Aggiunge il rilevamento di invio e apertura delle email di campagna.

Ogni destinatario mostra se la mail è partita e se è stata aperta, con conteggi in dashboard.

Co-authored-by: Cursor <cursoragent@cursor.com>

app/services/mailings/open_pixel.rb

@@ -0,0 +1,36 @@
+module Mailings
+  class OpenPixel
+    def self.call(html, recipient)
+      new(html, recipient).call
+    end
+
+    def initialize(html, recipient)
+      @html = html.to_s
+      @recipient = recipient
+    end
+
+    def call
+      return @html unless trackable?
+
+      url = tracking_url
+      return @html if url.blank?
+
+      tag = %(<img src="#{ERB::Util.html_escape(url)}" width="1" height="1" alt="" style="display:block;border:0;width:1px;height:1px;opacity:0;" />)
+      if @html.match?(/<\/body>/i)
+        @html.sub(/<\/body>/i, "#{tag}</body>")
+      else
+        "#{@html}#{tag}"
+      end
+    end
+
+    private
+
+    def trackable?
+      @recipient.respond_to?(:tracking_token) && @recipient.tracking_token.present?
+    end
+
+    def tracking_url
+      Rails.application.routes.url_helpers.mail_open_url(@recipient.tracking_token, **PublicUrl.options)
+    end
+  end
+end