inbound_controller.rb

class InboundController < ApplicationController
  require 'mail'
  skip_before_filter :verify_authenticity_token

  def create

    reader = MailReader.new params

    if reader.is_internal_reply?
      
      ticket = Ticket.find reader.ticket_id
      reply_ticket_status ticket, reader.from, reader.body
      UserMailer.new_reply_created(ticket.id).deliver
      CustomerMailer.new_reply_created(ticket.id).deliver
   
   elsif reader.is_customer_reply?

      ticket = Ticket.find reader.ticket_id
      reply_ticket_status ticket, reader.from, reader.body
      UserMailer.new_reply_created(ticket.id).deliver
   
    else
      new_ticket_status reader.from, reader.subject, reader.body
    end
  
  end


  private

    def reply_ticket_status ticket, from, body 
      if create_replies ticket, from, body
        head :ok
      else
       head :internal_server_error # return http status 500 - internal server error 
      end

    end

    def new_ticket_status from, subject, body
      ticket = Ticket.new sender: from, subject: subject, body: body
      if ticket.save
        head :ok # return http status 200 - ok
        UserMailer.new_ticket_created(ticket.id).deliver

      else
          head :internal_server_error # return http status 500 - internal server error 
      end
    end

    def create_replies ticket, sender, body
      # this is messy! Needs tidying up...
      just_reply_part = body.split(REPLY_ABOVE_THIS_LINE)[0]
      only_reply = just_reply_part.split(/On.*wrote:/).first
      # line_by_line = just_reply_part.split("\n")
      # actual_body = line_by_line[0..line_by_line.length-5].join("\n")
      ticket.replies.create sender: sender, body: only_reply
    end
end

inbound_controller_spec.rb

require 'spec_helper'

describe InboundController do

  describe "reply from support team" do

		context "upon creating successful reply " do
			let(:ticket) { OpenStruct.new(id:'10', from: '[email protected]', from: '[email protected]', body: 'body') }
			

			it "finds an exisiting ticket id" do
				MailReader.any_instance.stub(:is_internal_reply?).and_return(true)
				Ticket.stub(:find).with(ticket.id).and_return(ticket)
			end

			it "creates a reply ticket" do
				
			end

			it "delivers email to customer and internal support team" do
				
			end

			it "returns 200" do
				
			end
		
		context "failing to create a reply" do	
			it "returns 500" do
				
			end
		end

			
		end

	describe "reply from customer" do
			
	end

	describe "new ticket" do
			
	end

	describe "reply to [email protected] is not from support team"do
			
	end
end
end

mail_reader.rb

class MailReader

  def initialize params = {}
		@params = params
	end

	def to
		@params[:headers]['To']
	end

	def from
		@params[:headers]['From']
	end

	def subject
		@params[:headers]['Subject']
	end

	def body
 		@params[:plain]
 	end


	def is_internal_reply?
	  recipient = to

	  if match = recipient.match(/<(.+)>/)
	    recipient = match[1]
	  end
	  ticket_account,ticket_domain = SENDER_TICKET.downcase.split("@")
	  account,domain = recipient.downcase.split('@')
	  account.split("+").first == ticket_account && domain == ticket_domain
	end

	def ticket_id
	  if is_internal_reply?
		  partial = to.split('@').first
		  partial.split('+').last.to_i
	  else
	  	 match = subject.match(/\[([0-9]+)\]/)
	  	 match[1].to_i
	  end
	end

	def is_customer_reply?
		if subject.match(/\[([0-9]+)\]/).nil? && to == SENDER_CUSTOMER
			false
		else
			true
		end
	end

end