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 * regarding copyright ownership.  The ASF licenses this file   *
 * to you under the Apache License, Version 2.0 (the            *
 * "License"); you may not use this file except in compliance   *
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 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY       *
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package org.apache.james.jpa.healthcheck;

import static org.apache.james.core.healthcheck.Result.healthy;
import static org.apache.james.core.healthcheck.Result.unhealthy;

import javax.inject.Inject;
import javax.persistence.EntityManagerFactory;

import org.apache.james.core.healthcheck.ComponentName;
import org.apache.james.core.healthcheck.HealthCheck;
import org.apache.james.core.healthcheck.Result;

import reactor.core.publisher.Mono;

public class JPAHealthCheck implements HealthCheck {

    private final EntityManagerFactory entityManagerFactory;

    @Inject
    public JPAHealthCheck(EntityManagerFactory entityManagerFactory) {
        this.entityManagerFactory = entityManagerFactory;
    }

    @Override
    public ComponentName componentName() {
        return new ComponentName("JPA Backend");
    }

    @Override
    public Mono<Result> check() {
        return Mono.fromCallable(entityManagerFactory::createEntityManager)
            .map(entityManager -> entityManager.isOpen())
            .map(open -> {
                if (open) {
                    return healthy(componentName());
                } else {
                    return unhealthy(componentName(), "entityManager is not open");
                }
            })
            .onErrorResume(IllegalStateException.class,
                e -> Mono.just(unhealthy(componentName(), "EntityManagerFactory or EntityManager thrown an IllegalStateException, the connection is unhealthy", e)));
    }
}
