<?php
/**
 * Zend Framework
 *
 * LICENSE
 *
 * This source file is subject to version 1.0 of the Zend Framework
 * license, that is bundled with this package in the file LICENSE, and
 * is available through the world-wide-web at the following URL:
 * http://www.zend.com/license/framework/1_0.txt. If you did not receive
 * a copy of the Zend Framework license and are unable to obtain it
 * through the world-wide-web, please send a note to license@zend.com
 * so we can mail you a copy immediately.
 *
 * @package    Zend_Mail
 * @copyright  Copyright (c) 2005-2007 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://www.zend.com/license/framework/1_0.txt Zend Framework License version 1.0
 */

/**
 * Zend_Mail_Protocol_Exception
 */
require_once 'Zend/Mail/Protocol/Exception.php';

/**
 * @package    Zend_Mail
 * @copyright  Copyright (c) 2005-2007 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://www.zend.com/license/framework/1_0.txt Zend Framework License version 1.0
 */
class Zend_Mail_Protocol_Imap
{
    /**
     * socket to imap server
     * @var resource|null
     */
    protected $_socket;


    /**
     * Public constructor
     *
     * @param  string   $host  hostname of IP address of IMAP server, if given connect() is called
     * @param  int|null $port  port of IMAP server, null for default (143 or 993 for ssl)
     * @param  bool     $ssl   use ssl? 'SSL', 'TLS' or false
     * @throws Zend_Mail_Protocol_Exception
     */
    function __construct($host = '', $port = null, $ssl = false)
    {
        if ($host) {
            $this->connect($host, $port, $ssl);
        }
    }

    /**
     * Public destructor
     */
    public function __destruct()
    {
        $this->logout();
    }

    /**
     * Open connection to POP3 server
     *
     * @param  string      $host  hostname of IP address of POP3 server
     * @param  int|null    $port  of IMAP server, default is 143 (993 for ssl)
     * @param  string|bool $ssl   use 'SSL', 'TLS' or false
     * @return string welcome message
     * @throws Zend_Mail_Protocol_Exception
     */
    public function connect($host, $port = null, $ssl = false)
    {
        if ($ssl == 'SSL') {
            $host = 'ssl://' . $host;
        }

        if ($port === null) {
            $port = $ssl === 'SSL' ? 993 : 143;
        }

        $this->_socket = @fsockopen($host, $port);
        if (!$this->_socket) {
            throw new Zend_Mail_Protocol_Exception('cannot connect to host');
        }

        if (!$this->_assumedNextLine('* OK')) {
            throw new Zend_Mail_Protocol_Exception('host doesn\'t allow connection');
        }

        if ($ssl === 'TLS') {
            $result = $this->requestAndResponse('STARTTLS');
            $result = $result && stream_socket_enable_crypto($this->_socket, true, STREAM_CRYPTO_METHOD_TLS_CLIENT);
            if (!$result) {
                throw new Zend_Mail_Protocol_Exception('cannot enable TLS');
            }
        }
    }

    /**
     * get the next line from socket with error checking, but nothing else
     *
     * @return string next line
     * @throws Zend_Mail_Protocol_Exception
     */
    protected function _nextLine()
    {
        $line = @fgets($this->_socket);
        if ($line === false) {
            throw new Zend_Mail_Protocol_Exception('cannot read - connection closed?');
        }

        return $line;
    }

    /**
     * get next line and assume it starts with $start. some requests give a simple
     * feedback so we can quickly check if we can go on.
     *
     * @param  string $start the first bytes we assume to be in the next line
     * @return bool line starts with $start
     * @throws Zend_Mail_Protocol_Exception
     */
    protected function _assumedNextLine($start)
    {
        $line = $this->_nextLine();
        return strpos($line, $start) === 0;
    }

    /**
     * get next line and split the tag. that's the normal case for a response line
     *
     * @param  string $tag tag of line is returned by reference
     * @return string next line
     * @throws Zend_Mail_Protocol_Exception
     */
    protected function _nextTaggedLine(&$tag)
    {
        $line = $this->_nextLine();

        // seperate tag from line
        list($tag, $line) = explode(' ', $line, 2);

        return $line;
    }

    /**
     * split a given line in tokens. a token is literal of any form or a list
     *
     * @param  string $line line to decode
     * @return array tokens, literals are returned as string, lists as array
     * @throws Zend_Mail_Protocol_Exception
     */
    protected function _decodeLine($line)
    {
        $tokens = array();
        $stack = array();

