module ActionMailer #:nodoc:
  # Usage:
  #
  #   class ApplicationMailer < ActionMailer::Base
  #     def post_notification(recipients, post)
  #       @recipients          = recipients
  #       @from                = post.author.email_address_with_name
  #       @headers["bcc"]      = SYSTEM_ADMINISTRATOR_EMAIL
  #       @headers["reply-to"] = "notifications@example.com"
  #       @subject             = "[#{post.account.name} #{post.title}]"
  #       @body["post"]        = post
  #     end
  #     
  #     def comment_notification(recipient, comment)
  #       @recipients      = recipient.email_address_with_name
  #       @subject         = "[#{comment.post.project.client.firm.account.name}]" +
  #                          " Re: #{comment.post.title}"
  #       @body["comment"] = comment
  #       @from            = comment.author.email_address_with_name
  #       @sent_on         = comment.posted_on
  #     end
  #   end
  #
  #   # After this post_notification will look for "templates/application_mailer/post_notification.rhtml"
  #   ApplicationMailer.template_root = "templates"
  #  
  #   ApplicationMailer.create_comment_notification(david, hello_world)  # => a tmail object
  #   ApplicationMailer.deliver_comment_notification(david, hello_world) # sends the email
  #
  # = Configuration options
  #
  # These options are specified on the class level, like <tt>ActionMailer::Base.template_root = "/my/templates"</tt>
  #
  # * <tt>template_root</tt> - template root determines the base from which template references will be made.
  #
  # * <tt>logger</tt> - the logger is used for generating information on the mailing run if available.
  #   Can be set to nil for no logging. Compatible with both Ruby's own Logger and Log4r loggers.
  #
  # * <tt>server_settings</tt> -  Allows detailed configuration of the server:
  #   * <tt>:address</tt> Allows you to use a remote mail server. Just change it away from it's default "localhost" setting.
  #   * <tt>:port</tt> On the off change that your mail server doesn't run on port 25, you can change it.
  #   * <tt>:domain</tt> If you need to specify a HELO domain, you can do it here.
  #   * <tt>:user_name</tt> If your mail server requires authentication, set the username and password in these two settings.
  #   * <tt>:password</tt> If your mail server requires authentication, set the username and password in these two settings.
  #   * <tt>:authentication</tt> If your mail server requires authentication, you need to specify the authentication type here. 
  #     This is a symbol and one of :plain, :login, :cram_md5
  #
  # * <tt>raise_delivery_errors</tt> - whether or not errors should be raised if the email fails to be delivered.
  #
  # * <tt>delivery_method</tt> - Defines a delivery method. Possible values are :smtp (default), :sendmail, and :test.
  #   Sendmail is assumed to be present at "/usr/sbin/sendmail".
  #
  # * <tt>perform_deliveries</tt> - Determines whether deliver_* methods are actually carried out. By default they are,
  #   but this can be turned off to help functional testing.
  #
  # * <tt>deliveries</tt> - Keeps an array of all the emails sent out through the Action Mailer with delivery_method :test. Most useful
  #   for unit and functional testing.
  #
  # * <tt>default_charset</tt> - The default charset used for the body and to encode the subject. Defaults to UTF-8. You can also 
  #    pick a different charset from inside a method with <tt>@encoding</tt>.
  class Base
    private_class_method :new #:nodoc:

    cattr_accessor :template_root
    cattr_accessor :logger

    @@server_settings = { 
      :address        => "localhost", 
      :port           => 25, 
      :domain         => 'localhost.localdomain', 
      :user_name      => nil, 
      :password       => nil, 
      :authentication => nil
    }
    cattr_accessor :server_settings

    @@raise_delivery_errors = true
    cattr_accessor :raise_delivery_errors

    @@delivery_method = :smtp
    cattr_accessor :delivery_method
    
    @@perform_deliveries = true
    cattr_accessor :perform_deliveries
    
    @@deliveries = []
    cattr_accessor :deliveries

    @@default_charset = "utf-8"
    cattr_accessor :default_charset

    attr_accessor :recipients, :subject, :body, :from, :sent_on, :headers, :bcc, :cc, :charset

    def initialize
      @bcc = @cc = @from = @recipients = @sent_on = @subject = @body = nil
      @charset = @@default_charset.dup
      @headers = {}
    end

