Making rails 2 use mail instead of tmail

mil_with_mail.rb

module MailWithMail
  # stolen + made static from Rails 3.0 action_mailer/old_api.rb
  def self.set_content_type(m, user_content_type, class_default, params)
    case
    when user_content_type.present?
      user_content_type
    when m.has_attachments?
      if m.attachments.detect { |a| a.inline? }
        ["multipart", "related", params]
      else
        ["multipart", "mixed", params]
      end
    when m.multipart?
      ["multipart", "alternative", params]
    else
      m.content_type || class_default
    end
  end

  # stolen from mail/fields/content_type_field.rb
  def self.stringify(params)
    params.map { |k,v| "#{k}=#{Mail::Encodings.param_encode(v)}" }.join("; ")
  end

  def self.stringify_content_type(content_type, parameters)
    "#{content_type}; #{stringify(parameters)}"
  end
end

ActionMailer::Base.class_eval do
  # copy pasted from action_mailer 2.3.14 and modified to use Mail instead of TMail
  def create_mail
    m = Mail.new

    m.charset      = charset # has to be set first, other fields are set using this
    m.subject      = subject
    m.to, m.from   = recipients, from
    m.bcc          = bcc unless bcc.nil?
    m.cc           = cc unless cc.nil?
    m.reply_to     = reply_to unless reply_to.nil?
    m.mime_version = mime_version unless mime_version.nil?
    m.date         = sent_on.to_time rescue sent_on if sent_on

    headers.each { |k, v| m[k] = v.to_s }

    real_content_type, ctype_attrs = parse_content_type

    if @parts.empty?
      m.content_type MailWithMail.set_content_type(m, real_content_type, nil, ctype_attrs)
      m.body = normalize_new_lines(body)
    else
      if String === body
        part =  Mail::Part.new
        part.body = normalize_new_lines(body)

        part.content_type MailWithMail.set_content_type(part, real_content_type, nil, ctype_attrs)
        part.content_disposition = "inline"
        m.add_part part
      end

      @parts.each do |p|
        part = (Mail::Part === p ? p : p.to_mail(self, @account))
        m.add_part part
      end

      if real_content_type =~ /multipart/
        ctype_attrs.delete "charset"
        m.content_type MailWithMail.set_content_type(m, real_content_type, nil, ctype_attrs)
      end
    end

    # fix missing boundary for multipart in old mailer api <-> https://github.com/rails/rails/pull/3090
    if m.content_type =~ /^multipart/ && !m.content_type.include?("boundary=") && m.body.boundary.present?
      real_content_type, ctype_attrs = parse_content_type(m.content_type)
      main_type, sub_type = real_content_type.to_s.split("/")
      ctype_attrs["boundary"] = m.body.boundary
      m.content_type([main_type, sub_type, ctype_attrs])
    end

    @mail = m
  end

  # stolen + made static from Rails 3.0 action_mailer/old_api.rb
  def parse_content_type_from(content_type)
    old, @content_type = @content_type, content_type
    parse_content_type
  ensure
    @content_type = old
  end
end

ActionMailer::Part.class_eval do
  # copy pasted from action_mailer 2.3.14 and modified to use Mail instead of TMail
  def to_mail(defaults, account=nil)
    part = Mail::Part.new

    real_content_type, ctype_attrs = parse_content_type(defaults)

    if @parts.empty?
      # Always set the content_type after setting the body and or parts!
      # Also don't set filename and name when there is none (like in
      # non-attachment parts)
      if content_disposition == "attachment"
        part.body = body
        ctype_attrs.delete "charset"
        part.content_type = MailWithMail.set_content_type(part, real_content_type, nil,
          squish("name" => filename).merge(ctype_attrs))
        part.content_disposition = MailWithMail.stringify_content_type(content_disposition, squish("filename" => filename).merge(ctype_attrs))
      else
        part.content_transfer_encoding = transfer_encoding || "quoted-printable"
        #HACK: quoted-printable somehow does not encode "=", so we do it <-> breaks application_mailer_test
        part.body = if part.content_transfer_encoding.downcase == "quoted-printable" && body
          body.gsub("=", "=3D")
        else
          body
        end
        part.body # HACK: breaks billing_mailer_test/japanese_mobile without this line

        part.content_type = MailWithMail.set_content_type(part, real_content_type, nil, ctype_attrs)
        part.charset = charset || "UTF-8"
        part.content_disposition = content_disposition
      end
    else
      if String === body
        @parts.unshift ActionMailer::Part.new(:charset => charset, :body => @body, :content_type => 'text/plain')
        @body = nil
      end

      @parts.each do |p|
        prt = (Mail::Part === p ? p : p.to_mail(defaults, @account))
        part.add_part prt
      end

      if real_content_type =~ /multipart/
        ctype_attrs.delete 'charset'
        part.content_type = MailWithMail.set_content_type(part, real_content_type, nil, ctype_attrs)
      end
    end

    headers.each { |k,v| part[k] = v.to_s }

    part
  end
end

Mail::Part.class_eval do
  alias_method :original_filename, :filename
end