/*
 * SPDX-License-Identifier: Apache-2.0
 *
 * The OpenSearch Contributors require contributions made to
 * this file be licensed under the Apache-2.0 license or a
 * compatible open source license.
 */

/*
 * 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.
 */

/*
 * Modifications Copyright OpenSearch Contributors. See
 * GitHub history for details.
 */

package org.opensearch.action.get;

import org.opensearch.action.ActionListener;
import org.opensearch.action.RoutingMissingException;
import org.opensearch.action.support.ActionFilters;
import org.opensearch.action.support.single.shard.TransportSingleShardAction;
import org.opensearch.cluster.ClusterState;
import org.opensearch.cluster.metadata.IndexNameExpressionResolver;
import org.opensearch.cluster.routing.ShardIterator;
import org.opensearch.cluster.service.ClusterService;
import org.opensearch.common.inject.Inject;
import org.opensearch.core.common.io.stream.Writeable;
import org.opensearch.index.IndexService;
import org.opensearch.index.get.GetResult;
import org.opensearch.index.shard.IndexShard;
import org.opensearch.core.index.shard.ShardId;
import org.opensearch.indices.IndicesService;
import org.opensearch.threadpool.ThreadPool;
import org.opensearch.transport.TransportService;

import java.io.IOException;

/**
 * Performs the get operation.
 *
 * @opensearch.internal
 */
public class TransportGetAction extends TransportSingleShardAction<GetRequest, GetResponse> {

    private final IndicesService indicesService;

    @Inject
    public TransportGetAction(
        ClusterService clusterService,
        TransportService transportService,
        IndicesService indicesService,
        ThreadPool threadPool,
        ActionFilters actionFilters,
        IndexNameExpressionResolver indexNameExpressionResolver
    ) {
        super(
            GetAction.NAME,
            threadPool,
            clusterService,
            transportService,
            actionFilters,
            indexNameExpressionResolver,
            GetRequest::new,
            ThreadPool.Names.GET
        );
        this.indicesService = indicesService;
    }

    @Override
    protected boolean resolveIndex(GetRequest request) {
        return true;
    }

    @Override
    protected ShardIterator shards(ClusterState state, InternalRequest request) {
        return clusterService.operationRouting()
            .getShards(
                clusterService.state(),
                request.concreteIndex(),
                request.request().id(),
                request.request().routing(),
                request.request().preference()
            );
    }

    @Override
    protected void resolveRequest(ClusterState state, InternalRequest request) {
        // update the routing (request#index here is possibly an alias)
        request.request().routing(state.metadata().resolveIndexRouting(request.request().routing(), request.request().index()));
        // Fail fast on the node that received the request.
        if (request.request().routing() == null && state.getMetadata().routingRequired(request.concreteIndex())) {
            throw new RoutingMissingException(request.concreteIndex(), request.request().id());
        }
    }

    @Override
    protected void asyncShardOperation(GetRequest request, ShardId shardId, ActionListener<GetResponse> listener) throws IOException {
        IndexService indexService = indicesService.indexServiceSafe(shardId.getIndex());
        IndexShard indexShard = indexService.getShard(shardId.id());
        if (request.realtime()) { // we are not tied to a refresh cycle here anyway
            super.asyncShardOperation(request, shardId, listener);
        } else {
            indexShard.awaitShardSearchActive(b -> {
                try {
                    super.asyncShardOperation(request, shardId, listener);
                } catch (Exception ex) {
                    listener.onFailure(ex);
                }
            });
        }
    }

    @Override
    protected GetResponse shardOperation(GetRequest request, ShardId shardId) {
        IndexService indexService = indicesService.indexServiceSafe(shardId.getIndex());
        IndexShard indexShard = indexService.getShard(shardId.id());

        if (request.refresh() && !request.realtime()) {
            indexShard.refresh("refresh_flag_get");
        }

        GetResult result = indexShard.getService()
            .get(
                request.id(),
                request.storedFields(),
                request.realtime(),
                request.version(),
                request.versionType(),
                request.fetchSourceContext()
            );
        return new GetResponse(result);
    }

    @Override
    protected Writeable.Reader<GetResponse> getResponseReader() {
        return GetResponse::new;
    }

    @Override
    protected String getExecutor(GetRequest request, ShardId shardId) {
        final ClusterState clusterState = clusterService.state();
        if (clusterState.metadata().getIndexSafe(shardId.getIndex()).isSystem()) {
            return ThreadPool.Names.SYSTEM_READ;
        } else if (indicesService.indexServiceSafe(shardId.getIndex()).getIndexSettings().isSearchThrottled()) {
            return ThreadPool.Names.SEARCH_THROTTLED;
        } else {
            return super.getExecutor(request, shardId);
        }
    }
}