teichmann@475: package org.dive4elements.artifactdatabase.transition;
ingo@104: 
teichmann@500: import java.util.ArrayDeque;
ingo@108: import java.util.ArrayList;
teichmann@500: import java.util.Deque;
ingo@104: import java.util.HashMap;
teichmann@500: import java.util.HashSet;
ingo@104: import java.util.List;
ingo@104: import java.util.Map;
teichmann@500: import java.util.Set;
ingo@104: 
ingo@104: import org.apache.log4j.Logger;
ingo@104: 
teichmann@475: import org.dive4elements.artifacts.Artifact;
ingo@257: 
teichmann@475: import org.dive4elements.artifactdatabase.state.State;
teichmann@475: import org.dive4elements.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.
felix@400:      * @param transition 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@257:     public List<State> getReachableStates(
ingo@257:         Artifact    artifact,
ingo@257:         State       state,
ingo@257:         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@257:             State target = engine.getState(t.getTo());
ingo@257: 
ingo@257:             if (t.isValid(artifact, state, target)) {
ingo@257:                 reachable.add(target);
ingo@108:             }
ingo@108:         }
ingo@108: 
ingo@108:         return reachable;
ingo@104:     }
ingo@201: 
teichmann@500:     /** Returns all recursive reachable state ids for
teichmann@500:      *  a given pair of artifact id and state id.
teichmann@500:      */
teichmann@500:     public Set<String> allRecursiveSuccessorStateIds(
teichmann@500:         String artifactIdentifier,
teichmann@500:         String stateId
teichmann@500:     ) {
teichmann@500:         HashSet<String> result = new HashSet<String>();
teichmann@500: 
teichmann@500:         List<Transition> trans = transitions.get(artifactIdentifier);
teichmann@500: 
teichmann@500:         if (trans == null) {
teichmann@500:             return result;
teichmann@500:         }
teichmann@500: 
teichmann@500:         Map<String, Set<String>> succs = new HashMap<String, Set<String>>();
teichmann@500: 
teichmann@500:         for (Transition t: trans) {
teichmann@500:             String from = t.getFrom();
teichmann@500:             String to   = t.getTo();
teichmann@500: 
teichmann@500:             Set<String> s = succs.get(from);
teichmann@500:             if (s == null) {
teichmann@500:                 s = new HashSet<String>();
teichmann@500:                 succs.put(from, s);
teichmann@500:             }
teichmann@500:             s.add(to);
teichmann@500:         }
teichmann@500: 
teichmann@500:         Set<String> start = succs.get(stateId);
teichmann@500: 
teichmann@500:         if (start == null) {
teichmann@500:             return result;
teichmann@500:         }
teichmann@500: 
teichmann@500:         Deque<String> open = new ArrayDeque<String>(start);
teichmann@500: 
teichmann@500:         while (!open.isEmpty()) {
teichmann@500:             String cand = open.pop();
teichmann@500:             if (result.add(cand)) {
teichmann@500:                 Set<String> s = succs.get(cand);
teichmann@500:                 if (s != null) {
teichmann@500:                     open.addAll(s);
teichmann@500:                 }
teichmann@500:             }
teichmann@500:         }
teichmann@500: 
teichmann@500:         return result;
teichmann@500:     }
teichmann@500: 
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@257:      * @param artifact The owner artifact of state <i>state</i>.
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@257:         Artifact    artifact,
ingo@201:         String      targetId,
ingo@201:         State       state,
ingo@201:         StateEngine stateEngine)
ingo@201:     {
ingo@257:         List<State> reachable = getReachableStates(artifact, 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 :