Backup when updating modpack

HMCLCore/src/main/java/org/jackhuang/hmcl/mod/ModpackUpdateTask.java

@@ -1,4 +1,80 @@
+/**
+ * Hello Minecraft! Launcher
+ * Copyright (C) 2018  huangyuhui <huanghongxun2008@126.com> and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
 package org.jackhuang.hmcl.mod;
 
-public class ModpackUpdateTask {
+import org.jackhuang.hmcl.game.DefaultGameRepository;
+import org.jackhuang.hmcl.task.SilentException;
+import org.jackhuang.hmcl.task.Task;
+import org.jackhuang.hmcl.util.io.FileUtils;
+
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Collection;
+import java.util.Collections;
+
+public class ModpackUpdateTask extends Task {
+
+    private final DefaultGameRepository repository;
+    private final String id;
+    private final Task updateTask;
+    private final Path backupFolder;
+
+    public ModpackUpdateTask(DefaultGameRepository repository, String id, Task updateTask) {
+        this.repository = repository;
+        this.id = id;
+        this.updateTask = updateTask;
+
+        Path backup = repository.getBaseDirectory().toPath().resolve("backup");
+        while (true) {
+            int num = (int)(Math.random() * 10000000);
+            if (!Files.exists(backup.resolve(id + "-" + num))) {
+                backupFolder = backup.resolve(id + "-" + num);
+                break;
+            }
+        }
+    }
+
+    @Override
+    public boolean isRelyingOnDependencies() {
+        return false;
+    }
+
+    @Override
+    public Collection<? extends Task> getDependencies() {
+        return Collections.singleton(updateTask);
+    }
+
+    @Override
+    public void execute() throws Exception {
+        FileUtils.copyDirectory(repository.getVersionRoot(id).toPath(), backupFolder);
+    }
+
+    @Override
+    public void postExecute() throws Exception {
+        if (isDependenciesSucceeded()) {
+            // Keep backup game version for further repair.
+        } else {
+            // Restore backup
+            repository.removeVersionFromDisk(id);
+
+            FileUtils.copyDirectory(backupFolder, repository.getVersionRoot(id).toPath());
+
+            throw new SilentException();
+        }
+    }
 }