<?php

namespace SilverStripe\Security;

use SilverStripe\ORM\DataObject;
use SilverStripe\ORM\DB;
use SilverStripe\ORM\ManyManyList;
use SilverStripe\ORM\Queries\SQLSelect;

/**
 * Represents a set of Groups attached to a member.
 * Handles the hierarchy logic.
 */
class Member_GroupSet extends ManyManyList
{

	protected function linkJoinTable()
	{
		// Do not join the table directly
		if ($this->extraFields) {
			user_error('Member_GroupSet does not support many_many_extraFields', E_USER_ERROR);
		}
	}

	/**
	 * Link this group set to a specific member.
	 *
	 * Recursively selects all groups applied to this member, as well as any
	 * parent groups of any applied groups
	 *
	 * @param array|integer $id (optional) An ID or an array of IDs - if not provided, will use the current
	 * ids as per getForeignID
	 * @return array Condition In array(SQL => parameters format)
	 */
	public function foreignIDFilter($id = null)
	{
		if ($id === null) {
			$id = $this->getForeignID();
		}

		// Find directly applied groups
		$manyManyFilter = parent::foreignIDFilter($id);
		$query = new SQLSelect('"Group_Members"."GroupID"', '"Group_Members"', $manyManyFilter);
		$groupIDs = $query->execute()->column();

		// Get all ancestors, iteratively merging these into the master set
		$allGroupIDs = array();
		while ($groupIDs) {
			$allGroupIDs = array_merge($allGroupIDs, $groupIDs);
			$groupIDs = DataObject::get("SilverStripe\\Security\\Group")->byIDs($groupIDs)->column("ParentID");
			$groupIDs = array_filter($groupIDs);
		}

		// Add a filter to this DataList
		if (!empty($allGroupIDs)) {
			$allGroupIDsPlaceholders = DB::placeholders($allGroupIDs);
			return array("\"Group\".\"ID\" IN ($allGroupIDsPlaceholders)" => $allGroupIDs);
		} else {
			return array('"Group"."ID"' => 0);
		}
	}

	public function foreignIDWriteFilter($id = null)
	{
		// Use the ManyManyList::foreignIDFilter rather than the one
		// in this class, otherwise we end up selecting all inherited groups
		return parent::foreignIDFilter($id);
	}

	public function add($item, $extraFields = null)
	{
		// Get Group.ID
		$itemID = null;
		if (is_numeric($item)) {
			$itemID = $item;
		} else {
			if ($item instanceof Group) {
				$itemID = $item->ID;
			}
		}

		// Check if this group is allowed to be added
		if ($this->canAddGroups(array($itemID))) {
			parent::add($item, $extraFields);
		}
	}

	/**
	 * Determine if the following groups IDs can be added
	 *
	 * @param array $itemIDs
	 * @return boolean
	 */
	protected function canAddGroups($itemIDs)
	{
		if (empty($itemIDs)) {
			return true;
		}
		$member = $this->getMember();
		return empty($member) || $member->onChangeGroups($itemIDs);
	}

	/**
	 * Get foreign member record for this relation
	 *
	 * @return Member
	 */
	protected function getMember()
	{
		$id = $this->getForeignID();
		if ($id) {
			return DataObject::get_by_id('SilverStripe\\Security\\Member', $id);
		}
	}
}