package de.intevation.artifactdatabase.transition;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.apache.log4j.Logger;

/**
 * The TransitionEngine stores all transitions for each Artifact and should be
 * used to determine, if an Artifact is able to advance from one to another
 * state.
 *
 * @author <a href="mailto:ingo.weinzierl@intevation.de">Ingo Weinzierl</a>
 */
public class TransitionEngine {

    /** The logger used in this class. */
    private static Logger logger = Logger.getLogger(TransitionEngine.class);

    /**
     * A map that contains the transitions of the artifacts. The key is the name
     * of the artifact, its value is a list of all transitions of this artifact.
     */
    protected Map<String, List> transitions;


    /**
     * The default constructor.
     */
    public TransitionEngine() {
        transitions = new HashMap<String, List>();
    }


    /**
     * Add new transitions for a specific artifact.
     *
     * @param stateId the name of the Artifact.
     * @param transitions the list of transition of the artifact.
     *
     * @return true, if the transitions were added, otherwise false.
     */
    public boolean addTransition(String stateId, List transitions) {
        List tmp = this.transitions.get(stateId);

        if (tmp != null) {
            logger.info(
                "Transitions for the state '"
                + stateId
                + "' already stored.");

            return false;
        }

        logger.debug("Add new transitions for state '" + stateId + "'");
        return this.transitions.put(stateId, transitions) != null;
    }
}
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