/*
 * 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.action.admin.cluster.state;

import com.carrotsearch.hppc.cursors.ObjectObjectCursor;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.elasticsearch.action.ActionListener;
import org.elasticsearch.action.support.ActionFilters;
import org.elasticsearch.action.support.master.TransportMasterNodeReadAction;
import org.elasticsearch.cluster.ClusterState;
import org.elasticsearch.cluster.ClusterStateObserver;
import org.elasticsearch.cluster.NotMasterException;
import org.elasticsearch.cluster.block.ClusterBlockException;
import org.elasticsearch.cluster.metadata.DataStream;
import org.elasticsearch.cluster.metadata.IndexAbstraction;
import org.elasticsearch.cluster.metadata.IndexMetadata;
import org.elasticsearch.cluster.metadata.IndexNameExpressionResolver;
import org.elasticsearch.cluster.metadata.Metadata;
import org.elasticsearch.cluster.metadata.Metadata.Custom;
import org.elasticsearch.cluster.routing.RoutingTable;
import org.elasticsearch.cluster.service.ClusterService;
import org.elasticsearch.common.inject.Inject;
import org.elasticsearch.common.unit.TimeValue;
import org.elasticsearch.index.Index;
import org.elasticsearch.node.NodeClosedException;
import org.elasticsearch.tasks.CancellableTask;
import org.elasticsearch.tasks.Task;
import org.elasticsearch.tasks.TaskCancelledException;
import org.elasticsearch.threadpool.ThreadPool;
import org.elasticsearch.transport.TransportService;

import java.io.IOException;
import java.util.function.Predicate;

public class TransportClusterStateAction extends TransportMasterNodeReadAction<ClusterStateRequest, ClusterStateResponse> {

    private final Logger logger = LogManager.getLogger(getClass());

    static {
        final String property = System.getProperty("es.cluster_state.size");
        if (property != null) {
                throw new IllegalArgumentException("es.cluster_state.size is no longer respected but was [" + property + "]");
        }
    }

    @Inject
    public TransportClusterStateAction(TransportService transportService, ClusterService clusterService,
                                       ThreadPool threadPool, ActionFilters actionFilters,
                                       IndexNameExpressionResolver indexNameExpressionResolver) {
        super(ClusterStateAction.NAME, false, transportService, clusterService, threadPool, actionFilters,
              ClusterStateRequest::new, indexNameExpressionResolver, ClusterStateResponse::new, ThreadPool.Names.SAME);
    }

    @Override
    protected ClusterBlockException checkBlock(ClusterStateRequest request, ClusterState state) {
        // cluster state calls are done also on a fully blocked cluster to figure out what is going
        // on in the cluster. For example, which nodes have joined yet the recovery has not yet kicked
        // in, we need to make sure we allow those calls
        // return state.blocks().globalBlockedException(ClusterBlockLevel.METADATA);
        return null;
    }

    @Override
    protected void masterOperation(final ClusterStateRequest request, final ClusterState state,
                                   final ActionListener<ClusterStateResponse> listener) throws IOException {
        assert false : "task is required";
        throw new UnsupportedOperationException("task is required");
    }

    @Override
    protected void masterOperation(final Task task, final ClusterStateRequest request, final ClusterState state,
                                   final ActionListener<ClusterStateResponse> listener) throws IOException {

        assert task instanceof CancellableTask : task + " not cancellable";
        final CancellableTask cancellableTask = (CancellableTask) task;

        final Predicate<ClusterState> acceptableClusterStatePredicate
            = request.waitForMetadataVersion() == null ? clusterState -> true
            : clusterState -> clusterState.metadata().version() >= request.waitForMetadataVersion();

        final Predicate<ClusterState> acceptableClusterStateOrFailedPredicate = request.local()
            ? acceptableClusterStatePredicate
            : acceptableClusterStatePredicate.or(clusterState ->
                cancellableTask.isCancelled() || clusterState.nodes().isLocalNodeElectedMaster() == false);

        if (acceptableClusterStatePredicate.test(state)) {
            ActionListener.completeWith(listener, () -> buildResponse(request, state));
        } else {
            assert acceptableClusterStateOrFailedPredicate.test(state) == false;
            new ClusterStateObserver(state, clusterService, request.waitForTimeout(), logger, threadPool.getThreadContext())
                .waitForNextChange(new ClusterStateObserver.Listener() {

