<?php
/**
 * Redisent, a Redis interface for the modest
 * @author Justin Poliey <jdp34@njit.edu>
 * @copyright 2009 Justin Poliey <jdp34@njit.edu>
 * @license http://www.opensource.org/licenses/mit-license.php The MIT License
 * @package Redisent
 */

define('CRLF', sprintf('%s%s', chr(13), chr(10)));

/**
 * Wraps native Redis errors in friendlier PHP exceptions
 */
class RedisException extends Exception {
}

/**
 * Redisent, a Redis interface for the modest among us
 */
class Redisent {

    /**
     * Socket connection to the Redis server
     * @var resource
     * @access private
     */
    private $__sock;

    /**
     * Host of the Redis server
     * @var string
     * @access public
     */
    public $host;

    /**
     * Port on which the Redis server is running
     * @var integer
     * @access public
     */
    public $port;

    /**
     * Creates a Redisent connection to the Redis server on host {@link $host} and port {@link $port}.
     * @param string $host The hostname of the Redis server
     * @param integer $port The port number of the Redis server
     */
    function __construct($host, $port = 6379) {
        $this->host = $host;
        $this->port = $port;
        $this->__sock = fsockopen($this->host, $this->port, $errno, $errstr);
        if (!$this->__sock) {
            throw new \Exception("{$errno} - {$errstr}");
        }
    }

    function __destruct() {
        fclose($this->__sock);
    }

    function __call($name, $args) {

        /* Build the Redis unified protocol command */
        array_unshift($args, strtoupper($name));
        $command = sprintf('*%d%s%s%s', count($args), CRLF, implode(array_map(function($arg) {
            return sprintf('$%d%s%s', strlen($arg), CRLF, $arg);
        }, $args), CRLF), CRLF);

        /* Open a Redis connection and execute the command */
        for ($written = 0; $written < strlen($command); $written += $fwrite) {
            $fwrite = fwrite($this->__sock, substr($command, $written));
            if ($fwrite === FALSE) {
                throw new \Exception('Failed to write entire command to stream');
            }
        }

        /* Parse the response based on the reply identifier */
        $reply = trim(fgets($this->__sock, 512));
        switch (substr($reply, 0, 1)) {
            /* Error reply */
            case '-':
                throw new RedisException(substr(trim($reply), 4));
                break;
            /* Inline reply */
            case '+':
                $response = substr(trim($reply), 1);
                break;
            /* Bulk reply */
            case '$':
                $response = null;
                if ($reply == '$-1') {
                    break;
                }
                $read = 0;
                $size = substr($reply, 1);
                do {
                    $block_size = ($size - $read) > 1024 ? 1024 : ($size - $read);
                    $response .= fread($this->__sock, $block_size);
                    $read += $block_size;
                } while ($read < $size);
                fread($this->__sock, 2); /* discard crlf */
                break;
            /* Multi-bulk reply */
            case '*':
                $count = substr($reply, 1);
                if ($count == '-1') {
                    return null;
                }
                $response = array();
                for ($i = 0; $i < $count; $i++) {
                    $bulk_head = trim(fgets($this->__sock, 512));
                    $size = substr($bulk_head, 1);
                    if ($size == '-1') {
                        $response[] = null;
                    }
                    else {
                        $read = 0;
                        $block = "";
                        do {
                            $block_size = ($size - $read) > 1024 ? 1024 : ($size - $read);
                            $block .= fread($this->__sock, $block_size);
                            $read += $block_size;
                        } while ($read < $size);
                        fread($this->__sock, 2); /* discard crlf */
                        $response[] = $block;
                    }
                }
                break;
            /* Integer reply */
            case ':':
                $response = intval(substr(trim($reply), 1));
                break;
            default:
                throw new RedisException("invalid server response: {$reply}");
                break;
        }
        /* Party on */
        return $response;
    }

}