core: hack missing post path traction and grades

The path's context only extends until the end of the path. Hence, for an SvL located further along, the tractive effort and the slopes are missing. In this commit, we hack it to make it work, but we probably should extend the path's context so it goes until the last SvL. TBD at a later date.

Signed-off-by: Erashin <[email protected]>

core/envelope-sim/src/main/java/fr/sncf/osrd/envelope_sim/EnvelopeSimPath.java

@@ -111,6 +111,10 @@ public double getMinGrade(double begin, double end) {
         // TODO: Optimise method by adding in a cache.
         int indexBegin = getIndexBeforePos(begin);
         int indexEnd = getIndexBeforePos(end);
+        // TODO: Remove when we extend path properties until last SvL > path.length.
+        if (indexBegin == indexEnd && indexBegin == gradePositions.length - 1)
+            // Take last grade value in this case
+            return gradeValues[gradeValues.length - 1];
         var lowestGradient = gradeValues[indexBegin];
         for (int i = indexBegin; i < indexEnd; i++) {
             var grad = gradeValues[i];