'''
The module contains the MailIterator class.

Copyright (c) 2012 Intra2net AG
Author: Plamen Dimitrov and Thomas Jarosch

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, either version 3 of the License, or
(at your option) any later version.

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.
'''

import sys
import socket, imaplib
import re
import logging

MAILBOX_RESP = re.compile(r'\((?P<flags>.*?)\) "(?P<delimiter>.*)" (?P<name>.*)')
UIDVAL_RESP = re.compile(r'(?P<name>.*) \(UIDVALIDITY (?P<uidval>.*)\)')
ACLS_RESP = re.compile(b'(?P<user>\S+) (?P<acls>\S+)')

#imaplib.Debug = 4

class MailIterator:
    """This class communicates with the e-mail server."""

    # class attributes
    # IMAP4_SSL for connection with an IMAP server
    mail_con = None
    # list of tuples (uidvalidity, mailboxname) for the retrieved mailboxes
    mailboxes = None
    # logged in status
    logged_in = None

    def __init__(self, server, username, password):
        """Creates a connection and a user session."""

        # connect to server
        try:
            self.mail_con = imaplib.IMAP4(server)

            # socket functionality (currently unavailable)
            #imap_socket = socket.socket(socket.AF_UNIX)
            #imap_socket.connect("/var/imap/socket/imap")
            #self.mail_con.sock = imap_socket
            #self.mail_con.file = self.mail_con.sock.makefile('rb')

            logging.info("Connected to %s", server)
        except (socket.error, self.mail_con.error) as ex:
            logging.error("Could not connect to host: %s", ex)
            sys.exit()

        # log in
        try:

            # proxy authentication
            #self.mail_con.login("cyrus", "geheim")
            #self.mail_con.proxyauth(username)

            self.mail_con.login(username, password)
            self.logged_in = True
            logging.info("Logged in as %s.", username)
        except self.mail_con.error as ex:
            self.logged_in = False
            logging.error("Could not log in as user %s: %s", username, ex)
            sys.exit()

        # list mailboxes
        try:
            _result, mailboxes = self.mail_con.list()
        except self.mail_con.error as ex:
            logging.warning("Could not retrieve mailboxes for user %s: %s", username, ex)
        self.mailboxes = []
        for mailbox in mailboxes:
            mailbox = MAILBOX_RESP.match(mailbox.decode('iso-8859-1')).groups()
            self.mailboxes.append(mailbox)
        self.mailboxes = sorted(self.mailboxes, key=lambda box: box[2], reverse=True)

        return

    def __del__(self):
        """Closes the connection and the user session."""

        if self.logged_in:
            self.mail_con.logout()

    def clear_inbox_acls(self, user):
        """Resets the inbox acls for a given user."""

        try:
            _result, inbox_acls = self.mail_con.getacl("INBOX")
        except self.mail_con.error as ex:
            logging.warning("Could not get the acls of INBOX: %s", ex)
            return
        inbox_acls = ACLS_RESP.findall(inbox_acls[0][6:])
        logging.debug("Retrieved acls from INBOX are %s", inbox_acls)
        for acl_ref in inbox_acls:
            if acl_ref[0].decode('iso-8859-1') != user:
                try:
                    self.mail_con.deleteacl("INBOX", acl_ref[0])
                    logging.debug("Reset acls on INBOX for user %s", acl_ref[0].decode('iso-8859-1'))
                except self.mail_con.error as ex:
                    logging.warning("Could not reset acls on INBOX for user %s: %s", acl_ref[0], ex)

        return

    def add_acls(self, mailbox, mb_acls, original_user, target_user):
        """Add acls to mailbox."""

        mailbox = mailbox.replace("user/" + original_user + "/", "INBOX/")
        for acl_user in mb_acls:
            # (in case target user != original user):
            # - don't overwrite acls eventually set for the current targetuser
            # - don't set the default owner acls for the new folder
            if acl_user != target_user and acl_user != original_user:
                try:
                    self.mail_con.setacl(mailbox, acl_user, mb_acls[acl_user])
                    logging.debug("Set acls %s for user %s on mailbox %s", mb_acls[acl_user], acl_user, mailbox)
                except self.mail_con.error as ex:
                    logging.warning("Could not set acls %s for user %s on mailbox %s: %s", mb_acls[acl_user], acl_user, mailbox, ex)    

        return

    def delete_mailboxes(self, deleted_mailbox):
        """Delete specified mailbox or empty inbox."""

        for mailbox in self.mailboxes:
            pattern = '^\"?' + deleted_mailbox
            # if INBOX it cannot be deleted so add delimiter
            if deleted_mailbox == "INBOX":
                pattern += mailbox[1]
            if re.compile(pattern).match(mailbox[2]):
                result, data = self.mail_con.delete(mailbox[2])
                logging.debug("Deleted mailbox %s", mailbox[2])
                if result != "OK":
                    logging.warning("Could not delete mailbox %s: %s", mailbox[2], data[0]) 
        
        return

    def create_mailbox(self, mailbox):
        """Create new mailbox to inject messages."""

        if mailbox != "INBOX":
            result, data = self.mail_con.create(mailbox)
            logging.debug("Creating mailbox %s", mailbox)
            if result != "OK":
                logging.warning("Could not create mailbox %s: %s", mailbox, data[0].decode('iso-8859-1'))

        return

    def inject_message(self, message, mailbox, internal_date):
        """Inject a message into a mailbox."""

        result, data = self.mail_con.append(mailbox, "\\Seen", internal_date, message.encode())
        logging.debug("Appending message to mailbox %s", mailbox)
        if result != "OK":
            logging.warning("Could not append an e-mail to the mailbox %s: %s.", mailbox, data[0].decode('iso-8859-1'))
            #logging.debug("Email content:\n%s", message)

        return