LUCENE-9417: Tessellator might fail when several holes share are connected to the same vertex (#1614)

lucene/CHANGES.txt

@@ -294,6 +294,9 @@ Bug Fixes
 
 * LUCENE-9400: Tessellator might build illegal polygons when several holes share the shame vertex. (Ignacio Vera)
 
+* LUCENE-9417: Tessellator might build illegal polygons when several holes share are connected to the same
+  vertex. (Ignacio Vera)
+
 Other
 ---------------------
 

lucene/core/src/java/org/apache/lucene/geo/Tessellator.java

@@ -360,7 +360,16 @@ final public class Tessellator {
         if (hx >= p.getX() && p.getX() >= mx && hx != p.getX()
             && pointInEar(p.getX(), p.getY(), hy < my ? hx : qx, hy, mx, my, hy < my ? qx : hx, hy)) {
           tan = Math.abs(hy - p.getY()) / (hx - p.getX()); // tangential
-          if ((tan < tanMin || (tan == tanMin && p.getX() > connection.getX())) && isLocallyInside(p, holeNode)) {
+          if (isVertexEquals(p, connection) && isLocallyInside(p, holeNode)) {
+            // make sure we are not crossing the polygon. This might happen when several holes have a bridge to the same polygon vertex
+            // and this vertex has different vertex.
+            boolean crosses = GeoUtils.lineCrossesLine(p.getX(), p.getY(), holeNode.getX(), holeNode.getY(),
+                connection.next.getX(), connection.next.getY(), connection.previous.getX(), connection.previous.getY());
+            if (crosses == false) {
+              connection = p;
+              tanMin = tan;
+            }
+          } else if ((tan < tanMin || (tan == tanMin && p.getX() > connection.getX())) && isLocallyInside(p, holeNode)) {
             connection = p;
             tanMin = tan;
           }

lucene/core/src/test/org/apache/lucene/geo/TestTessellator.java

@@ -581,6 +581,20 @@ public class TestTessellator extends LuceneTestCase {
     checkPolygon(wkt);
   }
 
+  @Nightly
+  public void testComplexPolygon42() throws Exception {
+    String geoJson = GeoTestUtil.readShape("lucene-9417.geojson.gz");
+    Polygon[] polygons =Polygon.fromGeoJSON(geoJson);
+    for (int i = 0; i < polygons.length; i++) {
+      List<Tessellator.Triangle> tessellation = Tessellator.tessellate(polygons[i]);
+      // calculate the area of big polygons have numerical error
+      assertEquals(area(polygons[i]), area(tessellation), 1e-11);
+      for (Tessellator.Triangle t : tessellation) {
+       checkTriangleEdgesFromPolygon(polygons[i], t);
+      }
+    }
+  }
+
   private void checkPolygon(String wkt) throws Exception {
     Polygon polygon = (Polygon) SimpleWKTShapeParser.parse(wkt);
     List<Tessellator.Triangle> tessellation = Tessellator.tessellate(polygon);