--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/artifacts/src/main/java/org/dive4elements/river/artifacts/sinfo/tkhstate/BedHeightsFinder.java	Wed Feb 28 17:27:15 2018 +0100
@@ -0,0 +1,134 @@
+/** Copyright (C) 2017 by Bundesanstalt für Gewässerkunde
+ * Software engineering by
+ *  Björnsen Beratende Ingenieure GmbH
+ *  Dr. Schumacher Ingenieurbüro für Wasser und Umwelt
+ *
+ * This file is Free Software under the GNU AGPL (>=v3)
+ * and comes with ABSOLUTELY NO WARRANTY! Check out the
+ * documentation coming with Dive4Elements River for details.
+ */
+package org.dive4elements.river.artifacts.sinfo.tkhstate;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map.Entry;
+import java.util.NavigableMap;
+import java.util.TreeMap;
+
+import org.apache.commons.lang.math.DoubleRange;
+import org.dive4elements.river.artifacts.math.Linear;
+import org.dive4elements.river.artifacts.model.Calculation;
+import org.dive4elements.river.artifacts.sinfo.util.BedHeightInfo;
+import org.dive4elements.river.model.BedHeight;
+import org.dive4elements.river.model.BedHeightValue;
+import org.dive4elements.river.model.River;
+
+/**
+ * Provides bed heigts for vcarious calculations.
+ *
+ * @author Gernot Belger
+ */
+public final class BedHeightsFinder {
+
+    private final BedHeightInfo info;
+
+    private final NavigableMap<Double, BedHeightValue> values;
+
+    /**
+     * Create specific bed heights used in tkh-calculation
+     *
+     * @param problems
+     */
+    public static Collection<BedHeightsFinder> createTkhBedHeights(final River river, final Calculation problems, final DoubleRange range) {
+        // FIXME: determine relevant bed-heights by river: read from some configuration file
+        // '3' is already the right one for demo-model == '"DGM-2004_Epoche-2-SOBEK"'
+        final int bedheightId = 3;
+
+        final Collection<BedHeight> bedHeights = Collections.singletonList(BedHeight.getBedHeightById(bedheightId));
+
+        // TODO: check for overlapping ranges... and provide a warning message, else we get problems later
+
+        final List<BedHeightsFinder> result = new ArrayList<>(bedHeights.size());
+
+        for (final BedHeight bedHeight : bedHeights) {
+            result.add(createBedHeights(bedHeight, range));
+        }
+
+        return result;
+    }
+
+    /**
+     * Creates a {@link BedHeightsFinder} for a dataset from the database, specified by its id.
+     *
+     * @return <code>null</code> if no bed height with the given id exists.
+     */
+    public static BedHeightsFinder forId(final int id, final DoubleRange range) {
+
+        final BedHeight bedHeight = BedHeight.getBedHeightById(id);
+        if (bedHeight == null)
+            return null;
+
+        return BedHeightsFinder.createBedHeights(bedHeight, range);
+    }
+
+    /**
+     * Create a finder for a given bed height.
+     *
+     * @param range
+     */
+    private static BedHeightsFinder createBedHeights(final BedHeight bedHeight, final DoubleRange range) {
+
+        // FIXME: sort by station, but in what direction?
+        // FIXME: using river.getKmUp()?
+        final NavigableMap<Double, BedHeightValue> values = new TreeMap<>();
+
+        for (final BedHeightValue bedHeightValue : bedHeight.getValues()) {
+            final Double station = bedHeightValue.getStation();
+            if (station != null && range.containsDouble(station)) {
+
+                if (bedHeightValue.getHeight() != null)
+                    values.put(station, bedHeightValue);
+            }
+        }
+
+        final BedHeightInfo info = BedHeightInfo.from(bedHeight);
+
+        return new BedHeightsFinder(info, values);
+    }
+
+    private BedHeightsFinder(final BedHeightInfo info, final NavigableMap<Double, BedHeightValue> values) {
+        this.info = info;
+        this.values = values;
+    }
+
+    public BedHeightInfo getInfo() {
+        return this.info;
+    }
+
+    public Collection<Double> getStations() {
+        return this.values.keySet();
+    }
+
+    public double getMeanBedHeight(final double km) {
+
+        if (this.values.containsKey(km))
+            return this.values.get(km).getHeight();
+
+        final Entry<Double, BedHeightValue> floorEntry = this.values.floorEntry(km);
+        final Entry<Double, BedHeightValue> ceilingEntry = this.values.ceilingEntry(km);
+
+        if (floorEntry == null || ceilingEntry == null)
+            return Double.NaN;
+
+        final double floorKm = floorEntry.getKey();
+        final double floorHeight = floorEntry.getValue().getHeight();
+        final double ceilKm = ceilingEntry.getKey();
+        final double ceilHeight = ceilingEntry.getValue().getHeight();
+
+        // FIXME: check if we always want that...
+
+        return Linear.linear(km, floorKm, ceilKm, floorHeight, ceilHeight);
+    }
+}
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