package org.myorg.jpatickets.ejb;
   
   import java.io.StringWriter;
   import java.util.ArrayList;
   import java.util.HashMap;
   import java.util.List;
   import java.util.Map;
   import java.util.concurrent.TimeUnit;
   
  import javax.annotation.PostConstruct;
  import javax.annotation.Resource;
  import javax.ejb.AccessTimeout;
  import javax.ejb.ConcurrencyManagement;
  import javax.ejb.ConcurrencyManagementType;
  import javax.ejb.EJBException;
  import javax.ejb.LockType;
  import javax.ejb.Singleton;
  import javax.ejb.Startup;
  import javax.ejb.TransactionManagement;
  import javax.ejb.TransactionManagementType;
  import javax.persistence.EntityManager;
  import javax.persistence.EntityManagerFactory;
  import javax.persistence.Persistence;
  import javax.persistence.PersistenceUnit;
  import javax.transaction.UserTransaction;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  @Singleton
  @Startup
  @ConcurrencyManagement(ConcurrencyManagementType.CONTAINER)
  @AccessTimeout(value=1, unit=TimeUnit.SECONDS)
  @TransactionManagement(TransactionManagementType.BEAN)
  public class TicketsInitTxEJB {
      private static final Logger logger = LoggerFactory.getLogger(TicketsInitEJB.class);
      private static final String PU_NAME = "jpatickets-schemagen-labex";
      
      @PersistenceUnit(unitName=PU_NAME)
      private EntityManagerFactory emf;
      
      @Resource
      private UserTransaction utx;
      
      private String dropScript;
      private String createScript;
  
      @PostConstruct
      public void init() {
          StringWriter createScriptWriter = new StringWriter();
          StringWriter dropScriptWriter = new StringWriter();
          Map<String, Object> props = new HashMap<String, Object>();
          props.put("javax.persistence.schema-generation.scripts.create-database-schemas", "true");
          props.put("javax.persistence.schema-generation.scripts.action", "drop-and-create");
          props.put("hibernate.id.new_generator_mappings", "true"); //tell JSE schemagen to use SEQUENCE for @Id=AUTO
          props.put("javax.persistence.schema-generation.scripts.create-target", createScriptWriter);
          props.put("javax.persistence.schema-generation.scripts.drop-target", dropScriptWriter);
          Persistence.generateSchema(PU_NAME, props);
          dropScript = dropScriptWriter.toString();
          createScript = createScriptWriter.toString();
          logger.debug("createScript={}", createScript);
          logger.debug("dropScript={}", dropScript);
      }
      
      private List<String> getCommands(String script) {
          List<String> commands = new ArrayList<String>();
          for (String line : script.split("\n")) {
              commands.add(line);
          }
          return commands;
      }
  
      @javax.ejb.Lock(LockType.WRITE)
      public int dropDB() {
          logger.info("*** dropDB ***");
          int updates=0;
          EntityManager em = emf.createEntityManager();
          try {
              for (String nativeSQLCommand : getCommands(dropScript)) {
                  try {
                      utx.begin();
                      em.joinTransaction();
                      updates += em.createNativeQuery(nativeSQLCommand).executeUpdate();
                      utx.commit();
                  } catch (Exception ex) {
                      try { utx.rollback(); } catch (Exception ex2) { throw new EJBException(ex2); }
                      logger.warn("error executing SQL:" + ex + ", " + nativeSQLCommand);
                      //keep going
                  }
              }
          } finally {
              em.close();
          }
          return updates;
      }
      
      @javax.ejb.Lock(LockType.WRITE)
      public int createDB() {
          logger.info("*** createDB ***");
         int updates=0;
         EntityManager em = emf.createEntityManager();
         try {
             utx.begin();
             em.joinTransaction();
             //all in one transaction
             for (String nativeSQLCommand : getCommands(createScript)) {
                 updates += em.createNativeQuery(nativeSQLCommand).executeUpdate();
             }
             utx.commit();
         } catch (Exception ex) {
             logger.warn("error executing SQL:" + ex);
             try { utx.rollback(); } catch (Exception ex2) { throw new EJBException(ex2); }
         } finally {
             em.close();
         }
         return updates;
     }
 }