    class << self
      def method_missing(method_symbol, *parameters)#:nodoc:
        case method_symbol.id2name
          when /^create_([_a-z]\w*)/
            create_from_action($1, *parameters)
          when /^deliver_([_a-z]\w*)/
            begin
              deliver(send("create_" + $1, *parameters))
            rescue Object => e
              raise e if raise_delivery_errors
            end
        end
      end

      def mail(to, subject, body, from, timestamp = nil, headers = {}, charset = @@default_charset) #:nodoc:
        deliver(create(to, subject, body, from, timestamp, headers, charset))
      end

      def create(to, subject, body, from, timestamp = nil, headers = {}, charset = @@default_charset) #:nodoc:
        m = TMail::Mail.new
        m.body = body
        m.subject, = quote_any_if_necessary(charset, subject)
        m.to, m.from = quote_any_address_if_necessary(charset, to, from)

        m.date = timestamp.respond_to?("to_time") ? timestamp.to_time : (timestamp || Time.now)    

        m.set_content_type "text", "plain", { "charset" => charset }

        headers.each do |k, v|
          m[k] = v
        end

        return m
      end

      def deliver(mail) #:nodoc:
        logger.info "Sent mail:\n #{mail.encoded}" unless logger.nil?
        send("perform_delivery_#{delivery_method}", mail) if perform_deliveries
        return mail
      end

      def quoted_printable(text, charset)#:nodoc:
        text = text.gsub( /[^a-z ]/i ) { "=%02x" % $&[0] }.gsub( / /, "_" )
        "=?#{charset}?Q?#{text}?="
      end

      CHARS_NEEDING_QUOTING = /[\000-\011\013\014\016-\037\177-\377]/

      # Quote the given text if it contains any "illegal" characters
      def quote_if_necessary(text, charset)
        (text =~ CHARS_NEEDING_QUOTING) ?
          quoted_printable(text, charset) :
          text
      end

      # Quote any of the given strings if they contain any "illegal" characters
      def quote_any_if_necessary(charset, *args)
        args.map { |v| quote_if_necessary(v, charset) }
      end

      # Quote the given address if it needs to be. The address may be a
      # regular email address, or it can be a phrase followed by an address in
      # brackets. The phrase is the only part that will be quoted, and only if
      # it needs to be. This allows extended characters to be used in the
      # "to", "from", "cc", and "bcc" headers.
      def quote_address_if_necessary(address, charset)
        if Array === address
          address.map { |a| quote_address_if_necessary(a, charset) }
        elsif address =~ /^(\S.*)\s+(<.*>)$/
          address = $2
          phrase = quote_if_necessary($1.gsub(/^['"](.*)['"]$/, '\1'), charset)
          "\"#{phrase}\" #{address}"
        else
          address
        end
      end

      # Quote any of the given addresses, if they need to be.
      def quote_any_address_if_necessary(charset, *args)
        args.map { |v| quote_address_if_necessary(v, charset) }
      end

      def receive(raw_email)
        logger.info "Received mail:\n #{raw_email}" unless logger.nil?
        new.receive(TMail::Mail.parse(raw_email))
      end

      private
        def perform_delivery_smtp(mail)
          Net::SMTP.start(server_settings[:address], server_settings[:port], server_settings[:domain], 
              server_settings[:user_name], server_settings[:password], server_settings[:authentication]) do |smtp|
            smtp.sendmail(mail.encoded, mail.from, mail.destinations)
          end
        end

        def perform_delivery_sendmail(mail)
          IO.popen("/usr/sbin/sendmail -i -t","w+") do |sm|
            sm.print(mail.encoded)
            sm.flush
          end
        end

        def perform_delivery_test(mail)
          deliveries << mail
        end

        def create_from_action(method_name, *parameters)
          mailer = new
          mailer.body = {}
          mailer.send(method_name, *parameters)

          unless String === mailer.body then
            mailer.body = render_body mailer, method_name
          end

          mail = create(mailer.recipients, mailer.subject, mailer.body,
                        mailer.from, mailer.sent_on, mailer.headers,
                        mailer.charset)

          mail.bcc = quote_address_if_necessary(mailer.bcc, mailer.charset) unless mailer.bcc.nil?
          mail.cc  = quote_address_if_necessary(mailer.cc, mailer.charset)  unless mailer.cc.nil?

          return mail
        end
  
        def render_body(mailer, method_name)
          ActionView::Base.new(template_path, mailer.body).render_file(method_name)
        end
        
        def template_path
          template_root + "/" + Inflector.underscore(self.to_s)
        end
    end
  end
end