# Copyright (c) 2008-16 Peter H. Boling of RailsBling.com
# Released under the MIT license

module SanitizeEmail
  # Tools for modifying the header of an email
  module MailHeaderTools

    def self.prepend_subject_array(message)
      prepend = []
      if SanitizeEmail.use_actual_email_prepended_to_subject
        prepend << SanitizeEmail::MailHeaderTools.
          prepend_email_to_subject(Array(message.to))
      end
      if SanitizeEmail.use_actual_environment_prepended_to_subject
        prepend << SanitizeEmail::MailHeaderTools.
          prepend_environment_to_subject
      end
      # this will force later joins to add an extra space
      prepend << "" unless prepend.empty?
      prepend
    end

    def self.custom_subject(message)
      prepend_subject_array(message).join(" ")
    end

    def self.prepend_environment_to_subject
      SanitizeEmail::Config.config[:environment]
    end

    def self.prepend_email_to_subject(actual_addresses)
      "(#{Array(actual_addresses).uniq.join(',').gsub(/@/, ' at ').
        gsub(/[<>]/, '~')})"
    end

    def self.add_original_addresses_as_headers(message)
      # Add headers by string concat.
      # Setting hash values on message.headers does nothing, strangely.
      # See: http://goo.gl/v46GY
      {
        # can be an arrays, so casting it as arrays
        "X-Sanitize-Email-To" => Array(message.to).uniq,
        "X-Sanitize-Email-Cc" => Array(message.cc).uniq
        # Don't write out the BCC, as those addresses should not be visible
        #   in message headers for obvious reasons
      }.each { |header_key, header_value|
        # For each type of address line
        SanitizeEmail::MailHeaderTools.update_header(
          header_key,
          header_value,
          message
        )
      }
    end

    def self.prepend_custom_subject(message)
      message.subject = "" unless message.subject
      custom_subject = SanitizeEmail::MailHeaderTools.custom_subject(message)
      +(message.subject).prepend(custom_subject)
    end

    # According to https://github.com/mikel/mail
    #   this is the correct way to update headers.
    def self.update_header(header_key, header_value, message)
      # For each address, as header_value can be an array of addresses
      Array(header_value).each_with_index { |elem, index|
        num = index + 1
        new_header_key = num > 1 ?
          "#{header_key}-#{num}" :
          header_key
        message.header[new_header_key] = elem.to_s
      } if header_value
    end

  end
end