/*
 * Licensed to Elasticsearch under one or more contributor
 * license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright
 * ownership. Elasticsearch licenses this file to you under
 * the Apache License, Version 2.0 (the "License"); you may
 * not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.elasticsearch.client.node;

import org.elasticsearch.action.Action;
import org.elasticsearch.action.ActionListener;
import org.elasticsearch.action.ActionRequest;
import org.elasticsearch.action.ActionRequestBuilder;
import org.elasticsearch.action.ActionResponse;
import org.elasticsearch.action.GenericAction;
import org.elasticsearch.action.support.TransportAction;
import org.elasticsearch.client.Client;
import org.elasticsearch.client.support.AbstractClient;
import org.elasticsearch.cluster.node.DiscoveryNode;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.tasks.Task;
import org.elasticsearch.tasks.TaskListener;
import org.elasticsearch.threadpool.ThreadPool;

import java.util.Map;
import java.util.function.Supplier;

/**
 * Client that executes actions on the local node.
 */
public class NodeClient extends AbstractClient {

    private Map<GenericAction, TransportAction> actions;
    /**
     * The id of the local {@link DiscoveryNode}. Useful for generating task ids from tasks returned by
     * {@link #executeLocally(GenericAction, ActionRequest, TaskListener)}.
     */
    private Supplier<String> localNodeId;

    public NodeClient(Settings settings, ThreadPool threadPool) {
        super(settings, threadPool);
    }

    public void initialize(Map<GenericAction, TransportAction> actions, Supplier<String> localNodeId) {
        this.actions = actions;
        this.localNodeId = localNodeId;
    }

    @Override
    public void close() {
        // nothing really to do
    }

    @Override
    public <    Request extends ActionRequest,
                Response extends ActionResponse,
                RequestBuilder extends ActionRequestBuilder<Request, Response, RequestBuilder>
            > void doExecute(Action<Request, Response, RequestBuilder> action, Request request, ActionListener<Response> listener) {
        // Discard the task because the Client interface doesn't use it.
        executeLocally(action, request, listener);
    }

    /**
     * Execute an {@link Action} locally, returning that {@link Task} used to track it, and linking an {@link ActionListener}. Prefer this
     * method if you don't need access to the task when listening for the response. This is the method used to implement the {@link Client}
     * interface.
     */
    public <    Request extends ActionRequest,
                Response extends ActionResponse
            > Task executeLocally(GenericAction<Request, Response> action, Request request, ActionListener<Response> listener) {
        return transportAction(action).execute(request, listener);
    }

    /**
     * Execute an {@link Action} locally, returning that {@link Task} used to track it, and linking an {@link TaskListener}. Prefer this
     * method if you need access to the task when listening for the response.
     */
    public <    Request extends ActionRequest,
                Response extends ActionResponse
            > Task executeLocally(GenericAction<Request, Response> action, Request request, TaskListener<Response> listener) {
        return transportAction(action).execute(request, listener);
    }

    /**
     * The id of the local {@link DiscoveryNode}. Useful for generating task ids from tasks returned by
     * {@link #executeLocally(GenericAction, ActionRequest, TaskListener)}.
     */
    public String getLocalNodeId() {
        return localNodeId.get();
    }

    /**
     * Get the {@link TransportAction} for an {@link Action}, throwing exceptions if the action isn't available.
     */
    @SuppressWarnings("unchecked")
    private <    Request extends ActionRequest,
                Response extends ActionResponse
            > TransportAction<Request, Response> transportAction(GenericAction<Request, Response> action) {
        if (actions == null) {
            throw new IllegalStateException("NodeClient has not been initialized");
        }
        TransportAction<Request, Response> transportAction = actions.get(action);
        if (transportAction == null) {
            throw new IllegalStateException("failed to find action [" + action + "] to execute");
        }
        return transportAction;
    }
}