        /*
            We start to decode the response here. The unterstood tokens are:
                literal
                "literal" or also "lit\\er\"al"
                {bytes}<NL>literal
                (literals*)
            All tokens are returned in an array. Literals in braces (the last unterstood
            token in the list) are returned as an array of tokens. I.e. the following response:
                "foo" baz {3}<NL>bar ("f\\\"oo" bar)
            would be returned as:
                array('foo', 'baz', 'bar', array('f\\\"oo', 'bar'));
        */
        //  replace any trailling <NL> including spaces with a single space
        $line = rtrim($line) . ' ';
        while (($pos = strpos($line, ' ')) !== false) {
            $token = substr($line, 0, $pos);
            while ($token[0] == '(') {
                array_push($stack, $tokens);
                $tokens = array();
                $token = substr($token, 1);
            }
            if ($token[0] == '"') {
                if (preg_match('%^"((.|\\\\|\\")*?)"%', $line, $matches)) {
                    $tokens[] = $matches[1];
                    $line = substr($line, strlen($matches[0]) + 1);
                    continue;
                }
            }
            if ($token[0] == '{') {
                $endPos = strpos($token, '}');
                $chars = substr($token, 1, $endPos - 1);
                if (is_numeric($chars)) {
                    $token = '';
                    while (strlen($token) < $chars) {
                        $token .= $this->_nextLine();
                    }
                    $line = '';
                    if (strlen($token) > $chars) {
                        $line = substr($token, $chars);
                        $token = substr($token, 0, $chars);
                    } else {
                        $line .= $this->_nextLine();
                    }
                    $tokens[] = $token;
                    $line = trim($line) . ' ';
                    continue;
                }
            }
            if ($stack && $token[strlen($token) - 1] == ')') {
                // closing braces are not seperated by spaces, so we need to count them
                $braces = strlen($token);
                $token = rtrim($token, ')');
                // only count braces if more than one
                $braces -= strlen($token) + 1;
                // only add if token had more than just closing braces
                if ($token) {
                    $tokens[] = $token;
                }
                $token = $tokens;
                $tokens = array_pop($stack);
                // special handline if more than one closing brace
                while ($braces-- > 0) {
                    $tokens[] = $token;
                    $token = $tokens;
                    $tokens = array_pop($stack);
                }
            }
            $tokens[] = $token;
            $line = substr($line, $pos + 1);
        }

        // maybe the server forgot to send some closing braces
        while ($stack) {
            $child = $tokens;
            $tokens = array_pop($stack);
            $tokens[] = $child;
        }

        return $tokens;
    }

    /**
     * read a response "line" (could also be more than one real line if response has {..}<NL>)
     * and do a simple decode
     *
     * @param  array|string  $tokens    decoded tokens are returned by reference, if $dontParse
     *                                  is true the unparsed line is returned here
     * @param  string        $wantedTag check for this tag for response code. Default '*' is
     *                                  continuation tag.
     * @param  bool          $dontParse if true only the unparsed line is returned $tokens
     * @return bool if returned tag matches wanted tag
     * @throws Zend_Mail_Protocol_Exception
     */
    public function readLine(&$tokens = array(), $wantedTag = '*', $dontParse = false)
    {
        $line = $this->_nextTaggedLine($tag);
        if (!$dontParse) {
            $tokens = $this->_decodeLine($line);
        } else {
            $tokens = $line;
        }

        // if tag is wanted tag we might be at the end of a multiline response
        return $tag == $wantedTag;
    }

    /**
     * read all lines of response until given tag is found (last line of response)
     *
     * @param  string       $tag       the tag of your request
     * @param  string|array $filter    you can filter the response so you get only the
     *                                 given response lines
     * @param  bool         $dontParse if true every line is returned unparsed instead of
     *                                 the decoded tokens
     * @return null|bool|array tokens if success, false if error, null if bad request
     * @throws Zend_Mail_Protocol_Exception
     */
    public function readResponse($tag, $dontParse = false)
    {
        $lines = array();
        while (!$this->readLine($tokens, $tag, $dontParse)) {
            $lines[] = $tokens;
        }
        if ($dontParse) {
            // last to chars are still needed for response code
            $tokens = array(substr($tokens, 0, 2));
        }

