<?php
/* vim: set expandtab sw=4 ts=4 sts=4: */
/**
 * Set of functions used with the relation and pdf feature
 *
 * @package PhpMyAdmin
 */
namespace PhpMyAdmin;

use PhpMyAdmin\Core;
use PhpMyAdmin\DatabaseInterface;
use PhpMyAdmin\Message;
use PhpMyAdmin\RecentFavoriteTable;
use PhpMyAdmin\SqlParser\Parser;
use PhpMyAdmin\SqlParser\Utils\Table as TableUtils;
use PhpMyAdmin\Table;
use PhpMyAdmin\Template;
use PhpMyAdmin\Url;
use PhpMyAdmin\Util;

/**
 * PhpMyAdmin\Relation class
 *
 * @package PhpMyAdmin
 */
class Relation
{
    /**
     * Executes a query as controluser if possible, otherwise as normal user
     *
     * @param string  $sql        the query to execute
     * @param boolean $show_error whether to display SQL error messages or not
     * @param int     $options    query options
     *
     * @return resource|boolean the result set, or false if no result set
     *
     * @access  public
     *
     */
    public static function queryAsControlUser($sql, $show_error = true, $options = 0)
    {
        // Avoid caching of the number of rows affected; for example, this function
        // is called for tracking purposes but we want to display the correct number
        // of rows affected by the original query, not by the query generated for
        // tracking.
        $cache_affected_rows = false;

        if ($show_error) {
            $result = $GLOBALS['dbi']->query(
                $sql,
                DatabaseInterface::CONNECT_CONTROL,
                $options,
                $cache_affected_rows
            );
        } else {
            $result = @$GLOBALS['dbi']->tryQuery(
                $sql,
                DatabaseInterface::CONNECT_CONTROL,
                $options,
                $cache_affected_rows
            );
        } // end if... else...

        if ($result) {
            return $result;
        }

        return false;
    } // end of the "self::queryAsControlUser()" function

    /**
     * Returns current relation parameters
     *
     * @return array   $cfgRelation
     */
    public static function getRelationsParam()
    {
        if (empty($_SESSION['relation'][$GLOBALS['server']])
            || (empty($_SESSION['relation'][$GLOBALS['server']]['PMA_VERSION']))
            || $_SESSION['relation'][$GLOBALS['server']]['PMA_VERSION'] != PMA_VERSION
        ) {
            $_SESSION['relation'][$GLOBALS['server']] = self::checkRelationsParam();
        }

        // just for BC but needs to be before self::getRelationsParamDiagnostic()
        // which uses it
        $GLOBALS['cfgRelation'] = $_SESSION['relation'][$GLOBALS['server']];

        return $_SESSION['relation'][$GLOBALS['server']];
    }

    /**
     * prints out diagnostic info for pma relation feature
     *
     * @param array $cfgRelation Relation configuration
     *
     * @return string
     */
    public static function getRelationsParamDiagnostic(array $cfgRelation)
    {
        $retval = '<br>';

        $messages = array();
        $messages['error'] = '<span style="color:red"><strong>'
            . __('not OK')
            . '</strong></span>';

        $messages['ok'] = '<span style="color:green"><strong>'
            .  _pgettext('Correctly working', 'OK')
            . '</strong></span>';

        $messages['enabled']  = '<span style="color:green">' . __('Enabled') . '</span>';
        $messages['disabled'] = '<span style="color:red">'   . __('Disabled') . '</span>';

        if (strlen($cfgRelation['db']) == 0) {
            $retval .= __('Configuration of pmadb…') . ' '
                 . $messages['error']
                 . Util::showDocu('setup', 'linked-tables')
                 . '<br />' . "\n"
                 . __('General relation features')
                 . ' <font color="green">' . __('Disabled')
                 . '</font>' . "\n";
            if ($GLOBALS['cfg']['ZeroConf']) {
                if (strlen($GLOBALS['db']) == 0) {
                    $retval .= self::getHtmlFixPmaTables(true, true);
                } else {
                    $retval .= self::getHtmlFixPmaTables(true);
                }
            }
        } else {
            $retval .= '<table>' . "\n";

            if (! $cfgRelation['allworks']
                && $GLOBALS['cfg']['ZeroConf']
                // Avoid showing a "Create missing tables" link if it's a
                // problem of missing definition
                && self::arePmadbTablesDefined()
            ) {
                $retval .= self::getHtmlFixPmaTables(false);
                $retval .= '<br />';
            }

            $retval .= self::getDiagMessageForParameter(
                'pmadb',
                $cfgRelation['db'],
                $messages,
                'pmadb'
            );
            $retval .= self::getDiagMessageForParameter(
                'relation',
                isset($cfgRelation['relation']),
                $messages,
                'relation'
            );
            $retval .= self::getDiagMessageForFeature(
                __('General relation features'),
                'relwork',
                $messages
            );
            $retval .= self::getDiagMessageForParameter(
                'table_info',
                isset($cfgRelation['table_info']),
                $messages,
                'table_info'
            );
            $retval .= self::getDiagMessageForFeature(
                __('Display Features'),
                'displaywork',
                $messages
            );
            $retval .= self::getDiagMessageForParameter(
                'table_coords',
                isset($cfgRelation['table_coords']),
                $messages,
                'table_coords'
            );
            $retval .= self::getDiagMessageForParameter(
                'pdf_pages',
                isset($cfgRelation['pdf_pages']),
                $messages,
                'pdf_pages'
            );
            $retval .= self::getDiagMessageForFeature(
                __('Designer and creation of PDFs'),
                'pdfwork',
                $messages
            );
            $retval .= self::getDiagMessageForParameter(
                'column_info',
                isset($cfgRelation['column_info']),
                $messages,
                'column_info'
            );
            $retval .= self::getDiagMessageForFeature(
                __('Displaying Column Comments'),
                'commwork',
                $messages,
                false
            );
            $retval .= self::getDiagMessageForFeature(
                __('Browser transformation'),
                'mimework',
                $messages
            );
            if ($cfgRelation['commwork'] && ! $cfgRelation['mimework']) {
                $retval .= '<tr><td colspan=2 class="left error">';
                $retval .=  __(
                    'Please see the documentation on how to'
                    . ' update your column_info table.'
                );
                $retval .= Util::showDocu(
                    'config',
                    'cfg_Servers_column_info'
                );
                $retval .= '</td></tr>';
            }
            $retval .= self::getDiagMessageForParameter(
                'bookmarktable',
                isset($cfgRelation['bookmark']),
                $messages,
                'bookmark'
            );
            $retval .= self::getDiagMessageForFeature(
                __('Bookmarked SQL query'),
                'bookmarkwork',
                $messages
            );
            $retval .= self::getDiagMessageForParameter(
                'history',
                isset($cfgRelation['history']),
                $messages,
                'history'
            );
            $retval .= self::getDiagMessageForFeature(
                __('SQL history'),
                'historywork',
                $messages
            );
            $retval .= self::getDiagMessageForParameter(
                'recent',
                isset($cfgRelation['recent']),
                $messages,
                'recent'
            );
            $retval .= self::getDiagMessageForFeature(
                __('Persistent recently used tables'),
                'recentwork',
                $messages
            );
            $retval .= self::getDiagMessageForParameter(
                'favorite',
                isset($cfgRelation['favorite']),
                $messages,
                'favorite'
            );
            $retval .= self::getDiagMessageForFeature(
                __('Persistent favorite tables'),
                'favoritework',
                $messages
            );
            $retval .= self::getDiagMessageForParameter(
                'table_uiprefs',
                isset($cfgRelation['table_uiprefs']),
                $messages,
                'table_uiprefs'
            );
            $retval .= self::getDiagMessageForFeature(
                __('Persistent tables\' UI preferences'),
                'uiprefswork',
                $messages
            );
            $retval .= self::getDiagMessageForParameter(
                'tracking',
                isset($cfgRelation['tracking']),
                $messages,
                'tracking'
            );
            $retval .= self::getDiagMessageForFeature(
                __('Tracking'),
                'trackingwork',
                $messages
            );
            $retval .= self::getDiagMessageForParameter(
                'userconfig',
                isset($cfgRelation['userconfig']),
                $messages,
                'userconfig'
            );
            $retval .= self::getDiagMessageForFeature(
                __('User preferences'),
                'userconfigwork',
                $messages
            );
            $retval .= self::getDiagMessageForParameter(
                'users',
                isset($cfgRelation['users']),
                $messages,
                'users'
            );
            $retval .= self::getDiagMessageForParameter(
                'usergroups',
                isset($cfgRelation['usergroups']),
                $messages,
                'usergroups'
            );
            $retval .= self::getDiagMessageForFeature(
                __('Configurable menus'),
                'menuswork',
                $messages
            );
            $retval .= self::getDiagMessageForParameter(
                'navigationhiding',
                isset($cfgRelation['navigationhiding']),
                $messages,
                'navigationhiding'
            );
            $retval .= self::getDiagMessageForFeature(
                __('Hide/show navigation items'),
                'navwork',
                $messages
            );
            $retval .= self::getDiagMessageForParameter(
                'savedsearches',
                isset($cfgRelation['savedsearches']),
                $messages,
                'savedsearches'
            );
            $retval .= self::getDiagMessageForFeature(
                __('Saving Query-By-Example searches'),
                'savedsearcheswork',
                $messages
            );
            $retval .= self::getDiagMessageForParameter(
                'central_columns',
                isset($cfgRelation['central_columns']),
                $messages,
                'central_columns'
            );
            $retval .= self::getDiagMessageForFeature(
                __('Managing Central list of columns'),
                'centralcolumnswork',
                $messages
            );
            $retval .= self::getDiagMessageForParameter(
                'designer_settings',
                isset($cfgRelation['designer_settings']),
                $messages,
                'designer_settings'
            );
            $retval .= self::getDiagMessageForFeature(
                __('Remembering Designer Settings'),
                'designersettingswork',
                $messages
            );
            $retval .= self::getDiagMessageForParameter(
                'export_templates',
                isset($cfgRelation['export_templates']),
                $messages,
                'export_templates'
            );
            $retval .= self::getDiagMessageForFeature(
                __('Saving export templates'),
                'exporttemplateswork',
                $messages
            );
            $retval .= '</table>' . "\n";

