StatisticheUtils.java

/*
 * GovWay - A customizable API Gateway 
 * https://govway.org
 * 
 * Copyright (c) 2005-2025 Link.it srl (https://link.it).
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 3, as published by
 * the Free Software Foundation.
 *
 * 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 Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */
package org.openspcoop2.core.statistiche.utils;

import org.openspcoop2.core.constants.CostantiDB;
import org.openspcoop2.core.statistiche.model.StatisticaModel;
import org.openspcoop2.generic_project.beans.FunctionField;
import org.openspcoop2.generic_project.beans.IField;
import org.openspcoop2.generic_project.exception.ExpressionException;
import org.openspcoop2.generic_project.exception.ExpressionNotImplementedException;
import org.openspcoop2.generic_project.expression.IExpression;
import org.openspcoop2.generic_project.expression.impl.sql.ISQLFieldConverter;

/**     
 * StatisticheUtils
 *
 * @author Poli Andrea (poli@link.it)
 * @author $Author$
 * @version $Rev$, $Date$
 */
public class StatisticheUtils {
	
	private StatisticheUtils() {}

	public static void selezionaRecordValidi(IExpression expr, StatisticaModel model) throws ExpressionNotImplementedException, ExpressionException{
		// Seleziona record stabili: stato >= 1 (include stato 1, 2 e 3)
		// stato 1: intervalli precedenti stabili
		// stato 2: record ancora validi in fase di aggiornamento
		// stato 3: intervallo corrente stabile
		expr.greaterEquals(model.STATO_RECORD, CostantiDB.STATISTICHE_STATO_RECORD_VALIDO);
	}
	
	public static FunctionField calcolaMedia(ISQLFieldConverter fieldConverter, IField latenza, IField numeroRichieste, String alias) throws ExpressionException{
		// (SUM(latenza_servizio*richieste))/SUM(richieste)
		String columnLatenza = fieldConverter.toColumn(latenza, false);
		String columnRichieste = fieldConverter.toColumn(numeroRichieste, false);
		String  sbFunctionValue = getSqlCalcolaMedia(columnLatenza, columnRichieste);
		Class<?> functionValueType = Long.class;
		
		return new FunctionField(sbFunctionValue,functionValueType,"","",alias);
	}
	
	public static String getSqlCalcolaMedia(String columnLatenza, String columnRichieste) {
		// Calcola la media ponderata escludendo i record con latenza NULL o < 0
		// Formula: SUM(CASE WHEN latenza >= 0 THEN latenza*richieste ELSE 0 END) /
		//          SUM(CASE WHEN latenza >= 0 THEN richieste ELSE 0 END)
		// Compatibile con: PostgreSQL, MySQL, HSQL, Oracle, SQL Server
		StringBuilder sbFunctionValue = new StringBuilder("(");
		// Numeratore: somma solo le latenze valide (>= 0) moltiplicate per le richieste
		sbFunctionValue.append("SUM(CASE WHEN ").append(columnLatenza).append(" >= 0 THEN ");
		sbFunctionValue.append(columnLatenza).append("*").append(columnRichieste);
		sbFunctionValue.append(" ELSE 0 END)");
		sbFunctionValue.append("/");
		// Denominatore: somma solo le richieste con latenza valida (>= 0)
		sbFunctionValue.append("SUM(CASE WHEN ").append(columnLatenza).append(" >= 0 THEN ");
		sbFunctionValue.append(columnRichieste);
		sbFunctionValue.append(" ELSE 0 END)");
		sbFunctionValue.append(")");
		return sbFunctionValue.toString();
	}
}