EDIT

/**

* Copyright (C) 2017 EDIT

* European Distributed Institute of Taxonomy

* http://www.e-taxonomy.eu

*

* The contents of this file are subject to the Mozilla Public License Version 1.1

* See LICENSE.TXT at the top of this package for the full license terms.

*/

package eu.etaxonomy.cdm.api.service.idminter;

import org.apache.log4j.Logger;

import org.hibernate.Query;

import org.hibernate.SessionFactory;

import org.hibernate.StatelessSession;

import org.springframework.beans.factory.annotation.Autowired;

/**

 * @author a.kohlbecker

 * @since Dec 12, 2017

 *

 */

public class RegistrationIdentifierMinter implements IdentifierMinter<String> {

    private static final Logger logger = Logger.getLogger(RegistrationIdentifierMinter.class);

    enum Method {

        naturalNumberIncrement

    }

    private SessionFactory factory;

    @Autowired

    protected void setSessionFactory (SessionFactory  factory){

        this.factory = factory;

    }

    Integer minLocalId = 1;

    Integer maxLocalId = Integer.MAX_VALUE;

    String identifierFormatString = null;

    Method method = Method.naturalNumberIncrement;

    /**

     * {@inheritDoc}

     */

    @Override

    public void setMinLocalId(String min) {

        minLocalId = Integer.valueOf(min);

    }

    /**

     * {@inheritDoc}

     */

    @Override

    public void setMaxLocalId(String max) {

        maxLocalId = Integer.valueOf(max);

    }

    /**

     * {@inheritDoc}

     */

    @Override

    synchronized public Identifier<String> mint() throws OutOfIdentifiersException {

        if(identifierFormatString == null){

            logger.warn("identifierFormatString missing");

        }

        switch(method){

            case naturalNumberIncrement:

                return mintByNaturalNumberIncrement();

            default: throw new RuntimeException("unsupported genreation method: " + method);

        }

    }

    /**

     *

     */

    protected Identifier<String> mintByNaturalNumberIncrement() {

        Integer localid = null;

        Object result = null;

        StatelessSession session = factory.openStatelessSession();

        try{

            String filter = " where cast(reg.specificIdentifier as int) >= " + minLocalId + " AND cast(reg.specificIdentifier as int) <= " + maxLocalId;

            if(identifierFormatString != null){

                filter += " AND reg.identifier like '" + identifierFormatString.replaceAll("%s", "%") + "'";

            }

            String hql = "select max(cast(reg.specificIdentifier as int)) from Registration as reg" + filter;

            // a query with correlated sub-select should allow to filter out registrations which are not matching the formatString

            // but the hql below is not working as expected:

//          String filter = "";

//          if(identifierFormatString != null){

//              filter += " WHERE reg.identifier like '" + identifierFormatString.replaceAll("%s", "%") + "'";

//          }

//          String hql =

//                  "SELECT "

//                  //+ "max("

//                  // + " cast( "

//                  + " ( SELECT max(cast(reg.specificIdentifier as int)) FROM reg WHERE cast(reg.specificIdentifier as int) >= " + minLocalId + " AND cast(reg.specificIdentifier as int) <= " + maxLocalId + ") "

//                  //+ " as int)"

//                  //+ ")"

//                  + " FROM Registration reg " + filter;

            Query query = session.createQuery(hql);

            result = query.uniqueResult();

        } finally {

            session.close();

        }

        if(result != null){

            localid  = ((Integer)result) + 1;

            if(localid > maxLocalId){

                throw new OutOfIdentifiersException("No available identifiers left in range [" + minLocalId + ", " + maxLocalId + "]");

            }

        } else {

            localid = minLocalId;

        }

        if(localid != null){

            Identifier<String> identifier = new Identifier<String>();

            identifier.localId = localid.toString();

            if(identifierFormatString != null){

                identifier.identifier = String.format(identifierFormatString, identifier.localId);

            }

            return identifier;

        }

        return null; // should never happen

    }

    public void setGenerationMethod(Method method){

        this.method = method;

    }

    /**

     * @return the identifierFormatString

     */

    public String getIdentifierFormatString() {

        return identifierFormatString;

    }

    /**

     * @param identifierFormatString the identifierFormatString to set

     */

    public void setIdentifierFormatString(String identifierFormatString) {

        this.identifierFormatString = identifierFormatString;

    }

}