/*
 * 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", the "GNU Affero General Public License v3.0 only", 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", the "GNU Affero General Public
 * License v3.0 only", or the "Server Side Public License, v 1".
 */

package org.elasticsearch.action.update;

import org.elasticsearch.ElasticsearchStatusException;
import org.elasticsearch.ResourceAlreadyExistsException;
import org.elasticsearch.action.ActionListener;
import org.elasticsearch.action.ActionRunnable;
import org.elasticsearch.action.ActionType;
import org.elasticsearch.action.DocWriteRequest;
import org.elasticsearch.action.DocWriteResponse;
import org.elasticsearch.action.admin.indices.create.CreateIndexRequest;
import org.elasticsearch.action.admin.indices.create.CreateIndexResponse;
import org.elasticsearch.action.delete.DeleteRequest;
import org.elasticsearch.action.delete.DeleteResponse;
import org.elasticsearch.action.index.IndexRequest;
import org.elasticsearch.action.support.ActionFilters;
import org.elasticsearch.action.support.AutoCreateIndex;
import org.elasticsearch.action.support.SubscribableListener;
import org.elasticsearch.action.support.TransportActions;
import org.elasticsearch.action.support.single.instance.TransportInstanceSingleOperationAction;
import org.elasticsearch.client.internal.node.NodeClient;
import org.elasticsearch.cluster.ProjectState;
import org.elasticsearch.cluster.metadata.IndexMetadata;
import org.elasticsearch.cluster.metadata.IndexNameExpressionResolver;
import org.elasticsearch.cluster.metadata.InferenceFieldMetadata;
import org.elasticsearch.cluster.project.ProjectResolver;
import org.elasticsearch.cluster.routing.IndexRouting;
import org.elasticsearch.cluster.routing.RoutingTable;
import org.elasticsearch.cluster.routing.ShardIterator;
import org.elasticsearch.cluster.service.ClusterService;
import org.elasticsearch.common.bytes.BytesReference;
import org.elasticsearch.common.io.stream.NotSerializableExceptionWrapper;
import org.elasticsearch.common.io.stream.StreamInput;
import org.elasticsearch.common.xcontent.XContentHelper;
import org.elasticsearch.common.xcontent.support.XContentMapValues;
import org.elasticsearch.core.Tuple;
import org.elasticsearch.index.IndexNotFoundException;
import org.elasticsearch.index.IndexService;
import org.elasticsearch.index.engine.VersionConflictEngineException;
import org.elasticsearch.index.mapper.InferenceFieldMapper;
import org.elasticsearch.index.mapper.InferenceMetadataFieldsMapper;
import org.elasticsearch.index.mapper.Mapper;
import org.elasticsearch.index.mapper.MappingLookup;
import org.elasticsearch.index.shard.IndexShard;
import org.elasticsearch.index.shard.ShardId;
import org.elasticsearch.indices.IndicesService;
import org.elasticsearch.injection.guice.Inject;
import org.elasticsearch.rest.RestStatus;
import org.elasticsearch.tasks.Task;
import org.elasticsearch.threadpool.ThreadPool;
import org.elasticsearch.threadpool.ThreadPool.Names;
import org.elasticsearch.transport.TransportService;
import org.elasticsearch.xcontent.XContentType;

import java.io.IOException;
import java.util.Map;
import java.util.concurrent.Executor;

import static org.elasticsearch.ExceptionsHelper.unwrapCause;
import static org.elasticsearch.action.bulk.TransportBulkAction.unwrappingSingleItemBulkResponse;
import static org.elasticsearch.action.bulk.TransportSingleItemBulkWriteAction.toSingleItemBulkRequest;

public class TransportUpdateAction extends TransportInstanceSingleOperationAction<UpdateRequest, UpdateResponse> {

    public static final String NAME = "indices:data/write/update";
    public static final ActionType<UpdateResponse> TYPE = new ActionType<>(NAME);
    private final AutoCreateIndex autoCreateIndex;
    private final UpdateHelper updateHelper;
    private final IndicesService indicesService;
    private final NodeClient client;

