package pk.lucidxpo.ynami.persistence.model;
   
   import jakarta.persistence.Column;
   import jakarta.persistence.EntityListeners;
   import jakarta.persistence.Id;
   import jakarta.persistence.MappedSuperclass;
   import lombok.Data;
   import org.hibernate.annotations.CreationTimestamp;
   import org.hibernate.annotations.UpdateTimestamp;
  import org.springframework.data.annotation.CreatedBy;
  import org.springframework.data.annotation.LastModifiedBy;
  import org.springframework.data.jpa.domain.support.AuditingEntityListener;
  
  import java.time.Instant;
  
  import static org.hibernate.annotations.SourceType.DB;
  import static pk.lucidxpo.ynami.utils.Identity.randomID;
  
  @Data
  @MappedSuperclass
  @EntityListeners({AuditingEntityListener.class})
  public abstract class Auditable<U> implements Identifiable {
      //    TODO: consider replacing this class with org.springframework.data.jpa.domain.AbstractAuditable
      @Id
      @Column(nullable = false, updatable = false)
      private String id = randomID();
  
      // The @CreatedDate and @CreationTimestamp are convenient annotation which sets the field value to the current
      // timestamp when the entity is first saved. @CreatedDate is a Spring annotation. It is applicable to all stores
      // covered by Spring Data: JPA, JDBC, R2DBC, MongoDb, Cassandra and so on, whereas @CreationTimestamp is a Hibernate
      // annotation. It is applicable to Hibernate only. By default, both of these annotations use the current date of
      // the Java Virtual Machine when setting property values. Starting from Hibernate 6.0.0, we can optionally specify
      // the database as the source of the date. However, when using @CreationTimestamp and @UpdateTimestamp, we have to
      // keep in mind that Hibernate generates new timestamps on a per-field basis. This leads to multiple timestamps
      // being different, even though they were set by the same INSERT or UPDATE statement. Main reason to use the
      // @CreationTimestamp instead of @CreatedDate is, Spring Data Jpa sets the creation timestamp with nanoseconds
      // (9 digits) precision on java object but saves the object with microseconds (6 digits) precision in the database
      // on linux machines (this issue doesn't happen on MAC) and hence the assertions in the integration tests fail
      // due to difference in precisions. So, setting 'source = DB' on the @CreationTimestamp annotation helps resolve
      // this issue and tests work on both Mac and Linux.
      // Insertable => Whether the column is included in SQL INSERT statements generated by the persistence provider.
      // Updatable => Whether the column is included in SQL UPDATE statements generated by the persistence provider.
      @CreationTimestamp(source = DB)
      @Column(nullable = false, insertable = false, updatable = false)
      private Instant createdDate;
  
      // The @LastModifiedDate and @UpdateTimestamp are convenient annotation which automatically sets the field value to
      // the current timestamp on each entity update. @LastModifiedDate is a Spring annotation. It is applicable to all
      // stores covered by Spring Data: JPA, JDBC, R2DBC, MongoDb, Cassandra and so on, whereas @UpdateTimestamp is a
      // Hibernate annotation. It is applicable to Hibernate only.By default, both of these annotations use the current
      // date of the Java Virtual Machine when setting property values. Starting from Hibernate 6.0.0, we can optionally
      // specify the database as the source of the date. Main reason to use the @UpdateTimestamp instead of
      // @LastModifiedDate is, Spring Data Jpa sets the updation timestamp with nanoseconds (9 digits) precision on java
      // object but saves the object with microseconds (6 digits) precision in the database on linux machines (this issue
      // doesn't happen on MAC) and hence the assertions in the integration tests fail due to difference in precisions.
      // So, setting 'source = DB' on the @UpdateTimestamp annotation helps resolve this issue and tests work on both Mac
      // and Linux.
      // Insertable => Whether the column is included in SQL INSERT statements generated by the persistence provider.
      // Updatable => Whether the column is included in SQL UPDATE statements generated by the persistence provider.
      @UpdateTimestamp(source = DB)
      @Column(insertable = false, updatable = false)
      private Instant lastModifiedDate;
  
      //    @ManyToOne
      @CreatedBy
      @Column(nullable = false, updatable = false)
      private U createdBy;
  
      @Column(nullable = false)
  //    @ManyToOne
      @LastModifiedBy
      private U lastModifiedBy;
  }