Add timeline of public posts about a trending link to REST API (#30381)

app/models/link_feed.rb

@@ -0,0 +1,35 @@
+# frozen_string_literal: true
+
+class LinkFeed < PublicFeed
+  # @param [PreviewCard] preview_card
+  # @param [Account] account
+  # @param [Hash] options
+  def initialize(preview_card, account, options = {})
+    @preview_card = preview_card
+    super(account, options)
+  end
+
+  # @param [Integer] limit
+  # @param [Integer] max_id
+  # @param [Integer] since_id
+  # @param [Integer] min_id
+  # @return [Array<Status>]
+  def get(limit, max_id = nil, since_id = nil, min_id = nil)
+    scope = public_scope
+
+    scope.merge!(discoverable)
+    scope.merge!(attached_to_preview_card)
+
+    scope.to_a_paginated_by_id(limit, max_id: max_id, since_id: since_id, min_id: min_id)
+  end
+
+  private
+
+  def attached_to_preview_card
+    Status.joins(:preview_cards_status).where(preview_cards_status: { preview_card_id: @preview_card.id })
+  end
+
+  def discoverable
+    Account.discoverable
+  end
+end