Account merging support

Adds support for merging accounts with account migration by eliminating
duplicate data in favor of the target user's data.

closes #7803

Changelog.md

@@ -15,6 +15,7 @@
 
 ## Features
 * Make public stream accessible for logged out users [#7775](https://github.com/diaspora/diaspora/pull/7775)
+* Add account-merging support when receiving an account migration [#7803](https://github.com/diaspora/diaspora/pull/7803)
 
 # 0.7.4.1
 

app/models/account_migration.rb

@@ -148,13 +148,62 @@ class AccountMigration < ApplicationRecord
     }
   end
 
+  def eliminate_person_duplicates
+    duplicate_person_contacts.destroy_all
+    duplicate_person_likes.destroy_all
+    duplicate_person_participations.destroy_all
+    duplicate_person_poll_participations.destroy_all
+  end
+
+  def duplicate_person_contacts
+    Contact
+      .joins("INNER JOIN contacts as c2 ON (contacts.user_id = c2.user_id AND contacts.person_id=#{old_person.id} AND"\
+        " c2.person_id=#{new_person.id})")
+  end
+
+  def duplicate_person_likes
+    Like
+      .joins("INNER JOIN likes as l2 ON (likes.target_id = l2.target_id "\
+        "AND likes.target_type = l2.target_type "\
+        "AND likes.author_id=#{old_person.id} AND"\
+        " l2.author_id=#{new_person.id})")
+  end
+
+  def duplicate_person_participations
+    Participation
+      .joins("INNER JOIN participations as p2 ON (participations.target_id = p2.target_id "\
+        "AND participations.target_type = p2.target_type "\
+        "AND participations.author_id=#{old_person.id} AND"\
+        " p2.author_id=#{new_person.id})")
+  end
+
+  def duplicate_person_poll_participations
+    PollParticipation
+      .joins("INNER JOIN poll_participations as p2 ON (poll_participations.poll_id = p2.poll_id "\
+        "AND poll_participations.author_id=#{old_person.id} AND"\
+        " p2.author_id=#{new_person.id})")
+  end
+
+  def eliminate_user_duplicates
+    Aspect
+      .joins("INNER JOIN aspects as a2 ON (aspects.name = a2.name AND aspects.user_id=#{old_user.id}
+        AND a2.user_id=#{new_user.id})")
+      .destroy_all
+    Contact
+      .joins("INNER JOIN contacts as c2 ON (contacts.person_id = c2.person_id AND contacts.user_id=#{old_user.id} AND"\
+        " c2.user_id=#{new_user.id})")
+      .destroy_all
+  end
+
   def update_person_references
     logger.debug "Updating references from person id=#{old_person.id} to person id=#{new_person.id}"
+    eliminate_person_duplicates
     update_references(person_references, old_person, new_person.id)
   end
 
   def update_user_references
     logger.debug "Updating references from user id=#{old_user.id} to user id=#{new_user.id}"
+    eliminate_user_duplicates
     update_references(user_references, old_user, new_user.id)
   end
 

spec/models/account_migration_spec.rb

@@ -154,5 +154,66 @@ describe AccountMigration, type: :model do
         account_migration.perform!
       end
     end
+
+    context "with remote account merging (non-empty new person)" do
+      before do
+        FactoryGirl.create(
+          :contact,
+          person: new_person,
+          user:   FactoryGirl.create(:contact, person: old_person).user
+        )
+        FactoryGirl.create(
+          :like,
+          author: new_person,
+          target: FactoryGirl.create(:like, author: old_person).target
+        )
+        FactoryGirl.create(
+          :participation,
+          author: new_person,
+          target: FactoryGirl.create(:participation, author: old_person).target
+        )
+        FactoryGirl.create(
+          :poll_participation,
+          author:      new_person,
+          poll_answer: FactoryGirl.create(:poll_participation, author: old_person).poll_answer
+        )
+      end
+
+      it "runs without errors" do
+        expect {
+          account_migration.perform!
+        }.not_to raise_error
+        expect(new_person.likes.count).to eq(1)
+        expect(new_person.participations.count).to eq(1)
+        expect(new_person.poll_participations.count).to eq(1)
+        expect(new_person.contacts.count).to eq(1)
+      end
+    end
+
+    context "with local account merging (non-empty new user)" do
+      include_context "with local old user"
+      include_context "with local new user"
+
+      before do
+        FactoryGirl.create(
+          :aspect,
+          user: new_person.owner,
+          name: FactoryGirl.create(:aspect, user: old_person.owner).name
+        )
+        FactoryGirl.create(
+          :contact,
+          user:   new_person.owner,
+          person: FactoryGirl.create(:contact, user: old_person.owner).person
+        )
+      end
+
+      it "runs without errors" do
+        expect {
+          account_migration.perform!
+        }.not_to raise_error
+        expect(new_person.owner.contacts.count).to eq(1)
+        expect(new_person.owner.aspects.count).to eq(1)
+      end
+    end
   end
 end