<?php
/**
 * Copyright 2004-2017 Horde LLC (http://www.horde.org/)
 *
 * See the enclosed file LICENSE for license information (LGPL). If you
 * did not receive this file, see http://www.horde.org/licenses/lgpl21.
 *
 * @category  Horde
 * @copyright 2004-2017 Horde LLC
 * @license   http://www.horde.org/licenses/lgpl21 LGPL 2.1
 * @package   Mime
 */

/**
 * Message Disposition Notifications (RFC 3798).
 *
 * @author    Michael Slusarz <slusarz@horde.org>
 * @category  Horde
 * @copyright 2004-2017 Horde LLC
 * @license   http://www.horde.org/licenses/lgpl21 LGPL 2.1
 * @package   Mime
 */
class Horde_Mime_Mdn
{
    /* RFC 3798 header for requesting a MDN. */
    const MDN_HEADER = 'Disposition-Notification-To';

    /**
     * The Horde_Mime_Headers object.
     *
     * @var Horde_Mime_Headers
     */
    protected $_headers;

    /**
     * The text of the original message.
     *
     * @var string
     */
    protected $_msgtext = false;

    /**
     * Constructor.
     *
     * @param Horde_Mime_Headers $mime_headers  A headers object.
     */
    public function __construct(Horde_Mime_Headers $headers)
    {
        $this->_headers = $headers;
    }

    /**
     * Returns the address(es) to return the MDN to.
     *
     * @return ?string  The address(es) to send the MDN to. Returns null if no
     *                  MDN is requested.
     */
    public function getMdnReturnAddr(): ?string
    {
        /* RFC 3798 [2.1] requires the Disposition-Notification-To header
         * for an MDN to be created. */
        return ($hdr = $this->_headers[self::MDN_HEADER])
            ? strval($hdr)
            : null;
    }

    /**
     * Is user input required to send the MDN?
     * Explicit confirmation is needed in some cases to prevent mail loops
     * and the use of MDNs for mail bombing.
     *
     * @return boolean  Is explicit user input required to send the MDN?
     */
    public function userConfirmationNeeded()
    {
        $return_path = $this->_headers['Return-Path'];

        /* RFC 3798 [2.1]: Explicit confirmation is needed if there is no
         * Return-Path in the header. Also, "if the message contains more
         * than one Return-Path header, the implementation may [] treat the
         * situation as a failure of the comparison." */
        if (!$return_path || (count($return_path->value) > 1)) {
            return true;
        }

        /* RFC 3798 [2.1]: Explicit confirmation is needed if there is more
         * than one distinct address in the Disposition-Notification-To
         * header. */
        $addr_ob = ($hdr = $this->_headers[self::MDN_HEADER])
            ? $hdr->getAddressList(true)
            : array();

        switch (count($addr_ob)) {
        case 0:
            return false;

        case 1:
            // No-op
            break;

        default:
            return true;
        }

        /* RFC 3798 [2.1] states that "MDNs SHOULD NOT be sent automatically
         * if the address in the Disposition-Notification-To header differs
         * from the address in the Return-Path header." This comparison is
         * case-sensitive for the mailbox part and case-insensitive for the
         * host part. */
        $ret_ob = new Horde_Mail_Rfc822_Address($return_path->value);
        return (!$ret_ob->valid || !$addr_ob->match($ret_ob));
    }

    /**
     * When generating the MDN, should we return the enitre text of the
     * original message?  The default is no - we only return the headers of
     * the original message. If the text is passed in via this method, we
     * will return the entire message.
     *
     * @param string $text  The text of the original message.
     */
    public function originalMessageText($text)
    {
        $this->_msgtext = $text;
    }

    /**
     * Generate the MDN according to the specifications listed in RFC
     * 3798 [3].
     *
     * @param boolean $action   Was this MDN type a result of a manual
     *                          action on part of the user?
     * @param boolean $sending  Was this MDN sent as a result of a manual
     *                          action on part of the user?
     * @param string $type      The type of action performed by the user.
     *                          Per RFC 3798 [3.2.6.2] the following types are
     *                          valid:
     *                            - deleted
     *                            - displayed
     * @param string $name      The name of the local server.
     * @param Horde_Mail_Transport $mailer  Mail transport object.
     * @param array $opts       Additional options:
     *   - charset: (string) Default charset.
     *              DEFAULT: NONE
     *   - from_addr: (string) From address.
     *                DEFAULT: NONE
     * @param array $mod        The list of modifications. Per RFC 3798
     *                          [3.2.6.3] the following modifications are
     *                          valid:
     *                            - error
     * @param array $err        If $mod is 'error', the additional
     *                          information to provide. Key is the type of
     *                          modification, value is the text.
     */
    public function generate($action, $sending, $type, $name, $mailer,
                             array $opts = array(), array $mod = array(),
                             array $err = array())
    {
        $opts = array_merge(array(
            'charset' => null,
            'from_addr' => null
        ), $opts);

        if (!($hdr = $this->_headers[self::MDN_HEADER])) {
            throw new RuntimeException(
                'Need at least one address to send MDN to.'
            );
        }

