Add support for "nested" menu items

some menus were just getting too long, so this gives us a way to collapse
certain items, which user can expand as needed

tailbone/menus.py

@@ -2,7 +2,7 @@
 ################################################################################
 #
 #  Rattail -- Retail Software Framework
-#  Copyright © 2010-2018 Lance Edgar
+#  Copyright © 2010-2021 Lance Edgar
 #
 #  This file is part of Rattail.
 #
@@ -33,6 +33,7 @@ from rattail.util import import_module_path
 class MenuGroup(Object):
     title = None
     items = None
+    is_menu = True
     is_link = False
 
 
@@ -41,10 +42,19 @@ class MenuItem(Object):
     url = None
     target = None
     is_link = True
+    is_menu = False
+    is_sep = False
+
+
+class MenuItemMenu(Object):
+    title = None
+    items = None
+    is_menu = True
     is_sep = False
 
 
 class MenuSeparator(object):
+    is_menu = False
     is_sep = True
 
 
@@ -61,55 +71,108 @@ def make_simple_menus(request):
     # collect "simple" menus definition, but must refine that somewhat to
     # produce our final menus
     raw_menus = menus_module.simple_menus(request)
+    mark_allowed(request, raw_menus)
     final_menus = []
     for topitem in raw_menus:
 
-        if topitem.get('type') == 'link':
-            final_menus.append(
-                MenuItem(title=topitem['title'],
-                         url=topitem['url'],
-                         target=topitem.get('target')))
+        if topitem['allowed']:
 
-        else: # assuming 'menu' type
+            if topitem.get('type') == 'link':
+                final_menus.append(make_menu_entry(topitem))
 
-            # figure out which ones the user has permission to access
-            allowed = []
-            for item in topitem['items']:
+            else: # assuming 'menu' type
 
-                if item.get('type') == 'sep':
-                    allowed.append(item)
-
-                if item.get('perm'):
-                    if request.has_perm(item['perm']):
-                        allowed.append(item)
-                else:
-                    allowed.append(item)
-
-            if allowed:
-
-                # user must have access to something; construct items for the menu
                 menu_items = []
-                for item in allowed:
+                for item in topitem['items']:
+                    if not item['allowed']:
+                        continue
 
-                    # separator
-                    if item.get('type') == 'sep':
+                    # nested submenu
+                    if item.get('type') == 'menu':
+                        submenu_items = []
+                        for subitem in item['items']:
+                            if subitem['allowed']:
+                                submenu_items.append(make_menu_entry(subitem))
+                        menu_items.append(MenuItemMenu(
+                            title=item['title'],
+                            items=submenu_items))
+
+                    elif item.get('type') == 'sep':
+                        # we only want to add a sep, *if* we already have some
+                        # menu items (i.e. there is something to separate)
+                        # *and* the last menu item is not a sep (avoid doubles)
                         if menu_items and not menu_items[-1].is_sep:
-                            menu_items.append(MenuSeparator())
+                            menu_items.append(make_menu_entry(item))
 
-                    # menu item
-                    else:
-                        menu_items.append(
-                            MenuItem(title=item['title'],
-                                     url=item['url'],
-                                     target=item.get('target')))
+                    else: # standard menu item
+                        menu_items.append(make_menu_entry(item))
 
                 # remove final separator if present
                 if menu_items and menu_items[-1].is_sep:
                     menu_items.pop()
 
                 # only add if we wound up with something
+                assert menu_items
                 if menu_items:
-                    final_menus.append(
-                        MenuGroup(title=topitem['title'], items=menu_items))
+                    final_menus.append(MenuGroup(
+                        title=topitem['title'],
+                        items=menu_items))
 
     return final_menus
+
+
+def make_menu_entry(item):
+    """
+    Convert a simple menu entry dict, into a proper menu-related object, for
+    use in constructing final menu.
+    """
+    # separator
+    if item.get('type') == 'sep':
+        return MenuSeparator()
+
+    # standard menu item
+    return MenuItem(
+        title=item['title'],
+        url=item['url'],
+        target=item.get('target'))
+
+
+def is_allowed(request, item):
+    """
+    Logic to determine if a given menu item is "allowed" for current user.
+    """
+    perm = item.get('perm')
+    if perm:
+        return request.has_perm(perm)
+    return True
+
+
+def mark_allowed(request, menus):
+    """
+    Traverse the menu set, and mark each item as "allowed" (or not) based on
+    current user permissions.
+    """
+    for topitem in menus:
+
+        if topitem.get('type', 'menu') == 'menu':
+            topitem['allowed'] = False
+
+            for item in topitem['items']:
+
+                if item.get('type') == 'menu':
+                    for subitem in item['items']:
+                        subitem['allowed'] = is_allowed(request, subitem)
+
+                    item['allowed'] = False
+                    for subitem in item['items']:
+                        if subitem['allowed'] and subitem.get('type') != 'sep':
+                            item['allowed'] = True
+                            break
+
+                else:
+                    item['allowed'] = is_allowed(request, item)
+
+            for item in topitem['items']:
+                if item['allowed'] and item.get('type') != 'sep':
+                    topitem['allowed'] = True
+                    break