Allow to undo a change from event log.

src/Services/LogSystem/EventUndoHelper.php

@@ -0,0 +1,90 @@
+<?php
+/**
+ * This file is part of Part-DB (https://github.com/Part-DB/Part-DB-symfony).
+ *
+ * Copyright (C) 2019 - 2020 Jan Böhmer (https://github.com/jbtronics)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published
+ * by the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+namespace App\Services\LogSystem;
+
+
+use App\Entity\LogSystem\AbstractLogEntry;
+
+class EventUndoHelper
+{
+    public const MODE_UNDO = 'undo';
+    public const MODE_REVERT = 'revert';
+
+    protected const ALLOWED_MODES = [self::MODE_REVERT, self::MODE_UNDO];
+
+    protected $undone_event;
+    protected $mode;
+
+    public function __construct()
+    {
+        $undone_event = null;
+        $this->mode = self::MODE_UNDO;
+    }
+
+    public function setMode(string $mode): void
+    {
+        if (!in_array($mode, self::ALLOWED_MODES)) {
+            throw new \InvalidArgumentException('Invalid mode passed!');
+        }
+        $this->mode = $mode;
+    }
+
+    public function getMode(): string
+    {
+        return $this->mode;
+    }
+
+    /**
+     * Set which event log is currently undone.
+     * After the flush this message is cleared.
+     * @param  AbstractLogEntry|null  $message
+     */
+    public function setUndoneEvent(?AbstractLogEntry $undone_event): void
+    {
+        $this->undone_event = $undone_event;
+    }
+
+    /**
+     * Returns event that is currently undone.
+     * @return string|null
+     */
+    public function getUndoneEvent(): ?AbstractLogEntry
+    {
+        return $this->undone_event;
+    }
+
+    /**
+     * Clear the currently the set undone event.
+     */
+    public function clearUndoneEvent(): void
+    {
+        $this->undone_event = null;
+    }
+
+    /**
+     * Check if a event is undone
+     * @return bool
+     */
+    public function isUndo(): bool
+    {
+        return ($this->undone_event instanceof AbstractLogEntry);
+    }
+}