        // last line has response code
        if ($tokens[0] == 'OK') {
            return $lines ? $lines : true;
        } else if ($tokens[0] == 'NO'){
            return false;
        }
        return null;
    }

    /**
     * send a request
     *
     * @param  string $command your request command
     * @param  array  $tokens  additional parameters to command, use escapeString() to prepare
     * @param  string $tag     provide a tag otherwise an autogenerated is returned
     * @return null
     * @throws Zend_Mail_Protocol_Exception
     */
    public function sendRequest($command, $tokens = array(), &$tag = null)
    {
        if (!$tag) {
            $tag = 'TAG' . rand(100, 999);
        }

        $line = $tag . ' ' . $command;

        foreach ($tokens as $token) {
            if (is_array($token)) {
                if (@fputs($this->_socket, $line . ' ' . $token[0] . "\r\n") === false) {
                    throw new Zend_Mail_Protocol_Exception('cannot write - connection closed?');
                }
                if (!$this->_assumedNextLine('+ OK')) {
                    throw new Zend_Mail_Protocol_Exception('cannot send literal string');
                }
                $line .= $token[1];
            } else {
                $line .= ' ' . $token;
            }
        }

        if (@fputs($this->_socket, $line . "\r\n") === false) {
            throw new Zend_Mail_Protocol_Exception('cannot write - connection closed?');
        }
    }

    /**
     * send a request and get response at once
     *
     * @param  string $command   command as in sendRequest()
     * @param  array  $tokens    parameters as in sendRequest()
     * @param  bool   $dontParse if true unparsed lines are returned instead of tokens
     * @return mixed response as in readResponse()
     * @throws Zend_Mail_Protocol_Exception
     */
    public function requestAndResponse($command, $tokens = array(), $dontParse = false)
    {
        $this->sendRequest($command, $tokens, $tag);
        $response = $this->readResponse($tag, $dontParse);

        return $response;
    }

    /**
     * escape one or more literals i.e. for sendRequest
     *
     * @param  string|array $string the literal/-s
     * @return string|array escape literals, literals with newline ar returned
     *                      as array('{size}', 'string');
     */
    public function escapeString($string)
    {
        if (func_num_args() < 2) {
            if (strpos($string, "\n") !== false) {
                return array('{' . strlen($string) . '}', $string);
            } else {
                return '"' . str_replace(array('\\', '"'), array('\\\\', '\\"'), $string) . '"';
            }
        }
        $result = array();
        foreach (func_get_args() as $string) {
            $result[] = $this->escapeString($string);
        }
        return $result;
    }

    /**
     * escape a list with literals or lists
     *
     * @param  array $list list with literals or lists as PHP array
     * @return string escaped list for imap
     */
    public function escapeList($list)
    {
        $result = array();
        foreach ($list as $k => $v) {
            if (!is_array($v)) {
//              $result[] = $this->escapeString($v);
                $result[] = $v;
                continue;
            }
            $result[] = $this->escapeList($v);
        }
        return '(' . implode(' ', $result) . ')';
    }

    /**
     * Login to IMAP server.
     *
     * @param  string $user      username
     * @param  string $password  password
     * @return bool success
     * @throws Zend_Mail_Protocol_Exception
     */
    public function login($user, $password)
    {
        return $this->requestAndResponse('LOGIN', $this->escapeString($user, $password), true);
    }

    /**
     * logout of imap server
     *
     * @return bool success
     */
    public function logout()
    {
        $result = false;
        if ($this->_socket) {
            try {
                $result = $this->requestAndResponse('LOGOUT', array(), true);
            } catch (Zend_Mail_Protocol_Exception $e) {
                // ignoring exception
            }
            fclose($this->_socket);
            $this->_socket = null;
        }
        return $result;
    }


    /**
     * Get capabilities from IMAP server
     *
     * @return array list of capabilities
     * @throws Zend_Mail_Protocol_Exception
     */
    public function capability()
    {
        $response = $this->requestAndResponse('CAPABILITY');

        if (!$response) {
            return $response;
        }

        $capabilities = array();
        foreach ($response as $line) {
            $capabilities = array_merge($capabilities, $line);
        }
        return $capabilities;
    }

