<?php
/** 
 * Adminer plugin that display the first CHAR/VARCHAR column of the foreign key
 *
 * @category Plugin
 * @link http://www.adminer.org/plugins/#use
 * @author Bruno VIBERT <http://www.netapsys.fr>
 * @license http://www.apache.org/licenses/LICENSE-2.0 Apache License, Version 2.0
 * @license http://www.gnu.org/licenses/gpl-2.0.html GNU General Public License, version 2 (one or other)
 */
class AdminerDisplayForeignKeyName 
{

    protected static $_valueCache = array();
    
    /**
     * Get a cache entry
     */         
    protected static function _getCache( $key )
    {
        if( array_key_exists( $key, self::$_valueCache ) )
        {
            return self::$_valueCache[ $key ];
        }
        
        return false;
    }
    
    /**
     * Set a cache entry
     */ 
    protected static function _setCache( $key, $value )
    {
        self::$_valueCache[ $key ] = $value;
    }
    
    
    /**
     * Render a foreign key value
     */ 
    function selectVal($val, $link, $field, $original) {
        $return = ($val === null ? "<i>NULL</i>" : (preg_match("~char|binary~", $field["type"]) && !preg_match("~var~", $field["type"]) ? "<code>$val</code>" : $val));
        if (preg_match('~blob|bytea|raw|file~', $field["type"]) && !is_utf8($val)) 
        {
            $return = lang('%d byte(s)', strlen($original));
        }
        else
        {
            parse_str( substr($link, 1 ), $params );
            
            if( true == is_array($params) && true == array_key_exists('where', $params) ) 
            {
                $where = array();
                foreach( $params['where'] as $param )
                {
                   $where[] = join(' ', $param );
                }
                
                // Find the first char/varchar field to display
                $fieldName = false;
                foreach( fields( $params['select'] ) as $field )
                {
                    if( true == in_array( $field['type'], array('char','varchar' ) ) )
                    {
                        $fieldName = $field['field'];
                        break;
                    }
                }
                
                if( false !== $fieldName )
                {
                    $query  = sprintf('SELECT %s FROM %s WHERE %s LIMIT 1', $fieldName, $params['select'], join(' AND ', $where ) );
                    
                    $return = self::_getCache( md5( $query ) );
                    if( false === $return )
                    {
                        $result = connection() -> query( $query );
                        if($result -> num_rows == 1 )
                        {
                            $row    = $result -> fetch_assoc();
                            $value  = $row[$fieldName];
                            $length = ( isset( $_GET['text_length'] ) )? (int) $_GET['text_length'] : 100;
                            
                            if( strlen($value) > $length )
                                $value = substr( $value, 0, $length ).'...';
                            
                            $return = sprintf('<strong>[%s]</strong> %s', $original,  $value );
                            self::_setCache( md5( $query ),$return );
                        }
                    }
                }
            }
        }
        
        return ($link ? "<a href='" . h($link) . "'" . (is_url($link) ? " rel='noreferrer'" : "") . ">$return</a>" : $return);
    }
}