            if (! $cfgRelation['allworks']) {

                $retval .= '<p>' . __('Quick steps to set up advanced features:')
                    . '</p>';

                $items = array();
                $items[] = sprintf(
                    __(
                        'Create the needed tables with the '
                        . '<code>%screate_tables.sql</code>.'
                    ),
                    htmlspecialchars(SQL_DIR)
                ) . ' ' . Util::showDocu('setup', 'linked-tables');
                $items[] = __('Create a pma user and give access to these tables.') . ' '
                    . Util::showDocu('config', 'cfg_Servers_controluser');
                $items[] = __(
                    'Enable advanced features in configuration file '
                    . '(<code>config.inc.php</code>), for example by '
                    . 'starting from <code>config.sample.inc.php</code>.'
                ) . ' ' . Util::showDocu('setup', 'quick-install');
                $items[] = __(
                    'Re-login to phpMyAdmin to load the updated configuration file.'
                );

                $retval .= Template::get('list/unordered')->render(
                    array('items' => $items,)
                );
            }
        }

        return $retval;
    }

    /**
     * prints out one diagnostic message for a feature
     *
     * @param string  $feature_name       feature name in a message string
     * @param string  $relation_parameter the $GLOBALS['cfgRelation'] parameter to check
     * @param array   $messages           utility messages
     * @param boolean $skip_line          whether to skip a line after the message
     *
     * @return string
     */
    public static function getDiagMessageForFeature($feature_name,
        $relation_parameter, array $messages, $skip_line = true
    ) {
        $retval = '    <tr><td colspan=2 class="right">' . $feature_name . ': ';
        if (isset($GLOBALS['cfgRelation'][$relation_parameter])
            && $GLOBALS['cfgRelation'][$relation_parameter]
        ) {
            $retval .= $messages['enabled'];
        } else {
            $retval .= $messages['disabled'];
        }
        $retval .= '</td></tr>';
        if ($skip_line) {
            $retval .= '<tr><td>&nbsp;</td></tr>';
        }
        return $retval;
    }

    /**
     * prints out one diagnostic message for a configuration parameter
     *
     * @param string  $parameter            config parameter name to display
     * @param boolean $relationParameterSet whether this parameter is set
     * @param array   $messages             utility messages
     * @param string  $docAnchor            anchor in documentation
     *
     * @return string
     */
    public static function getDiagMessageForParameter($parameter,
        $relationParameterSet, array $messages, $docAnchor
    ) {
        $retval = '<tr><th class="left">';
        $retval .= '$cfg[\'Servers\'][$i][\'' . $parameter . '\']  ... ';
        $retval .= '</th><td class="right">';
        if ($relationParameterSet) {
            $retval .= $messages['ok'];
        } else {
            $retval .= sprintf(
                $messages['error'],
                Util::getDocuLink('config', 'cfg_Servers_' . $docAnchor)
            );
        }
        $retval .= '</td></tr>' . "\n";
        return $retval;
    }

    /**
     * Defines the relation parameters for the current user
     * just a copy of the functions used for relations ;-)
     * but added some stuff to check what will work
     *
     * @access  protected
     * @return array    the relation parameters for the current user
     */
    public static function checkRelationsParam()
    {
        $cfgRelation                   = array();
        $cfgRelation['PMA_VERSION']    = PMA_VERSION;

        $workToTable = array(
            'relwork' => 'relation',
            'displaywork' => array('relation', 'table_info'),
            'bookmarkwork' => 'bookmarktable',
            'pdfwork' => array('table_coords', 'pdf_pages'),
            'commwork' => 'column_info',
            'mimework' => 'column_info',
            'historywork' => 'history',
            'recentwork' => 'recent',
            'favoritework' => 'favorite',
            'uiprefswork' => 'table_uiprefs',
            'trackingwork' => 'tracking',
            'userconfigwork' => 'userconfig',
            'menuswork' => array('users', 'usergroups'),
            'navwork' => 'navigationhiding',
            'savedsearcheswork' => 'savedsearches',
            'centralcolumnswork' => 'central_columns',
            'designersettingswork' => 'designer_settings',
            'exporttemplateswork' => 'export_templates',
        );

        foreach ($workToTable as $work => $table) {
            $cfgRelation[$work] = false;
        }
        $cfgRelation['allworks']       = false;
        $cfgRelation['user']           = null;
        $cfgRelation['db']             = null;

        if ($GLOBALS['server'] == 0
            || empty($GLOBALS['cfg']['Server']['pmadb'])
            || ! $GLOBALS['dbi']->selectDb(
                $GLOBALS['cfg']['Server']['pmadb'], DatabaseInterface::CONNECT_CONTROL
            )
        ) {
            // No server selected -> no bookmark table
            // we return the array with the falses in it,
            // to avoid some 'Uninitialized string offset' errors later
            $GLOBALS['cfg']['Server']['pmadb'] = false;
            return $cfgRelation;
        }

        $cfgRelation['user']  = $GLOBALS['cfg']['Server']['user'];
        $cfgRelation['db']    = $GLOBALS['cfg']['Server']['pmadb'];

        //  Now I just check if all tables that i need are present so I can for
        //  example enable relations but not pdf...
        //  I was thinking of checking if they have all required columns but I
        //  fear it might be too slow

        $tab_query = 'SHOW TABLES FROM '
            . Util::backquote(
                $GLOBALS['cfg']['Server']['pmadb']
            );
        $tab_rs    = self::queryAsControlUser(
            $tab_query, false, DatabaseInterface::QUERY_STORE
        );

        if (! $tab_rs) {
            // query failed ... ?
            //$GLOBALS['cfg']['Server']['pmadb'] = false;
            return $cfgRelation;
        }

        while ($curr_table = @$GLOBALS['dbi']->fetchRow($tab_rs)) {
            if ($curr_table[0] == $GLOBALS['cfg']['Server']['bookmarktable']) {
                $cfgRelation['bookmark']        = $curr_table[0];
            } elseif ($curr_table[0] == $GLOBALS['cfg']['Server']['relation']) {
                $cfgRelation['relation']        = $curr_table[0];
            } elseif ($curr_table[0] == $GLOBALS['cfg']['Server']['table_info']) {
                $cfgRelation['table_info']      = $curr_table[0];
            } elseif ($curr_table[0] == $GLOBALS['cfg']['Server']['table_coords']) {
                $cfgRelation['table_coords']    = $curr_table[0];
            } elseif ($curr_table[0] == $GLOBALS['cfg']['Server']['column_info']) {
                $cfgRelation['column_info']     = $curr_table[0];
            } elseif ($curr_table[0] == $GLOBALS['cfg']['Server']['pdf_pages']) {
                $cfgRelation['pdf_pages']       = $curr_table[0];
            } elseif ($curr_table[0] == $GLOBALS['cfg']['Server']['history']) {
                $cfgRelation['history']         = $curr_table[0];
            } elseif ($curr_table[0] == $GLOBALS['cfg']['Server']['recent']) {
                $cfgRelation['recent']          = $curr_table[0];
            } elseif ($curr_table[0] == $GLOBALS['cfg']['Server']['favorite']) {
                $cfgRelation['favorite']        = $curr_table[0];
            } elseif ($curr_table[0] == $GLOBALS['cfg']['Server']['table_uiprefs']) {
                $cfgRelation['table_uiprefs']   = $curr_table[0];
            } elseif ($curr_table[0] == $GLOBALS['cfg']['Server']['tracking']) {
                $cfgRelation['tracking']        = $curr_table[0];
            } elseif ($curr_table[0] == $GLOBALS['cfg']['Server']['userconfig']) {
                $cfgRelation['userconfig']      = $curr_table[0];
            } elseif ($curr_table[0] == $GLOBALS['cfg']['Server']['users']) {
                $cfgRelation['users']           = $curr_table[0];
            } elseif ($curr_table[0] == $GLOBALS['cfg']['Server']['usergroups']) {
                $cfgRelation['usergroups']      = $curr_table[0];
            } elseif ($curr_table[0] == $GLOBALS['cfg']['Server']['navigationhiding']) {
                $cfgRelation['navigationhiding']      = $curr_table[0];
            } elseif ($curr_table[0] == $GLOBALS['cfg']['Server']['savedsearches']) {
                $cfgRelation['savedsearches']    = $curr_table[0];
            } elseif ($curr_table[0] == $GLOBALS['cfg']['Server']['central_columns']) {
                $cfgRelation['central_columns']    = $curr_table[0];
            } elseif ($curr_table[0] == $GLOBALS['cfg']['Server']['designer_settings']) {
                $cfgRelation['designer_settings'] = $curr_table[0];
            } elseif ($curr_table[0] == $GLOBALS['cfg']['Server']['export_templates']) {
                $cfgRelation['export_templates']    = $curr_table[0];
            }
        } // end while
        $GLOBALS['dbi']->freeResult($tab_rs);

        if (isset($cfgRelation['relation'])) {
            $cfgRelation['relwork']     = true;
        }

        if (isset($cfgRelation['relation']) && isset($cfgRelation['table_info'])) {
            $cfgRelation['displaywork'] = true;
        }

        if (isset($cfgRelation['table_coords']) && isset($cfgRelation['pdf_pages'])) {
            $cfgRelation['pdfwork']     = true;
        }

        if (isset($cfgRelation['column_info'])) {
            $cfgRelation['commwork']    = true;
            // phpMyAdmin 4.3+
            // Check for input transformations upgrade.
            $cfgRelation['mimework'] = self::tryUpgradeTransformations();
        }

        if (isset($cfgRelation['history'])) {
            $cfgRelation['historywork']     = true;
        }

        if (isset($cfgRelation['recent'])) {
            $cfgRelation['recentwork']      = true;
        }

        if (isset($cfgRelation['favorite'])) {
            $cfgRelation['favoritework']    = true;
        }

        if (isset($cfgRelation['table_uiprefs'])) {
            $cfgRelation['uiprefswork']     = true;
        }

        if (isset($cfgRelation['tracking'])) {
            $cfgRelation['trackingwork']     = true;
        }

        if (isset($cfgRelation['userconfig'])) {
            $cfgRelation['userconfigwork']   = true;
        }

        if (isset($cfgRelation['bookmark'])) {
            $cfgRelation['bookmarkwork']     = true;
        }

        if (isset($cfgRelation['users']) && isset($cfgRelation['usergroups'])) {
            $cfgRelation['menuswork']        = true;
        }

        if (isset($cfgRelation['navigationhiding'])) {
            $cfgRelation['navwork']          = true;
        }

        if (isset($cfgRelation['savedsearches'])) {
            $cfgRelation['savedsearcheswork']      = true;
        }

        if (isset($cfgRelation['central_columns'])) {
            $cfgRelation['centralcolumnswork']      = true;
        }

        if (isset($cfgRelation['designer_settings'])) {
            $cfgRelation['designersettingswork']    = true;
        }

        if (isset($cfgRelation['export_templates'])) {
            $cfgRelation['exporttemplateswork']      = true;
        }

        $allWorks = true;
        foreach ($workToTable as $work => $table) {
            if (! $cfgRelation[$work]) {
                if (is_string($table)) {
                    if (isset($GLOBALS['cfg']['Server'][$table])
                        && $GLOBALS['cfg']['Server'][$table] !== false
                    ) {
                        $allWorks = false;
                        break;
                    }
                } elseif (is_array($table)) {
                    $oneNull = false;
                    foreach ($table as $t) {
                        if (isset($GLOBALS['cfg']['Server'][$t])
                            && $GLOBALS['cfg']['Server'][$t] === false
                        ) {
                            $oneNull = true;
                            break;
                        }
                    }
                    if (! $oneNull) {
                        $allWorks = false;
                        break;
                    }
                }
            }
        }
        $cfgRelation['allworks'] = $allWorks;

        return $cfgRelation;
    } // end of the 'self::checkRelationsParam()' function

    /**
     * Check whether column_info table input transformation
     * upgrade is required and try to upgrade silently
     *
     * @return bool false if upgrade failed
     *
     * @access  public
     */
    public static function tryUpgradeTransformations()
    {
        // From 4.3, new input oriented transformation feature was introduced.
        // Check whether column_info table has input transformation columns
        $new_cols = array(
            "input_transformation",
            "input_transformation_options"
        );
        $query = 'SHOW COLUMNS FROM '
            . Util::backquote($GLOBALS['cfg']['Server']['pmadb'])
            . '.' . Util::backquote(
                $GLOBALS['cfg']['Server']['column_info']
            )
            . ' WHERE Field IN (\'' . implode('\', \'', $new_cols) . '\')';
        $result = self::queryAsControlUser(
            $query, false, DatabaseInterface::QUERY_STORE
        );
        if ($result) {
            $rows = $GLOBALS['dbi']->numRows($result);
            $GLOBALS['dbi']->freeResult($result);
            // input transformations are present
            // no need to upgrade
            if ($rows === 2) {
                return true;
                // try silent upgrade without disturbing the user
            }

            // read upgrade query file
            $query = @file_get_contents(SQL_DIR . 'upgrade_column_info_4_3_0+.sql');
            // replace database name from query to with set in config.inc.php
            $query = str_replace(
                '`phpmyadmin`',
                Util::backquote($GLOBALS['cfg']['Server']['pmadb']),
                $query
            );
            // replace pma__column_info table name from query
            // to with set in config.inc.php
            $query = str_replace(
                '`pma__column_info`',
                Util::backquote(
                    $GLOBALS['cfg']['Server']['column_info']
                ),
                $query
            );
            $GLOBALS['dbi']->tryMultiQuery($query, DatabaseInterface::CONNECT_CONTROL);
            // skips result sets of query as we are not interested in it
            while ($GLOBALS['dbi']->moreResults(DatabaseInterface::CONNECT_CONTROL)
                && $GLOBALS['dbi']->nextResult(DatabaseInterface::CONNECT_CONTROL)
            ) {
            }
            $error = $GLOBALS['dbi']->getError(DatabaseInterface::CONNECT_CONTROL);
            // return true if no error exists otherwise false
            return empty($error);
        }
        // some failure, either in upgrading or something else
        // make some noise, time to wake up user.
        return false;
    }

    /**
     * Gets all Relations to foreign tables for a given table or
     * optionally a given column in a table
     *
     * @param string $db     the name of the db to check for
     * @param string $table  the name of the table to check for
     * @param string $column the name of the column to check for
     * @param string $source the source for foreign key information
     *
     * @return array    db,table,column
     *
     * @access  public
     */
    public static function getForeigners($db, $table, $column = '', $source = 'both')
    {
        $cfgRelation = self::getRelationsParam();
        $foreign = array();

        if ($cfgRelation['relwork'] && ($source == 'both' || $source == 'internal')) {
            $rel_query = '
                SELECT `master_field`,
                    `foreign_db`,
                    `foreign_table`,
                    `foreign_field`
                FROM ' . Util::backquote($cfgRelation['db'])
                    . '.' . Util::backquote($cfgRelation['relation']) . '
                WHERE `master_db`    = \'' . $GLOBALS['dbi']->escapeString($db) . '\'
                    AND `master_table` = \'' . $GLOBALS['dbi']->escapeString($table)
                . '\' ';
            if (strlen($column) > 0) {
                $rel_query .= ' AND `master_field` = '
                    . '\'' . $GLOBALS['dbi']->escapeString($column) . '\'';
            }
            $foreign = $GLOBALS['dbi']->fetchResult(
                $rel_query, 'master_field', null, DatabaseInterface::CONNECT_CONTROL
            );
        }

        if (($source == 'both' || $source == 'foreign') && strlen($table) > 0) {
            $tableObj = new Table($table, $db);
            $show_create_table = $tableObj->showCreate();
            if ($show_create_table) {
                $parser = new Parser($show_create_table);
                /**
                 * @var \PhpMyAdmin\SqlParser\Statements\CreateStatement $stmt
                 */
                $stmt = $parser->statements[0];
                $foreign['foreign_keys_data'] = TableUtils::getForeignKeys(
                    $stmt
                );
            }
        }

        /**
         * Emulating relations for some information_schema tables
         */
        $isInformationSchema = mb_strtolower($db) == 'information_schema';
            $isMysql = mb_strtolower($db) == 'mysql';
        if (($isInformationSchema || $isMysql)
            && ($source == 'internal' || $source == 'both')
        ) {
            if ($isInformationSchema) {
                $relations_key = 'information_schema_relations';
                include_once './libraries/information_schema_relations.inc.php';
            } else {
                $relations_key = 'mysql_relations';
                include_once './libraries/mysql_relations.inc.php';
            }
            if (isset($GLOBALS[$relations_key][$table])) {
                foreach ($GLOBALS[$relations_key][$table] as $field => $relations) {
                    if ((strlen($column) === 0 || $column == $field)
                        && (! isset($foreign[$field])
                        || strlen($foreign[$field]) === 0)
                    ) {
                        $foreign[$field] = $relations;
                    }
                }
            }
        }

        return $foreign;
    } // end of the 'self::getForeigners()' function

    /**
     * Gets the display field of a table
     *
     * @param string $db    the name of the db to check for
     * @param string $table the name of the table to check for
     *
     * @return string   field name
     *
     * @access  public
     */
    public static function getDisplayField($db, $table)
    {
        $cfgRelation = self::getRelationsParam();

        /**
         * Try to fetch the display field from DB.
         */
        if ($cfgRelation['displaywork']) {
            $disp_query = '
                SELECT `display_field`
                FROM ' . Util::backquote($cfgRelation['db'])
                    . '.' . Util::backquote($cfgRelation['table_info']) . '
                WHERE `db_name`    = \'' . $GLOBALS['dbi']->escapeString($db) . '\'
                    AND `table_name` = \'' . $GLOBALS['dbi']->escapeString($table)
                . '\'';

            $row = $GLOBALS['dbi']->fetchSingleRow(
                $disp_query, 'ASSOC', DatabaseInterface::CONNECT_CONTROL
            );
            if (isset($row['display_field'])) {
                return $row['display_field'];
            }
        }

        /**
         * Emulating the display field for some information_schema tables.
         */
        if ($db == 'information_schema') {
            switch ($table) {
            case 'CHARACTER_SETS':
                return 'DESCRIPTION';
            case 'TABLES':
                return 'TABLE_COMMENT';
            }
        }

        /**
         * Pick first char field
         */
        $columns = $GLOBALS['dbi']->getColumnsFull($db, $table);
        if ($columns) {
            foreach ($columns as $column) {
                if ($GLOBALS['dbi']->types->getTypeClass($column['DATA_TYPE']) == 'CHAR') {
                    return $column['COLUMN_NAME'];
                }
            }
        }

        /**
         * No Luck...
         */
        return false;

    } // end of the 'self::getDisplayField()' function

    /**
     * Gets the comments for all columns of a table or the db itself
     *
     * @param string $db    the name of the db to check for
     * @param string $table the name of the table to check for
     *
     * @return array    [column_name] = comment
     *
     * @access  public
     */
    public static function getComments($db, $table = '')
    {
        $comments = array();

        if ($table != '') {
            // MySQL native column comments
            $columns = $GLOBALS['dbi']->getColumns($db, $table, null, true);
            if ($columns) {
                foreach ($columns as $column) {
                    if (! empty($column['Comment'])) {
                        $comments[$column['Field']] = $column['Comment'];
                    }
                }
            }
        } else {
            $comments[] = self::getDbComment($db);
        }

        return $comments;
    } // end of the 'self::getComments()' function

    /**
     * Gets the comment for a db
     *
     * @param string $db the name of the db to check for
     *
     * @return string   comment
     *
     * @access  public
     */
    public static function getDbComment($db)
    {
        $cfgRelation = self::getRelationsParam();
        $comment = '';

        if ($cfgRelation['commwork']) {
            // pmadb internal db comment
            $com_qry = "
                SELECT `comment`
                FROM " . Util::backquote($cfgRelation['db'])
                    . "." . Util::backquote($cfgRelation['column_info'])
                    . "
                WHERE db_name     = '" . $GLOBALS['dbi']->escapeString($db) . "'
                    AND table_name  = ''
                    AND column_name = '(db_comment)'";
            $com_rs = self::queryAsControlUser(
                $com_qry, true, DatabaseInterface::QUERY_STORE
            );

            if ($com_rs && $GLOBALS['dbi']->numRows($com_rs) > 0) {
                $row = $GLOBALS['dbi']->fetchAssoc($com_rs);
                $comment = $row['comment'];
            }
            $GLOBALS['dbi']->freeResult($com_rs);
        }

        return $comment;
    } // end of the 'self::getDbComment()' function

    /**
     * Gets the comment for a db
     *
     * @access  public
     *
     * @return string   comment
     */
    public static function getDbComments()
    {
        $cfgRelation = self::getRelationsParam();
        $comments = array();

        if ($cfgRelation['commwork']) {
            // pmadb internal db comment
            $com_qry = "
                SELECT `db_name`, `comment`
                FROM " . Util::backquote($cfgRelation['db'])
                    . "." . Util::backquote($cfgRelation['column_info'])
                    . "
                WHERE `column_name` = '(db_comment)'";
            $com_rs = self::queryAsControlUser(
                $com_qry, true, DatabaseInterface::QUERY_STORE
            );

            if ($com_rs && $GLOBALS['dbi']->numRows($com_rs) > 0) {
                while ($row = $GLOBALS['dbi']->fetchAssoc($com_rs)) {
                    $comments[$row['db_name']] = $row['comment'];
                }
            }
            $GLOBALS['dbi']->freeResult($com_rs);
        }

        return $comments;
    } // end of the 'self::getDbComments()' function

    /**
     * Set a database comment to a certain value.
     *
     * @param string $db      the name of the db
     * @param string $comment the value of the column
     *
     * @return boolean  true, if comment-query was made.
     *
     * @access  public
     */
    public static function setDbComment($db, $comment = '')
    {
        $cfgRelation = self::getRelationsParam();

        if (! $cfgRelation['commwork']) {
            return false;
        }

        if (strlen($comment) > 0) {
            $upd_query = 'INSERT INTO '
                . Util::backquote($cfgRelation['db']) . '.'
                . Util::backquote($cfgRelation['column_info'])
                . ' (`db_name`, `table_name`, `column_name`, `comment`)'
                . ' VALUES (\''
                . $GLOBALS['dbi']->escapeString($db)
                . "', '', '(db_comment)', '"
                . $GLOBALS['dbi']->escapeString($comment)
                . "') "
                . ' ON DUPLICATE KEY UPDATE '
                . "`comment` = '" . $GLOBALS['dbi']->escapeString($comment) . "'";
        } else {
            $upd_query = 'DELETE FROM '
                . Util::backquote($cfgRelation['db']) . '.'
                . Util::backquote($cfgRelation['column_info'])
                . ' WHERE `db_name`     = \'' . $GLOBALS['dbi']->escapeString($db)
                . '\'
                    AND `table_name`  = \'\'
                    AND `column_name` = \'(db_comment)\'';
        }

        if (isset($upd_query)) {
            return self::queryAsControlUser($upd_query);
        }

        return false;
    } // end of 'self::setDbComment()' function

    /**
     * Set a SQL history entry
     *
     * @param string $db       the name of the db
     * @param string $table    the name of the table
     * @param string $username the username
     * @param string $sqlquery the sql query
     *
     * @return void
     *
     * @access  public
     */
    public static function setHistory($db, $table, $username, $sqlquery)
    {
        $maxCharactersInDisplayedSQL = $GLOBALS['cfg']['MaxCharactersInDisplayedSQL'];
        // Prevent to run this automatically on Footer class destroying in testsuite
        if (defined('TESTSUITE')
            || mb_strlen($sqlquery) > $maxCharactersInDisplayedSQL
        ) {
            return;
        }

        $cfgRelation = self::getRelationsParam();

        if (! isset($_SESSION['sql_history'])) {
            $_SESSION['sql_history'] = array();
        }

        $_SESSION['sql_history'][] = array(
            'db' => $db,
            'table' => $table,
            'sqlquery' => $sqlquery,
        );

        if (count($_SESSION['sql_history']) > $GLOBALS['cfg']['QueryHistoryMax']) {
            // history should not exceed a maximum count
            array_shift($_SESSION['sql_history']);
        }

        if (! $cfgRelation['historywork'] || ! $GLOBALS['cfg']['QueryHistoryDB']) {
            return;
        }

        self::queryAsControlUser(
            'INSERT INTO '
            . Util::backquote($cfgRelation['db']) . '.'
            . Util::backquote($cfgRelation['history']) . '
                  (`username`,
                    `db`,
                    `table`,
                    `timevalue`,
                    `sqlquery`)
            VALUES
                  (\'' . $GLOBALS['dbi']->escapeString($username) . '\',
                   \'' . $GLOBALS['dbi']->escapeString($db) . '\',
                   \'' . $GLOBALS['dbi']->escapeString($table) . '\',
                   NOW(),
                   \'' . $GLOBALS['dbi']->escapeString($sqlquery) . '\')'
        );

        self::purgeHistory($username);

    } // end of 'self::setHistory()' function

    /**
     * Gets a SQL history entry
     *
     * @param string $username the username
     *
     * @return array    list of history items
     *
     * @access  public
     */
    public static function getHistory($username)
    {
        $cfgRelation = self::getRelationsParam();

        if (! $cfgRelation['historywork']) {
            return false;
        }

        /**
         * if db-based history is disabled but there exists a session-based
         * history, use it
         */
        if (! $GLOBALS['cfg']['QueryHistoryDB']) {
            if (isset($_SESSION['sql_history'])) {
                return array_reverse($_SESSION['sql_history']);
            }
            return false;
        }

        $hist_query = '
             SELECT `db`,
                    `table`,
                    `sqlquery`,
                    `timevalue`
               FROM ' . Util::backquote($cfgRelation['db'])
                . '.' . Util::backquote($cfgRelation['history']) . '
              WHERE `username` = \'' . $GLOBALS['dbi']->escapeString($username) . '\'
           ORDER BY `id` DESC';

        return $GLOBALS['dbi']->fetchResult(
            $hist_query, null, null, DatabaseInterface::CONNECT_CONTROL
        );
    } // end of 'self::getHistory()' function

    /**
     * purges SQL history
     *
     * deletes entries that exceeds $cfg['QueryHistoryMax'], oldest first, for the
     * given user
     *
     * @param string $username the username
     *
     * @return void
     *
     * @access  public
     */
    public static function purgeHistory($username)
    {
        $cfgRelation = self::getRelationsParam();
        if (! $GLOBALS['cfg']['QueryHistoryDB'] || ! $cfgRelation['historywork']) {
            return;
        }

        if (! $cfgRelation['historywork']) {
            return;
        }

        $search_query = '
            SELECT `timevalue`
            FROM ' . Util::backquote($cfgRelation['db'])
                . '.' . Util::backquote($cfgRelation['history']) . '
            WHERE `username` = \'' . $GLOBALS['dbi']->escapeString($username) . '\'
            ORDER BY `timevalue` DESC
            LIMIT ' . $GLOBALS['cfg']['QueryHistoryMax'] . ', 1';

        if ($max_time = $GLOBALS['dbi']->fetchValue(
            $search_query, 0, 0, DatabaseInterface::CONNECT_CONTROL
        )) {
            self::queryAsControlUser(
                'DELETE FROM '
                . Util::backquote($cfgRelation['db']) . '.'
                . Util::backquote($cfgRelation['history']) . '
                  WHERE `username` = \'' . $GLOBALS['dbi']->escapeString($username)
                . '\'
                    AND `timevalue` <= \'' . $max_time . '\''
            );
        }
    } // end of 'self::purgeHistory()' function

    /**
     * Prepares the dropdown for one mode
     *
     * @param array  $foreign the keys and values for foreigns
     * @param string $data    the current data of the dropdown
     * @param string $mode    the needed mode
     *
     * @return array   the <option value=""><option>s
     *
     * @access  protected
     */
    public static function buildForeignDropdown(array $foreign, $data, $mode)
    {
        $reloptions = array();

        // id-only is a special mode used when no foreign display column
        // is available
        if ($mode == 'id-content' || $mode == 'id-only') {
            // sort for id-content
            if ($GLOBALS['cfg']['NaturalOrder']) {
                uksort($foreign, 'strnatcasecmp');
            } else {
                ksort($foreign);
            }
        } elseif ($mode == 'content-id') {
            // sort for content-id
            if ($GLOBALS['cfg']['NaturalOrder']) {
                natcasesort($foreign);
            } else {
                asort($foreign);
            }
        }

        foreach ($foreign as $key => $value) {
            if (mb_strlen($value) <= $GLOBALS['cfg']['LimitChars']
            ) {
                $vtitle = '';
                $value  = htmlspecialchars($value);
            } else {
                $vtitle  = htmlspecialchars($value);
                $value  = htmlspecialchars(
                    mb_substr(
                        $value, 0, $GLOBALS['cfg']['LimitChars']
                    ) . '...'
                );
            }

            $reloption = '<option value="' . htmlspecialchars($key) . '"';
            if ($vtitle != '') {
                $reloption .= ' title="' . $vtitle . '"';
            }

            if ((string) $key == (string) $data) {
                $reloption .= ' selected="selected"';
            }

            if ($mode == 'content-id') {
                $reloptions[] = $reloption . '>'
                    . $value . '&nbsp;-&nbsp;' . htmlspecialchars($key) .  '</option>';
            } elseif ($mode == 'id-content') {
                $reloptions[] = $reloption . '>'
                    . htmlspecialchars($key) .  '&nbsp;-&nbsp;' . $value . '</option>';
            } elseif ($mode == 'id-only') {
                $reloptions[] = $reloption . '>'
                    . htmlspecialchars($key) . '</option>';
            }
        } // end foreach

        return $reloptions;
    } // end of 'self::buildForeignDropdown' function

    /**
     * Outputs dropdown with values of foreign fields
     *
     * @param array  $disp_row        array of the displayed row
     * @param string $foreign_field   the foreign field
     * @param string $foreign_display the foreign field to display
     * @param string $data            the current data of the dropdown (field in row)
     * @param int    $max             maximum number of items in the dropdown
     *
     * @return string   the <option value=""><option>s
     *
     * @access  public
     */
    public static function foreignDropdown(array $disp_row, $foreign_field, $foreign_display, $data,
        $max = null
    ) {
        if (null === $max) {
            $max = $GLOBALS['cfg']['ForeignKeyMaxLimit'];
        }

        $foreign = array();

        // collect the data
        foreach ($disp_row as $relrow) {
            $key   = $relrow[$foreign_field];

            // if the display field has been defined for this foreign table
            if ($foreign_display) {
                $value  = $relrow[$foreign_display];
            } else {
                $value = '';
            } // end if ($foreign_display)

            $foreign[$key] = $value;
        } // end foreach

        // put the dropdown sections in correct order
        $top = array();
        $bottom = array();
        if ($foreign_display) {
            if (Core::isValid($GLOBALS['cfg']['ForeignKeyDropdownOrder'], 'array')) {
                if (Core::isValid($GLOBALS['cfg']['ForeignKeyDropdownOrder'][0])) {
                    $top = self::buildForeignDropdown(
                        $foreign,
                        $data,
                        $GLOBALS['cfg']['ForeignKeyDropdownOrder'][0]
                    );
                }
                if (Core::isValid($GLOBALS['cfg']['ForeignKeyDropdownOrder'][1])) {
                    $bottom = self::buildForeignDropdown(
                        $foreign,
                        $data,
                        $GLOBALS['cfg']['ForeignKeyDropdownOrder'][1]
                    );
                }
            } else {
                $top = self::buildForeignDropdown($foreign, $data, 'id-content');
                $bottom = self::buildForeignDropdown($foreign, $data, 'content-id');
            }
        } else {
            $top = self::buildForeignDropdown($foreign, $data, 'id-only');
        }

        // beginning of dropdown
        $ret = '<option value="">&nbsp;</option>';
        $top_count = count($top);
        if ($max == -1 || $top_count < $max) {
            $ret .= implode('', $top);
            if ($foreign_display && $top_count > 0) {
                // this empty option is to visually mark the beginning of the
                // second series of values (bottom)
                $ret .= '<option value="">&nbsp;</option>';
            }
        }
        if ($foreign_display) {
            $ret .= implode('', $bottom);
        }

        return $ret;
    } // end of 'self::foreignDropdown()' function

    /**
     * Gets foreign keys in preparation for a drop-down selector
     *
     * @param array|boolean $foreigners     array of the foreign keys
     * @param string        $field          the foreign field name
     * @param bool          $override_total whether to override the total
     * @param string        $foreign_filter a possible filter
     * @param string        $foreign_limit  a possible LIMIT clause
     * @param bool          $get_total      optional, whether to get total num of rows
     *                                      in $foreignData['the_total;]
     *                                      (has an effect of performance)
     *
     * @return array    data about the foreign keys
     *
     * @access  public
     */
    public static function getForeignData(
        $foreigners, $field, $override_total,
        $foreign_filter, $foreign_limit, $get_total=false
    ) {
        // we always show the foreign field in the drop-down; if a display
        // field is defined, we show it besides the foreign field
        $foreign_link = false;
        do {
            if (! $foreigners) {
                break;
            }
            $foreigner = self::searchColumnInForeigners($foreigners, $field);
            if ($foreigner != false) {
                $foreign_db      = $foreigner['foreign_db'];
                $foreign_table   = $foreigner['foreign_table'];
                $foreign_field   = $foreigner['foreign_field'];
            } else {
                break;
            }

            // Count number of rows in the foreign table. Currently we do
            // not use a drop-down if more than ForeignKeyMaxLimit rows in the
            // foreign table,
            // for speed reasons and because we need a better interface for this.
            //
            // We could also do the SELECT anyway, with a LIMIT, and ensure that
            // the current value of the field is one of the choices.

            // Check if table has more rows than specified by
            // $GLOBALS['cfg']['ForeignKeyMaxLimit']
            $moreThanLimit = $GLOBALS['dbi']->getTable($foreign_db, $foreign_table)
                ->checkIfMinRecordsExist($GLOBALS['cfg']['ForeignKeyMaxLimit']);

            if ($override_total == true
                || !$moreThanLimit
            ) {
                // foreign_display can be false if no display field defined:
                $foreign_display = self::getDisplayField($foreign_db, $foreign_table);

                $f_query_main = 'SELECT ' . Util::backquote($foreign_field)
                    . (
                        ($foreign_display == false)
                            ? ''
                            : ', ' . Util::backquote($foreign_display)
                    );
                $f_query_from = ' FROM ' . Util::backquote($foreign_db)
                    . '.' . Util::backquote($foreign_table);
                $f_query_filter = empty($foreign_filter) ? '' : ' WHERE '
                    . Util::backquote($foreign_field)
                    . ' LIKE "%' . $GLOBALS['dbi']->escapeString($foreign_filter) . '%"'
                    . (
                    ($foreign_display == false)
                        ? ''
                        : ' OR ' . Util::backquote($foreign_display)
                        . ' LIKE "%' . $GLOBALS['dbi']->escapeString($foreign_filter)
                        . '%"'
                    );
                $f_query_order = ($foreign_display == false) ? '' :' ORDER BY '
                    . Util::backquote($foreign_table) . '.'
                    . Util::backquote($foreign_display);

                $f_query_limit = ! empty($foreign_limit) ? ($foreign_limit) : '';

                if (!empty($foreign_filter)) {
                    $the_total = $GLOBALS['dbi']->fetchValue(
                        'SELECT COUNT(*)' . $f_query_from . $f_query_filter
                    );
                    if ($the_total === false) {
                        $the_total = 0;
                    }
                }

                $disp  = $GLOBALS['dbi']->tryQuery(
                    $f_query_main . $f_query_from . $f_query_filter
                    . $f_query_order . $f_query_limit
                );
                if ($disp && $GLOBALS['dbi']->numRows($disp) > 0) {
                    // If a resultset has been created, pre-cache it in the $disp_row
                    // array. This helps us from not needing to use mysql_data_seek by
                    // accessing a pre-cached PHP array. Usually those resultsets are
                    // not that big, so a performance hit should not be expected.
                    $disp_row = array();
                    while ($single_disp_row = @$GLOBALS['dbi']->fetchAssoc($disp)) {
                        $disp_row[] = $single_disp_row;
                    }
                    @$GLOBALS['dbi']->freeResult($disp);
                } else {
                    // Either no data in the foreign table or
                    // user does not have select permission to foreign table/field
                    // Show an input field with a 'Browse foreign values' link
                    $disp_row = null;
                    $foreign_link = true;
                }
            } else {
                $disp_row = null;
                $foreign_link = true;
            }
        } while (false);

        if ($get_total) {
            $the_total = $GLOBALS['dbi']->getTable($foreign_db, $foreign_table)
                ->countRecords(true);
        }

        $foreignData = array();
        $foreignData['foreign_link'] = $foreign_link;
        $foreignData['the_total'] = isset($the_total) ? $the_total : null;
        $foreignData['foreign_display'] = (
            isset($foreign_display) ? $foreign_display : null
        );
        $foreignData['disp_row'] = isset($disp_row) ? $disp_row : null;
        $foreignData['foreign_field'] = isset($foreign_field) ? $foreign_field : null;

        return $foreignData;
    } // end of 'self::getForeignData()' function

    /**
     * Rename a field in relation tables
     *
     * usually called after a column in a table was renamed
     *
     * @param string $db       database name
     * @param string $table    table name
     * @param string $field    old field name
     * @param string $new_name new field name
     *
     * @return void
     */
    public static function renameField($db, $table, $field, $new_name)
    {
        $cfgRelation = self::getRelationsParam();

        if ($cfgRelation['displaywork']) {
            $table_query = 'UPDATE '
                . Util::backquote($cfgRelation['db']) . '.'
                . Util::backquote($cfgRelation['table_info'])
                . '   SET display_field = \'' . $GLOBALS['dbi']->escapeString(
                    $new_name
                ) . '\''
                . ' WHERE db_name       = \'' . $GLOBALS['dbi']->escapeString($db)
                . '\''
                . '   AND table_name    = \'' . $GLOBALS['dbi']->escapeString($table)
                . '\''
                . '   AND display_field = \'' . $GLOBALS['dbi']->escapeString($field)
                . '\'';
            self::queryAsControlUser($table_query);
        }

        if ($cfgRelation['relwork']) {
            $table_query = 'UPDATE '
                . Util::backquote($cfgRelation['db']) . '.'
                . Util::backquote($cfgRelation['relation'])
                . '   SET master_field = \'' . $GLOBALS['dbi']->escapeString(
                    $new_name
                ) . '\''
                . ' WHERE master_db    = \'' . $GLOBALS['dbi']->escapeString($db)
                . '\''
                . '   AND master_table = \'' . $GLOBALS['dbi']->escapeString($table)
                . '\''
                . '   AND master_field = \'' . $GLOBALS['dbi']->escapeString($field)
                . '\'';
            self::queryAsControlUser($table_query);

            $table_query = 'UPDATE '
                . Util::backquote($cfgRelation['db']) . '.'
                . Util::backquote($cfgRelation['relation'])
                . '   SET foreign_field = \'' . $GLOBALS['dbi']->escapeString(
                    $new_name
                ) . '\''
                . ' WHERE foreign_db    = \'' . $GLOBALS['dbi']->escapeString($db)
                . '\''
                . '   AND foreign_table = \'' . $GLOBALS['dbi']->escapeString($table)
                . '\''
                . '   AND foreign_field = \'' . $GLOBALS['dbi']->escapeString($field)
                . '\'';
            self::queryAsControlUser($table_query);

        } // end if relwork
    }


    /**
     * Performs SQL query used for renaming table.
     *
     * @param string $table        Relation table to use
     * @param string $source_db    Source database name
     * @param string $target_db    Target database name
     * @param string $source_table Source table name
     * @param string $target_table Target table name
     * @param string $db_field     Name of database field
     * @param string $table_field  Name of table field
     *
     * @return void
     */
    public static function renameSingleTable($table,
        $source_db, $target_db,
        $source_table, $target_table,
        $db_field, $table_field
    ) {
        $query = 'UPDATE '
            . Util::backquote($GLOBALS['cfgRelation']['db']) . '.'
            . Util::backquote($GLOBALS['cfgRelation'][$table])
            . ' SET '
            . $db_field . ' = \'' . $GLOBALS['dbi']->escapeString($target_db)
            . '\', '
            . $table_field . ' = \'' . $GLOBALS['dbi']->escapeString($target_table)
            . '\''
            . ' WHERE '
            . $db_field . '  = \'' . $GLOBALS['dbi']->escapeString($source_db) . '\''
            . ' AND '
            . $table_field . ' = \'' . $GLOBALS['dbi']->escapeString($source_table)
            . '\'';
        self::queryAsControlUser($query);
    }


    /**
     * Rename a table in relation tables
     *
     * usually called after table has been moved
     *
     * @param string $source_db    Source database name
     * @param string $target_db    Target database name
     * @param string $source_table Source table name
     * @param string $target_table Target table name
     *
     * @return void
     */
    public static function renameTable($source_db, $target_db, $source_table, $target_table)
    {
        // Move old entries from PMA-DBs to new table
        if ($GLOBALS['cfgRelation']['commwork']) {
            self::renameSingleTable(
                'column_info',
                $source_db, $target_db,
                $source_table, $target_table,
                'db_name', 'table_name'
            );
        }

        // updating bookmarks is not possible since only a single table is
        // moved, and not the whole DB.

        if ($GLOBALS['cfgRelation']['displaywork']) {
            self::renameSingleTable(
                'table_info',
                $source_db, $target_db,
                $source_table, $target_table,
                'db_name', 'table_name'
            );
        }

        if ($GLOBALS['cfgRelation']['relwork']) {
            self::renameSingleTable(
                'relation',
                $source_db, $target_db,
                $source_table, $target_table,
                'foreign_db', 'foreign_table'
            );

            self::renameSingleTable(
                'relation',
                $source_db, $target_db,
                $source_table, $target_table,
                'master_db', 'master_table'
            );
        }

        if ($GLOBALS['cfgRelation']['pdfwork']) {
            if ($source_db == $target_db) {
                // rename within the database can be handled
                self::renameSingleTable(
                    'table_coords',
                    $source_db, $target_db,
                    $source_table, $target_table,
                    'db_name', 'table_name'
                );
            } else {
                // if the table is moved out of the database we can no loger keep the
                // record for table coordinate
                $remove_query = "DELETE FROM "
                    . Util::backquote($GLOBALS['cfgRelation']['db']) . "."
                    . Util::backquote($GLOBALS['cfgRelation']['table_coords'])
                    . " WHERE db_name  = '" . $GLOBALS['dbi']->escapeString($source_db) . "'"
                    . " AND table_name = '" . $GLOBALS['dbi']->escapeString($source_table)
                    . "'";
                self::queryAsControlUser($remove_query);
            }
        }

        if ($GLOBALS['cfgRelation']['uiprefswork']) {
            self::renameSingleTable(
                'table_uiprefs',
                $source_db, $target_db,
                $source_table, $target_table,
                'db_name', 'table_name'
            );
        }

        if ($GLOBALS['cfgRelation']['navwork']) {
            // update hidden items inside table
            self::renameSingleTable(
                'navigationhiding',
                $source_db, $target_db,
                $source_table, $target_table,
                'db_name', 'table_name'
            );

            // update data for hidden table
            $query = "UPDATE "
                . Util::backquote($GLOBALS['cfgRelation']['db']) . "."
                . Util::backquote(
                    $GLOBALS['cfgRelation']['navigationhiding']
                )
                . " SET db_name = '" . $GLOBALS['dbi']->escapeString($target_db)
                . "',"
                . " item_name = '" . $GLOBALS['dbi']->escapeString($target_table)
                . "'"
                . " WHERE db_name  = '" . $GLOBALS['dbi']->escapeString($source_db)
                . "'"
                . " AND item_name = '" . $GLOBALS['dbi']->escapeString($source_table)
                . "'"
                . " AND item_type = 'table'";
            self::queryAsControlUser($query);
        }
    }

    /**
     * Create a PDF page
     *
     * @param string $newpage     name of the new PDF page
     * @param array  $cfgRelation Relation configuration
     * @param string $db          database name
     *
     * @return int $pdf_page_number
     */
    public static function createPage($newpage, array $cfgRelation, $db)
    {
        if (! isset($newpage) || $newpage == '') {
            $newpage = __('no description');
        }
        $ins_query   = 'INSERT INTO '
            . Util::backquote($GLOBALS['cfgRelation']['db']) . '.'
            . Util::backquote($cfgRelation['pdf_pages'])
            . ' (db_name, page_descr)'
            . ' VALUES (\''
            . $GLOBALS['dbi']->escapeString($db) . '\', \''
            . $GLOBALS['dbi']->escapeString($newpage) . '\')';
        self::queryAsControlUser($ins_query, false);

        return $GLOBALS['dbi']->insertId(DatabaseInterface::CONNECT_CONTROL);
    }

    /**
     * Get child table references for a table column.
     * This works only if 'DisableIS' is false. An empty array is returned otherwise.
     *
     * @param string $db     name of master table db.
     * @param string $table  name of master table.
     * @param string $column name of master table column.
     *
     * @return array $child_references
     */
    public static function getChildReferences($db, $table, $column = '')
    {
        $child_references = array();
        if (! $GLOBALS['cfg']['Server']['DisableIS']) {
            $rel_query = "SELECT `column_name`, `table_name`,"
                . " `table_schema`, `referenced_column_name`"
                . " FROM `information_schema`.`key_column_usage`"
                . " WHERE `referenced_table_name` = '"
                . $GLOBALS['dbi']->escapeString($table) . "'"
                . " AND `referenced_table_schema` = '"
                . $GLOBALS['dbi']->escapeString($db) . "'";
            if ($column) {
                $rel_query .= " AND `referenced_column_name` = '"
                    . $GLOBALS['dbi']->escapeString($column) . "'";
            }

            $child_references = $GLOBALS['dbi']->fetchResult(
                $rel_query, array('referenced_column_name', null)
            );
        }
        return $child_references;
    }

    /**
     * Check child table references and foreign key for a table column.
     *
     * @param string     $db                    name of master table db.
     * @param string     $table                 name of master table.
     * @param string     $column                name of master table column.
     * @param array|null $foreigners_full       foreiners array for the whole table.
     * @param array|null $child_references_full child references for the whole table.
     *
     * @return array $column_status telling about references if foreign key.
     */
    public static function checkChildForeignReferences(
        $db, $table, $column, $foreigners_full = null, $child_references_full = null
    ) {
        $column_status = array();
        $column_status['isEditable'] = false;
        $column_status['isReferenced'] = false;
        $column_status['isForeignKey'] = false;
        $column_status['references'] = array();

        $foreigners = array();
        if ($foreigners_full !== null) {
            if (isset($foreigners_full[$column])) {
                $foreigners[$column] = $foreigners_full[$column];
            }
            if (isset($foreigners_full['foreign_keys_data'])) {
                $foreigners['foreign_keys_data'] = $foreigners_full['foreign_keys_data'];
            }
        } else {
            $foreigners = self::getForeigners($db, $table, $column, 'foreign');
        }
        $foreigner = self::searchColumnInForeigners($foreigners, $column);

        $child_references = array();
        if ($child_references_full !== null) {
            if (isset($child_references_full[$column])) {
                $child_references = $child_references_full[$column];
            }
        } else {
            $child_references = self::getChildReferences($db, $table, $column);
        }

        if (sizeof($child_references, 0) > 0
            || $foreigner
        ) {
            if (sizeof($child_references, 0) > 0) {
                $column_status['isReferenced'] = true;
                foreach ($child_references as $columns) {
                    array_push(
                        $column_status['references'],
                        Util::backquote($columns['table_schema'])
                        . '.' . Util::backquote($columns['table_name'])
                    );
                }
            }

            if ($foreigner) {
                $column_status['isForeignKey'] = true;
            }
        } else {
            $column_status['isEditable'] = true;
        }

        return $column_status;
    }

    /**
     * Search a table column in foreign data.
     *
     * @param array  $foreigners Table Foreign data
     * @param string $column     Column name
     *
     * @return bool|array
     */
    public static function searchColumnInForeigners(array $foreigners, $column)
    {
        if (isset($foreigners[$column])) {
            return $foreigners[$column];
        }

        $foreigner = array();
        foreach ($foreigners['foreign_keys_data'] as $one_key) {
            $column_index = array_search($column, $one_key['index_list']);
            if ($column_index !== false) {
                $foreigner['foreign_field']
                    = $one_key['ref_index_list'][$column_index];
                $foreigner['foreign_db'] = isset($one_key['ref_db_name'])
                    ? $one_key['ref_db_name']
                    : $GLOBALS['db'];
                $foreigner['foreign_table'] = $one_key['ref_table_name'];
                $foreigner['constraint'] = $one_key['constraint'];
                $foreigner['on_update'] = isset($one_key['on_update'])
                    ? $one_key['on_update']
                    : 'RESTRICT';
                $foreigner['on_delete'] = isset($one_key['on_delete'])
                    ? $one_key['on_delete']
                    : 'RESTRICT';

                return $foreigner;
            }
        }

        return false;
    }

    /**
     * Returns default PMA table names and their create queries.
     *
     * @return array table name, create query
     */
    public static function getDefaultPmaTableNames()
    {
        $pma_tables = array();
        $create_tables_file = file_get_contents(
            SQL_DIR . 'create_tables.sql'
        );

