revert an explicit permission to the proper default

In /accounts/*/role_overrides

The value was being saved correctly, but the UI was incorrect and super
confusing. It'd always show a bold "explicit" green checkmark, rather
than the semi-transparent check/cross depending on the actual default.

refs #3711

Change-Id: Ide0a0603b6c820ea0ec94646c4327239d980b09c
Reviewed-on: https://gerrit.instructure.com/2194
Tested-by: Hudson <hudson@instructure.com>
Reviewed-by: Brian Whitmer <brian@instructure.com>

app/models/role_override.rb

@@ -479,13 +479,16 @@ class RoleOverride < ActiveRecord::Base
   def self.css_class_for(context, permission, enrollment_type)
     generated_permission = self.permission_for(context, permission, enrollment_type)
     
-    css = ""
+    css = []
     if generated_permission[:readonly]
-      css += "six-checkbox-disabled-#{generated_permission[:enabled] ? 'checked' : 'unchecked' }"
+      css << "six-checkbox-disabled-#{generated_permission[:enabled] ? 'checked' : 'unchecked' }"
     else
-      css += "six-checkbox#{generated_permission[:explicit] ? '' : '-default' }-#{generated_permission[:enabled] ? 'checked' : 'unchecked' }"
+      if generated_permission[:explicit]
+        css << "six-checkbox-default-#{generated_permission[:prior_default] ? 'checked' : 'unchecked'}"
+      end
+      css << "six-checkbox#{generated_permission[:explicit] ? '' : '-default' }-#{generated_permission[:enabled] ? 'checked' : 'unchecked' }"
     end
-    css
+    css.join(' ')
   end
   
   def self.readonly_for(context, permission, enrollment_type)
@@ -550,16 +553,17 @@ class RoleOverride < ActiveRecord::Base
     overrides = @@role_override_chain[permissionless_key]
     unless overrides
       contexts = []
-      while context
-        contexts << context
-        if context.respond_to?(:course)
-          context = context.course
-        elsif context.respond_to?(:account)
-          context = context.account
-        elsif context.respond_to?(:parent_account)
-          context = context.parent_account
+      context_walk = context
+      while context_walk
+        contexts << context_walk
+        if context_walk.respond_to?(:course)
+          context_walk = context_walk.course
+        elsif context_walk.respond_to?(:account)
+          context_walk = context_walk.account
+        elsif context_walk.respond_to?(:parent_account)
+          context_walk = context_walk.parent_account
         else
-          context = nil
+          context_walk = nil
         end
       end
       context_codes = contexts.reverse.map(&:asset_string)
@@ -579,6 +583,16 @@ class RoleOverride < ActiveRecord::Base
       
         if !generated_permission[:locked] && context_override = override
           unless context_override.enabled.nil?
+            if context_override.context == context
+              # if the explicit override is for the target context, the prior default
+              # is the parent context's value
+              generated_permission[:prior_default] = generated_permission[:enabled]
+            else
+              # otherwise, the prior default is the same as the new override,
+              # since changing it in the target context will create a new
+              # override
+              generated_permission[:prior_default] = context_override.enabled?
+            end
             generated_permission.merge!({
               :enabled => context_override.enabled?,
               :explicit => !context_override.enabled.nil?

app/views/role_overrides/index.html.erb

@@ -168,7 +168,7 @@
     </table>
     <div class="button-container">
       <button type="submit" class="button">Save Changes</button>
-      <a class="cancel_button button-secondary" href="<%= url_for(:back) %>">Cancel</button>
+      <a class="cancel_button button-secondary" href="<%= url_for(:back) %>">Cancel</a>
     </div>
   <% end -%>
 </div>

spec/models/role_override_spec.rb

@@ -0,0 +1,62 @@
+#
+# Copyright (C) 2011 Instructure, Inc.
+#
+# This file is part of Canvas.
+#
+# Canvas is free software: you can redistribute it and/or modify it under
+# the terms of the GNU Affero General Public License as published by the Free
+# Software Foundation, version 3 of the License.
+#
+# Canvas 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 Affero General Public License for more
+# details.
+#
+# You should have received a copy of the GNU Affero General Public License along
+# with this program. If not, see <http://www.gnu.org/licenses/>.
+#
+
+require File.expand_path(File.dirname(__FILE__) + '/../spec_helper.rb')
+
+describe RoleOverride do
+  it "should retain the prior permission when it encounters the first explicit override" do
+    course_model
+    RoleOverride.create!(:context => @course, :permission => 'moderate_forum',
+                         :enrollment_type => "TeacherEnrollment", :enabled => false)
+    permissions = RoleOverride.permission_for(@course.account, :moderate_forum, "TeacherEnrollment")
+    permissions[:enabled].should == true
+    permissions.key?(:prior_default).should == false
+    permissions[:explicit].should == false
+
+    permissions = RoleOverride.permission_for(@course, :moderate_forum, "TeacherEnrollment")
+    permissions[:enabled].should == false
+    permissions[:prior_default].should == true
+    permissions[:explicit].should == true
+  end
+
+  it "should use the immediately parent context as the prior permission when there are multiple explicit levels" do
+    a1 = account_model
+    a2 = account_model(:parent_account => a1)
+    a3 = account_model(:parent_account => a2)
+
+    RoleOverride.create!(:context => a1, :permission => 'moderate_forum',
+                         :enrollment_type => "TeacherEnrollment", :enabled => false)
+    RoleOverride.create!(:context => a2, :permission => 'moderate_forum',
+                         :enrollment_type => "TeacherEnrollment", :enabled => true)
+
+    permissions = RoleOverride.permission_for(a1, :moderate_forum, "TeacherEnrollment")
+    permissions[:enabled].should == false
+    permissions[:prior_default].should == true
+    permissions[:explicit].should == true
+
+    permissions = RoleOverride.permission_for(a2, :moderate_forum, "TeacherEnrollment")
+    permissions[:enabled].should == true
+    permissions[:prior_default].should == false
+    permissions[:explicit].should == true
+
+    permissions = RoleOverride.permission_for(a3, :moderate_forum, "TeacherEnrollment")
+    permissions[:enabled].should == true
+    permissions[:prior_default].should == true
+    permissions[:explicit].should == true
+  end
+end