diff -r 2b30c5426f1e -r 815589aed866 server/python/django/renkanmanager/utils.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/server/python/django/renkanmanager/utils.py	Tue Jul 22 18:01:03 2014 +0200
@@ -0,0 +1,102 @@
+# -*- coding: utf-8 -*-
+'''
+Created on Mar 13, 2012
+
+@author: ymh and tc
+'''
+from django.core.cache import cache
+from django.core.exceptions import ValidationError
+from django.http.response import Http404
+from django.shortcuts import get_object_or_404
+from django.utils.encoding import smart_str
+from renkanmanager.models import Renkan
+import md5
+import re
+import uuid
+
+import logging
+logger = logging.getLogger(__name__)
+
+
+def fix_cache_key(key):
+    cache_key = re.sub(r'\s+', '-', key)
+    cache_key = smart_str(cache_key)
+    if len(cache_key) > (250-(2+len(cache.key_prefix)+len(str(cache.version)))-33):
+        cache_key = cache_key[:(250-(2+len(cache.key_prefix)+len(str(cache.version)))-33)] + '-' + md5.new(cache_key).hexdigest()
+    return cache_key
+
+
+
+class NodePlacer():
+    
+    cat_nb_nodes = {}
+    
+    def init(self, cat_nb_nodes_initial):
+        raise NotImplementedError( "Should have implemented get_place" )
+    
+    def get_place(self, category):
+        if not category or category not in self.cat_nb_nodes:
+            raise Http404
+        return self.cat_nb_nodes[category].pop(0)
+
+
+
+class LineNodePlacer(NodePlacer):
+    
+    max_length = 0
+    
+    def init(self, cat_nb_nodes_initial):
+        for c in cat_nb_nodes_initial:
+            nb = cat_nb_nodes_initial[c]
+            if isinstance(cat_nb_nodes_initial[c], tuple):
+                _, nb = nb
+            self.max_length = nb if nb > self.max_length else self.max_length
+        for i_cat,c in enumerate(cat_nb_nodes_initial):
+            self.cat_nb_nodes[c] = []
+            order = i_cat
+            nb = cat_nb_nodes_initial[c]
+            if isinstance(cat_nb_nodes_initial[c], tuple):
+                order, nb = nb
+            offset = float(self.max_length - nb) / 2
+            for i in xrange(nb):
+                self.cat_nb_nodes[c].append({ "x": order*300, "y": 100*(i+offset) })
+        #logger.debug(self.cat_nb_nodes)
+
+
+
+class CircleNodePlacer(NodePlacer):
+    #TODO: Does not work. Meant to be a real circle placer
+    def init(self, cat_nb_nodes_initial):
+        for c in cat_nb_nodes_initial:
+            self.max_length = cat_nb_nodes_initial[c] if cat_nb_nodes_initial[c] > self.max_length else self.max_length
+        for i_cat,c in enumerate(cat_nb_nodes_initial):
+            self.cat_nb_nodes[c] = []
+            offset = float(self.max_length - cat_nb_nodes_initial[c]) / 2
+            for i in xrange(cat_nb_nodes_initial[c]):
+                self.cat_nb_nodes[c].append({ "x": i_cat*400, "y": 200*(i+offset) })
+        #logger.debug(self.cat_nb_nodes)
+
+
+
+def renkan_copier(user, old_rk_id):
+    old_rk = get_object_or_404(Renkan, rk_id=old_rk_id)
+    rk = Renkan()
+    rk.rk_id = unicode(uuid.uuid1())
+    rk.owner = user
+    rk.content = old_rk.content
+    #TODO : update title and uuid in the content's json data
+    rk.title = old_rk.title + " (copy)"
+    rk.save()
+    return rk
+
+
+
+def renkan_deleter(user, rk_id):
+    rk = get_object_or_404(Renkan, rk_id=rk_id)
+    if rk.owner==user:
+        rk.delete()
+    else:
+        raise ValidationError("You are not allowed to remove this renkan")
+
+
+