New item field "Post-type" and new table "permissionset" (#5408)

* "post-type" replaces "bookmark" and "type"

* Removed some more type

* Added index to permission set

* The permission set is now stored

* The permission set is now removed upon expiry

* Post update now stores the permission set

* New file

* Permissions are now sorted

* Changed documentation

src/Model/PermissionSet.php

@@ -0,0 +1,60 @@
+<?php
+/**
+ * @file src/Model/PermissionSet.php
+ */
+namespace Friendica\Model;
+
+use Friendica\BaseObject;
+use Friendica\Database\DBM;
+use dba;
+
+require_once 'include/dba.php';
+
+/**
+ * @brief functions for interacting with the permission set of an object (item, photo, event, ...)
+ */
+class PermissionSet extends BaseObject
+{
+	/**
+	 * Fetch the id of a given permission set. Generate a new one when needed
+	 *
+	 * @param array $postarray The array from an item, picture or event post
+	 * @return id
+	 */
+	public static function fetchIDForPost($postarray)
+	{
+		$condition = ['uid' => $postarray['uid'],
+			'allow_cid' => self::sortPermissions($postarray['allow_cid']),
+			'allow_gid' => self::sortPermissions($postarray['allow_gid']),
+			'deny_cid' => self::sortPermissions($postarray['deny_cid']),
+			'deny_gid' => self::sortPermissions($postarray['deny_gid'])];
+
+		$set = dba::selectFirst('permissionset', ['id'], $condition);
+
+		if (!DBM::is_result($set)) {
+			dba::insert('permissionset', $condition, true);
+
+			$set = dba::selectFirst('permissionset', ['id'], $condition);
+		}
+		return $set['id'];
+	}
+
+	private static function sortPermissions($permissionlist)
+	{
+		$cleaned_list = trim($permissionlist, '<>');
+
+		if (empty($cleaned_list)) {
+			return $permissionlist;
+		}
+
+		$elements = explode('><', $cleaned_list);
+
+		if (count($elements) <= 1) {
+			return $permissionlist;
+		}
+
+		asort($elements);
+
+		return '<' . implode('><', $elements) . '>';
+	}
+}