#!/usr/bin/python
# -*- coding: utf-8 -*-

# SàT plugin for managing Maildir type mail boxes
# Copyright (C) 2011  Jérôme Poisson (goffi@goffi.org)

# This program 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.

# 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 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/>.

from sat.core.i18n import _
from sat.core.constants import Const as C
from logging import debug, info, error
import warnings
warnings.filterwarnings('ignore', 'the MimeWriter', DeprecationWarning, 'twisted')  # FIXME: to be removed, see http://twistedmatrix.com/trac/ticket/4038
from twisted.internet import protocol
from twisted.words.protocols.jabber import error as jab_error
from twisted.cred import portal, checkers
from twisted.mail import imap4, maildir
from email.parser import Parser
import email.message
from email.charset import Charset
import os
from cStringIO import StringIO
from twisted.internet import reactor
from sat.core.exceptions import ProfileUnknownError
from sat.memory.persistent import PersistentBinaryDict

from zope.interface import implements

PLUGIN_INFO = {
    "name": "Maildir Plugin",
    "import_name": "Maildir",
    "type": "Misc",
    "protocols": [],
    "dependencies": [],
    "main": "MaildirBox",
    "handler": "no",
    "description": _("""Intercept "normal" type messages, and put them in a Maildir type box""")
}

MAILDIR_PATH = "Maildir"


class MaildirError(Exception):
    pass


class MaildirBox(object):

    def __init__(self, host):
        info(_("Plugin Maildir initialization"))
        self.host = host

        self.__observed = {}
        self.data = {}  # list of profile spectific data. key = profile, value = PersistentBinaryDict where key=mailbox name,
                     # and value is a dictionnary with the following value
                     #    - cur_idx: value of the current unique integer increment (UID)
                     #    - message_id (as returned by MaildirMailbox): a tuple of (UID, [flag1, flag2, ...])
        pList = host.memory.getProfilesList  # shorter :)
        self.__mailboxes = {}  # key: profile, value: {boxname: MailboxUser instance}

        #the triggers
        host.trigger.add("MessageReceived", self.messageReceivedTrigger)

    def profileConnected(self, profile):
        """Called on profile connection, create profile data"""
        self.data[profile] = PersistentBinaryDict("plugin_maildir", profile)
        self.__mailboxes[profile] = {}

        def dataLoaded(ignore):
            if not self.data[profile]:
                #the mailbox is new, we initiate the data
                self.data[profile]["INBOX"] = {"cur_idx": 0}
        self.data[profile].load().addCallback(dataLoaded)

    def profileDisconnected(self, profile):
        """Called on profile disconnection, free profile's resources"""
        del self.__mailboxes[profile]
        del self.data[profile]

    def messageReceivedTrigger(self, message, post_treat, profile):
        """This trigger catch normal message and put the in the Maildir box.
        If the message is not of "normal" type, do nothing
        @param message: message xmlstrem
        @return: False if it's a normal message, True else"""
        for e in message.elements():
            if e.name == "body":
                mess_type = message['type'] if message.hasAttribute('type') else 'normal'
                if mess_type != 'normal':
                    return True
                self.accessMessageBox("INBOX", profile_key=profile).addMessage(message)
                return False

    def accessMessageBox(self, boxname, observer=None, profile_key=C.PROF_KEY_NONE):
        """Create and return a MailboxUser instance
        @param boxname: name of the box
        @param observer: method to call when a NewMessage arrive"""
        profile = self.host.memory.getProfileName(profile_key)
        if not profile:
            raise ProfileUnknownError(profile_key)
        if boxname not in self.__mailboxes[profile]:
            self.__mailboxes[profile][boxname] = MailboxUser(self, boxname, observer, profile=profile)
        else:
            if observer:
                self.addObserver(observer, profile, boxname)
        return self.__mailboxes[profile][boxname]

    def _getProfilePath(self, profile):
        """Return a unique path for profile's mailbox
        The path must be unique, usable as a dir name, and bijectional"""
        return profile.replace('/', '_').replace('..', '_')  # FIXME: this is too naive to work well, must be improved

    def _removeBoxAccess(self, boxname, mailboxUser, profile):
        """Remove a reference to a box
        @param name: name of the box
        @param mailboxUser: MailboxUser instance"""
        if boxname not in self.__mailboxes:
            err_msg = _("Trying to remove an mailboxUser not referenced")
            error(_("INTERNAL ERROR: ") + err_msg)
            raise MaildirError(err_msg)
        assert self.__mailboxes[profile][boxname] == mailboxUser
        del self.__mailboxes[profile][boxname]

