Remove duplicate ways

Signed-off-by: Taylor Smock <tsmock@meta.com>

src/main/java/org/openstreetmap/josm/plugins/mapwithai/backend/GetDataRunnable.java

@@ -7,6 +7,7 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
@@ -268,6 +269,7 @@ public class GetDataRunnable extends RecursiveTask<DataSet> {
         mergeNodes(dataSet);
         cleanupDataSet(dataSet);
         mergeWays(dataSet);
+        removeDuplicateWays(dataSet);
         PreConflatedDataUtils.removeConflatedData(dataSet, info);
         removeAlreadyAddedData(dataSet);
         List<Way> ways = dataSet.searchWays(boundsToUse.toBBox()).stream().filter(w -> w.hasKey("highway"))
@@ -280,6 +282,27 @@ public class GetDataRunnable extends RecursiveTask<DataSet> {
                         .forEach(GetDataRunnable::cleanupArtifacts);
     }
 
+    /**
+     * Remove duplicate ways (mostly from MS buildings)
+     *
+     * @param dataSet The dataset to filter
+     * @see <a href="https://github.com/facebook/Rapid/issues/873">Rapid #873</a>
+     */
+    private static void removeDuplicateWays(DataSet dataSet) {
+        final Collection<Way> toDelete = new ArrayList<>();
+        final Map<Integer, long[]> visited = new HashMap<>();
+        for (Way way : dataSet.getWays()) {
+            long[] nodeIds = way.getNodes().stream().mapToLong(AbstractPrimitive::getUniqueId).sorted().toArray();
+            int hash = Arrays.hashCode(nodeIds);
+            if (visited.containsKey(hash) && Arrays.equals(visited.get(hash), nodeIds)) {
+                toDelete.add(way);
+            } else {
+                visited.put(hash, nodeIds);
+            }
+        }
+        Optional.ofNullable(DeleteCommand.delete(toDelete, true, true)).ifPresent(Command::executeCommand);
+    }
+
     /**
      * Remove empty tags from primitives
      *