Merge "legacy User" into currently logged in User

app/controllers/profiles_controller.rb

@@ -38,6 +38,36 @@ def update_notifications
     end
   end
 
+  def merge
+    @legacy_user = User.find_by(id: session[:pending_merge_user_id])
+    @provider = session[:pending_merge_provider]
+
+    unless @legacy_user && @provider
+      redirect_to edit_profile_path
+    end
+  end
+
+  def confirm_merge
+    legacy_user = User.find_by(id: session[:pending_merge_user_id])
+    provider = session[:pending_merge_provider]
+    uid = session[:pending_merge_uid]
+
+    unless legacy_user && provider && uid
+      flash[:danger] = 'Merge session expired. Please try again.'
+      redirect_to edit_profile_path and return
+    end
+
+    current_user.merge_from!(legacy_user)
+    current_user.identities.create!(provider: provider, uid: uid)
+
+    session.delete(:pending_merge_user_id)
+    session.delete(:pending_merge_provider)
+    session.delete(:pending_merge_uid)
+
+    flash[:info] = "Successfully merged accounts and connected #{Identity::PROVIDER_NAMES[provider]}."
+    redirect_to edit_profile_path
+  end
+
   private
 
   def user_params

app/controllers/users/omniauth_callbacks_controller.rb

@@ -29,12 +29,18 @@ def link_identity_to_current_user
       else
         flash[:danger] = "This #{provider_name} account is already connected to another user."
       end
+      redirect_to edit_profile_path
+    elsif (legacy_user = User.find_by(provider: auth_hash.provider, uid: auth_hash.uid))
+      # Found a legacy user - need to merge
+      session[:pending_merge_user_id] = legacy_user.id
+      session[:pending_merge_provider] = auth_hash.provider
+      session[:pending_merge_uid] = auth_hash.uid
+      redirect_to merge_profile_path
     else
       current_user.identities.create!(provider: auth_hash.provider, uid: auth_hash.uid)
       flash[:info] = "Successfully connected #{provider_name} to your account."
+      redirect_to edit_profile_path
     end
-
-    redirect_to edit_profile_path
   end
 
   def authenticate_with_hash(user = nil)

app/models/user.rb

@@ -156,6 +156,21 @@ def profile_errors
     end
     profile_errors
   end
+
+  # Merge another user's associations into this user
+  def merge_from!(other_user)
+    transaction do
+      other_user.invitations.update_all(user_id: id)
+      other_user.teammates.update_all(user_id: id)
+      other_user.speakers.update_all(user_id: id)
+      other_user.ratings.update_all(user_id: id)
+      other_user.comments.update_all(user_id: id)
+      other_user.notifications.update_all(user_id: id)
+
+      # Clear legacy OAuth fields so the old user can't be found via from_omniauth
+      other_user.update_columns(provider: nil, uid: nil)
+    end
+  end
 end
 
 # == Schema Information

app/views/profiles/merge.html.haml

@@ -0,0 +1,39 @@
+.row
+  .col-md-12
+    %header.page-header
+      %h1 Merge Accounts
+
+.row
+  .col-md-8
+    .widget
+      .widget-header
+        %i.bi.bi-exclamation-triangle
+        %h3 Account Merge Required
+      .widget-content
+        %p
+          The #{Identity::PROVIDER_NAMES[@provider]} account you're trying to connect is already linked to another account.
+          To connect it to your current account, we need to merge the two accounts.
+
+        %h4 What will be merged:
+        %ul
+          - if @legacy_user.speakers.any?
+            %li
+              %strong= pluralize(@legacy_user.speakers.count, 'proposal')
+          - if @legacy_user.teammates.any?
+            %li
+              %strong= pluralize(@legacy_user.teammates.count, 'team membership')
+          - if @legacy_user.ratings.any?
+            %li
+              %strong= pluralize(@legacy_user.ratings.count, 'rating')
+          - if @legacy_user.comments.any?
+            %li
+              %strong= pluralize(@legacy_user.comments.count, 'comment')
+          - if @legacy_user.speakers.empty? && @legacy_user.teammates.empty? && @legacy_user.ratings.empty? && @legacy_user.comments.empty?
+            %li No proposals, team memberships, or other data to merge.
+
+        %p.text-muted
+          The old account's profile information (name, email, bio) will not be transferred.
+
+        .mt-4
+          = button_to 'Merge Accounts', merge_profile_path, class: 'btn btn-primary', data: {turbo_confirm: 'Are you sure you want to merge these accounts? This cannot be undone.'}
+          = link_to 'Cancel', edit_profile_path, class: 'btn btn-secondary ms-2'

config/routes.rb

@@ -6,6 +6,8 @@
   resource :profile, only: [:show, :edit, :update] do
     get :notifications
     patch :notifications, action: :update_notifications
+    get :merge
+    post :merge, action: :confirm_merge
   end
   get '/my-proposals' => 'proposals#index', as: :proposals
 

spec/controllers/users/omniauth_callbacks_controller_spec.rb

@@ -94,5 +94,20 @@
         expect(flash[:danger]).to eq('This GitHub account is already connected to another user.')
       end
     end
+
+    context 'when legacy user exists with same provider/uid' do
+      it 'redirects to merge page' do
+        legacy_user = create(:user, provider: 'github', uid: github_auth_hash.uid)
+        user = create(:user)
+        sign_in(user)
+
+        get :github
+
+        expect(response).to redirect_to(merge_profile_path)
+        expect(session[:pending_merge_user_id]).to eq(legacy_user.id)
+        expect(session[:pending_merge_provider]).to eq('github')
+        expect(session[:pending_merge_uid]).to eq(github_auth_hash.uid)
+      end
+    end
   end
 end

spec/models/user_spec.rb

@@ -259,4 +259,33 @@
       expect(user.profile_errors.messages[:email][0]).to eq unconfirmed_email_err_msg
     end
   end
+
+  describe '#merge_from!' do
+    let(:current_user) { create(:user) }
+    let(:legacy_user) { create(:user, provider: 'twitter', uid: '12345') }
+    let(:event) { create(:event) }
+    let(:proposal) { create(:proposal, event: event) }
+
+    it 'transfers all associations and clears legacy OAuth fields' do
+      invitation = create(:invitation, user: legacy_user, email: '[email protected]', proposal: proposal)
+      teammate = create(:teammate, user: legacy_user, event: event, role: 'reviewer')
+      speaker = create(:speaker, user: legacy_user, proposal: proposal)
+      rating = create(:rating, user: legacy_user, proposal: proposal)
+      comment = create(:comment, user: legacy_user, proposal: proposal)
+      notification = create(:notification, user: legacy_user)
+
+      current_user.merge_from!(legacy_user)
+
+      expect(invitation.reload.user_id).to eq(current_user.id)
+      expect(teammate.reload.user_id).to eq(current_user.id)
+      expect(speaker.reload.user_id).to eq(current_user.id)
+      expect(rating.reload.user_id).to eq(current_user.id)
+      expect(comment.reload.user_id).to eq(current_user.id)
+      expect(notification.reload.user_id).to eq(current_user.id)
+
+      legacy_user.reload
+      expect(legacy_user.provider).to be_nil
+      expect(legacy_user.uid).to be_nil
+    end
+  end
 end