RedNet Chat Remote 0.5 - server

<?php

$db = mysql_connect('localhost', '********', '*********');
mysql_select_db('*********', $db);

class RedNet_Message
{
    public $ID;
    public $protocol = 'rednet';
    public $session = null;
    public $channel = 1;
    public $origin = -1;
    public $nickname = null;
    public $header = null;
    public $body = null;
    public $status = null;
    public $online = null;
    public $sender = null;

    public $bodySerialized = false;

    public function fromArray($data)
    {
        if (isset($data['ID'])) {
            $this->ID = $data['ID'];
        }

        if (isset($data['protocol'])) {
            $this->protocol = $data['protocol'];
        }

        if (isset($data['session']) && is_numeric($data['session'])) {
            $this->session = $data['session'];
        }

        if (isset($data['channel'])) {
            $this->channel = (int) $data['channel'];
        }

        if (isset($data['origin'])) {
            $this->origin = (int) $data['origin'];
        }

        if (isset($data['nickname'])) {
            $this->nickname = $data['nickname'];
        }

        if (isset($data['header'])) {
            $this->header = $data['header'];
        }

        if (isset($data['body'])) {
            $this->body = $data['body'];
        }
    }

    public function toSerializedLua()
    {
        $serialized = array();

        $id = $this->ID;
        if (!is_numeric($id)) {
            $id = 'nil';
        }

        if (!is_string($this->body)) {
            $body = 'nil';
        } else {
            if (!$this->bodySerialized) {
                $body = '"' . $this->body . '"';
            } else {
                $body = $this->body;
            }
        }

        $session = $this->session;
        if (!is_numeric($session)) {
            $session = 'nil';
        }

        $nickname = 'nil';
        if (is_string($this->nickname)) {
            $nickname = '"' . $this->nickname . '"';
        }

        $online = 'nil';
        if (is_string($this->online)) {
            $online = '"' . $this->online . '"';
        }

        $sender = 'nil';
        if (is_string($this->sender)) {
            $sender = '"' . $this->sender . '"';
        }

        $serialized[] = '["ID"]=' . $id;
        $serialized[] = '["protocol"]="' . $this->protocol . '"';
        $serialized[] = '["session"]=' . $session;
        $serialized[] = '["origin"]=' . $this->origin;
        $serialized[] = '["nickname"]=' . $nickname;
        $serialized[] = '["header"]="' . $this->header . '"';
        $serialized[] = '["body"]=' . $body;
        $serialized[] = '["status"]="' . $this->status . '"';
        $serialized[] = '["online"]=' . $online . '';
        $serialized[] = '["sender"]=' . $sender . '';
        $serialized[] = '["channel"]=' . $this->channel;

        return '{' . implode(',', $serialized) . ',}';
    }
}

$request = new Rednet_Message();
$request->fromArray($_POST);

$response = new Rednet_Message();
$response->fromArray($_POST);

switch ($request->header) {
    case 'join' :

        if (strlen($request->nickname) > 1) {

            $result = mysql_query("SELECT ID, nickname, origin, active, channel
                FROM sessions
                WHERE nickname = '" . $request->nickname . "'
            ", $db);

            if (mysql_num_rows($result) === 0) {
                $time = getTime();

                mysql_query("INSERT INTO sessions (
                    origin, started, nickname, lastupdate, channel
                ) VALUES (
                    " . $request->origin . ", " . $time . ", '" . $request->nickname . "', " . $time . ", " . $request->body . "
                )", $db);

                $response->session = mysql_insert_id($db);

                mysql_query("INSERT INTO messages
                    (session, header, body, datetime, channel)
                    VALUES ('" . $response->session . "', 'status', '" . $request->nickname . " joined channel " . $request->body . "', " . getTime() . ", " . $request->body . ")
                ");

                $response->channel = $request->body;
                $response->status = 'ok';
            } else {
                $row = mysql_fetch_assoc($result);

                $response->session = $row['ID'];

                if ((int) $row['origin'] === $request->origin) {
                    $time = getTime();
                    if ((int) $row['active'] === 0) {
                        mysql_query("UPDATE sessions SET started = " . $time . ", lastupdate = " . $time . ", active  = 1 WHERE ID = " . $row['ID'], $db);

                        mysql_query("INSERT INTO messages
                            (session, header, body, datetime, channel)
                            VALUES ('" . $response->session . "', 'status', '" . $request->nickname . " is now online ', " . getTime() . ", " . $row['channel'] . ")
                        ");

                        $response->channel = $row['channel'];
                    } else {
                        if ($request->body != $row['channel']) {
                            mysql_query("UPDATE sessions SET channel = " . $request->body . " WHERE ID = " . $row['ID']);

                            mysql_query("INSERT INTO messages
                                (session, header, body, datetime, channel)
                                VALUES ('" . $response->session . "', 'status', '" . $request->nickname . " joined channel " . $request->body . "', " . getTime() . ", " . $request->body . ")
                            ");

                            $response->channel = $request->body;
                        } else {
                            $response->channel = $row['channel'];
                        }
                    }