    def _checkBoxReference(self, boxname, profile):
        """Check if there is a reference on a box, and return it
        @param boxname: name of the box to check
        @return: MailboxUser instance or None"""
        if profile in self.__mailboxes:
            if boxname in self.__mailboxes[profile]:
                return self.__mailboxes[profile][boxname]

    def __getBoxData(self, boxname, profile):
        """Return the date of a box"""
        try:
            return self.data[profile][boxname]  # the boxname MUST exist in the data
        except KeyError:
            err_msg = _("Boxname doesn't exist in internal data")
            error(_("INTERNAL ERROR: ") + err_msg)
            raise MaildirError(err_msg)

    def getUid(self, boxname, message_id, profile):
        """Return an unique integer, always ascending, for a message
        This is mainly needed for the IMAP protocol
        @param boxname: name of the box where the message is
        @param message_id: unique id of the message as given by MaildirMailbox
        @return: Integer UID"""
        box_data = self.__getBoxData(boxname, profile)
        if message_id in box_data:
            ret = box_data[message_id][0]
        else:
            box_data['cur_idx'] += 1
            box_data[message_id] = [box_data['cur_idx'], []]
            ret = box_data[message_id]
            self.data[profile].force(boxname)
        return ret

    def getNextUid(self, boxname, profile):
        """Return next unique integer that will generated
        This is mainly needed for the IMAP protocol
        @param boxname: name of the box where the message is
        @return: Integer UID"""
        box_data = self.__getBoxData(boxname, profile)
        return box_data['cur_idx'] + 1

    def getNextExistingUid(self, boxname, uid, profile):
        """Give the next uid of existing message
        @param boxname: name of the box where the message is
        @param uid: uid to start from
        @return: uid or None if the is no more message"""
        box_data = self.__getBoxData(boxname, profile)
        idx = uid + 1
        while self.getIdFromUid(boxname, idx, profile) is None:  # TODO: this is highly inefficient because getIdfromUid is inefficient, fix this
            idx += 1
            if idx > box_data['cur_idx']:
                return None
        return idx

    def getMaxUid(self, boxname, profile):
        """Give the max existing uid
        @param boxname: name of the box where the message is
        @return: uid"""
        box_data = self.__getBoxData(boxname, profile)
        return box_data['cur_idx']

    def getIdFromUid(self, boxname, message_uid, profile):
        """Return the message unique id from it's integer UID
        @param boxname: name of the box where the message is
        @param message_uid: unique integer identifier
        @return: unique id of the message as given by MaildirMailbox or None if not found"""
        box_data = self.__getBoxData(boxname, profile)
        for message_id in box_data.keys():  # TODO: this is highly inefficient on big mailbox, must be replaced in the future
            if message_id == 'cur_idx':
                continue
            if box_data[message_id][0] == message_uid:
                return message_id
        return None

    def getFlags(self, boxname, mess_id, profile):
        """Return the messages flags
        @param boxname: name of the box where the message is
        @param message_idx: message id as given by MaildirMailbox
        @return: list of strings"""
        box_data = self.__getBoxData(boxname, profile)
        if mess_id not in box_data:
            raise MaildirError("Trying to get flags from an unexisting message")
        return box_data[mess_id][1]

    def setFlags(self, boxname, mess_id, flags, profile):
        """Change the flags of the message
        @param boxname: name of the box where the message is
        @param message_idx: message id as given by MaildirMailbox
        @param flags: list of strings
        """
        box_data = self.__getBoxData(boxname, profile)
        assert(type(flags) == list)
        flags = [flag.upper() for flag in flags]  # we store every flag UPPERCASE
        if mess_id not in box_data:
            raise MaildirError("Trying to set flags for an unexisting message")
        box_data[mess_id][1] = flags
        self.data[profile].force(boxname)

    def getMessageIdsWithFlag(self, boxname, flag, profile):
        """Return ids of messages where a flag is set
        @param boxname: name of the box where the message is
        @param flag: flag to check
        @return: list of id (as given by MaildirMailbox)"""
        box_data = self.__getBoxData(boxname, profile)
        assert(isinstance(flag, basestring))
        flag = flag.upper()
        result = []
        for key in box_data:
            if key == 'cur_idx':
                continue
            if flag in box_data[key][1]:
                result.append(key)
        return result

    def purgeDeleted(self, boxname, profile):
        """Remove data for messages with flag "\\Deleted"
        @param boxname: name of the box where the message is
        """
        box_data = self.__getBoxData(boxname, profile)
        for mess_id in self.getMessageIdsWithFlag(boxname, "\\Deleted", profile):
            del(box_data[mess_id])
        self.data[profile].force(boxname)

