Use standard reactive flags

Use connected and available to keep separate from joined and changed.

provides.py

@@ -1,4 +1,4 @@
-# Copyright 2017 Canonical Ltd
+# Copyright 2019 Canonical Ltd
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -12,14 +12,35 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import uuid
-
-from charms.reactive import hook
-from charms.reactive import set_flag, clear_flag
-from charms.reactive import Endpoint
+from charms.reactive import (
+    Endpoint,
+    clear_flag,
+    set_flag,
+    when,
+    when_any,
+)
 
 
 class WebSSOFIDServiceProviderProvides(Endpoint):
+
+    @when('endpoint.{endpoint_name}.joined')
+    def joined(self):
+        set_flag(self.expand_name('{endpoint_name}.connected'))
+
+    @when('endpoint.{endpoint_name}.changed')
+    def changed(self):
+        set_flag(self.expand_name('{endpoint_name}.available'))
+
+    @when_any('endpoint.{endpoint_name}.broken',
+              'endpoint.{endpoint_name}.departed')
+    def departed(self):
+        flags = (
+            self.expand_name('{endpoint_name}.available'),
+            self.expand_name('{endpoint_name}.connected'),
+        )
+        for flag in flags:
+            clear_flag(flag)
+
     def publish(self, protocol_name, idp_name, user_facing_name):
         # can have multiple dashboard charms in general, therefore,
         # all relation objects and all units must be handled