/*
    * This file is part of ***  M y C o R e  ***
    * See http://www.mycore.de/ for details.
    *
    * MyCoRe is free software: you can redistribute it and/or modify
    * it under the terms of the GNU General Public License as published by
    * the Free Software Foundation, either version 3 of the License, or
    * (at your option) any later version.
    *
   * MyCoRe is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with MyCoRe.  If not, see <http://www.gnu.org/licenses/>.
   */
  
  package org.mycore.backend.jpa.access;
  
  import java.sql.Timestamp;
  import java.text.DateFormat;
  import java.text.SimpleDateFormat;
  import java.util.Collection;
  import java.util.List;
  import java.util.Locale;
  
  import org.apache.logging.log4j.LogManager;
  import org.apache.logging.log4j.Logger;
  import org.mycore.access.mcrimpl.MCRAccessRule;
  import org.mycore.access.mcrimpl.MCRRuleStore;
  import org.mycore.backend.jpa.MCREntityManagerProvider;
  import org.mycore.common.MCRException;
  import org.mycore.common.config.MCRConfiguration2;
  
  import com.google.common.cache.CacheBuilder;
  import com.google.common.cache.CacheLoader;
  import com.google.common.cache.LoadingCache;
  
  import jakarta.persistence.EntityManager;
  import jakarta.persistence.criteria.CriteriaBuilder;
  import jakarta.persistence.criteria.CriteriaQuery;
  import jakarta.persistence.criteria.Root;
  
  /**
   * JPA implementation for RuleStore, storing access rules
   * 
   * @author Arne Seifert
   * @author Thomas Scheffler (yagee)
   */
  public class MCRJPARuleStore extends MCRRuleStore {
      private static final Logger LOGGER = LogManager.getLogger();
  
      private static int CACHE_SIZE = MCRConfiguration2.getInt("MCR.AccessPool.CacheSize").orElse(2048);
  
      private static LoadingCache<String, MCRAccessRule> ruleCache = CacheBuilder.newBuilder().maximumSize(CACHE_SIZE)
          .build(new CacheLoader<String, MCRAccessRule>() {
              @Override
              public MCRAccessRule load(String ruleid) {
                  MCRAccessRule rule = null;
                  EntityManager entityManager = MCREntityManagerProvider.getCurrentEntityManager();
                  MCRACCESSRULE hibrule = entityManager.find(MCRACCESSRULE.class, ruleid);
                  LOGGER.debug("Getting MCRACCESSRULE done");
  
                  if (hibrule != null) {
                      LOGGER.debug("new MCRAccessRule");
                      rule = new MCRAccessRule(ruleid, hibrule.getCreator(), hibrule.getCreationdate(),
                          hibrule.getRule(),
                          hibrule.getDescription());
                      LOGGER.debug("new MCRAccessRule done");
                  }
                  return rule;
              }
          });
  
      /**
       * Method creates new rule in database by given rule-object
       * 
       * @param rule
       *            as MCRAccessRule
       */
      @Override
      public void createRule(MCRAccessRule rule) {
  
          if (!existsRule(rule.getId())) {
              EntityManager em = MCREntityManagerProvider.getCurrentEntityManager();
              MCRACCESSRULE hibrule = new MCRACCESSRULE();
  
              DateFormat df = new SimpleDateFormat(SQL_DATE_FORMAT, Locale.ROOT);
              hibrule.setCreationdate(Timestamp.valueOf(df.format(rule.getCreationTime())));
              hibrule.setCreator(rule.getCreator());
              hibrule.setRid(rule.getId());
              hibrule.setRule(rule.getRuleString());
              hibrule.setDescription(rule.getDescription());
              em.persist(hibrule);
          } else {
              LOGGER.error("rule with id '{}' can't be created, rule still exists.", rule.getId());
          }
      }
 
     /**
      * Method retrieves the ruleIDs of rules, whose string-representation starts with given data
      */
     @Override
     public Collection<String> retrieveRuleIDs(String ruleExpression, String description) {
         EntityManager em = MCREntityManagerProvider.getCurrentEntityManager();
         CriteriaBuilder sb = em.getCriteriaBuilder();
         CriteriaQuery<String> query = sb.createQuery(String.class);
         Root<MCRACCESSRULE> ar = query.from(MCRACCESSRULE.class);
         return em.createQuery(
             query.select(
                 ar.get(MCRACCESSRULE_.rid))
                 .where(
                     sb.and(
                         sb.like(ar.get(MCRACCESSRULE_.rule), ruleExpression),
                         sb.like(ar.get(MCRACCESSRULE_.description), description))))
             .getResultList();
     }
 
     /**
      * Method updates accessrule by given rule. internal: get rule object from session set values, update via session
      */
     @Override
     public void updateRule(MCRAccessRule rule) {
         EntityManager em = MCREntityManagerProvider.getCurrentEntityManager();
         MCRACCESSRULE hibrule = em.find(MCRACCESSRULE.class, rule.getId());
 
         DateFormat df = new SimpleDateFormat(SQL_DATE_FORMAT, Locale.ROOT);
         hibrule.setCreationdate(Timestamp.valueOf(df.format(rule.getCreationTime())));
         hibrule.setCreator(rule.getCreator());
         hibrule.setRule(rule.getRuleString());
         hibrule.setDescription(rule.getDescription());
         ruleCache.put(rule.getId(), rule);
     }
 
     /**
      * Method deletes accessrule for given ruleid
      */
     @Override
     public void deleteRule(String ruleid) {
         EntityManager em = MCREntityManagerProvider.getCurrentEntityManager();
         em.createQuery("delete MCRACCESSRULE where RID = '" + ruleid + "'").executeUpdate();
         ruleCache.invalidate(ruleid);
     }
 
     /**
      * Method returns MCRAccessRule by given id
      * 
      * @param ruleid
      *            as string
      * @return MCRAccessRule
      */
     @Override
     public MCRAccessRule getRule(String ruleid) {
         return ruleCache.getUnchecked(ruleid);
     }
 
     @Override
     public Collection<String> retrieveAllIDs() {
         EntityManager em = MCREntityManagerProvider.getCurrentEntityManager();
         CriteriaQuery<String> query = em.getCriteriaBuilder().createQuery(String.class);
         return em.createQuery(
             query.select(
                 query.from(MCRACCESSRULE.class).get(MCRACCESSRULE_.rid)))
             .getResultList();
     }
 
     /**
      * Method checks existance of rule in db
      * 
      * @param ruleid
      *            id as string
      * @return boolean value
      */
     @Override
     public boolean existsRule(String ruleid) throws MCRException {
         if (ruleCache.getIfPresent(ruleid) != null) {
             return true;
         }
         return MCREntityManagerProvider.getCurrentEntityManager().find(MCRACCESSRULE.class, ruleid) != null;
     }
 
     @Override
     public int getNextFreeRuleID(String prefix) {
         int ret = 1;
         EntityManager em = MCREntityManagerProvider.getCurrentEntityManager();
         List<String> l = em
             .createQuery("select max(rid) from MCRACCESSRULE where rid like '" + prefix + "%'", String.class)
             .getResultList();
         if (l.size() > 0) {
             String max = l.get(0);
             if (max == null) {
                 ret = 1;
             } else {
                 int lastNumber = Integer.parseInt(max.substring(prefix.length()));
                 ret = lastNumber + 1;
             }
         } else {
             return 1;
         }
         return ret;
     }
 }