Allow Member.add_user to handle access requesters

Changes include:

- Ensure Member.add_user is not called directly when not necessary
- New GroupMember.add_users_to_group to have the same abstraction level as for Project
- Refactor Member.add_user to take a source instead of an array of members
- Fix Rubocop offenses
- Always use Project#add_user instead of project.team.add_user
- Factorize users addition as members in Member.add_users_to_source
- Make access_level a keyword argument in GroupMember.add_users_to_group and ProjectMember.add_users_to_projects
- Destroy any requester before adding them as a member
- Improve the way we handle access requesters in Member.add_user
  Instead of removing the requester and creating a new member,
  we now simply accepts their access request. This way, they will
  receive a "access request granted" email.
- Fix error that was previously silently ignored
- Stop raising when access level is invalid in Member, let Rails validation do their work

Signed-off-by: Rémy Coutable <remy@rymai.me>

2 files changed, 31 insertions, 29 deletions

diff --git a/app/models/members/group_member.rb b/app/models/members/group_member.rb
index 2f13d339c89..1b54a85d064 100644
--- a/app/models/members/group_member.rb
+++ b/app/models/members/group_member.rb
@@ -12,6 +12,22 @@ class GroupMember < Member
     Gitlab::Access.options_with_owner
   end
 
+  def self.access_levels
+    Gitlab::Access.sym_options_with_owner
+  end
+
+  def self.add_users_to_group(group, users, access_level, current_user: nil, expires_at: nil)
+    self.transaction do
+      add_users_to_source(
+        group,
+        users,
+        access_level,
+        current_user: current_user,
+        expires_at: expires_at
+      )
+    end
+  end
+
   def group
     source
   end
diff --git a/app/models/members/project_member.rb b/app/models/members/project_member.rb
index ec2d40eb11c..125f26369d7 100644
--- a/app/models/members/project_member.rb
+++ b/app/models/members/project_member.rb
@@ -34,36 +34,20 @@ class ProjectMember < Member
     #     :master
     #   )
     #
-    def add_users_to_projects(project_ids, user_ids, access, current_user: nil, expires_at: nil)
-      access_level = if roles_hash.has_key?(access)
-                       roles_hash[access]
-                     elsif roles_hash.values.include?(access.to_i)
-                       access
-                     else
-                       raise "Non valid access"
-                     end
-
-      users = user_ids.map { |user_id| Member.user_for_id(user_id) }
-
-      ProjectMember.transaction do
+    def add_users_to_projects(project_ids, users, access_level, current_user: nil, expires_at: nil)
+      self.transaction do
         project_ids.each do |project_id|
           project = Project.find(project_id)
 
-          users.each do |user|
-            Member.add_user(
-              project.project_members,
-              user,
-              access_level,
-              current_user: current_user,
-              expires_at: expires_at
-            )
-          end
+          add_users_to_source(
+            project,
+            users,
+            access_level,
+            current_user: current_user,
+            expires_at: expires_at
+          )
         end
       end
-
-      true
-    rescue
-      false
     end
 
     def truncate_teams(project_ids)
@@ -84,13 +68,15 @@ class ProjectMember < Member
       truncate_teams [project.id]
     end
 
-    def roles_hash
-      Gitlab::Access.sym_options
-    end
-
     def access_level_roles
       Gitlab::Access.options
     end
+
+    private
+
+    def can_update_member?(current_user, member)
+      super || (member.owner? && member.new_record?)
+    end
   end
 
   def access_field