class Rails::MailersController

def find_part(format)
  if part = @email.find_first_mime_type(format)
    part
  elsif @email.mime_type == format
    @email
  end
end

def find_preferred_part(*formats)
  formats.each do |format|
    if part = @email.find_first_mime_type(format)
      return part
    end
  end
  if formats.any?{ |f| @email.mime_type == f }
    @email
  end
end

def find_preview
  candidates = []
  params[:path].to_s.scan(%r{/|$}){ candidates << $` }
  preview = candidates.detect{ |candidate| ActionMailer::Preview.exists?(candidate) }
  if preview
    @preview = ActionMailer::Preview.find(preview)
  else
    raise AbstractController::ActionNotFound, "Mailer preview '#{params[:path]}' not found"
  end
end

def index
  @previews = ActionMailer::Preview.all
  @page_title = "Mailer Previews"
end

def preview
  if params[:path] == @preview.preview_name
    @page_title = "Mailer Previews for #{@preview.preview_name}"
    render action: 'mailer'
  else
    @email_action = File.basename(params[:path])
    if @preview.email_exists?(@email_action)
      @email = @preview.call(@email_action)
      if params[:part]
        part_type = Mime::Type.lookup(params[:part])
        if part = find_part(part_type)
          response.content_type = part_type
          render plain: part.respond_to?(:decoded) ? part.decoded : part
        else
          raise AbstractController::ActionNotFound, "Email part '#{part_type}' not found in #{@preview.name}##{@email_action}"
        end
      else
        @part = find_preferred_part(request.format, Mime[:html], Mime[:text])
        render action: 'email', layout: false, formats: %w[html]
      end
    else
      raise AbstractController::ActionNotFound, "Email '#{@email_action}' not found in #{@preview.name}"
    end
  end
end

def show_previews?
  ActionMailer::Base.show_previews
end