Feature: Conversation creation email notifications (#576)

* Clean up the mailers

* Disable assignment mailer if setting is turned off

* Email notifications on conversation create

* Specs

app/mailers/conversation_reply_mailer.rb

@@ -0,0 +1,26 @@
+class ConversationReplyMailer < ApplicationMailer
+  default from: ENV.fetch('MAILER_SENDER_EMAIL', 'accounts@chatwoot.com')
+  layout 'mailer'
+
+  def reply_with_summary(conversation, message_queued_time)
+    return unless smtp_config_set_or_development?
+
+    @conversation = conversation
+    @contact = @conversation.contact
+    @agent = @conversation.assignee
+
+    recap_messages = @conversation.messages.where('created_at < ?', message_queued_time).order(created_at: :asc).last(10)
+    new_messages = @conversation.messages.where('created_at >= ?', message_queued_time)
+
+    @messages = recap_messages + new_messages
+    @messages = @messages.select(&:reportable?)
+
+    mail(to: @contact&.email, reply_to: @agent&.email, subject: mail_subject(@messages.last))
+  end
+
+  private
+
+  def mail_subject(last_message, trim_length = 30)
+    "[##{@conversation.display_id}] #{last_message.content.truncate(trim_length)}"
+  end
+end