    @Inject
    public TransportUpdateAction(
        ThreadPool threadPool,
        ClusterService clusterService,
        ProjectResolver projectResolver,
        TransportService transportService,
        UpdateHelper updateHelper,
        ActionFilters actionFilters,
        IndexNameExpressionResolver indexNameExpressionResolver,
        IndicesService indicesService,
        AutoCreateIndex autoCreateIndex,
        NodeClient client
    ) {
        super(
            NAME,
            threadPool,
            clusterService,
            projectResolver,
            transportService,
            actionFilters,
            indexNameExpressionResolver,
            UpdateRequest::new
        );
        this.updateHelper = updateHelper;
        this.indicesService = indicesService;
        this.autoCreateIndex = autoCreateIndex;
        this.client = client;
    }

    @Override
    protected Executor executor(ShardId shardId) {
        return executor(indicesService.indexServiceSafe(shardId.getIndex()));
    }

    private Executor executor(IndexService indexService) {
        return threadPool.executor(indexService.getIndexSettings().getIndexMetadata().isSystem() ? Names.SYSTEM_WRITE : Names.WRITE);
    }

    @Override
    protected UpdateResponse newResponse(StreamInput in) throws IOException {
        return new UpdateResponse(in);
    }

    @Override
    protected boolean retryOnFailure(Exception e) {
        return TransportActions.isShardNotAvailableException(e);
    }

    @Override
    protected void resolveRequest(ProjectState state, UpdateRequest docWriteRequest) {
        docWriteRequest.routing(state.metadata().resolveWriteIndexRouting(docWriteRequest.routing(), docWriteRequest.index()));
    }

    @Override
    protected void doExecute(Task task, final UpdateRequest request, final ActionListener<UpdateResponse> listener) {
        final ProjectState state = getProjectState();
        if (request.isRequireAlias() && (state.metadata().hasAlias(request.index()) == false)) {
            throw new IndexNotFoundException(
                "[" + DocWriteRequest.REQUIRE_ALIAS + "] request flag is [true] and [" + request.index() + "] is not an alias",
                request.index()
            );
        }
        // if we don't have a master, we don't have metadata, that's fine, let it find a master using create index API
        if (autoCreateIndex.shouldAutoCreate(request.index(), state.metadata())) {
            client.admin()
                .indices()
                .create(
                    new CreateIndexRequest().index(request.index()).cause("auto(update api)").masterNodeTimeout(request.timeout()),
                    new ActionListener<CreateIndexResponse>() {
                        @Override
                        public void onResponse(CreateIndexResponse result) {
                            innerExecute(task, request, listener);
                        }

                        @Override
                        public void onFailure(Exception e) {
                            if (unwrapCause(e) instanceof ResourceAlreadyExistsException) {
                                // we have the index, do it
                                try {
                                    innerExecute(task, request, listener);
                                } catch (Exception inner) {
                                    inner.addSuppressed(e);
                                    listener.onFailure(inner);
                                }
                            } else {
                                listener.onFailure(e);
                            }
                        }
                    }
                );
        } else {
            innerExecute(task, request, listener);
        }
    }

    private void innerExecute(final Task task, final UpdateRequest request, final ActionListener<UpdateResponse> listener) {
        super.doExecute(task, request, listener);
    }

    @Override
    protected ShardIterator shards(ProjectState projectState, UpdateRequest request) {
        if (request.getShardId() != null) {
            return projectState.routingTable().index(request.concreteIndex()).shard(request.getShardId().getId()).primaryShardIt();
        }
        IndexMetadata indexMetadata = projectState.metadata().index(request.concreteIndex());
        if (indexMetadata == null) {
            throw new IndexNotFoundException(request.concreteIndex());
        }
        IndexRouting indexRouting = IndexRouting.fromIndexMetadata(indexMetadata);
        int shardId = indexRouting.updateShard(request.id(), request.routing());
        return RoutingTable.shardRoutingTable(projectState.routingTable().index(request.concreteIndex()), shardId).primaryShardIt();
    }

