create user merge table

fixes CNVS-27291

test plan
 - merge users
 - data should be populated

Change-Id: I5720933484494f582bad4b294a7e6b4edea66b92
Reviewed-on: https://gerrit.instructure.com/72700
Tested-by: Jenkins
Reviewed-by: Cody Cutrer <cody@instructure.com>
QA-Review: Jeremy Putnam <jeremyp@instructure.com>
Product-Review: Rob Orton <rob@instructure.com>

app/models/user_merge_data.rb

@@ -0,0 +1,33 @@
+#
+# Copyright (C) 2016 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/>.
+#
+class UserMergeData < ActiveRecord::Base
+  belongs_to :user
+  belongs_to :from_user, class_name: 'User'
+  has_many :user_merge_data_records
+
+  strong_params
+
+  def add_more_data(objects)
+    objects.each do |o|
+      r = self.user_merge_data_records.new(context: o, previous_user_id: o.user_id)
+      r.previous_workflow_state = o.workflow_state if o.class.columns_hash.key?('workflow_state')
+      r.save!
+    end
+  end
+
+end

app/models/user_merge_data_record.rb

@@ -0,0 +1,24 @@
+#
+# Copyright (C) 2016 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/>.
+#
+class UserMergeDataRecord < ActiveRecord::Base
+  belongs_to :previous_user, class_name: 'User'
+  belongs_to :user_merge_data
+  belongs_to :context, polymorphic: [:account_user, :enrollment, :pseudonym]
+
+  strong_params
+end

db/migrate/20160222035553_create_user_merge_data.rb

@@ -0,0 +1,29 @@
+class CreateUserMergeData < ActiveRecord::Migration
+  tag :predeploy
+
+  def change
+    create_table :user_merge_data do |t|
+      t.integer :user_id, limit: 8, null: false
+      t.integer :from_user_id, limit: 8, null: false
+      t.timestamps null: false
+      t.string :workflow_state, null: false, default: 'active'
+    end
+
+    create_table :user_merge_data_records do |t|
+      t.integer :user_merge_data_id, limit: 8, null: false
+      t.integer :context_id, limit: 8, null: false
+      t.integer :previous_user_id, limit: 8, null: false
+      t.string :context_type, null: false
+      t.string :previous_workflow_state
+    end
+
+    add_index :user_merge_data, :user_id
+    add_index :user_merge_data, :from_user_id
+    add_index :user_merge_data_records, :user_merge_data_id
+    add_index :user_merge_data_records, [:context_id, :context_type, :user_merge_data_id, :previous_user_id],
+              unique: true, name: "index_user_merge_data_records_on_context_id_and_context_type"
+
+    add_foreign_key :user_merge_data, :users
+    add_foreign_key :user_merge_data_records, :user_merge_data, column: :user_merge_data_id
+  end
+end

lib/user_merge.rb

@@ -13,6 +13,9 @@ class UserMerge
   def into(target_user)
     return unless target_user
     return if target_user == from_user
+    user_merge_data = target_user.shard.activate do
+      UserMergeData.create!(user: target_user, from_user: from_user)
+    end
 
     if target_user.avatar_state == :none && from_user.avatar_state != :none
       [:avatar_image_source, :avatar_image_url, :avatar_image_updated_at, :avatar_state].each do |attr|
@@ -96,11 +99,13 @@ class UserMerge
 
     destroy_conflicting_module_progressions(@from_user, target_user)
 
-    move_enrollments(@from_user, target_user)
+    move_enrollments(target_user, user_merge_data)
 
     Shard.with_each_shard(from_user.associated_shards + from_user.associated_shards(:weak) + from_user.associated_shards(:shadow)) do
-      max_position = Pseudonym.where(:user_id => target_user).order(:position).last.try(:position) || 0
-      Pseudonym.where(:user_id => from_user).update_all(["user_id=?, position=position+?", target_user, max_position])
+      max_position = Pseudonym.where(user_id: target_user).order(:position).last.try(:position) || 0
+      pseudonyms_to_move = Pseudonym.where(user_id: from_user)
+      user_merge_data.add_more_data(pseudonyms_to_move)
+      pseudonyms_to_move.update_all(["user_id=?, position=position+?", target_user, max_position])
 
       target_user.communication_channels.email.unretired.each do |cc|
         Rails.cache.delete([cc.path, 'invited_enrollments2'].cache_key)
@@ -165,9 +170,12 @@ class UserMerge
         Rails.logger.error "migrating discussions failed: #{e}"
       end
 
+      account_users = AccountUser.where(user_id: from_user)
+      user_merge_data.add_more_data(account_users)
+      account_users.update_all(user_id: target_user)
+
       updates = {}
-      ['account_users', 'access_tokens', 'asset_user_accesses',
-       'attachments',
+      ['access_tokens', 'asset_user_accesses', 'attachments',
        'calendar_events', 'collaborations',
        'context_module_progressions',
        'group_memberships', 'page_comments',
@@ -291,31 +299,46 @@ class UserMerge
                       END, sis_batch_id DESC, updated_at DESC").first
   end
 
