/*
 * Hello Minecraft! Launcher
 * Copyright (C) 2020  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.task;

import org.jetbrains.annotations.Nullable;

import java.util.*;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicInteger;

public abstract class TaskExecutor {
    protected final Task<?> firstTask;
    protected final List<TaskListener> taskListeners = new ArrayList<>();
    protected final AtomicInteger totTask = new AtomicInteger(0);
    protected final AtomicBoolean cancelled = new AtomicBoolean(false);
    protected Exception exception;
    private final List<String> stages;

    public TaskExecutor(Task<?> task) {
        this.firstTask = task;
        this.stages = task instanceof Task.StagesHintTask ? ((Task<?>.StagesHintTask) task).getStages() : Collections.emptyList();
    }

    public void addTaskListener(TaskListener taskListener) {
        taskListeners.add(taskListener);
    }

    /**
     * Reason why the task execution failed.
     * If cancelled, null is returned.
     */
    @Nullable
    public Exception getException() {
        return exception;
    }

    public abstract TaskExecutor start();

    public abstract boolean test();

    /**
     * Cancel the subscription ant interrupt all tasks.
     */
    public abstract void cancel();

    public boolean isCancelled() {
        return cancelled.get();
    }

    public int getTaskCount() {
        return totTask.get();
    }

    public List<String> getStages() {
        return stages;
    }
}
