Navbar (#31)

* started workin on 'navbar' module

* changed bootstrap theme to bootswatch/Simplex

* big work on navbar logic

* starting creating menus using navbar

* converted app views to new Wepage decorator, updated navbar

* reimplemented DernieresMaraudes as a dropdown instead of ContextMixin

* reorganised static files, minor code cleanups

* turned Link.href into lazy-evaluated property

* collapsed 'navbar' module into 'website', dynamic building of ApplicationMenu subclasses

* minor cleanup

* blah blah blah

* added way to add admin/non-admin links

* minor style change : red border for active page instead of all dropdowns

* deleted file

* prepare adding removing menu templates files, being replaced by code

* essayé de généraliser le code pour les modaux bootstrap, non testé git status

* more preparation and thinking on navbar app_menus logic...

* added LinkManager and DropdownManager, getting closer...

* small fix in DropdownManager.__get__

* boosted up work: keep it simple so it can be merged fast, major layout changes

* added month filter on maraudes:liste

* added 'as_icon' filter to display boolean/null values as bootstrap icons

* remove inactive user from planning selection

* removed all unused 'menu' templates

* set up django_select2 to use static files

* small fix after review

website/navbar.py

@@ -0,0 +1,102 @@
+""" Draft for navbar application menu 
+"""
+
+from django.urls import reverse
+
+registered = []
+
+
+class Link:
+    """ Navbar link
+
+    Constructor takes one required argument :
+        - text : text to display for the link
+
+    and two optional arguments :
+        - target : str or tuple (str, dict)
+        - icon : bootstrap icon name, no validation
+
+    """
+
+    def __init__(self, text, target="#", icon=None):
+        self.text = text
+        self._target = target
+        self.icon = icon
+
+    @property
+    def href(self):
+        """ Lazy creation of html 'href' value, using 'target' instance attribute """
+        if not hasattr(self, '_href'):
+            if self._target == "#": #Create void link
+                self._href = "#"
+            else:
+                try:
+                    target, kwargs = self._target
+                except ValueError:
+                    target = self._target
+                    kwargs = {}
+                assert type(target) == str
+                assert type(kwargs) == dict
+                self._href = reverse(target, **kwargs)
+        return self._href
+
+
+
+class LinkManager:
+    """ Per-class manager of links """
+
+    def __init__(self):
+        self.items = []
+
+    def __get__(self, instance, owner):
+        if instance: #Filtering done at each call, not optimized at all !
+            if not instance.user.is_superuser:
+                return [link for link in self.items if link.admin_link == False]
+            else:
+                return self.items.copy()
+        return self
+
+    def add(self, link):
+        self.items.append(link)
+
+    def __repr__(self):
+        return '<LinkManager: [' + ', '.join((l.text for l in self.items)) + ']>'
+
+
+
+class MenuRegistry(type):
+    """ Metaclass that registers subclass into module level variable 'registered' """
+    def __new__(metacls, name, bases, attrs):
+        cls = type.__new__(metacls, name, bases, attrs)
+        if name != "ApplicationMenu":
+            print('registering menu', cls)
+            registered.append(cls)
+            # Create Link instance for header attributes
+            try:
+                header, target, icon = cls.header
+            except ValueError:
+                header = cls.header
+                target = "#"
+                icon = None
+            cls.header = Link(header, target, icon)
+            cls.links = LinkManager()
+        return cls
+
+
+
+class ApplicationMenu(metaclass=MenuRegistry):
+    name = None
+    header = None
+
+    def __init__(self, view, user):
+        self.view = view
+        self.user = user
+        self.is_active = self.name == self.view.app_name
+
+    @classmethod
+    def add_link(cls, link, admin=False):
+        if not isinstance(link, Link):
+            link = Link(*link)
+        link.admin_link = admin
+        cls.links.add(link)
+