<?php
/**
 * Zend Framework (http://framework.zend.com/)
 *
 * @link      http://github.com/zendframework/zf2 for the canonical source repository
 * @copyright Copyright (c) 2005-2015 Zend Technologies USA Inc. (http://www.zend.com)
 * @license   http://framework.zend.com/license/new-bsd New BSD License
 */

namespace Zend\Mail\Protocol;

/**
 * SMTP implementation of Zend\Mail\Protocol\AbstractProtocol
 *
 * Minimum implementation according to RFC2821: EHLO, MAIL FROM, RCPT TO, DATA, RSET, NOOP, QUIT
 */
class Smtp extends AbstractProtocol
{
    /**
     * The transport method for the socket
     *
     * @var string
     */
    protected $transport = 'tcp';

    /**
     * Indicates that a session is requested to be secure
     *
     * @var string
     */
    protected $secure;

    /**
     * Indicates an smtp session has been started by the HELO command
     *
     * @var bool
     */
    protected $sess = false;

    /**
     * Indicates an smtp AUTH has been issued and authenticated
     *
     * @var bool
     */
    protected $auth = false;

    /**
     * Indicates a MAIL command has been issued
     *
     * @var bool
     */
    protected $mail = false;

    /**
     * Indicates one or more RCTP commands have been issued
     *
     * @var bool
     */
    protected $rcpt = false;

    /**
     * Indicates that DATA has been issued and sent
     *
     * @var bool
     */
    protected $data = null;

    /**
     * Constructor.
     *
     * The first argument may be an array of all options. If so, it must include
     * the 'host' and 'port' keys in order to ensure that all required values
     * are present.
     *
     * @param  string|array $host
     * @param  null|int $port
     * @param  null|array   $config
     * @throws Exception\InvalidArgumentException
     */
    public function __construct($host = '127.0.0.1', $port = null, array $config = null)
    {
        // Did we receive a configuration array?
        if (is_array($host)) {
            // Merge config array with principal array, if provided
            if (is_array($config)) {
                $config = array_replace_recursive($host, $config);
            } else {
                $config = $host;
            }

            // Look for a host key; if none found, use default value
            if (isset($config['host'])) {
                $host = $config['host'];
            } else {
                $host = '127.0.0.1';
            }

            // Look for a port key; if none found, use default value
            if (isset($config['port'])) {
                $port = $config['port'];
            } else {
                $port = null;
            }
        }

        // If we don't have a config array, initialize it
        if (null === $config) {
            $config = array();
        }

        if (isset($config['ssl'])) {
            switch (strtolower($config['ssl'])) {
                case 'tls':
                    $this->secure = 'tls';
                    break;

                case 'ssl':
                    $this->transport = 'ssl';
                    $this->secure = 'ssl';
                    if ($port == null) {
                        $port = 465;
                    }
                    break;

                default:
                    throw new Exception\InvalidArgumentException($config['ssl'] . ' is unsupported SSL type');
                    break;
            }
        }

        // If no port has been specified then check the master PHP ini file. Defaults to 25 if the ini setting is null.
        if ($port == null) {
            if (($port = ini_get('smtp_port')) == '') {
                $port = 25;
            }
        }

        parent::__construct($host, $port);
    }


    /**
     * Connect to the server with the parameters given in the constructor.
     *
     * @return bool
     */
    public function connect()
    {
        return $this->_connect($this->transport . '://' . $this->host . ':' . $this->port);
    }


    /**
     * Initiate HELO/EHLO sequence and set flag to indicate valid smtp session
     *
     * @param  string $host The client hostname or IP address (default: 127.0.0.1)
     * @throws Exception\RuntimeException
     */
    public function helo($host = '127.0.0.1')
    {
        // Respect RFC 2821 and disallow HELO attempts if session is already initiated.
        if ($this->sess === true) {
            throw new Exception\RuntimeException('Cannot issue HELO to existing session');
        }

        // Validate client hostname
        if (!$this->validHost->isValid($host)) {
            throw new Exception\RuntimeException(implode(', ', $this->validHost->getMessages()));
        }

        // Initiate helo sequence
        $this->_expect(220, 300); // Timeout set for 5 minutes as per RFC 2821 4.5.3.2
        $this->_ehlo($host);

        // If a TLS session is required, commence negotiation
        if ($this->secure == 'tls') {
            $this->_send('STARTTLS');
            $this->_expect(220, 180);
            if (!stream_socket_enable_crypto($this->socket, true, STREAM_CRYPTO_METHOD_TLS_CLIENT)) {
                throw new Exception\RuntimeException('Unable to connect via TLS');
            }
            $this->_ehlo($host);
        }

        $this->_startSession();
        $this->auth();
    }

    /**
     * Returns the perceived session status
     *
     * @return bool
     */
    public function hasSession()
    {
        return $this->sess;
    }

