Use edition links for worldwide organisation offices

We are switching worldwide organisations to use edition links which do
not support multi-level link expanstion.

Therefore we need to switch the rendering code to use the new link
fields that have been added, in the absence of multi-level links.

app/presenters/worldwide_organisation_presenter.rb

@@ -78,7 +78,9 @@ def people_in_non_primary_roles
 
   def main_office
     return unless (office_item = content_item.dig("links", "main_office")&.first)
-    return unless (office_contact_item = office_item.dig("links", "contact")&.first)
+
+    office_contact_item = contact_for_office(office_item["content_id"])
+    return unless office_contact_item
 
     WorldwideOffice.new(
       contact: WorldwideOrganisation::LinkedContactPresenter.new(office_contact_item),
@@ -93,7 +95,7 @@ def home_page_offices
     return [] unless content_item.dig("links", "home_page_offices")
 
     content_item.dig("links", "home_page_offices").map { |office|
-      next unless (contact = office.dig("links", "contact")&.first)
+      next unless (contact = contact_for_office(office["content_id"]))
 
       WorldwideOrganisation::LinkedContactPresenter.new(contact)
     }.compact
@@ -128,6 +130,18 @@ def sponsoring_organisations
 
 private
 
+  def contact_for_office(office_content_id)
+    contact_mapping = content_item.dig("details", "office_contact_associations").select { |office_contact_association|
+      office_contact_association["office_content_id"] == office_content_id
+    }.first
+
+    return unless contact_mapping
+
+    content_item.dig("links", "contacts").select { |contact|
+      contact["content_id"] == contact_mapping["contact_content_id"]
+    }.first
+  end
+
   def presented_title_for_roles(roles)
     roles
       .map { |role| role["title"] }