/*
 * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
 * or more contributor license agreements. Licensed under the Elastic License
 * 2.0 and the Server Side Public License, v 1; you may not use this file except
 * in compliance with, at your election, the Elastic License 2.0 or the Server
 * Side Public License, v 1.
 */

package org.elasticsearch.test.tasks;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.elasticsearch.common.settings.Setting;
import org.elasticsearch.common.settings.Setting.Property;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.tasks.RemovedTaskListener;
import org.elasticsearch.tasks.Task;
import org.elasticsearch.tasks.TaskAwareRequest;
import org.elasticsearch.tasks.TaskManager;
import org.elasticsearch.threadpool.ThreadPool;
import org.elasticsearch.tracing.Tracer;

import java.util.Collection;
import java.util.Set;
import java.util.concurrent.CopyOnWriteArrayList;

import static org.elasticsearch.core.Strings.format;

/**
 * A mock task manager that allows adding listeners for events
 */
public class MockTaskManager extends TaskManager {

    private static final Logger logger = LogManager.getLogger(MockTaskManager.class);

    public static final Setting<Boolean> USE_MOCK_TASK_MANAGER_SETTING = Setting.boolSetting(
        "tests.mock.taskmanager.enabled",
        false,
        Property.NodeScope
    );

    private final Collection<MockTaskManagerListener> listeners = new CopyOnWriteArrayList<>();

    public MockTaskManager(Settings settings, ThreadPool threadPool, Set<String> taskHeaders) {
        super(settings, threadPool, taskHeaders, Tracer.NOOP);
    }

    @Override
    public Task register(String type, String action, TaskAwareRequest request) {
        Task task = super.register(type, action, request);
        for (MockTaskManagerListener listener : listeners) {
            try {
                listener.onTaskRegistered(task);
            } catch (Exception e) {
                logger.warn(() -> format("failed to notify task manager listener about registering the task with id %s", task.getId()), e);
            }
        }
        return task;
    }

    @Override
    public Task unregister(Task task) {
        Task removedTask = super.unregister(task);
        if (removedTask != null) {
            for (MockTaskManagerListener listener : listeners) {
                try {
                    listener.onTaskUnregistered(task);
                } catch (Exception e) {
                    logger.warn(
                        () -> format("failed to notify task manager listener about unregistering the task with id %s", task.getId()),
                        e
                    );
                }
            }
        } else {
            logger.warn("trying to remove the same with id {} twice", task.getId());
        }
        return removedTask;
    }

    @Override
    public void registerRemovedTaskListener(RemovedTaskListener removedTaskListener) {
        for (MockTaskManagerListener listener : listeners) {
            listener.subscribeForRemovedTasks(removedTaskListener);
        }
        super.registerRemovedTaskListener(removedTaskListener);
    }

    public void addListener(MockTaskManagerListener listener) {
        listeners.add(listener);
    }

    public void removeListener(MockTaskManagerListener listener) {
        listeners.remove(listener);
    }
}
