ingo@104: package de.intevation.artifactdatabase.transition;
ingo@104: 
ingo@108: import java.util.ArrayList;
ingo@104: import java.util.HashMap;
ingo@104: import java.util.List;
ingo@104: import java.util.Map;
ingo@104: 
ingo@104: import org.apache.log4j.Logger;
ingo@104: 
ingo@108: import de.intevation.artifactdatabase.state.State;
ingo@108: import de.intevation.artifactdatabase.state.StateEngine;
ingo@108: 
ingo@108: 
ingo@104: /**
ingo@104:  * The TransitionEngine stores all transitions for each Artifact and should be
ingo@104:  * used to determine, if an Artifact is able to advance from one to another
ingo@104:  * state.
ingo@104:  *
ingo@104:  * @author <a href="mailto:ingo.weinzierl@intevation.de">Ingo Weinzierl</a>
ingo@104:  */
ingo@104: public class TransitionEngine {
ingo@104: 
ingo@104:     /** The logger used in this class. */
ingo@104:     private static Logger logger = Logger.getLogger(TransitionEngine.class);
ingo@104: 
ingo@104:     /**
ingo@104:      * A map that contains the transitions of the artifacts. The key is the name
ingo@104:      * of the artifact, its value is a list of all transitions of this artifact.
ingo@104:      */
ingo@104:     protected Map<String, List> transitions;
ingo@104: 
ingo@104: 
ingo@104:     /**
ingo@104:      * The default constructor.
ingo@104:      */
ingo@104:     public TransitionEngine() {
ingo@104:         transitions = new HashMap<String, List>();
ingo@104:     }
ingo@104: 
ingo@104: 
ingo@104:     /**
ingo@104:      * Add new transitions for a specific artifact.
ingo@104:      *
ingo@104:      * @param stateId the name of the Artifact.
ingo@104:      * @param transitions the list of transition of the artifact.
ingo@104:      *
ingo@104:      * @return true, if the transitions were added, otherwise false.
ingo@104:      */
ingo@108:     public boolean addTransition(String stateId, Transition transition) {
ingo@108:         List tmp = transitions.get(stateId);
ingo@104: 
ingo@108:         if (tmp == null) {
ingo@108:             tmp = new ArrayList<Transition>();
ingo@104:         }
ingo@104: 
ingo@108:         tmp.add(transition);
ingo@108: 
ingo@104:         logger.debug("Add new transitions for state '" + stateId + "'");
ingo@108: 
ingo@108:         return transitions.put(stateId, tmp) != null;
ingo@108:     }
ingo@108: 
ingo@108: 
ingo@108:     /**
ingo@108:      * This method returns all existing transitions of a state.
ingo@108:      *
ingo@108:      * @param state The state
ingo@108:      *
ingo@108:      * @return the existing transition of <i>state</i>.
ingo@108:      */
ingo@108:     public List<Transition> getTransitions(State state) {
ingo@108:         return transitions.get(state.getID());
ingo@108:     }
ingo@108: 
ingo@108: 
ingo@108:     /**
ingo@108:      * This method returns the reachable states of <i>state</i>.
ingo@108:      *
ingo@108:      * @param state The current state.
ingo@108:      * @param engine The state engine.
ingo@108:      *
ingo@108:      * @return a list of reachable states.
ingo@108:      */
ingo@108:     public List<State> getReachableStates(State state, StateEngine engine) {
ingo@108:         List<Transition> transitions = getTransitions(state);
ingo@108:         List<State>      reachable   = new ArrayList<State>();
ingo@108: 
ingo@201:         if (transitions == null) {
ingo@201:             return reachable;
ingo@201:         }
ingo@201: 
ingo@108:         for (Transition t: transitions) {
ingo@108:             if (t.isValid(state)) {
ingo@108:                 reachable.add(engine.getState(t.getTo()));
ingo@108:             }
ingo@108:         }
ingo@108: 
ingo@108:         return reachable;
ingo@104:     }
ingo@201: 
ingo@201: 
ingo@201:     /**
ingo@201:      * Determines if a state with a given identifier is reachable from a current
ingo@201:      * state.
ingo@201:      *
ingo@201:      * @param targetId The identifier of the target state.
ingo@201:      * @param state The start state.
ingo@201:      * @param stateEngine The StateEngine.
ingo@201:      *
ingo@201:      * @return true, if the target state is reachable, otherwise false.
ingo@201:      */
ingo@201:     public boolean isStateReachable(
ingo@201:         String      targetId,
ingo@201:         State       state,
ingo@201:         StateEngine stateEngine)
ingo@201:     {
ingo@201:         List<State> reachable = getReachableStates(state, stateEngine);
ingo@201: 
ingo@201:         if (reachable == null || reachable.size() == 0) {
ingo@201:             return false;
ingo@201:         }
ingo@201: 
ingo@201:         for (State s: reachable) {
ingo@201:             if (targetId.equals(s.getID())) {
ingo@201:                 return true;
ingo@201:             }
ingo@201:         }
ingo@201: 
ingo@201:         return false;
ingo@201:     }
ingo@104: }
ingo@104: // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :