<?php
/**
 * Database relation table
 *
 * $Id$
 *
 * @author gERD Schaufelberger <gerd@php-tools.net>
 * @license PHP License
 * @package WB
 * @subpackage db
 */

/**
 * Database relation table
 *
 * Generic utility datasource to load, delete and store 1:n foreign key relations.
 *
 * @version 1.1.0
 * @package WB
 * @subpackage db
 */
class WBDatasource_RelationTable extends WBStdClass
{
    /**
     * Table
     * @var WBDatasource_Table
     */
    private $table;

    /**
     * list of known relations
     * @var array
     */
    private $config =   array();

    /**
     * key of primary table
     * @var string
     */
    private $primary;

    /**
     * list of current relations
     * @var array
     */
    private $relations  =   array();

    /**
     * Inject WBDatasource_Table
     *
     * Optionally inject table object - this prevents from creating a new one
     *
     * @param WBDatasource_Table $table
     */
    public function setTable($table)
    {
        $this->table    =   $table;
    }

    /**
     * Set relation config for table
     *
     * Tell which table needs foreign relations and which.
     *
     * Usually the configuration comes from form definitions like:
     *
     * <relation>
     *    <element id="downloaddir">
     *      <table>userdownloaddir</table>
     *      <foreigntable>vfsdir</foreigntable>
     *   </element>
     *    <element id="organisation">
     *      <table>userorganisation</table>
     *      <foreigntable>organisation</foreigntable>
     *      <foreignprimarymap>orgkey</foreignprimarymap>
     *   </element>
     * </relation>
     *
     * This XML boils down to an array:
     * $config => array(
     *                 'downloaddir'    =>  array(
     *                                          'table'             =>  'article',
     *                                            ),
     *                 'downloaddir'    =>  array(
     *                                          'table'             =>  'userdownloaddir',
     *                                          'foreigntable'      =>  'vfsdir'
     *                                            ),
     *                 'organisation'   =>  array(
     *                                          'table'             =>  'userorganisation',
     *                                          'foreigntable'      =>  'organisation'
     *                                          'foreignprimarymap' =>  'orgkey'
     *                                            ),
     *                 'tagrelation'    =>  array(
     *                                          'table'             =>  'tagreference',
     *                                          'foreigntable'      =>  'tag',
     *                                          'namespace'         =>  'somestring'
     *                                            ),
     *                 );
     *
     *
     * @param string $table
     * @param array $config
     */
    public function setConfig($table, $config)
    {
        $this->startTable();
        $this->primary  =   $this->table->getIdentifier($table);
        $this->config   =   $config;

        // primary key mapping in relation table
        foreach ($this->config as $t => &$rel) {

            if (!isset($rel['foreigntable'])) {
                $rel['foreigntable']    =   $rel['table'];
            }
            if (!isset($rel['foreignprimarymap']) || empty($rel['foreignprimarymap'])) {
                $rel['foreignprimarymap']   =   $this->table->getIdentifier($rel['foreigntable']);
            }
        }
    }

    public function getConfig4Key($key)
    {
        if (!empty($this->config[$key])) {
            return $this->config[$key];
        }

        return array();
    }


    /**
     * Inject foreign keys
     *
     * Load foreign keys from table and inject into data.
     * Also return native relation data
     *
     * @param array $data
     * @return array
     */
    public function inject(&$data)
    {
        if (empty($this->primary)) {
            throw new WBException_Call('Call setConfig() first!', 1, __CLASS__);
        }

        $relData    =   array();
        foreach ($this->config as $k => $rel) {
            $clause     =   array();
            $clause[]   =   array(
                                    'field' =>  $this->primary,
                                    'value' =>  $data[$this->primary]
                                );
            // namespace settings
            if (!empty($rel['namespace'])) {
                $clause[0]['field'] =   'xid';
                if ('__empty' == $rel['namespace']) {
                    $rel['namespace']   =   '';
                }
                $clause[]   =   array(
                                    'field' =>  'namespace',
                                    'value' =>  trim($rel['namespace'])
                                );
            }

            $key            =   $rel['foreignprimarymap'];
            $list           =   $this->table->get($rel['table'], null, null, $clause);
            $relData[$k]    =   $list;
            $data[$k]       =   array();
            foreach ($list as $l) {
                $data[$k][] =   $l[$key];
            }
        }

        return $relData;
    }

    /**
     * Extract foreign keys from data
     *
     * Find foreign key values in data array and remove items
     *
     * @param array $data
     */
    public function extract(&$data)
    {
        if (empty($this->primary)) {
            throw new WBException_Call('Call setConfig() first!', 1, __CLASS__);
        }

        $this->relations    =   array();
        foreach ($this->config as $k => $rel) {
            if (!isset($data[$k])) {
                continue;
            }
            $this->relations[$k]    =   array();
            if (!is_array($data[$k])) {
                $data[$k]   =   trim($data[$k]);
                if (empty($data[$k])) {
                    $data[$k]   =   array();
                } else {
                    $data[$k]   =   explode(',', $data[$k]);
                }
            }
            $this->relations[$k]    =   $data[$k];
            unset($data[$k]);
        }
    }

    /**
     * Remove foreign keys
     *
     * Wipe out relation
     *
     * @param string $id
     */
    public function delete($id, $extracted = false)
    {
        if ('__new' == $id) {
            return;
        }
        if (empty($this->primary)) {
            throw new WBException_Call('Call setConfig() first!', 1, __CLASS__);
        }

        foreach ($this->config as $k => $rel) {
            if ($extracted && !isset($this->relations[$k])) {
                continue;
            }

            $primary    =   $this->primary;
            $clause     =   array();
            if (!empty($rel['namespace'])) {
                $primary    =   'xid';
                if ('__empty' == $rel['namespace']) {
                    $rel['namespace']   =   '';
                }
                $clause[]   =   array(
                                        'field' =>  'namespace',
                                        'value' =>  trim($rel['namespace'])
                                    );
            }
            $clause[]   =   array(
                                    'field' =>  $primary,
                                    'value' => $id
                                );

            if ($rel['table'] == $rel['foreigntable']) {
                $save   =   array(
                                $this->primary  =>  0
                                );
                $this->table->save($rel['table'], null, $save, $clause);
            }
            else {
                $this->table->delete($rel['table'], null, null, $clause);
            }
        }
    }

    /**
     * Add foreign keys
     *
     * Save foreign keys to relation table. Please note, that the foreign keys need
     * to be extracted from data first.
     *
     * @see extract()
     * @param string $id
     */
    public function add($id)
    {
        if (empty($this->primary)) {
            throw new WBException_Call('Call setConfig() first!', 1, __CLASS__);
        }

        foreach ($this->config as $k => $rel) {
            if (!isset($this->relations[$k]) || empty($this->relations[$k])) {
                continue;
            }

            $key    =   $rel['foreignprimarymap'];
            if ($rel['table'] == $rel['foreigntable']) {
                // save key in payload table
                $clause     =   array();
                $clause[]   =   array(
                                        'field'     =>  $key,
                                        'relation'  =>  'in',
                                        'value'     =>  $this->relations[$k]
                                    );
                $save   =   array(
                                $this->primary  =>  $id
                                );
                $this->table->save($rel['table'], null, $save, $clause);
            }
            else {
                // save in relation table
                $save   =   array();

                $p      =   $this->primary;
                if (!empty($rel['namespace'])) {
                    $p  =   'xid';
                }
                $s      =   array(
                                $p      =>  $id,
                                $key    =>  ''
                            );

                if (!empty($rel['namespace'])) {
                    if ('__empty' == $rel['namespace']) {
                        $rel['namespace']   =   '';
                    }
                    $s['namespace'] =   $rel['namespace'];
                }
                foreach ($this->relations[$k] as $v) {
                    $s[$key]    =   $v;
                    $save[]     =   $s;
                }
                $this->table->save($rel['table'], '__new', $save);
            }
        }
    }

    /**
     * Start table
     *
     * If not injected, instantiate WBDatasource_Table
     */
    private function startTable()
    {
        if ($this->table) {
            return;
        }
        $this->table    =   WBClass::create('WBDatasource_Table');
    }
}