    /**
     * Send EHLO or HELO depending on capabilities of smtp host
     *
     * @param  string $host The client hostname or IP address (default: 127.0.0.1)
     * @throws \Exception|Exception\ExceptionInterface
     */
    protected function _ehlo($host)
    {
        // Support for older, less-compliant remote servers. Tries multiple attempts of EHLO or HELO.
        try {
            $this->_send('EHLO ' . $host);
            $this->_expect(250, 300); // Timeout set for 5 minutes as per RFC 2821 4.5.3.2
        } catch (Exception\ExceptionInterface $e) {
            $this->_send('HELO ' . $host);
            $this->_expect(250, 300); // Timeout set for 5 minutes as per RFC 2821 4.5.3.2
        } catch (\Exception $e) {
            throw $e;
        }
    }


    /**
     * Issues MAIL command
     *
     * @param  string $from Sender mailbox
     * @throws Exception\RuntimeException
     */
    public function mail($from)
    {
        if ($this->sess !== true) {
            throw new Exception\RuntimeException('A valid session has not been started');
        }

        $this->_send('MAIL FROM:<' . $from . '>');
        $this->_expect(250, 300); // Timeout set for 5 minutes as per RFC 2821 4.5.3.2

        // Set mail to true, clear recipients and any existing data flags as per 4.1.1.2 of RFC 2821
        $this->mail = true;
        $this->rcpt = false;
        $this->data = false;
    }


    /**
     * Issues RCPT command
     *
     * @param  string $to Receiver(s) mailbox
     * @throws Exception\RuntimeException
     */
    public function rcpt($to)
    {
        if ($this->mail !== true) {
            throw new Exception\RuntimeException('No sender reverse path has been supplied');
        }

        // Set rcpt to true, as per 4.1.1.3 of RFC 2821
        $this->_send('RCPT TO:<' . $to . '>');
        $this->_expect(array(250, 251), 300); // Timeout set for 5 minutes as per RFC 2821 4.5.3.2
        $this->rcpt = true;
    }


    /**
     * Issues DATA command
     *
     * @param  string $data
     * @throws Exception\RuntimeException
     */
    public function data($data)
    {
        // Ensure recipients have been set
        if ($this->rcpt !== true) { // Per RFC 2821 3.3 (page 18)
            throw new Exception\RuntimeException('No recipient forward path has been supplied');
        }

        $this->_send('DATA');
        $this->_expect(354, 120); // Timeout set for 2 minutes as per RFC 2821 4.5.3.2

        // Ensure newlines are CRLF (\r\n)
        if (PHP_EOL === "\n") {
            $data = str_replace("\n", "\r\n", str_replace("\r", '', $data));
        }

        foreach (explode(self::EOL, $data) as $line) {
            if (strpos($line, '.') === 0) {
                // Escape lines prefixed with a '.'
                $line = '.' . $line;
            }
            $this->_send($line);
        }

        $this->_send('.');
        $this->_expect(250, 600); // Timeout set for 10 minutes as per RFC 2821 4.5.3.2
        $this->data = true;
    }


    /**
     * Issues the RSET command end validates answer
     *
     * Can be used to restore a clean smtp communication state when a transaction has been cancelled or commencing a new transaction.
     *
     */
    public function rset()
    {
        $this->_send('RSET');
        // MS ESMTP doesn't follow RFC, see [ZF-1377]
        $this->_expect(array(250, 220));

        $this->mail = false;
        $this->rcpt = false;
        $this->data = false;
    }

    /**
     * Issues the NOOP command end validates answer
     *
     * Not used by Zend\Mail, could be used to keep a connection alive or check if it is still open.
     *
     */
    public function noop()
    {
        $this->_send('NOOP');
        $this->_expect(250, 300); // Timeout set for 5 minutes as per RFC 2821 4.5.3.2
    }

    /**
     * Issues the VRFY command end validates answer
     *
     * Not used by Zend\Mail.
     *
     * @param  string $user User Name or eMail to verify
     */
    public function vrfy($user)
    {
        $this->_send('VRFY ' . $user);
        $this->_expect(array(250, 251, 252), 300); // Timeout set for 5 minutes as per RFC 2821 4.5.3.2
    }

    /**
     * Issues the QUIT command and clears the current session
     *
     */
    public function quit()
    {
        if ($this->sess) {
            $this->auth = false;
            $this->_send('QUIT');
            $this->_expect(221, 300); // Timeout set for 5 minutes as per RFC 2821 4.5.3.2
            $this->_stopSession();
        }
    }

    /**
     * Default authentication method
     *
     * This default method is implemented by AUTH adapters to properly authenticate to a remote host.
     *
     * @throws Exception\RuntimeException
     */
    public function auth()
    {
        if ($this->auth === true) {
            throw new Exception\RuntimeException('Already authenticated for this session');
        }
    }

    /**
     * Closes connection
     *
     */
    public function disconnect()
    {
        $this->_disconnect();
    }

    /**
     * Disconnect from remote host and free resource
     */
    protected function _disconnect()
    {
        // Make sure the session gets closed
        $this->quit();
        parent::_disconnect();
    }

    /**
     * Start mail session
     *
     */
    protected function _startSession()
    {
        $this->sess = true;
    }

    /**
     * Stop mail session
     *
     */
    protected function _stopSession()
    {
        $this->sess = false;
    }
}
