package ****.conditions;

import static ****.KEY_DATA_MODEL;
import static ****.KEY_XVARS;
import ****.Constants;
import ****.DataModel;
import ****.RuleResult;

import java.io.InputStreamReader;
import java.util.HashMap;
import java.util.Map;

import org.drools.RuleBase;
import org.drools.RuleBaseFactory;
import org.drools.StatefulSession;
import org.drools.compiler.PackageBuilder;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.opensymphony.module.propertyset.PropertySet;
import com.opensymphony.workflow.Condition;
import com.opensymphony.workflow.WorkflowException;

/**
 * A class used by osworkflow to evaluate a condition.
 *  
 */
public class DroolsCondition implements Condition {

	private static final String RULE = "rule";

	private static final String RULE_GROUP = "ruleGroup";

	private static final Logger LOG = LoggerFactory.getLogger(Constants.VTPIE_LOGGER);

	private  Map<String, RuleBase> MPRULE = new HashMap<String, RuleBase>();

	@SuppressWarnings("unchecked")
	public boolean passesCondition(Map transientVars, Map args, PropertySet arg2) throws WorkflowException {

		LOG.trace("Drools start");

		StatefulSession session = setupRule((String) args.get(RULE));

		LOG.trace("Drools elaborating");

		String ruleGroupName = (String) args.get(RULE_GROUP);

		RuleResult result = new RuleResult();
		DataModel dm = (DataModel) transientVars.get(KEY_DATA_MODEL);

		session.insert(result);
		session.insert(dm);
		session.insert(transientVars.get(KEY_XVARS));

		if (!"".equals(ruleGroupName) && ruleGroupName != null)
			session.getAgenda().activateRuleFlowGroup(ruleGroupName);

		session.fireAllRules();
		session.dispose();

		LOG.info("Drools Condition {}: {}", ruleGroupName, result.isVerified());

		return result.isVerified();
	}

	private StatefulSession setupRule(String ruleFile) throws WorkflowException {
		RuleBase ruleBase = MPRULE.get(ruleFile);
		if (ruleBase == null) {
			try {
				synchronized (MPRULE) {
					LOG.info("Drools builder Conditions : " + ruleFile);
					PackageBuilder builder = new PackageBuilder();
					builder
							.addPackageFromDrl(new InputStreamReader(DroolsCondition.class
									.getResourceAsStream(ruleFile)));
					ruleBase = RuleBaseFactory.newRuleBase();
					ruleBase.addPackage(builder.getPackage());
					MPRULE.put(ruleFile, ruleBase);
				}
			} catch (Exception e) {
				throw new WorkflowException(e);
			}
		}
		return ruleBase.newStatefulSession();
	}
}