Style improvements and cache from settings validation added

[imap-fix-internaldate] / src / mail_iterator.py

'''
mail_iterator.py - The module contains the MailIterator class.

Copyright (c) 2012 Intra2net AG
Author: Plamen Dimitrov

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 imaplib
import re
import time
import logging

MAILBOX_RESP = re.compile(r'\((?P<flags>.*?)\) "(?P<delimiter>.*)" (?P<name>.*)')
UIDVAL_RESP = re.compile(r'(?P<name>.*) \(UIDVALIDITY (?P<uidval>.*)\)')

#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
    # skip shared folders
    skip_shared_folders = None

    def __init__(self, server, username, password, skip_shared_folders = False):
        """Creates a connection and a user session."""
        try:
            self.mail_con = imaplib.IMAP4_SSL(server)
            self.mail_con.login(username, password)
            logging.info("Logged in as %s.", username)
        except:
            self.logged_in = False
            raise UserWarning("Could not log in as user " + username + ".")
        self.logged_in = True
        try:
            _result, self.mailboxes = self.mail_con.list()
        except:
            raise UserWarning("Could not retrieve mailboxes for user " + username + ".")
        self.skip_shared_folders = skip_shared_folders

    def __del__(self):
        """Closes the connection and the user session."""
        if(self.logged_in):
            self.mail_con.close()
            self.mail_con.logout()

    def __iter__(self):
        """Iterates through all mailboxes, returns (uidval,name)."""
        for mailbox in self.mailboxes:
            logging.debug("Checking mailbox %s.", mailbox)
            mailbox = MAILBOX_RESP.match(mailbox.decode('iso-8859-1')).groups()
            # detect if mailbox is shared and if skip flag is set iterate further
            if(self.skip_shared_folders and mailbox[2].split(mailbox[1])[0] == '"user'):
                logging.info("Mailbox %s is shared and therefore skipped.", mailbox[2])
                continue
            # retrieve uidvalidity
            try:
                _result, data = self.mail_con.status(mailbox[2], '(UIDVALIDITY)')
            except:
                raise UserWarning("Could not retrieve mailbox uidvalidity.")
            uidval = UIDVAL_RESP.match(data[0].decode('iso-8859-1')).groups()
            logging.debug("Extracted mailbox info is %s %s.", data[0], uidval)
            # select mailbox if writable
            try:
                self.mail_con.select(mailbox[2])
            except self.mail_con.readonly:
                logging.warning("Mailbox %s is not writable and therefore skipped.", mailbox[2])               
                continue
            yield (mailbox[2], uidval[1])

    def fetch_messages(self):
        """Fetches the messages from the current mailbox, return list of uids."""
        try:
            _result, data = self.mail_con.uid('search', None, "ALL")
        except:
            raise UserWarning("Could not fetch messages.")
        mailid_list = data[0].split()
        return mailid_list

    def fetch_internal_date(self, mid):
        """Fetches the internal date of a message, returns a time tuple."""
        try:
            _result, data = self.mail_con.uid('fetch', mid, '(INTERNALDATE)')
        except:
            raise UserWarning("Could not fetch the internal date of message " + mid.decode('iso-8859-1') + ".")
        internal_date = imaplib.Internaldate2tuple(data[0])
        return internal_date

    def fetch_received_date(self, mid):
        """Fetches the received date of a message, returns bytes reponse."""
        try:
            _result, data = self.mail_con.uid('fetch', mid, '(BODY.PEEK[HEADER.FIELDS (RECEIVED)])')
        except:
            raise UserWarning("Could not fetch the received header of message " + mid.decode('iso-8859-1') + ".")
        return data[0][1].decode('iso-8859-1')

    def fetch_basic_date(self, mid):
        """Fetches the basic date of a message, returns bytes reponse."""
        try:
            _result, data = self.mail_con.uid('fetch', mid, '(BODY.PEEK[HEADER.FIELDS (DATE)])')
        except:
            raise UserWarning("Could not fetch the date header of message " + mid.decode('iso-8859-1') + ".")
        return data[0][1].decode('iso-8859-1')

    def update_message(self, mid, mailbox, internal_date):
        """Replaces a message with one with correct internal date."""
        internal_date_sec = time.mktime(internal_date.timetuple())
        try:
            result, data = self.mail_con.uid('fetch', mid, '(RFC822)')
            #logging.debug("Entire e-mail is: %s", data[0][1])

            # retrieve and select flags to upload
            fetched_flags = self.mail_con.uid('fetch', mid, '(FLAGS)')[1][0]
            parsed_flags = imaplib.ParseFlags(fetched_flags)
            selected_flags = ()
            for flag in parsed_flags:
                if(flag != b'\\Recent'):
                    selected_flags += (flag,)
            logging.debug("Selected flags %s from parsed flags %s.", selected_flags, parsed_flags)                    
            flags_str = " ".join(flag.decode('iso-8859-1') for flag in selected_flags)

            # upload message copy and delete old one
            result, data = self.mail_con.append(mailbox, flags_str,
                                                internal_date_sec, data[0][1])
            logging.debug("Adding corrected copy of the message reponse: %s %s", result, data)
        except:
            raise UserWarning("Could not replace the e-mail " + mid.decode('iso-8859-1') + ".")
        try:
            result, data = self.mail_con.uid('STORE', mid, '+FLAGS', r'(\Deleted)')
            logging.debug("Removing old copy of the message reponse: %s %s", result, data)
        except:
            raise UserWarning("Could not delete the e-mail " + mid.decode('iso-8859-1') + ".")
        self.mail_con.expunge()
        return