class ActionMailer::InlinePreviewInterceptor


ActionMailer::Base.register_preview_interceptor(ActionMailer::InlinePreviewInterceptor)
other mailer preview interceptor:
This interceptor is not enabled by default, to use it just register it like any
when previewing a HTML email in a web browser.
that use inline cid: style urls to data: style urls so that they are visible
Implements a mailer preview interceptor that converts image tag src attributes

def self.previewing_email(message) #:nodoc:

:nodoc: 
def self.previewing_email(message) #:nodoc:
  new(message).transform!
end

def data_url(part) 

def data_url(part)
  "data:#{part.mime_type};base64,#{strict_encode64(part.body.raw_source)}"
end

def find_part(cid) 

def find_part(cid)
  message.all_parts.find{ |p| p.attachment? && p.cid == cid }
end

def html_part 

def html_part
  @html_part ||= message.html_part
end

def html_source 

def html_source
  html_part.body.raw_source
end

def initialize(message) #:nodoc:

:nodoc: 
def initialize(message) #:nodoc:
  @message = message
end

def message 

def message
  @message
end

def transform! #:nodoc:

:nodoc: 
def transform! #:nodoc:
  return message if html_part.blank?
  html_source.gsub!(PATTERN) do |match|
    if part = find_part(match[9..-2])
      %[src="#{data_url(part)}"]
    else
      match
    end
  end
  message
end