--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/server/hookhelper.py	Wed Nov 05 15:52:50 2008 +0100
@@ -0,0 +1,110 @@
+"""helper functions for application hooks
+
+:organization: Logilab
+:copyright: 2001-2008 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
+:contact: http://www.logilab.fr/ -- mailto:contact@logilab.fr
+"""
+__docformat__ = "restructuredtext en"
+
+from smtplib import SMTP
+from threading import Lock
+
+from cubicweb import RepositoryError
+from cubicweb.server.pool import Operation, SingleLastOperation
+
+
+def entity_name(session, eid):
+    """return the "name" attribute of the entity with the given eid"""
+    return entity_attr(session, eid, 'name')
+
+def entity_attr(session, eid, attr):
+    """return an arbitrary attribute of the entity with the given eid"""
+    rset = session.execute('Any N WHERE X eid %%(x)s, X %s N' % attr,
+                           {'x': eid}, 'x')
+    return rset[0][0]
+
+def rproperty(session, rtype, eidfrom, eidto, rprop):
+    rschema = session.repo.schema[rtype]
+    subjtype = session.describe(eidfrom)[0]
+    objtype = session.describe(eidto)[0]
+    return rschema.rproperty(subjtype, objtype, rprop)
+
+def check_internal_entity(session, eid, internal_names):
+    """check that the entity's name is not in the internal_names list.
+    raise a RepositoryError if so, else return the entity's name
+    """
+    name = entity_name(session, eid)
+    if name in internal_names:
+        raise RepositoryError('%s entity can\'t be deleted' % name)
+    return name
+
+def get_user_sessions(repo, ueid):
+    for session in repo._sessions.values():
+        if ueid == session.user.eid:
+            yield session
+        
+
+# mail related ################################################################
+
+SMTP_LOCK = Lock()
+
+class SendMailOp(SingleLastOperation):
+    def __init__(self, session, msg=None, recipients=None, **kwargs):
+        # may not specify msg yet, as
+        # `cubicweb.sobjects.supervision.SupervisionMailOp`
+        if msg is not None:
+            assert recipients
+            self.to_send = [(msg, recipients)]
+        else:
+            assert recipients is None
+            self.to_send = []
+        super(SendMailOp, self).__init__(session, **kwargs) 
+       
+    def register(self, session):
+        previous = super(SendMailOp, self).register(session)
+        if previous:
+            self.to_send = previous.to_send + self.to_send
+        
+    def commit_event(self):
+        self.repo.threaded_task(self.sendmails)
+
+    def sendmails(self):        
+        server, port = self.config['smtp-host'], self.config['smtp-port']
+        SMTP_LOCK.acquire()
+        try:
+            try:
+                smtp = SMTP(server, port)
+            except Exception, ex:
+                self.exception("can't connect to smtp server %s:%s (%s)",
+                               server, port, ex)
+                return
+            heloaddr = '%s <%s>' % (self.config['sender-name'],
+                                    self.config['sender-addr'])
+            for msg, recipients in self.to_send:
+                try:
+                    smtp.sendmail(heloaddr, recipients, msg.as_string())
+                except Exception, ex:
+                    self.exception("error sending mail to %s (%s)",
+                                   recipients, ex)
+            smtp.close()
+        finally:
+            SMTP_LOCK.release()
+            
+
+# state related ###############################################################
+
+def previous_state(session, eid):
+    """return the state of the entity with the given eid,
+    usually since it's changing in the current transaction. Due to internal
+    relation hooks, the relation may has been deleted at this point, so
+    we have handle that
+    """
+    for eidfrom, rtype, eidto in reversed(session.query_data('pendingrelations', ())):
+        if rtype == 'in_state' and eidfrom == eid:
+            rset = session.execute('Any S,N WHERE S eid %(x)s, S name N',
+                                   {'x': eidto}, 'x')
+            return rset.get_entity(0, 0)
+    rset = session.execute('Any S,N WHERE X eid %(x)s, X in_state S, S name N',
+                           {'x': eid}, 'x')
+    if rset:
+        return rset.get_entity(0, 0)