                    $response->status = 'ok';
                } else {
                    $response->status = 'error';
                    $response->body = 'Username invalid or already in use';
                }
            }


        }

        break;

    case 'leave' :
        $result = mysql_query("SELECT active, nickname
            FROM sessions
            WHERE ID = " . $request->session . " AND active = 1
        ", $db);

        if (mysql_num_rows($result) > 0) {
            $row = mysql_fetch_assoc($result);

            mysql_query("UPDATE sessions SET active = 0 WHERE ID = " . $request->session, $db);

            mysql_query("INSERT INTO messages
                (session, header, body, datetime, channel)
                VALUES ('" . $request->session . "', 'status', '" . $row['nickname'] . " is now offline ', " . getTime() . ", " . $request->channel . ")
            ");
        }

        $response->session = null;
        $response->status = 'ok';

        break;

    case 'update' :
        $result = mysql_query("SELECT started, lastupdate FROM sessions WHERE ID = " . $request->session, $db);
        $row = mysql_fetch_assoc($result);

        $result = mysql_query("SELECT M.ID, M.session, M.target, M.header, M.body, S.origin, S.nickname from messages M LEFT JOIN sessions S ON M.session = S.ID WHERE (M.target IS NULL OR M.target = " . $request->session . ") AND M.datetime >= " . $row['lastupdate'] . " AND M.datetime >= " . $row['started'] . " AND ((M.header = 'msg' AND M.channel IS NULL OR M.channel = " . $request->channel . ")) ORDER BY M.datetime");

        mysql_query("UPDATE sessions SET lastupdate = " . getTime() . " WHERE ID = " . $request->session);

        $i = 1;
        if (mysql_num_rows($result) > 0) {
            while ($row = mysql_fetch_assoc($result)) {
                $message = new Rednet_Message();
                $message->fromArray($row);

                if ($row['header'] == 'msg' && $row['nickname'] != $request->nickname) {
                    $message->sender = $row['nickname'];
                }

                $response->body .= '[' . $i . ']=' . $message->toSerializedLua() . ',';
                $i++;
            }

            $response->body = '{' . $response->body . '}';
            $response->bodySerialized = true;
        }

        $response->status = 'ok';

        $result = mysql_query("SELECT ID, nickname, lastupdate, started, channel FROM sessions WHERE active = 1 AND channel = " . $request->channel . " ORDER BY started");

        if (mysql_num_rows($result) > 0) {
            $online = array();
            while ($row = mysql_fetch_assoc($result)) {
                if (getTime() - (int) $row['lastupdate'] > 10000) {
                    mysql_query("UPDATE sessions SET active = 0 WHERE ID = " . $row['ID']);
                    mysql_query("INSERT INTO messages
                        (session, header, body, datetime, channel)
                        VALUES ('" . $row['ID'] . "', 'status', '" . $row['nickname'] . " timed out.', " . getTime() . ", " . $row['channel'] . ")
                    ");
                } else {
                    if ($row['nickname'] != '') {
                        $online[] = $row['nickname'];
                    }
                }
            }

            $online = implode(', ', $online);
            $response->online = substr($online, 0, strlen($online));
        }


        break;

    case 'say' :
        $body = $request->body . '';
        $body = ucfirst($body);

        $lead = substr($body, strlen($body) - 1);

        if ($lead != '.' && $lead != '?' && $lead != '!') {
            $body .= '.';
        }


        mysql_query("INSERT INTO messages
            (session, header, body, datetime, channel)
            VALUES ('" . $request->session . "', 'say', '" . $request->nickname . ": " . $body . "', " . getTime() . ", " . $request->channel . ")
        ");

        break;

    case 'msg' :
        $body = $request->body . '';
        $body = explode(' ', $body);
        $nickname = $body[0];
        array_shift($body);
        $message = implode(' ', $body);

        $result = mysql_query("SELECT ID, nickname FROM sessions WHERE nickname = '" . $nickname . "' AND active = 1");
        if (mysql_num_rows($result) == 0) {
            $response->status = 'error';
            $response->body = $nickname . ' is not available';
        } else {
            $row = mysql_fetch_assoc($result);

            mysql_query("INSERT INTO messages
                (session, target, header, body, datetime)
                VALUES ('" . $request->session . "', '" . $row['ID'] . "', 'msg', '[" . $request->nickname . " > " . $row['nickname'] . "] " . $message . "', " . getTime() . ")
            ");

            mysql_query("INSERT INTO messages
                (session, target, header, body, datetime)
                VALUES ('" . $request->session . "', '" . $request->session . "', 'msg', '[" . $request->nickname . " > " . $row['nickname'] . "] " . $message . "', " . getTime() . ")
            ");

            $response->status = 'ok';
            $response->body = $row['nickname'];
        }

        break;

    default :
        $response->status = 'error';
        $response->body = 'Unknown method';
        break;
}

mysql_close($db);

echo $response->toSerializedLua();

function getTime()
{
    return microtime(true) * 1000;
}