    @Override
    protected void shardOperation(final UpdateRequest request, final ActionListener<UpdateResponse> listener) {
        try {
            shardOperation(request, listener, 0);
        } catch (IOException e) {
            listener.onFailure(e);
        }
    }

    protected void shardOperation(final UpdateRequest request, final ActionListener<UpdateResponse> listener, final int retryCount)
        throws IOException {
        final ShardId shardId = request.getShardId();
        final IndexService indexService = indicesService.indexServiceSafe(shardId.getIndex());
        final IndexShard indexShard = indexService.getShard(shardId.getId());
        final MappingLookup mappingLookup = indexShard.mapperService().mappingLookup();

        var executor = executor(indexService);
        assert ThreadPool.assertCurrentThreadPool(Names.SYSTEM_WRITE, Names.WRITE);

        SubscribableListener.<Void>newForked((l) -> indexShard.ensureMutable(l, false))
        // Make sure to fork back to a `write` thread pool if necessary
        .<UpdateHelper.Result>andThen(executor, threadPool.getThreadContext(), (l, unused) -> ActionListener.completeWith(l, () -> {
            assert ThreadPool.assertCurrentThreadPool(Names.SYSTEM_WRITE, Names.WRITE);
            return deleteInferenceResults(
                request,
                updateHelper.prepare(request, indexShard, threadPool::absoluteTimeInMillis), // Gets the doc using the engine
                indexService.getMetadata(),
                mappingLookup
            );
        }))
            // Proceed with a single item bulk request
            .<UpdateResponse>andThen((l, result) -> {
                switch (result.getResponseResult()) {
                    case CREATED -> {
                        IndexRequest upsertRequest = result.action();
                        // we fetch it from the index request so we don't generate the bytes twice, its already done in the index request
                        final BytesReference upsertSourceBytes = upsertRequest.source();
                        client.bulk(
                            toSingleItemBulkRequest(upsertRequest),
                            unwrappingSingleItemBulkResponse(ActionListener.<DocWriteResponse>wrap(response -> {
                                UpdateResponse update = new UpdateResponse(
                                    response.getShardInfo(),
                                    response.getShardId(),
                                    response.getId(),
                                    response.getSeqNo(),
                                    response.getPrimaryTerm(),
                                    response.getVersion(),
                                    response.getResult()
                                );
                                if (request.fetchSource() != null && request.fetchSource().fetchSource()) {
                                    Tuple<XContentType, Map<String, Object>> sourceAndContent = XContentHelper.convertToMap(
                                        upsertSourceBytes,
                                        true,
                                        upsertRequest.getContentType()
                                    );
                                    update.setGetResult(
                                        UpdateHelper.extractGetResult(
                                            request,
                                            request.concreteIndex(),
                                            mappingLookup,
                                            response.getSeqNo(),
                                            response.getPrimaryTerm(),
                                            response.getVersion(),
                                            sourceAndContent.v2(),
                                            sourceAndContent.v1(),
                                            upsertSourceBytes
                                        )
                                    );
                                } else {
                                    update.setGetResult(null);
                                }
                                update.setForcedRefresh(response.forcedRefresh());
                                l.onResponse(update);
                            }, exception -> handleUpdateFailureWithRetry(l, request, exception, retryCount)))
                        );
                    }
                    case UPDATED -> {
                        IndexRequest indexRequest = result.action();
