/*
 * 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; you may not use this file except in compliance with the Elastic License
 * 2.0.
 */

package org.elasticsearch.system_indices.task;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.elasticsearch.action.ActionListener;
import org.elasticsearch.cluster.ClusterState;
import org.elasticsearch.cluster.ClusterStateUpdateTask;
import org.elasticsearch.cluster.service.ClusterService;
import org.elasticsearch.core.SuppressForbidden;

import java.util.HashMap;

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

/**
 * Handles updating the {@link FeatureMigrationResults} in the cluster state.
 */
public class MigrationResultsUpdateTask extends ClusterStateUpdateTask {
    private static final Logger logger = LogManager.getLogger(MigrationResultsUpdateTask.class);

    private final String featureName;
    private final SingleFeatureMigrationResult status;
    private final ActionListener<ClusterState> listener;

    private MigrationResultsUpdateTask(String featureName, SingleFeatureMigrationResult status, ActionListener<ClusterState> listener) {
        this.featureName = featureName;
        this.status = status;
        this.listener = listener;
    }

    /**
     * Creates a task that will update the status of a feature migration.
     * @param featureName The name of the feature whose status should be updated.
     * @param status The status to be associated with the given feature.
     * @param listener A listener that will be called upon successfully updating the cluster state.
     */
    public static MigrationResultsUpdateTask upsert(
        String featureName,
        SingleFeatureMigrationResult status,
        ActionListener<ClusterState> listener
    ) {
        return new MigrationResultsUpdateTask(featureName, status, listener);
    }

    /**
     * Submit the update task so that it will actually be executed.
     * @param clusterService The cluster service to which this task should be submitted.
     */
    public void submit(ClusterService clusterService) {
        String source = format("record [%s] migration [%s]", featureName, status.succeeded() ? "success" : "failure");
        submitUnbatchedTask(clusterService, source, this);
    }

    @SuppressForbidden(reason = "legacy usage of unbatched task") // TODO add support for batching here
    private static void submitUnbatchedTask(
        ClusterService clusterService,
        @SuppressWarnings("SameParameterValue") String source,
        ClusterStateUpdateTask task
    ) {
        clusterService.submitUnbatchedStateUpdateTask(source, task);
    }

    @Override
    public ClusterState execute(ClusterState currentState) throws Exception {
        final var project = currentState.metadata().getProject();
        FeatureMigrationResults currentResults = project.custom(FeatureMigrationResults.TYPE);
        if (currentResults == null) {
            currentResults = new FeatureMigrationResults(new HashMap<>());
        }
        FeatureMigrationResults newResults = currentResults.withResult(featureName, status);
        return currentState.copyAndUpdateProject(project.id(), builder -> builder.putCustom(FeatureMigrationResults.TYPE, newResults));
    }

    @Override
    public void clusterStateProcessed(ClusterState oldState, ClusterState newState) {
        listener.onResponse(newState);
    }

    @Override
    public void onFailure(Exception clusterStateUpdateException) {
        if (status.succeeded()) {
            logger.warn(
                () -> "failed to update cluster state after successful migration of feature [" + featureName + "]",
                clusterStateUpdateException
            );
        } else {
            logger.error(
                () -> format(
                    "failed to update cluster state after failed migration of feature [%s] on index [%s]",
                    featureName,
                    status.getFailedResourceName()
                ),
                clusterStateUpdateException
            );
        }
        listener.onFailure(clusterStateUpdateException);
    }
}