        $to = $hdr->getAddressList(true);
        $ua = Horde_Mime_Headers_UserAgent::create();

        if ($orig_recip = $this->_headers['Original-Recipient']) {
            $orig_recip = $orig_recip->value_single;
        }

        /* Set up the mail headers. */
        $msg_headers = new Horde_Mime_Headers();
        $msg_headers->addHeaderOb(Horde_Mime_Headers_MessageId::create());
        $msg_headers->addHeaderOb($ua);
        /* RFC 3834 [5.2] */
        $msg_headers->addHeader('Auto-Submitted', 'auto-replied');
        $msg_headers->addHeaderOb(Horde_Mime_Headers_Date::create());
        if ($opts['from_addr']) {
            $msg_headers->addHeader('From', $opts['from_addr']);
        }
        $msg_headers->addHeader('To', $to);
        $msg_headers->addHeader('Subject', Horde_Mime_Translation::t("Disposition Notification"));

        /* MDNs are a subtype of 'multipart/report'. */
        $msg = new Horde_Mime_Part();
        $msg->setType('multipart/report');
        $msg->setContentTypeParameter('report-type', 'disposition-notification');

        /* The first part is a human readable message. */
        $part_one = new Horde_Mime_Part();
        $part_one->setType('text/plain');
        $part_one->setCharset($opts['charset']);
        if ($type == 'displayed') {
            $contents = sprintf(
                Horde_Mime_Translation::t("The message sent on %s to %s with subject \"%s\" has been displayed.\n\nThis is no guarantee that the message has been read or understood."),
                $this->_headers['Date'],
                $this->_headers['To'],
                $this->_headers['Subject']
            );
            $flowed = new Horde_Text_Flowed($contents, $opts['charset']);
            $flowed->setDelSp(true);
            $part_one->setContentTypeParameter('format', 'flowed');
            $part_one->setContentTypeParameter('DelSp', 'Yes');
            $part_one->setContents($flowed->toFlowed());
        }
        // TODO: Messages for other notification types.
        $msg[] = $part_one;

        /* The second part is a machine-parseable description. */
        $part_two = new Horde_Mime_Part();
        $part_two->setType('message/disposition-notification');

        $part_two_h = new Horde_Mime_Headers();
        $part_two_h->addHeader('Reporting-UA', $name . '; ' . $ua);
        if (!empty($orig_recip)) {
            $part_two_h->addHeader('Original-Recipient', 'rfc822;' . $orig_recip);
        }
        if ($opts['from_addr']) {
            $part_two_h->addHeader('Final-Recipient', 'rfc822;' . $opts['from_addr']);
        }

        if ($msg_id = $this->_headers['Message-ID']) {
            $part_two_h->addHeader('Original-Message-ID', strval($msg_id));
        }

        /* Create the Disposition field now (RFC 3798 [3.2.6]). */
        $dispo = (($action) ? 'manual-action' : 'automatic-action') .
            '/' .
            (($sending) ? 'MDN-sent-manually' : 'MDN-sent-automatically') .
            '; ' .
            $type;
        if (!empty($mod)) {
            $dispo .= '/' . implode(', ', $mod);
        }
        $part_two_h->addHeader('Disposition', $dispo);

        if (in_array('error', $mod) && isset($err['error'])) {
            $part_two_h->addHeader('Error', $err['error']);
        }

        $part_two->setContents(trim($part_two_h->toString()) . "\n");
        $msg[] = $part_two;

        /* The third part is the text of the original message.  RFC 3798 [3]
         * allows us to return only a portion of the entire message - this
         * is left up to the user. */
        $part_three = new Horde_Mime_Part();
        $part_three->setType('message/rfc822');
        $part_three_text = array(trim($this->_headers->toString()) . "\n");
        if (!empty($this->_msgtext)) {
            $part_three_text[] = "\n" . $this->_msgtext;
        }
        $part_three->setContents($part_three_text);
        $msg[] = $part_three;

        return $msg->send($to, $msg_headers, $mailer);
    }

    /**
     * Add a MDN (read receipt) request header.
     *
     * @param mixed $to  The address(es) the receipt should be mailed to.
     */
    public function addMdnRequestHeaders($to)
    {
        /* This is the RFC 3798 way of requesting a receipt. */
        $this->_headers->addHeader(self::MDN_HEADER, $to);
    }

}
