3 files changed, 57 insertions, 30 deletions

diff --git a/app/models/concerns/case_sensitivity.rb b/app/models/concerns/case_sensitivity.rb
new file mode 100644
index 00000000000..fe0cea8465f
--- /dev/null
+++ b/app/models/concerns/case_sensitivity.rb
@@ -0,0 +1,28 @@
+# Concern for querying columns with specific case sensitivity handling.
+module CaseSensitivity
+  extend ActiveSupport::Concern
+
+  module ClassMethods
+    # Queries the given columns regardless of the casing used.
+    #
+    # Unlike other ActiveRecord methods this method only operates on a Hash.
+    def iwhere(params)
+      criteria   = self
+      cast_lower = Gitlab::Database.postgresql?
+
+      params.each do |key, value|
+        column = ActiveRecord::Base.connection.quote_table_name(key)
+
+        if cast_lower
+          condition = "LOWER(#{column}) = LOWER(:value)"
+        else
+          condition = "#{column} = :value"
+        end
+
+        criteria = criteria.where(condition, value: value)
+      end
+
+      criteria
+    end
+  end
+end
diff --git a/app/models/concerns/mentionable.rb b/app/models/concerns/mentionable.rb
index 715fc6f689d..193c91f1742 100644
--- a/app/models/concerns/mentionable.rb
+++ b/app/models/concerns/mentionable.rb
@@ -47,54 +47,49 @@ module Mentionable
     self
   end
 
-  # Determine whether or not a cross-reference Note has already been created between this Mentionable and
-  # the specified target.
-  def has_mentioned?(target)
-    SystemNoteService.cross_reference_exists?(target, local_reference)
+  def all_references(current_user = self.author, text = self.mentionable_text, load_lazy_references: true)
+    ext = Gitlab::ReferenceExtractor.new(self.project, current_user, load_lazy_references: load_lazy_references)
+    ext.analyze(text)
+    ext
   end
 
   def mentioned_users(current_user = nil, load_lazy_references: true)
-    return [] if mentionable_text.blank?
-
-    ext = Gitlab::ReferenceExtractor.new(self.project, current_user, load_lazy_references: load_lazy_references)
-    ext.analyze(mentionable_text)
-    ext.users.uniq
+    all_references(current_user, load_lazy_references: load_lazy_references).users
   end
 
   # Extract GFM references to other Mentionables from this Mentionable. Always excludes its #local_reference.
-  def references(p = project, current_user = self.author, text = mentionable_text, load_lazy_references: true)
+  def referenced_mentionables(current_user = self.author, text = self.mentionable_text, load_lazy_references: true)
     return [] if text.blank?
 
-    ext = Gitlab::ReferenceExtractor.new(p, current_user, load_lazy_references: load_lazy_references)
-    ext.analyze(text)
-    (ext.issues + ext.merge_requests + ext.commits).uniq - [local_reference]
+    refs = all_references(current_user, text, load_lazy_references: load_lazy_references)
+    (refs.issues + refs.merge_requests + refs.commits) - [local_reference]
   end
 
   # Create a cross-reference Note for each GFM reference to another Mentionable found in +mentionable_text+.
-  def create_cross_references!(p = project, a = author, without = [])
-    refs = references(p)
-
+  def create_cross_references!(author = self.author, without = [], text = self.mentionable_text)
+    refs = referenced_mentionables(author, text)
+    
     # We're using this method instead of Array diffing because that requires
     # both of the object's `hash` values to be the same, which may not be the
     # case for otherwise identical Commit objects.
-    refs.reject! { |ref| without.include?(ref) }
+    refs.reject! { |ref| without.include?(ref) || cross_reference_exists?(ref) }
 
     refs.each do |ref|
-      SystemNoteService.cross_reference(ref, local_reference, a)
+      SystemNoteService.cross_reference(ref, local_reference, author)
     end
   end
 
   # When a mentionable field is changed, creates cross-reference notes that
   # don't already exist
-  def create_new_cross_references!(p = project, a = author)
+  def create_new_cross_references!(author = self.author)
     changes = detect_mentionable_changes
 
     return if changes.empty?
 
     original_text = changes.collect { |_, vals| vals.first }.join(' ')
 
-    preexisting = references(p, self.author, original_text)
-    create_cross_references!(p, a, preexisting)
+    preexisting = referenced_mentionables(author, original_text)
+    create_cross_references!(author, preexisting)
   end
 
   private
@@ -116,4 +111,10 @@ module Mentionable
     # Only include changed fields that are mentionable
     source.select { |key, val| mentionable.include?(key) }
   end
+  
+  # Determine whether or not a cross-reference Note has already been created between this Mentionable and
+  # the specified target.
+  def cross_reference_exists?(target)
+    SystemNoteService.cross_reference_exists?(target, local_reference)
+  end
 end
diff --git a/app/models/concerns/participable.rb b/app/models/concerns/participable.rb
index 0888de62f0a..85367f89f4f 100644
--- a/app/models/concerns/participable.rb
+++ b/app/models/concerns/participable.rb
@@ -37,7 +37,7 @@ module Participable
 
   # Be aware that this method makes a lot of sql queries.
   # Save result into variable if you are going to reuse it inside same request
-  def participants(current_user = self.author, project = self.project, load_lazy_references: true)
+  def participants(current_user = self.author, load_lazy_references: true)
     participants = self.class.participant_attrs.flat_map do |attr|
       value =
         if attr.respond_to?(:call)
@@ -46,16 +46,14 @@ module Participable
           send(attr)
         end
 
-      participants_for(value, current_user, project)
+      participants_for(value, current_user)
     end.compact.uniq
 
     if load_lazy_references
       participants = Gitlab::Markdown::ReferenceFilter::LazyReference.load(participants).uniq
 
-      if project
-        participants.select! do |user|
-          user.can?(:read_project, project)
-        end
+      participants.select! do |user|
+        user.can?(:read_project, project)
       end
     end
 
@@ -64,14 +62,14 @@ module Participable
 
   private
 
-  def participants_for(value, current_user = nil, project = nil)
+  def participants_for(value, current_user = nil)
     case value
     when User, Gitlab::Markdown::ReferenceFilter::LazyReference
       [value]
     when Enumerable, ActiveRecord::Relation
-      value.flat_map { |v| participants_for(v, current_user, project) }
+      value.flat_map { |v| participants_for(v, current_user) }
     when Participable
-      value.participants(current_user, project, load_lazy_references: false)
+      value.participants(current_user, load_lazy_references: false)
     end
   end
 end