'] = Settings.mailreceiver

    s = smtplib.SMTP()
    s.connect()
    s.sendmail(Settings.mailsender, [Settings.mailreceiver], themail.as_string())
    s.close()

  def listPopUsers(self):
    sysuser = self.getSysuser()
  
    cr = self.cnx.cursor()
    cr.execute("SELECT id FROM mailpasswd WHERE id LIKE %(user)s" % {
               'user': psycopg.QuotedString(sysuser + '%')})
    self.cnx.commit()

    result = cr.fetchall()
    return [line[0] for line in result]

  def hasPopUser(self, username):
    """Checks whether the specified POP3/IMAP user exists in the domain."""
    return ([user for user in self.listPopUsers() if (user == username)])
  
  def updatePopPassword(self, username, password=PasswordTools.generate_password()):
    """Updates the password of the given POP3/IMAP user."""
    if self.hasPopUser(username):
      crypted = PasswordTools.md5_crypt_password(password)

      cr = self.cnx.cursor()
      cr.execute("UPDATE mailpasswd SET clear=%(clear)s, crypt=%(crypt)s WHERE id=%(user)s" % {
                 'clear': psycopg.QuotedString(password),
		 'crypt': psycopg.QuotedString(crypted),
		 'user': psycopg.QuotedString(username)})
      self.cnx.commit()
      print("updated password of user %s to %s" % (username, password))
    else:
      raise InvalidPopUser(self, username)
 
if __name__ == '__main__':
  domain = Domain('centrum-warenhaus-dresden.de')
  # list pop users
  print ", ".join(domain.listPopUsers())
  # check for not existing user
  #try:
  #  domain.updatePopPassword('usr03p2', 'test')
  #except InvalidPopUser, ipu:
  #  print ipu
  #domain.updatePopPassword('usr05p2')