    def cleanTable(self, boxname, existant_id, profile):
        """Remove mails which no longuer exist from the table
        @param boxname: name of the box to clean
        @param existant_id: list of id which actually exist"""
        box_data = self.__getBoxData(boxname, profile)
        to_remove = []
        for key in box_data:
            if key not in existant_id and key != "cur_idx":
                to_remove.append(key)
        for key in to_remove:
            del box_data[key]

    def addObserver(self, callback, profile, boxname, signal="NEW_MESSAGE"):
        """Add an observer for maildir box changes
        @param callback: method to call when the the box is updated
        @param boxname: name of the box to observe
        @param signal: which signal is observed by the caller"""
        if (profile, boxname) not in self.__observed:
            self.__observed[(profile, boxname)] = {}
        if signal not in self.__observed[(profile, boxname)]:
            self.__observed[(profile, boxname)][signal] = set()
        self.__observed[(profile, boxname)][signal].add(callback)

    def removeObserver(self, callback, profile, boxname, signal="NEW_MESSAGE"):
        """Remove an observer of maildir box changes
        @param callback: method to remove from obervers
        @param boxname: name of the box which was observed
        @param signal: which signal was observed by the caller"""
        if (profile, boxname) not in self.__observed:
            err_msg = _("Trying to remove an observer for an inexistant mailbox")
            error(_("INTERNAL ERROR: ") + err_msg)
            raise MaildirError(err_msg)
        if signal not in self.__observed[(profile, boxname)]:
            err_msg = _("Trying to remove an inexistant observer, no observer for this signal")
            error(_("INTERNAL ERROR: ") + err_msg)
            raise MaildirError(err_msg)
        if not callback in self.__observed[(profile, boxname)][signal]:
            err_msg = _("Trying to remove an inexistant observer")
            error(_("INTERNAL ERROR: ") + err_msg)
            raise MaildirError(err_msg)
        self.__observed[(profile, boxname)][signal].remove(callback)

    def emitSignal(self, profile, boxname, signal_name):
        """Emit the signal to observer"""
        debug('emitSignal %s %s %s' % (profile, boxname, signal_name))
        try:
            for observer_cb in self.__observed[(profile, boxname)][signal_name]:
                observer_cb()
        except KeyError:
            pass


class MailboxUser(object):
    """This class is used to access a mailbox"""

    def xmppMessage2mail(self, message):
        """Convert the XMPP's XML message to a basic rfc2822 message
        @param xml: domish.Element of the message
        @return: string email"""
        mail = email.message.Message()
        mail['MIME-Version'] = "1.0"
        mail['Content-Type'] = "text/plain; charset=UTF-8; format=flowed"
        mail['Content-Transfer-Encoding'] = "8bit"
        mail['From'] = message['from'].encode('utf-8')
        mail['To'] = message['to'].encode('utf-8')
        mail['Date'] = email.utils.formatdate().encode('utf-8')
        #TODO: save thread id
        for e in message.elements():
            if e.name == "body":
                mail.set_payload(e.children[0].encode('utf-8'))
            elif e.name == "subject":
                mail['Subject'] = e.children[0].encode('utf-8')
        return mail.as_string()

    def __init__(self, _maildir, name, observer=None, profile=C.PROF_KEY_NONE):
        """@param _maildir: the main MaildirBox instance
           @param name: name of the mailbox
           @param profile: real profile (ie not a profile_key)
           THIS OBJECT MUST NOT BE USED DIRECTLY: use MaildirBox.accessMessageBox instead"""
        if _maildir._checkBoxReference(name, profile):
            error("INTERNAL ERROR: MailboxUser MUST NOT be instancied directly")
            raise MaildirError('double MailboxUser instanciation')
        if name != "INBOX":
            raise NotImplementedError
        self.name = name
        self.profile = profile
        self.maildir = _maildir
        profile_path = self.maildir._getProfilePath(profile)
        full_profile_path = os.path.join(self.maildir.host.memory.getConfig('', 'local_dir'), 'maildir', profile_path)
        if not os.path.exists(full_profile_path):
            os.makedirs(full_profile_path, 0700)
        mailbox_path = os.path.join(full_profile_path, MAILDIR_PATH)
        self.mailbox_path = mailbox_path
        self.mailbox = maildir.MaildirMailbox(mailbox_path)
        self.observer = observer
        self.__uid_table_update()

        if observer:
            debug("adding observer for %s (%s)" % (name, profile))
            self.maildir.addObserver(observer, profile, name, "NEW_MESSAGE")

    def __uid_table_update(self):
        existant_id = []
        for mess_idx in range(self.getMessageCount()):
            #we update the uid table
            existant_id.append(self.getId(mess_idx))
            self.getUid(mess_idx)
        self.maildir.cleanTable(self.name, existant_id, profile=self.profile)