    /**
     * Examine and select have the same response. The common code for both
     * is in this method
     *
     * @param  string $command can be 'EXAMINE' or 'SELECT' and this is used as command
     * @param  string $box which folder to change to or examine
     * @return bool|array false if error, array with returned information
     *                    otherwise (flags, exists, recent, uidvalidity)
     * @throws Zend_Mail_Protocol_Exception
     */
    public function examineOrSelect($command = 'EXAMINE', $box = 'INBOX')
    {
        $this->sendRequest($command, (array)$this->escapeString($box), $tag);

        $result = array();
        while (!$this->readLine($tokens, $tag)) {
            if ($tokens[0] == 'FLAGS') {
                array_shift($tokens);
                $result['flags'] = $tokens;
                continue;
            }
            switch ($tokens[1]) {
                case 'EXISTS':
                case 'RECENT':
                    $result[strtolower($tokens[1])] = $tokens[0];
                    break;
                case '[UIDVALIDITY':
                    $result['uidvalidity'] = (int)$tokens[2];
                    break;
                default:
                    // ignore
            }
        }

        if ($tokens[0] != 'OK') {
            return false;
        }
        return $result;
    }

    /**
     * change folder
     *
     * @param  string $box change to this folder
     * @return bool|array see examineOrselect()
     * @throws Zend_Mail_Protocol_Exception
     */
    public function select($box = 'INBOX')
    {
        return $this->examineOrSelect('SELECT', $box);
    }

    /**
     * examine folder
     *
     * @param  string $box examine this folder
     * @return bool|array see examineOrselect()
     * @throws Zend_Mail_Protocol_Exception
     */
    public function examine($box = 'INBOX')
    {
        return $this->examineOrSelect('EXAMINE', $box);
    }

    /**
     * fetch one or more items of one or more messages
     *
     * @param  string|array $items items to fetch from message(s) as string (if only one item)
     *                             or array of strings
     * @param  int          $from  message for items or start message if $to !== null
     * @param  int|null     $to    if null only one message ($from) is fetched, else it's the
     *                             last message, INF means last message avaible
     * @return string|array if only one item of one message is fetched it's returned as string
     *                      if items of one message are fetched it's returned as (name => value)
     *                      if one items of messages are fetched it's returned as (msgno => value)
     *                      if items of messages are fetchted it's returned as (msgno => (name => value))
     * @throws Zend_Mail_Protocol_Exception
     */
    public function fetch($items, $from, $to = null)
    {
        if ($to === null) {
            $set = (int)$from;
        } else if (is_array($from)) {
            $set = implode(',', $from);
        } else if ($to === INF) {
            $set = (int)$from . ':*';
        } else {
            $set = (int)$from . ':' . (int)$to;
        }

        $items = (array)$items;
        $itemList = $this->escapeList($items);

        $this->sendRequest('FETCH', array($set, $itemList), $tag);

        $result = array();
        while (!$this->readLine($tokens, $tag)) {
            if ($tokens[1] != 'FETCH') {
                continue;
            }
            if ($to === null && $tokens[0] != $from) {
                continue;
            }
            if (count($items) == 1) {
                $data = next($tokens[2]);
            } else {
                $data = array();
                while (key($tokens[2]) !== null) {
                    $data[current($tokens[2])] = next($tokens[2]);
                    next($tokens[2]);
                }
            }
            if ($to === null && $tokens[0] == $from) {
                return $data;
            }
            $result[$tokens[0]] = $data;
        }

        if ($to === null) {
            throw new Zend_Mail_Protocol_Exception('the single id was not found in response');
        }

        return $result;
    }

    /**
     * get mailbox list
     *
     * this method can't be named after the IMAP command 'LIST', as list is a reserved keyword
     *
     * @param  string $reference mailbox reference for list
     * @param  string $mailbox   mailbox name match with wildcards
     * @return array mailboxes that matched $mailbox as array(globalName => array('delim' => .., 'flags' => ..))
     * @throws Zend_Mail_Protocol_Exception
     */
    public function listMailbox($reference = '', $mailbox = '*')
    {
        $result = array();
        $list = $this->requestAndResponse('LIST', $this->escapeString($reference, $mailbox));
        if (!$list) {
            return $result;
        }

        foreach ($list as $item) {
            if (count($item) != 4 || $item[0] != 'LIST') {
                continue;
            }
            $result[$item[3]] = array('delim' => $item[2], 'flags' => $item[1]);
        }

        return $result;
    }
}