                        // we fetch it from the index request so we don't generate the bytes twice, its already done in the index request
                        final BytesReference indexSourceBytes = indexRequest.source();
                        client.bulk(
                            toSingleItemBulkRequest(indexRequest),
                            unwrappingSingleItemBulkResponse(ActionListener.<DocWriteResponse>wrap(response -> {
                                UpdateResponse update = new UpdateResponse(
                                    response.getShardInfo(),
                                    response.getShardId(),
                                    response.getId(),
                                    response.getSeqNo(),
                                    response.getPrimaryTerm(),
                                    response.getVersion(),
                                    response.getResult()
                                );
                                update.setGetResult(
                                    UpdateHelper.extractGetResult(
                                        request,
                                        request.concreteIndex(),
                                        mappingLookup,
                                        response.getSeqNo(),
                                        response.getPrimaryTerm(),
                                        response.getVersion(),
                                        result.updatedSourceAsMap(),
                                        result.updateSourceContentType(),
                                        indexSourceBytes
                                    )
                                );
                                update.setForcedRefresh(response.forcedRefresh());
                                l.onResponse(update);
                            }, exception -> handleUpdateFailureWithRetry(l, request, exception, retryCount)))
                        );
                    }
                    case DELETED -> {
                        DeleteRequest deleteRequest = result.action();
                        client.bulk(
                            toSingleItemBulkRequest(deleteRequest),
                            unwrappingSingleItemBulkResponse(ActionListener.<DeleteResponse>wrap(response -> {
                                UpdateResponse update = new UpdateResponse(
                                    response.getShardInfo(),
                                    response.getShardId(),
                                    response.getId(),
                                    response.getSeqNo(),
                                    response.getPrimaryTerm(),
                                    response.getVersion(),
                                    response.getResult()
                                );
                                update.setGetResult(
                                    UpdateHelper.extractGetResult(
                                        request,
                                        request.concreteIndex(),
                                        mappingLookup,
                                        response.getSeqNo(),
                                        response.getPrimaryTerm(),
                                        response.getVersion(),
                                        result.updatedSourceAsMap(),
                                        result.updateSourceContentType(),
                                        null
                                    )
                                );
                                update.setForcedRefresh(response.forcedRefresh());
                                l.onResponse(update);
                            }, exception -> handleUpdateFailureWithRetry(l, request, exception, retryCount)))
                        );
                    }
                    case NOOP -> {
                        UpdateResponse update = result.action();
                        IndexService indexServiceOrNull = indicesService.indexService(shardId.getIndex());
                        if (indexServiceOrNull != null) {
                            IndexShard shard = indexService.getShardOrNull(shardId.getId());
                            if (shard != null) {
                                shard.noopUpdate();
                            }
                        }
                        l.onResponse(update);
                    }
                    default -> throw new IllegalStateException("Illegal result " + result.getResponseResult());
                }
            })
            .addListener(listener);
    }

