FIX: Remove full nested quotes on direct reply (#8581)

It used to check how many quotes were inside a post, without taking
considering that some quotes can contain other quotes. This commit
selects only top level quotes.

I had to use XPath because I could not find an equivalent CSS
selector.

spec/components/cooked_post_processor_spec.rb

@@ -1662,6 +1662,24 @@ describe CookedPostProcessor do
       RAW
     end
 
+    let(:raw3) do
+      <<~RAW.strip
+      [quote="#{post.user.username}, post:#{post.post_number}, topic:#{topic.id}"]
+
+      this is the “first” post
+
+      [/quote]
+
+      [quote="#{post.user.username}, post:#{post.post_number}, topic:#{topic.id}"]
+
+      this is the “first” post
+
+      [/quote]
+
+      and this is the third reply
+      RAW
+    end
+
     before do
       SiteSetting.remove_full_quote = true
     end
@@ -1686,6 +1704,13 @@ describe CookedPostProcessor do
       end
     end
 
+    it 'does nothing if there are multiple quotes' do
+      reply = Fabricate(:post, topic: topic, raw: raw3)
+      CookedPostProcessor.new(reply).remove_full_quote_on_direct_reply
+      expect(topic.ordered_posts.pluck(:id)).to eq([post.id, reply.id])
+      expect(reply.raw).to eq(raw3)
+    end
+
     it 'does not delete quote if not first paragraph' do
       reply = Fabricate(:post, topic: topic, raw: raw2)
       CookedPostProcessor.new(reply).remove_full_quote_on_direct_reply
@@ -1715,6 +1740,19 @@ describe CookedPostProcessor do
       expect(reply.raw).to eq("and this is the third reply")
     end
 
+    it "works with nested quotes" do
+      reply1 = Fabricate(:post, topic: topic, raw: raw)
+      reply2 = Fabricate(:post, topic: topic, raw: <<~RAW.strip)
+        [quote="#{reply1.user.username}, post:#{reply1.post_number}, topic:#{topic.id}"]
+        #{raw}
+        [/quote]
+
+        quoting a post with a quote
+      RAW
+
+      CookedPostProcessor.new(reply2).remove_full_quote_on_direct_reply
+      expect(reply2.raw).to eq('quoting a post with a quote')
+    end
   end
 
 end