/**
 * Copyright 2010 JBoss Inc
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.drools.conf;

/**
 * An Enum for Event Processing option.
 * 
 * drools.eventProcessingMode = <identity|equality>
 * 
 * When the rulebase is compiled in the CLOUD (default) event processing mode,
 * it behaves just like a regular rulebase.
 * 
 * When the rulebase is compiled in the STREAM event processing mode, additional
 * assumptions are made. These assumptions allow the engine to perform a few optimisations
 * like:
 * 
 * <li> reasoning over absence of events (NOT CE), automatically adds an appropriate duration attribute
 * to the rule in order to avoid early rule firing. </li>
 * <li> memory management techniques may be employed when an event no longer can match other events
 * due to session clock continuous increment. </li>
 * 
 * @author etirelli
 *
 */
public enum EventProcessingOption
        implements SingleValueKnowledgeBaseOption {

    CLOUD("cloud"), 
    STREAM("stream");

    /**
     * The property name for the sequential mode option
     */
    public static final String PROPERTY_NAME = "drools.eventProcessingMode";

    private String             string;

    EventProcessingOption(String mode) {
        this.string = mode;
    }

    /**
     * {@inheritDoc}
     */
    public String getPropertyName() {
        return PROPERTY_NAME;
    }

    public String getMode() {
        return string;
    }

    public String toString() {
        return "EventProcessingOption( "+string+ " )";
    }

    public String toExternalForm() {
        return this.string;
    }

    public static EventProcessingOption determineEventProcessingMode(String mode) {
        if ( STREAM.getMode().equalsIgnoreCase( mode ) ) {
            return STREAM;
        } else if ( CLOUD.getMode().equalsIgnoreCase( mode ) ) {
            return CLOUD;
        }
        throw new IllegalArgumentException( "Illegal enum value '" + mode + "' for EventProcessingMode" );
    }
}