package com.ankurm.hibernatedemo;

import static org.assertj.core.api.Assertions.assertThat;

import com.ankurm.hibernatedemo.model.WidgetSequence;
import jakarta.persistence.EntityManager;
import jakarta.persistence.EntityManagerFactory;
import org.hibernate.SessionFactory;
import org.hibernate.stat.Statistics;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

/**
 * Backs ankurm.com post 4861. Docs: docs/03-inserting-objects.md.
 * Run with {@code ./mvnw -Dtest=SequenceBatchTest test}.
 *
 * <p>{@link WidgetSequence} sets {@code allocationSize = 25}, matching
 * {@code hibernate.jdbc.batch_size} in application.yml. See {@code AllocationSizeSweepTest} for
 * what happens when the two are deliberately mismatched.
 */
@SpringBootTest
class SequenceBatchTest {

    private static final int ROW_COUNT = 30;

    @Autowired
    private EntityManagerFactory emf;

    @Test
    void sequenceGeneratorAllowsBatching_fourPreparedStatementsForThirtyRows() {
        SessionFactory sessionFactory = emf.unwrap(SessionFactory.class);
        Statistics stats = sessionFactory.getStatistics();
        stats.clear();

        EntityManager em = emf.createEntityManager();
        em.getTransaction().begin();
        for (int i = 1; i <= ROW_COUNT; i++) {
            em.persist(new WidgetSequence("sequence-" + i));
        }
        em.getTransaction().commit();
        em.close();

        assertThat(stats.getEntityInsertCount()).isEqualTo(ROW_COUNT);
        assertThat(stats.getPrepareStatementCount())
                .as("30 rows at batch_size=25 is 2 insert batches (25 + 5); allocationSize=25 "
                        + "means the first 25 ids come from one sequence call and the remaining "
                        + "5 force a second -- 2 insert batches + 2 sequence calls = 4")
                .isEqualTo(4);
    }
}