        $queries = explode(';', $create_tables_file);

        foreach ($queries as $query) {
            if (preg_match(
                '/CREATE TABLE IF NOT EXISTS `(.*)` \(/',
                $query,
                $table
            )
            ) {
                $pma_tables[$table[1]] = $query . ';';
            }
        }

        return $pma_tables;
    }

    /**
     * Create a table named phpmyadmin to be used as configuration storage
     *
     * @return bool
     */
    public static function createPmaDatabase()
    {
        $GLOBALS['dbi']->tryQuery("CREATE DATABASE IF NOT EXISTS `phpmyadmin`");
        if ($error = $GLOBALS['dbi']->getError()) {
            if ($GLOBALS['errno'] == 1044) {
                $GLOBALS['message'] =    __(
                    'You do not have necessary privileges to create a database named'
                    . ' \'phpmyadmin\'. You may go to \'Operations\' tab of any'
                    . ' database to set up the phpMyAdmin configuration storage there.'
                );
            } else {
                $GLOBALS['message'] = $error;
            }
            return false;
        }
        return true;
    }

    /**
     * Creates PMA tables in the given db, updates if already exists.
     *
     * @param string  $db     database
     * @param boolean $create whether to create tables if they don't exist.
     *
     * @return void
     */
    public static function fixPmaTables($db, $create = true)
    {
        $tablesToFeatures = array(
            'pma__bookmark' => 'bookmarktable',
            'pma__relation' => 'relation',
            'pma__table_info' => 'table_info',
            'pma__table_coords' => 'table_coords',
            'pma__pdf_pages' => 'pdf_pages',
            'pma__column_info' => 'column_info',
            'pma__history' => 'history',
            'pma__recent' => 'recent',
            'pma__favorite' => 'favorite',
            'pma__table_uiprefs' => 'table_uiprefs',
            'pma__tracking' => 'tracking',
            'pma__userconfig' => 'userconfig',
            'pma__users' => 'users',
            'pma__usergroups' => 'usergroups',
            'pma__navigationhiding' => 'navigationhiding',
            'pma__savedsearches' => 'savedsearches',
            'pma__central_columns' => 'central_columns',
            'pma__designer_settings' => 'designer_settings',
            'pma__export_templates' => 'export_templates',
        );

        $existingTables = $GLOBALS['dbi']->getTables($db, DatabaseInterface::CONNECT_CONTROL);

        $createQueries = null;
        $foundOne = false;
        foreach ($tablesToFeatures as $table => $feature) {
            if (! in_array($table, $existingTables)) {
                if ($create) {
                    if ($createQueries == null) { // first create
                        $createQueries = self::getDefaultPmaTableNames();
                        $GLOBALS['dbi']->selectDb($db);
                    }
                    $GLOBALS['dbi']->tryQuery($createQueries[$table]);
                    if ($error = $GLOBALS['dbi']->getError()) {
                        $GLOBALS['message'] = $error;
                        return;
                    }
                    $foundOne = true;
                    $GLOBALS['cfg']['Server'][$feature] = $table;
                }
            } else {
                $foundOne = true;
                $GLOBALS['cfg']['Server'][$feature] = $table;
            }
        }

        if (! $foundOne) {
            return;
        }
        $GLOBALS['cfg']['Server']['pmadb'] = $db;
        $_SESSION['relation'][$GLOBALS['server']] = self::checkRelationsParam();

        $cfgRelation = self::getRelationsParam();
        if ($cfgRelation['recentwork'] || $cfgRelation['favoritework']) {
            // Since configuration storage is updated, we need to
            // re-initialize the favorite and recent tables stored in the
            // session from the current configuration storage.
            if ($cfgRelation['favoritework']) {
                $fav_tables = RecentFavoriteTable::getInstance('favorite');
                $_SESSION['tmpval']['favorite_tables'][$GLOBALS['server']]
                    = $fav_tables->getFromDb();
            }

            if ($cfgRelation['recentwork']) {
                $recent_tables = RecentFavoriteTable::getInstance('recent');
                $_SESSION['tmpval']['recent_tables'][$GLOBALS['server']]
                    = $recent_tables->getFromDb();
            }

            // Reload navi panel to update the recent/favorite lists.
            $GLOBALS['reload'] = true;
        }
    }

    /**
     * Get Html for PMA tables fixing anchor.
     *
     * @param boolean $allTables whether to create all tables
     * @param boolean $createDb  whether to create the pmadb also
     *
     * @return string Html
     */
    public static function getHtmlFixPmaTables($allTables, $createDb = false)
    {
        $retval = '';

        $url_query = Url::getCommon(array('db' => $GLOBALS['db']));
        if ($allTables) {
            if ($createDb) {
                $url_query .= '&amp;goto=db_operations.php&amp;create_pmadb=1';
                $message = Message::notice(
                    __(
                        '%sCreate%s a database named \'phpmyadmin\' and setup '
                        . 'the phpMyAdmin configuration storage there.'
                    )
                );
            } else {
                $url_query .= '&amp;goto=db_operations.php&amp;fixall_pmadb=1';
                $message = Message::notice(
                    __(
                        '%sCreate%s the phpMyAdmin configuration storage in the '
                        . 'current database.'
                    )
                );
            }
        } else {
            $url_query .= '&amp;goto=db_operations.php&amp;fix_pmadb=1';
            $message = Message::notice(
                __('%sCreate%s missing phpMyAdmin configuration storage tables.')
            );
        }
        $message->addParamHtml('<a href="./chk_rel.php' . $url_query . '">');
        $message->addParamHtml('</a>');

        $retval .= $message->getDisplay();

        return $retval;
    }

    /**
     * Gets the relations info and status, depending on the condition
     *
     * @param boolean $condition whether to look for foreigners or not
     * @param string  $db        database name
     * @param string  $table     table name
     *
     * @return array ($res_rel, $have_rel)
     */
    public static function getRelationsAndStatus($condition, $db, $table)
    {
        if ($condition) {
            // Find which tables are related with the current one and write it in
            // an array
            $res_rel = self::getForeigners($db, $table);

            if (count($res_rel) > 0) {
                $have_rel = true;
            } else {
                $have_rel = false;
            }
        } else {
            $have_rel = false;
            $res_rel = array();
        } // end if
        return(array($res_rel, $have_rel));
    }

    /**
     * Verifies if all the pmadb tables are defined
     *
     * @return boolean
     */
    public static function arePmadbTablesDefined()
    {
        if (empty($GLOBALS['cfg']['Server']['bookmarktable'])
            || empty($GLOBALS['cfg']['Server']['relation'])
            || empty($GLOBALS['cfg']['Server']['table_info'])
            || empty($GLOBALS['cfg']['Server']['table_coords'])
            || empty($GLOBALS['cfg']['Server']['column_info'])
            || empty($GLOBALS['cfg']['Server']['pdf_pages'])
            || empty($GLOBALS['cfg']['Server']['history'])
            || empty($GLOBALS['cfg']['Server']['recent'])
            || empty($GLOBALS['cfg']['Server']['favorite'])
            || empty($GLOBALS['cfg']['Server']['table_uiprefs'])
            || empty($GLOBALS['cfg']['Server']['tracking'])
            || empty($GLOBALS['cfg']['Server']['userconfig'])
            || empty($GLOBALS['cfg']['Server']['users'])
            || empty($GLOBALS['cfg']['Server']['usergroups'])
            || empty($GLOBALS['cfg']['Server']['navigationhiding'])
            || empty($GLOBALS['cfg']['Server']['savedsearches'])
            || empty($GLOBALS['cfg']['Server']['central_columns'])
            || empty($GLOBALS['cfg']['Server']['designer_settings'])
            || empty($GLOBALS['cfg']['Server']['export_templates'])
        ) {
            return false;
        }

        return true;
    }

    /**
     * Get tables for foreign key constraint
     *
     * @param string $foreignDb        Database name
     * @param string $tblStorageEngine Table storage engine
     *
     * @return array Table names
     */
    public static function getTables($foreignDb, $tblStorageEngine)
    {
        $tables = array();
        $tablesRows = $GLOBALS['dbi']->query(
            'SHOW TABLE STATUS FROM ' . Util::backquote($foreignDb),
            DatabaseInterface::CONNECT_USER,
            DatabaseInterface::QUERY_STORE
        );
        while ($row = $GLOBALS['dbi']->fetchRow($tablesRows)) {
            if (isset($row[1]) && mb_strtoupper($row[1]) == $tblStorageEngine) {
                $tables[] = $row[0];
            }
        }
        if ($GLOBALS['cfg']['NaturalOrder']) {
            usort($tables, 'strnatcasecmp');
        }
        return $tables;
    }
}