                @Override
                public void onNewClusterState(ClusterState newState) {
                    if (cancellableTask.isCancelled()) {
                        listener.onFailure(new TaskCancelledException("task cancelled"));
                    } else if (acceptableClusterStatePredicate.test(newState)) {
                        ActionListener.completeWith(listener, () -> buildResponse(request, newState));
                    } else {
                        listener.onFailure(new NotMasterException(
                            "master stepped down waiting for metadata version " + request.waitForMetadataVersion()));
                    }
                }

                @Override
                public void onClusterServiceClose() {
                    listener.onFailure(new NodeClosedException(clusterService.localNode()));
                }

                @Override
                public void onTimeout(TimeValue timeout) {
                    try {
                        if (cancellableTask.isCancelled()) {
                            listener.onFailure(new TaskCancelledException("task cancelled"));
                        } else {
                            listener.onResponse(new ClusterStateResponse(state.getClusterName(), null, true));
                        }
                    } catch (Exception e) {
                        listener.onFailure(e);
                    }
                }
            }, acceptableClusterStateOrFailedPredicate);
        }
    }

    private ClusterStateResponse buildResponse(final ClusterStateRequest request,
                                               final ClusterState currentState) {
        logger.trace("Serving cluster state request using version {}", currentState.version());
        ClusterState.Builder builder = ClusterState.builder(currentState.getClusterName());
        builder.version(currentState.version());
        builder.stateUUID(currentState.stateUUID());
        builder.minimumMasterNodesOnPublishingMaster(currentState.getMinimumMasterNodesOnPublishingMaster());

        if (request.nodes()) {
            builder.nodes(currentState.nodes());
        }
        if (request.routingTable()) {
            if (request.indices().length > 0) {
                RoutingTable.Builder routingTableBuilder = RoutingTable.builder();
                String[] indices = indexNameExpressionResolver.concreteIndexNames(currentState, request);
                for (String filteredIndex : indices) {
                    if (currentState.routingTable().getIndicesRouting().containsKey(filteredIndex)) {
                        routingTableBuilder.add(currentState.routingTable().getIndicesRouting().get(filteredIndex));
                    }
                }
                builder.routingTable(routingTableBuilder.build());
            } else {
                builder.routingTable(currentState.routingTable());
            }
        }
        if (request.blocks()) {
            builder.blocks(currentState.blocks());
        }

        Metadata.Builder mdBuilder = Metadata.builder();
        mdBuilder.clusterUUID(currentState.metadata().clusterUUID());
        mdBuilder.coordinationMetadata(currentState.coordinationMetadata());

        if (request.metadata()) {
            if (request.indices().length > 0) {
                mdBuilder.version(currentState.metadata().version());
                String[] indices = indexNameExpressionResolver.concreteIndexNames(currentState, request);
                for (String filteredIndex : indices) {
                    // If the requested index is part of a data stream then that data stream should also be included:
                    IndexAbstraction indexAbstraction = currentState.metadata().getIndicesLookup().get(filteredIndex);
                    if (indexAbstraction.getParentDataStream() != null) {
                        DataStream dataStream = indexAbstraction.getParentDataStream().getDataStream();
                        mdBuilder.put(dataStream);
                        // Also the IMD of other backing indices need to be included, otherwise the cluster state api
                        // can't create a valid cluster state instance:
                        for (Index backingIndex : dataStream.getIndices()) {
                            mdBuilder.put(currentState.metadata().index(backingIndex), false);
                        }
                    } else {
                        IndexMetadata indexMetadata = currentState.metadata().index(filteredIndex);
                        if (indexMetadata != null) {
                            mdBuilder.put(indexMetadata, false);
                        }
                    }
                }
            } else {
                mdBuilder = Metadata.builder(currentState.metadata());
            }

            // filter out metadata that shouldn't be returned by the API
            for (ObjectObjectCursor<String, Custom> custom : currentState.metadata().customs()) {
                if (custom.value.context().contains(Metadata.XContentContext.API) == false) {
                    mdBuilder.removeCustom(custom.key);
                }
            }
        }
        builder.metadata(mdBuilder);

        if (request.customs()) {
            for (ObjectObjectCursor<String, ClusterState.Custom> custom : currentState.customs()) {
                if (custom.value.isPrivate() == false) {
                    builder.putCustom(custom.key, custom.value);
                }
            }
        }

        return new ClusterStateResponse(currentState.getClusterName(), builder.build(), false);
    }

}
