--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/artifact-database/src/main/java/org/dive4elements/artifactdatabase/state/StateEngine.java	Thu Apr 25 10:57:18 2013 +0200
@@ -0,0 +1,172 @@
+package de.intevation.artifactdatabase.state;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import org.apache.log4j.Logger;
+
+import de.intevation.artifactdatabase.data.StateData;
+
+
+/**
+ * The StateEngine stores all states and associated information about
+ * outputs and facets for each Artifact.
+ *
+ * @author <a href="mailto:ingo.weinzierl@intevation.de">Ingo Weinzierl</a>
+ */
+public class StateEngine {
+
+    /** The logger used in this class. */
+    private static Logger logger = Logger.getLogger(StateEngine.class);
+
+    /**
+     * A map that contains the states of the artifacts. The key of this map is
+     * the name of an artifact, its value is a list of all states the artifact
+     * can reach.
+     */
+    protected Map<String, List<State>> states;
+
+
+    /**
+     * A map that contains all existing states. The key of this map is the ID of
+     * the state, its value is the state itself.
+     */
+    protected Map<String, State> allStates;
+
+
+    /**
+     * The default constructor.
+     */
+    public StateEngine() {
+        states    = new HashMap<String, List<State>>();
+        allStates = new HashMap<String, State>();
+    }
+
+
+    /**
+     * This method adds a state into the map <i>allStates</i>.
+     *
+     * @param state The state to add.
+     */
+    protected void addState(State state) {
+        allStates.put(state.getID(), state);
+    }
+
+
+    /**
+     * Returns the state based on its ID.
+     *
+     * @param stateId The ID of the desired state.
+     *
+     * @return the state.
+     */
+    public State getState(String stateId) {
+        return allStates.get(stateId);
+    }
+
+
+    public StateData getStateData(String artifact, String dataName) {
+        List<State> artifactStates = getStates(artifact);
+
+        if (artifactStates == null || artifactStates.size() == 0) {
+            logger.warn("No States for Artifact '" + artifact + "' existing.");
+            return null;
+        }
+
+        for (State state: artifactStates) {
+            StateData sd = state.getData(dataName);
+
+            if (sd != null) {
+                return sd;
+            }
+        }
+
+        logger.warn(
+            "No StateData for Artifact '" + artifact +
+            "' with name '" + dataName + "' existing.");
+
+        return null;
+    }
+
+
+    /**
+     * Add new states for a specific artifact.
+     *
+     * @param artifact The name of the artifact.
+     * @param states A list of states that the artifact can reach.
+     *
+     * @return true, if the states were added, otherwise false.
+     */
+    public boolean addStates(String artifact, List<State> states) {
+        List tmp = this.states.get(artifact);
+
+        if (tmp != null) {
+            logger.info(
+                "States for the artifact '" + artifact + "' already stored.");
+
+            return false;
+        }
+
+        // add the state to the map with all existing states
+        for (State s: states) {
+            addState(s);
+        }
+
+        logger.debug("Add new states for the artifact '" + artifact + "'");
+        return this.states.put(artifact, states) != null;
+    }
+
+
+    /**
+     * Returns the state list of an artifact specified by its name.
+     *
+     * @param artifact The name of the artifact (e.g. "winfo").
+     *
+     * @return the list of states of this artifact or <i>null</i> if no states
+     * are existing for this <i>artifact</i>.
+     */
+    public List<State> getStates(String artifact) {
+        return states.get(artifact);
+    }
+
+
+    /**
+     * Return mapping of output to facets for an artifact in its states.
+     */
+    public Map<String, List<String>> getCompatibleFacets(List<String> aStates) {
+        Map<String, List<String>> compatibilityMatrix =
+            new HashMap<String, List<String>>();
+
+        // For all states that the artifact had seen, add outputs facets.
+        logger.debug("Searching in " + aStates);
+        for (String stateId: aStates) {
+
+            State state = allStates.get(stateId);
+            if (state == null) {
+                logger.debug("No state found for id " + stateId);
+                continue;
+            }
+
+            for (Output output: state.getOutputs()) {
+                List<Facet> outFacets = output.getFacets();
+                logger.debug("Facets for output " + output.getName() + " :" + outFacets);
+
+                List<String> oldFacets = compatibilityMatrix.get(output.getName());
+
+                if (oldFacets == null) {
+                    oldFacets = new ArrayList<String>();
+                }
+
+                for (Facet facet: outFacets) {
+                    oldFacets.add(facet.getName());
+                }
+
+                compatibilityMatrix.put(output.getName(), oldFacets);
+            }
+        }
+        return compatibilityMatrix;
+    }
+}
+// vim:set ts=4 sw=4 et sta sts=4 fenc=utf8 :