/*
    * #%L
    * Bitrepository Audit Trail Service
    * %%
    * Copyright (C) 2010 - 2013 The State and University Library, The Royal Library and The State Archives, Denmark
    * %%
    * This program is free software: you can redistribute it and/or modify
    * it under the terms of the GNU Lesser General Public License as 
    * published by the Free Software Foundation, either version 2.1 of the 
   * License, or (at your option) any later version.
   * 
   * This program 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 Lesser Public License for more details.
   * 
   * You should have received a copy of the GNU General Lesser Public 
   * License along with this program.  If not, see
   * <http://www.gnu.org/licenses/lgpl-2.1.html>.
   * #L%
   */
  package org.bitrepository.audittrails.store;
  
  import static org.bitrepository.audittrails.store.AuditDatabaseConstants.ACTOR_TABLE;
  import static org.bitrepository.audittrails.store.AuditDatabaseConstants.AUDITTRAIL_TABLE;
  import static org.bitrepository.audittrails.store.AuditDatabaseConstants.CONTRIBUTOR_TABLE;
  import static org.bitrepository.audittrails.store.AuditDatabaseConstants.DATABASE_VERSION_ENTRY;
  import static org.bitrepository.audittrails.store.AuditDatabaseConstants.FILE_TABLE;
  
  import java.util.Map;
  
  import org.bitrepository.service.database.DBConnector;
  import org.bitrepository.service.database.DatabaseMigrator;
  import org.bitrepository.service.database.DatabaseUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Migration class for the AuditTrailDatabase of the AuditTrailService.
   * Will only try to perform the migration on an embedded derby database.
   */
  public class AuditTrailServiceDatabaseMigrator extends DatabaseMigrator {
      /** The log.*/
      private static Logger log = LoggerFactory.getLogger(DatabaseUtils.class);
      
      /** The name of the update script for version 1 to 2.*/
      private static final String UPDATE_SCRIPT_VERSION_1_TO_2 = "sql/derby/auditTrailServiceDBUpdate1to2.sql";
      /** The name of the update script for version 2 to 3.*/
      private static final String UPDATE_SCRIPT_VERSION_2_TO_3 = "sql/derby/auditTrailServiceDBUpdate2to3.sql";
      /** The name of the update script for version 3 to 4.*/
      private static final String UPDATE_SCRIPT_VERSION_3_TO_4 = "sql/derby/auditTrailServiceDBUpdate3to4.sql";
      /** The current version of the database. */
      private final Integer currentVersion = 4;
      
      /**
       * Constructor.
       * @param connector connection to the database.
       */
      public AuditTrailServiceDatabaseMigrator(DBConnector connector) {
          super(connector);
      }
      
      @Override
      public void migrate() {
          Map<String, Integer> versions = getTableVersions();
          
          if(!versions.containsKey(FILE_TABLE)) {
              throw new IllegalStateException("The database does not contain '" + FILE_TABLE 
                      + "' table as required.");
          }
          if(!versions.containsKey(AUDITTRAIL_TABLE)) {
              throw new IllegalStateException("The database does not contain '" + AUDITTRAIL_TABLE 
                      + "' table as required.");
          }
          if(!versions.containsKey(CONTRIBUTOR_TABLE)) {
              throw new IllegalStateException("The database does not contain '" + CONTRIBUTOR_TABLE 
                      + "' table as required.");
          }
          if(!versions.containsKey(ACTOR_TABLE)) {
              throw new IllegalStateException("The database does not contain '" + ACTOR_TABLE 
                      + "' table as required.");
          }
          
          if(!versions.containsKey(DATABASE_VERSION_ENTRY) || versions.get(DATABASE_VERSION_ENTRY) < 2) {
              log.warn("Migrating AuditServiceDB from version 1 to 2.");
              migrateDerbyDatabase(UPDATE_SCRIPT_VERSION_1_TO_2);
          }
          if(!versions.containsKey(DATABASE_VERSION_ENTRY) || versions.get(DATABASE_VERSION_ENTRY) < 3) {
              log.warn("Migrating AuditServiceDB from version 2 to 3.");
              migrateDerbyDatabase(UPDATE_SCRIPT_VERSION_2_TO_3);
          }
          if(!versions.containsKey(DATABASE_VERSION_ENTRY) || versions.get(DATABASE_VERSION_ENTRY) < 4) {
              log.warn("Migrating AuditServiceDB from version 3 to 4.");
              migrateDerbyDatabase(UPDATE_SCRIPT_VERSION_3_TO_4);
          }
      }
  
      @Override
      public boolean needsMigration() {
         Map<String, Integer> versions = getTableVersions();
         
         if(!versions.containsKey(DATABASE_VERSION_ENTRY)) {
             throw new IllegalStateException("The database does not contain '" + DATABASE_VERSION_ENTRY 
                     + "' table as required.");
         }
         
         if(versions.get(DATABASE_VERSION_ENTRY) < currentVersion) {
             return true;
         } else {
             return false;
         }
     }
 }