# copyright 2003-2010 LOGILAB S.A. (Paris, FRANCE), all rights reserved.

# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr

#

# This file is part of CubicWeb.

#

# CubicWeb is free software: you can redistribute it and/or modify it under the

# terms of the GNU Lesser General Public License as published by the Free

# Software Foundation, either version 2.1 of the License, or (at your option)

# any later version.

#

# CubicWeb 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 Lesser General Public License for more

# details.

#

# You should have received a copy of the GNU Lesser General Public License along

# with CubicWeb.  If not, see <http://www.gnu.org/licenses/>.

"""CubicWeb server connections pool : the repository has a limited number of

connections pools, each of them dealing with a set of connections on each source

used by the repository. A connections pools (`ConnectionsPool`) is an

abstraction for a group of connection to each source.

"""

__docformat__ = "restructuredtext en"

import sys

class ConnectionsPool(object):

    """handle connections on a set of sources, at some point associated to a

    user session

    """

    def __init__(self, sources):

        # dictionnary of (source, connection), indexed by sources'uri

        self.source_cnxs = {}

        for source in sources:

            self.add_source(source)

        if not 'system' in self.source_cnxs:

            self.source_cnxs['system'] = self.source_cnxs[sources[0].uri]

        self._cursors = {}

    def __getitem__(self, uri):

        """subscription notation provide access to sources'cursors"""

        try:

            cursor = self._cursors[uri]

        except KeyError:

            cursor = self.source_cnxs[uri][1].cursor()

            if cursor is not None:

                # None possible on sources without cursor support such as ldap

                self._cursors[uri] = cursor

        return cursor

    def add_source(self, source):

        assert not source.uri in self.source_cnxs

        self.source_cnxs[source.uri] = (source, source.get_connection())

    def remove_source(self, source):

        source, cnx = self.source_cnxs.pop(source.uri)

        cnx.close()

        self._cursors.pop(source.uri, None)

    def commit(self):

        """commit the current transaction for this user"""

        # FIXME: what happends if a commit fail

        # would need a two phases commit or like, but I don't know how to do

        # this using the db-api...

        for source, cnx in self.source_cnxs.values():

            # let exception propagates

            cnx.commit()

    def rollback(self):

        """rollback the current transaction for this user"""

        for source, cnx in self.source_cnxs.values():

            # catch exceptions, rollback other sources anyway

            try:

                cnx.rollback()

            except:

                source.critical('rollback error', exc_info=sys.exc_info())

                # error on rollback, the connection is much probably in a really

                # bad state. Replace it by a new one.

                self.reconnect(source)

    def close(self, i_know_what_i_do=False):

        """close all connections in the pool"""

        if i_know_what_i_do is not True: # unexpected closing safety belt

            raise RuntimeError('pool shouldn\'t be closed')

        for cu in self._cursors.values():

            try:

                cu.close()

            except:

                continue

        for _, cnx in self.source_cnxs.values():

            try:

                cnx.close()

            except:

                continue

    # internals ###############################################################

    def pool_set(self):

        """pool is being set"""

        self.check_connections()

    def pool_reset(self):

        """pool is being reseted"""

        for source, cnx in self.source_cnxs.values():

            source.pool_reset(cnx)

    def sources(self):

        """return the source objects handled by this pool"""

        # implementation details of flying insert requires the system source

        # first

        yield self.source_cnxs['system'][0]

        for uri, (source, cnx) in self.source_cnxs.items():

            if uri == 'system':

                continue

            yield source

        #return [source_cnx[0] for source_cnx in self.source_cnxs.values()]

    def source(self, uid):

        """return the source object with the given uri"""

        return self.source_cnxs[uid][0]

    def connection(self, uid):

        """return the connection on the source object with the given uri"""

        return self.source_cnxs[uid][1]

    def reconnect(self, source=None):

        """reopen a connection for this source or all sources if none specified

        """

        if source is None:

            sources = self.sources()

        else:

            sources = (source,)

        for source in sources:

            try:

                # properly close existing connection if any

                self.source_cnxs[source.uri][1].close()

            except:

                pass

            source.info('trying to reconnect')

            self.source_cnxs[source.uri] = (source, source.get_connection())

            self._cursors.pop(source.uri, None)

    def check_connections(self):

        for source, cnx in self.source_cnxs.itervalues():

            newcnx = source.check_connection(cnx)

            if newcnx is not None:

                self.reset_connection(source, newcnx)

    def reset_connection(self, source, cnx):

        self.source_cnxs[source.uri] = (source, cnx)

        self._cursors.pop(source.uri, None)

from cubicweb.server.hook import Operation, LateOperation, SingleLastOperation

from logilab.common.deprecation import class_moved, class_renamed

Operation = class_moved(Operation)

PreCommitOperation = class_renamed('PreCommitOperation', Operation)

LateOperation = class_moved(LateOperation)

SingleLastOperation = class_moved(SingleLastOperation)