[#139] Send conversation emails (#442)

* [#139] Delayed emails for conversations

* Added the setex and get methods to Redis wrapper
* Set the priorities for the sidekiq queues
* Was not able to use mailhog for testing email in local, switched back to letter opener and added comments on using the SMTP settings
* Added after create hood in messages to queue the sending of mail after 2 minutes using sidekiq worker and also set the redis key for the conversation to avoid the email sending for every message
* Added the sidekiq worker to send the email and delete the conversation redis key
* Added the mailer and mail template
* mailer sends the last 10 messages along with the new messages from the time it was queued

* Send email only in development or if smtp config is set

* Send email only in development or if smtp config is set
* Set the SMTP_PORT in production variable

* Adding redis to circle CI

* Specs for the conversation email changes

* Added specs for conversation email sidekiq worker
* Added specs for conversation mailer
* Added specs in message model for the after create hook for notify email

* Send emails only when there is a reply from agent

* set development to use mailhog

* Adding comments for using letter opener

app/mailers/application_mailer.rb

@@ -4,4 +4,8 @@ class ApplicationMailer < ActionMailer::Base
 
   # helpers
   helper :frontend_urls
+
+  def smtp_config_set_or_development?
+    ENV.fetch('SMTP_ADDRESS', nil).present? || Rails.env.development?
+  end
 end

app/mailers/assignment_mailer.rb

@@ -3,7 +3,7 @@ class AssignmentMailer < ApplicationMailer
   layout 'mailer'
 
   def conversation_assigned(conversation, agent)
-    return if ENV.fetch('SMTP_ADDRESS', nil).blank?
+    return unless smtp_config_set_or_development?
 
     @agent = agent
     @conversation = conversation

app/mailers/conversation_mailer.rb

@@ -0,0 +1,26 @@
+class ConversationMailer < ApplicationMailer
+  default from: ENV.fetch('MAILER_SENDER_EMAIL', 'accounts@chatwoot.com')
+  layout 'mailer'
+
+  def new_message(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, from: @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