FIX: allow sending PMs to staff via flag even when PMs are disabled (#6938)

* FIX: allow sending PMs to staff via flag even when PMs are disabled
FIX: allow sending PMs to staff via flag even if the user trust level is insufficient

* Update lib/topic_creator.rb

Co-Authored-By: techAPJ <arpit@techapj.com>

lib/guardian.rb

@@ -343,7 +343,7 @@ class Guardian
     can_send_private_message?(group)
   end
 
-  def can_send_private_message?(target)
+  def can_send_private_message?(target, notify_moderators: false)
     is_user = target.is_a?(User)
     is_group = target.is_a?(Group)
 
@@ -351,11 +351,11 @@ class Guardian
     # User is authenticated
     authenticated? &&
     # Have to be a basic level at least
-    @user.has_trust_level?(SiteSetting.min_trust_to_send_messages) &&
+    (@user.has_trust_level?(SiteSetting.min_trust_to_send_messages) || notify_moderators) &&
     # User disabled private message
     (is_staff? || is_group || target.user_option.allow_private_messages) &&
     # PMs are enabled
-    (is_staff? || SiteSetting.enable_personal_messages) &&
+    (is_staff? || SiteSetting.enable_personal_messages || notify_moderators) &&
     # Can't send PMs to suspended users
     (is_staff? || is_group || !target.suspended?) &&
     # Check group messageable level

lib/guardian/post_guardian.rb

@@ -48,7 +48,7 @@ module PostGuardian
         (!SiteSetting.allow_flagging_staff?) &&
         post&.user&.staff?
 
-      if [:notify_user, :notify_moderators].include?(action_key) &&
+      if action_key == :notify_user &&
          (!SiteSetting.enable_personal_messages? ||
          !@user.has_trust_level?(SiteSetting.min_trust_to_send_messages))
 

lib/topic_creator.rb

@@ -260,7 +260,10 @@ class TopicCreator
   end
 
   def check_can_send_permission!(topic, obj)
-    rollback_with!(topic, :cant_send_pm) unless @opts[:skip_validations] || @guardian.can_send_private_message?(obj)
+    unless @opts[:skip_validations] ||
+      @guardian.can_send_private_message?(obj, notify_moderators: topic&.subtype == TopicSubtype.notify_moderators))
+      rollback_with!(topic, :cant_send_pm)
+    end
   end
 
   def find_or_create_user(email, display_name)

spec/components/guardian_spec.rb

@@ -171,15 +171,13 @@ describe Guardian do
       SiteSetting.enable_personal_messages = false
       user.trust_level = TrustLevel[2]
       expect(Guardian.new(user).post_can_act?(post, :notify_user)).to be_falsey
-      expect(Guardian.new(user).post_can_act?(post, :notify_moderators)).to be_falsey
     end
 
-    it "returns false for notify_user and notify_moderators if private messages are enabled but threshold not met" do
+    it "returns false for notify_user if private messages are enabled but threshold not met" do
       SiteSetting.enable_personal_messages = true
       SiteSetting.min_trust_to_send_messages = 2
       user.trust_level = TrustLevel[1]
       expect(Guardian.new(user).post_can_act?(post, :notify_user)).to be_falsey
-      expect(Guardian.new(user).post_can_act?(post, :notify_moderators)).to be_falsey
     end
 
     describe "trust levels" do

spec/components/topic_creator_spec.rb

@@ -154,6 +154,12 @@ describe TopicCreator do
 
           expect(TopicCreator.create(user, Guardian.new(user), pm_to_email_valid_attrs)).to be_valid
         end
+
+        it "enable_personal_messages setting should not be checked when sending private message to staff via flag" do
+          SiteSetting.enable_personal_messages = false
+          SiteSetting.min_trust_to_send_messages = TrustLevel[4]
+          expect(TopicCreator.create(user, Guardian.new(user), pm_valid_attrs.merge(subtype: TopicSubtype.notify_moderators))).to be_valid
+        end
       end
 
       context 'failure cases' do