-  def move_enrollments(from_user, target_user)
-    [:associated_user_id, :user_id].each do |column|
+  def handle_conflicts(column, target_user, user_merge_data)
     users = [from_user, target_user]
-      Shard.with_each_shard(from_user.associated_shards) do
-        Enrollment.transaction do
     conflict_scope(column).where(column => users).find_each do |e|
 
       scope = enrollment_conflicts(e, column, users)
       keeper = enrollment_keeper(scope)
 
       # delete all conflicts from target user
-            scope.where("id<>?", keeper).where(column => target_user).delete_all
+      to_delete = scope.where("id<>?", keeper).where(column => target_user)
+      user_merge_data.add_more_data(to_delete)
+      to_delete.delete_all
 
       # mark all conflicts on from_user as deleted so they will be left
-            scope.active.where("id<>?", keeper).where(column => from_user).destroy_all
+      to_delete = scope.active.where("id<>?", keeper).where(column => from_user)
+      user_merge_data.add_more_data(to_delete)
+      to_delete.destroy_all
+    end
   end
 
+  def remove_self_observers(target_user, user_merge_data)
     # prevent observing self by marking them as deleted
-          Enrollment.active.where("type = 'ObserverEnrollment' AND
+    to_delete = Enrollment.active.where("type = 'ObserverEnrollment' AND
                                                    (associated_user_id = :target_user AND user_id = :from_user OR
                                                    associated_user_id = :from_user AND user_id = :target_user)",
-                                  {target_user: target_user, from_user: from_user}).destroy_all
+                                                  {target_user: target_user, from_user: from_user})
+    user_merge_data.add_more_data(to_delete)
+    to_delete.destroy_all
+  end
+
+  def move_enrollments(target_user, user_merge_data)
+    [:associated_user_id, :user_id].each do |column|
+      Shard.with_each_shard(from_user.associated_shards) do
+        Enrollment.transaction do
+          handle_conflicts(column, target_user, user_merge_data)
+          remove_self_observers(target_user, user_merge_data)
 
           # move all the enrollments that are not marked as deleted to the target user
-          Enrollment.active.where(column => from_user).update_all(column => target_user)
+          to_move = Enrollment.active.where(column => from_user)
+          user_merge_data.add_more_data(to_move)
+          to_move.update_all(column => target_user)
         end
       end
     end

spec/lib/user_merge_spec.rb

@@ -17,14 +17,29 @@ describe UserMerge do
     end
 
     it "should move pseudonyms to the new user" do
-      user2.pseudonyms.create!(:unique_id => 'sam@yahoo.com')
+      pseudonym = user2.pseudonyms.create!(unique_id: 'sam@yahoo.com')
+      pseudonym2 = user2.pseudonyms.create!(unique_id: 'sam2@yahoo.com')
       UserMerge.from(user2).into(user1)
+      merge_data = UserMergeData.where(user_id: user1).first
+      expect(merge_data.from_user_id).to eq user2.id
+      expect(merge_data.user_merge_data_records.pluck(:context_id).sort).to eq [pseudonym.id, pseudonym2.id].sort
       user2.reload
       expect(user2.pseudonyms).to be_empty
       user1.reload
       expect(user1.pseudonyms.map(&:unique_id)).to be_include('sam@yahoo.com')
     end
 
+    it "should move admins to the new user" do
+      account1 = account_model
+      admin = account1.account_users.create(user: user2)
+      UserMerge.from(user2).into(user1)
+      merge_data = UserMergeData.where(user_id: user1).first
+      expect(merge_data.from_user_id).to eq user2.id
+      expect(merge_data.user_merge_data_records.where(context_type: 'AccountUser').first.context_id).to eq admin.id
+      user1.reload
+      expect(user1.account_users.first.id).to eq admin.id
+    end
+
     it "should use avatar information from merged user if none exists" do
       user2.avatar_image = {'type' => 'external', 'url' => 'https://example.com/image.png'}
       user2.save!
@@ -219,9 +234,14 @@ describe UserMerge do
       enrollment4 = course1.enroll_teacher(user1)
 
       UserMerge.from(user1).into(user2)
+      merge_data = UserMergeData.where(user_id: user2).first
+      expect(merge_data.user_merge_data_records.pluck(:context_id).sort).
+        to eq [enrollment1.id, enrollment3.id, enrollment4.id].sort
       enrollment1.reload
       expect(enrollment1.user).to eq user1
       expect(enrollment1).to be_deleted
+      merge_data_record = merge_data.user_merge_data_records.where(context_id: enrollment1).first
+      expect(merge_data_record.previous_workflow_state).to eq 'invited'
       enrollment2.reload
       expect(enrollment2).to be_active
       expect(enrollment2.user).to eq user2
@@ -271,6 +291,9 @@ describe UserMerge do
       enrollment2 = course1.enroll_user(user2, 'ObserverEnrollment', enrollment_state: 'active', associated_user_id: user1.id)
 
       UserMerge.from(user1).into(user2)
+      merge_data = UserMergeData.where(user_id: user2).first
+      o = merge_data.user_merge_data_records.where(context_id: enrollment2).first
+      expect(o.previous_workflow_state).to eq 'active'
       expect(enrollment1.reload.user).to eql user2
       expect(enrollment2.reload.workflow_state).to eql 'deleted'
     end