    def __del__(self):
        if self.observer:
            debug("removing observer for %s" % self.name)
            self._maildir.removeObserver(self.observer, self.name, "NEW_MESSAGE")
        self.maildir._removeBoxAccess(self.name, self, profile=self.profile)

    def addMessage(self, message):
        """Add a message to the box
        @param message: XMPP XML message"""
        self.mailbox.appendMessage(self.xmppMessage2mail(message)).addCallback(self.emitSignal, "NEW_MESSAGE")

    def emitSignal(self, ignore, signal):
        """Emit the signal to the observers"""
        if signal == "NEW_MESSAGE":
            self.getUid(self.getMessageCount() - 1)  # XXX: we make an uid for the last message added
        self.maildir.emitSignal(self.profile, self.name, signal)

    def getId(self, mess_idx):
        """Return the Unique ID of the message
        @mess_idx: message index"""
        return self.mailbox.getUidl(mess_idx)

    def getUid(self, mess_idx):
        """Return a unique interger id for the message, always ascending"""
        mess_id = self.getId(mess_idx)
        return self.maildir.getUid(self.name, mess_id, profile=self.profile)

    def getNextUid(self):
        return self.maildir.getNextUid(self.name, profile=self.profile)

    def getNextExistingUid(self, uid):
        return self.maildir.getNextExistingUid(self.name, uid, profile=self.profile)

    def getMaxUid(self):
        return self.maildir.getMaxUid(self.name, profile=self.profile)

    def getMessageCount(self):
        """Return number of mails present in this box"""
        return len(self.mailbox.list)

    def getMessageIdx(self, mess_idx):
        """Return the full message
        @mess_idx: message index"""
        return self.mailbox.getMessage(mess_idx)

    def getIdxFromUid(self, mess_uid):
        """Return the message index from the uid
        @param mess_uid: message unique identifier
        @return: message index, as managed by MaildirMailbox"""
        for mess_idx in range(self.getMessageCount()):
            if self.getUid(mess_idx) == mess_uid:
                return mess_idx
        raise IndexError

    def getIdxFromId(self, mess_id):
        """Return the message index from the unique index
        @param mess_id: message unique index as given by MaildirMailbox
        @return: message sequence index"""
        for mess_idx in range(self.getMessageCount()):
            if self.mailbox.getUidl(mess_idx) == mess_id:
                return mess_idx
        raise IndexError

    def getMessage(self, mess_idx):
        """Return the full message
        @param mess_idx: message index"""
        return self.mailbox.getMessage(mess_idx)

    def getMessageUid(self, mess_uid):
        """Return the full message
        @param mess_idx: message unique identifier"""
        return self.mailbox.getMessage(self.getIdxFromUid(mess_uid))

    def getFlags(self, mess_idx):
        """Return the flags of the message
        @param mess_idx: message index
        @return: list of strings"""
        id = self.getId(mess_idx)
        return self.maildir.getFlags(self.name, id, profile=self.profile)

    def getFlagsUid(self, mess_uid):
        """Return the flags of the message
        @param mess_uid: message unique identifier
        @return: list of strings"""
        id = self.maildir.getIdFromUid(self.name, mess_uid, profile=self.profile)
        return self.maildir.getFlags(self.name, id, profile=self.profile)

    def setFlags(self, mess_idx, flags):
        """Change the flags of the message
        @param mess_idx: message index
        @param flags: list of strings
        """
        id = self.getId(mess_idx)
        self.maildir.setFlags(self.name, id, flags, profile=self.profile)

    def setFlagsUid(self, mess_uid, flags):
        """Change the flags of the message
        @param mess_uid: message unique identifier
        @param flags: list of strings
        """
        id = self.maildir.getIdFromUid(self.name, mess_uid, profile=self.profile)
        return self.maildir.setFlags(self.name, id, flags, profile=self.profile)

    def getMessageIdsWithFlag(self, flag):
        """Return ids of messages where a flag is set
        @param flag: flag to check
        @return: list of id (as given by MaildirMailbox)"""
        return self.maildir.getMessageIdsWithFlag(self.name, flag, profile=self.profile)

    def removeDeleted(self):
        """Actually delete message flagged "\\Deleted"
        Also purge the internal data of these messages
        """
        for mess_id in self.getMessageIdsWithFlag("\\Deleted"):
            print ("Deleting %s" % mess_id)
            self.mailbox.deleteMessage(self.getIdxFromId(mess_id))
        self.mailbox = maildir.MaildirMailbox(self.mailbox_path)  # We need to reparse the dir to have coherent indexing
        self.maildir.purgeDeleted(self.name, profile=self.profile)

    def emptyTrash(self):
        """Delete everything in the .Trash dir"""
        pass #TODO