File: classes/cchat.class.php

<?php

declare(strict_types=1);

class Chatbox
{
    /**
        * Crypto Chatbox.
        *
        * @author        Martin Latter
        * @copyright     Martin Latter, September 2013
        * @version       2.05
        * @license       GNU GPL version 3.0 (GPL v3); http://www.gnu.org/licenses/gpl.html
        * @link          https://github.com/Tinram/CChat.git
    */

    const DEBUG = false;

    const DB_HOST     = 'localhost';
    const DB_NAME     = 'cchat';
    const DB_TABLE    = 'chatbox';
    const DB_USERNAME = 'messenger';
    const DB_PASSWORD = 'P@55w0rd';

    const MESSAGE_BUFFER = 3600; # 1 hour of messages displayed

    const BR = '<br>';
    const LB = '~';


    /**
        * Connect to the database.
        *
        * @return   mysqli object
    */

    private static function getConnection(): mysqli
    {
        $oConnection = new mysqli(self::DB_HOST, self::DB_USERNAME, self::DB_PASSWORD, self::DB_NAME);

        if ($oConnection->connect_errno > 0)
        {
            die('Connection failed: ' . $oConnection->connect_errno . ') ' . $oConnection->connect_error);
        }

        return $oConnection;
    }


    /**
        * Output chatbox message.
        *
        * @return   string
    */

    public static function outputMessages(): string
    {
        $iTime = time() - self::MESSAGE_BUFFER;
        $sOutput = '';
        $sTemp = '';
        $oConn = self::getConnection();

        $sQuery = '
            SELECT name, message
            FROM ' . self::DB_TABLE . '
            WHERE date > ' . $iTime;

        $rResults = $oConn->query($sQuery);

        while ($aResults = $rResults->fetch_assoc())
        {
            $sOutput .= stripslashes($aResults['name']) . ': ';
            $sTemp = $aResults['message'];
            $sTemp = '<span class="m">' . $sTemp . '</span>';
            $sOutput .= stripslashes($sTemp);
            $sOutput .= self::BR;
        }

        $rResults->close();
        $oConn->close();

        return $sOutput;
    }


    /**
        * Check for new chatbox message.
        *
        * @return   string
    */

    public static function checkForUpdate(): string
    {
        if ( ! isset($_POST['id']))
        {
            exit;
        }

        $sOutput = '';
        $sTemp = '';
        $oConn = self::getConnection();
        $sID = self::dbSafe($_POST['id'], $oConn);

        if ($sID !== '0')
        {
            $sQuery = '
                SELECT id
                FROM ' . self::DB_TABLE .'
                WHERE id > ' . $sID;

            $rResults = $oConn->query($sQuery);
            $aResults = $rResults->fetch_row();

            if ( ! $aResults) # no new messages
            {
                $a = array('id' => $sID, 'n' => '', 'm' => '');
                $sOutput .= '[' . json_encode($a) . ']';
            }
            else # new messages
            {
                $aJSON = array();

                $sQuery = '
                    SELECT id, name, message
                    FROM ' . self::DB_TABLE . '
                    WHERE id > ' . $sID;

                $rResults = $oConn->query($sQuery); # need to query again, else blank results between browser windows

                while ($aResults = $rResults->fetch_assoc())
                {
                    $sTemp = str_ireplace(self::LB, self::BR, $aResults['message']);
                    $aJSON[] = json_encode(array('id' => $aResults['id'], 'n' => $aResults['name'], 'm' => $sTemp));
                }

                $sOutput .= '[' . join(',', $aJSON) . ']';

                $rResults->close();
                $oConn->close();
            }
        }
        else
        {
            $sQuery = '
                SELECT id
                FROM ' . self::DB_TABLE . '
                ORDER BY id
                DESC LIMIT 1';

            $rResults = $oConn->query($sQuery);
            $aResult = $rResults->fetch_row();
            $sID = $aResult[0];

            $rResults->close();
            $oConn->close();

            $a = array('id' => $sID, 'n' => '', 'm' => '');
            $sOutput .= '[' . json_encode($a) . ']';
        }

        return $sOutput;
    }


    /**
        * Add a chatbox message to the database.
        *
        * @return   string|null
    */

    public static function addMessage(): ?string
    {
        if ( ! isset($_POST['n']))
        {
            return '';
        }

        $bInsertion = false;

        $oConn = self::getConnection();

        $sName = self::dbSafe(rawurldecode($_POST['n']), $oConn);
        $sMessage = self::dbSafe($_POST['m'], $oConn);
        $iDate = time();

        $sInsert = '
            INSERT INTO ' . self::DB_TABLE . '
                (name, message, date)
            VALUES(?, ?, ?)';

        $oStmt = $oConn->stmt_init();
        $oStmt->prepare($sInsert);
        $oStmt->bind_param('ssi', $sName, $sMessage, $iDate);
        $oStmt->execute();

        if ($oStmt->affected_rows)
        {
            $bInsertion = true;
        }

        $iID = $oStmt->insert_id; # find ID from insert

        $oStmt->close();
        $oConn->close();

        if ($bInsertion)
        {
            $a = array('id' => $iID, 'n' => $sName, 'm' => $sMessage);
            $sOutput = json_encode($a); # NB no square brackets
            return $sOutput;
        }
        else
        {
            if (self::DEBUG)
            {
                return 'Row could not be inserted into table.';
            }
            else
            {
                return null;
            }
        }
    }


    /**
        * Sanitize string for database input.
        *
        * @param    string $sExt, external string to be sanitized
        * @param    object $oConn, database connection
        *
        * @return   string
    */

    private static function dbSafe($sExt, mysqli &$oConn): string
    {
        return $oConn->real_escape_string(strip_tags(stripslashes(trim($sExt))));
    }
}