/******************************************************************************
 * Product: Adempiere ERP & CRM Smart Business Solution                       *
 * Copyright (C) 1999-2006 ComPiere, Inc. All Rights Reserved.                *
 * This program is free software; you can redistribute it and/or modify it    *
 * under the terms version 2 of the GNU General Public License 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, write to the Free Software Foundation, Inc.,    *
 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.                     *
 * For the text or an alternative of this public license, you may reach us    *
 * ComPiere, Inc., 2620 Augustine Dr. #245, Santa Clara, CA 95054, USA        *
 * or via info@compiere.org or http://www.compiere.org/license.html           *
 *****************************************************************************/
package org.compiere.util;

import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Map;
import java.util.Properties;
import java.util.concurrent.ConcurrentHashMap;
import java.util.logging.Level;

import org.idempiere.expression.logic.LogicEvaluator;

/**
 *	Expression Evaluator	
 *	
 *  @author Jorg Janke
 *  @version $Id: Evaluator.java,v 1.3 2006/07/30 00:54:36 jjanke Exp $
 */
public class Evaluator
{
	/**	Static Logger	*/
	private static CLogger	s_log	= CLogger.getCLogger (Evaluator.class);
	
	private static final Map<String, SQLLogicResult> sqlLogicCache = new ConcurrentHashMap<>();

	/** Value object for SQL logic result */
	public static class SQLLogicResult {
		long timestamp;
		boolean value;
	}

	/**
	 * 	Check if All Variables are Defined
	 *	@param source source
	 *	@param logic logic info
	 *	@return true if fully defined
	 */
	public static boolean isAllVariablesDefined (Evaluatee source, String logic)
	{
		if (logic == null || logic.length() == 0)
			return true;
		//
		int pos = 0;
		while (pos < logic.length())
		{
			int first = logic.indexOf('@', pos);
			if (first == -1)
				return true;
			int second = logic.indexOf('@', first+1);
			if (second == -1)
			{
				s_log.severe("No second @ in Logic: " + logic);
				return false;
			}
			String variable = logic.substring(first+1, second-1);
			String eval = source.get_ValueAsString (variable);
			if (s_log.isLoggable(Level.FINEST)) s_log.finest(variable + "=" + eval);
			if (eval == null || eval.length() == 0)
				return false;
			//	
			pos = second + 1;
		}
		return true;
	}	//	isAllVariablesDefined
	
	/**
	 *	Evaluate logic expression
	 *  @see LogicEvaluator#evaluateLogic(Evaluatee, String)
	 *  @param source class implementing get_ValueAsString(variable)
	 *  @param logic logic expression
	 *  @return logic result
	 */
	public static boolean evaluateLogic (Evaluatee source, String logic)
	{
		return LogicEvaluator.evaluateLogic(source, logic);
	}   //  evaluateLogic

	/**
	 *  Parse expression and add variables with @ to the list.
	 *  @param list list to be added to
	 *  @param parseString expression to parse for variables
	 */
	public static void parseDepends (ArrayList<String> list, String parseString)
	{
		if (parseString == null || parseString.length() == 0)
			return;
		String s = parseString;
		//  while we have variables
		while (s.indexOf('@') != -1)
		{
			int pos = s.indexOf('@');
			s = s.substring(pos+1);
			pos = s.indexOf('@');
			if (pos == -1)
				continue;	//	error number of @@ not correct
			String variable = s.substring(0, pos);
			s = s.substring(pos+1);
			if (variable.startsWith("~")) 
				variable = variable.substring(1);
			// strip also @tabno|
			variable = variable.replaceFirst("[0-9][0-9]*\\|", "");
			if (variable.indexOf(".") > 0)
				variable = variable.substring(0, variable.indexOf("."));
			if (variable.indexOf(":") > 0)
				variable = variable.substring(0, variable.indexOf(":"));
			list.add(variable);
		}
	}   //  parseDepends

	/**
	 * Evaluate a SQL logic expression (with @SQL= prefix)
	 * @param sqlLogic
	 * @param ctx
	 * @param windowNo
	 * @param tabNo
	 * @param targetObjectName expression logic is evaluated for, that target object (for logging purpose) can be field name, toolbar button name,..
	 * @return result of logic expression
	 */
	public static boolean parseSQLLogic(String sqlLogic, Properties ctx, int windowNo, int tabNo, String targetObjectName) {
		String sql = sqlLogic.substring(5); // remove @SQL=
		boolean reverse = false;
		if (sql.startsWith("!")) {
			reverse = true;
			sql = sql.substring(1); //remove !
		}
		sql = Env.parseContext(ctx, windowNo, tabNo, sql, false, false); // replace

		// variables
		if (sql.equals("")) {
			s_log.log(Level.WARNING,"(" + targetObjectName + ") - SQL variable parse failed: " + sqlLogic);
		} else {
			SQLLogicResult cache = sqlLogicCache.get(sql);
			if (cache != null) {
				long since = System.currentTimeMillis() - cache.timestamp;
				if (since <= 500) {
					cache.timestamp = System.currentTimeMillis();
					if (cache.value)
						return reverse ? false : true;
					else
						return reverse ? true : false;
				}
			}
			PreparedStatement stmt = null;
			ResultSet rs = null;
			try {
				stmt = DB.prepareStatement(sql, null);
				rs = stmt.executeQuery();
				boolean hasNext = rs.next();
				if (cache == null) {
					cache = new SQLLogicResult();
					sqlLogicCache.put(sql, cache);
				}
				cache.value = hasNext;
				cache.timestamp = System.currentTimeMillis();					
				if (hasNext)
					return reverse ? false : true;
				else
					return reverse ? true : false;
			} catch (SQLException e) {
				s_log.log(Level.WARNING, "(" + targetObjectName + ") " + sql, e);
			} finally {
				DB.close(rs, stmt);
				rs = null;
				stmt = null;
			}
		}
		return false;
	}
}	//	Evaluator