    private void handleUpdateFailureWithRetry(
        final ActionListener<UpdateResponse> listener,
        final UpdateRequest request,
        final Exception failure,
        int retryCount
    ) {
        final Throwable cause = unwrapCause(failure);
        if (cause instanceof VersionConflictEngineException versionConflictEngineException && retryCount < request.retryOnConflict()) {
            logger.trace(
                "Retry attempt [{}] of [{}] on version conflict on [{}][{}][{}]",
                retryCount + 1,
                request.retryOnConflict(),
                request.index(),
                request.getShardId(),
                request.id()
            );

            final Executor executor;
            try {
                executor = executor(request.getShardId());
            } catch (Exception e) {
                // might fail if shard no longer exists locally, in which case we cannot retry
                e.addSuppressed(versionConflictEngineException);
                listener.onFailure(e);
                return;
            }
            executor.execute(ActionRunnable.wrap(listener, l -> shardOperation(request, l, retryCount + 1)));
            return;
        }
        listener.onFailure(cause instanceof Exception ? (Exception) cause : new NotSerializableExceptionWrapper(cause));
    }

    /**
     * <p>
     * Delete stale inference results from the provided {@link UpdateHelper.Result} instance.
     * </p>
     * <p>
     * We need to do this because when handling Bulk API requests (which the Update API generates), we assume any inference results present
     * in source are up-to-date.
     * We do this to support reindex and update by query use cases without re-generating inference results unnecessarily.
     * </p>
     *
     * @param updateRequest The update request
     * @param result The result generated using the update request
     * @param indexMetadata The index metadata
     * @param mappingLookup The index's mapping lookup
     * @return A result with stale inference results removed from source
     */
    private static UpdateHelper.Result deleteInferenceResults(
        UpdateRequest updateRequest,
        UpdateHelper.Result result,
        IndexMetadata indexMetadata,
        MappingLookup mappingLookup
    ) {
        if (result.getResponseResult() != DocWriteResponse.Result.UPDATED || InferenceMetadataFieldsMapper.isEnabled(mappingLookup)) {
            return result;
        }

        Map<String, InferenceFieldMetadata> inferenceFields = indexMetadata.getInferenceFields();
        if (inferenceFields.isEmpty()) {
            return result;
        }

        if (updateRequest.script() != null) {
            throw new ElasticsearchStatusException(
                "Cannot apply update with a script on indices that contain inference field(s)",
                RestStatus.BAD_REQUEST
            );
        }

        IndexRequest doc = updateRequest.doc();
        if (doc == null) {
            // No doc update, nothing to do
            return result;
        }

        Map<String, Object> updateRequestSource = doc.sourceAsMap();
        Map<String, Object> updatedSource = result.updatedSourceAsMap();
        boolean updatedSourceModified = false;
        for (var entry : inferenceFields.entrySet()) {
            String inferenceFieldName = entry.getKey();
            Mapper mapper = mappingLookup.getMapper(inferenceFieldName);

            if (mapper instanceof InferenceFieldMapper) {
                String[] sourceFields = entry.getValue().getSourceFields();
                for (String sourceField : sourceFields) {
                    if (sourceField.equals(inferenceFieldName) == false
                        && XContentMapValues.extractValue(sourceField, updateRequestSource) != null) {
                        // Replace the inference field's value with its original value (i.e. the user-specified value).
                        // This has two important side effects:
                        // - The inference field value will remain parsable by its mapper
                        // - The inference results will be removed, forcing them to be re-generated downstream
                        updatedSource.put(inferenceFieldName, getOriginalValueLegacy(inferenceFieldName, updatedSource));
                        updatedSourceModified = true;
                        break;
                    }
                }
            } else {
                throw new IllegalStateException(
                    "Field [" + inferenceFieldName + "] is of type [ " + mapper.typeName() + "], which is not an inference field"
                );
            }
        }

        UpdateHelper.Result returnedResult = result;
        if (updatedSourceModified) {
            XContentType contentType = result.updateSourceContentType();
            IndexRequest indexRequest = result.action();
            indexRequest.source(updatedSource, contentType);

            returnedResult = new UpdateHelper.Result(indexRequest, result.getResponseResult(), updatedSource, contentType);
        }

        return returnedResult;
    }

    /**
     * Get the field's original value (i.e. the value the user specified) from the provided source.
     *
     * @param sourceAsMap The source as a map
     * @return The field's original value, or {@code null} if none was provided
     */
    private static Object getOriginalValueLegacy(String fullPath, Map<String, Object> sourceAsMap) {
        // TODO: Fix bug here when semantic text field is in an object
        Object fieldValue = sourceAsMap.get(fullPath);
        if (fieldValue == null) {
            return null;
        } else if (fieldValue instanceof Map<?, ?> == false) {
            // Don't try to further validate the non-map value, that will be handled when the source is fully parsed
            return fieldValue;
        }

        Map<String, Object> fieldValueMap = XContentMapValues.nodeMapValue(fieldValue, "Field [" + fullPath + "]");
        return XContentMapValues.extractValue("text", fieldValueMap);
    }
}