Fix wrong coverage around antimeridian

geo/src/main/java/com/github/davidmoten/geo/GeoHash.java

@@ -633,35 +633,42 @@ void add(long l) {
         }
     }
 
-    static CoverageLongs coverBoundingBoxLongs(double topLeftLat, final double topLeftLon,
-            final double bottomRightLat, final double bottomRightLon, final int length) {
+    static CoverageLongs coverBoundingBoxLongs(double topLeftLat, double topLeftLon,
+            double bottomRightLat, double bottomRightLon, final int length) {
         Preconditions.checkArgument(topLeftLat >= bottomRightLat,
                 "topLeftLat must be >= bottomRighLat");
-        Preconditions.checkArgument(topLeftLon <= bottomRightLon,
-                "topLeftLon must be <= bottomRighLon");
         Preconditions.checkArgument(length > 0, "length must be greater than zero");
         final double actualWidthDegreesPerHash = widthDegrees(length);
         final double actualHeightDegreesPerHash = heightDegrees(length);
 
         LongSet hashes = new LongSet();
 
-        double diff = longitudeDiff(bottomRightLon, topLeftLon);
-        double maxLon = topLeftLon + diff;
+        double diff = bottomRightLon - topLeftLon;
+        if (diff < 0) {
+            // case where bottomRightLon cross the antimeridian
+            bottomRightLon += 360;
+            diff = bottomRightLon - topLeftLon;
+        } else if (diff > 360) {
+            // case where this bounding box displays more than one copy of the world
+            topLeftLon = -180;
+            bottomRightLon = 180;
+            diff = 360;
+        }
 
         for (double lat = bottomRightLat; lat <= topLeftLat; lat += actualHeightDegreesPerHash) {
-            for (double lon = topLeftLon; lon <= maxLon; lon += actualWidthDegreesPerHash) {
-                hashes.add(encodeHashToLong(lat, lon, length));
+            for (double lon = topLeftLon; lon <= bottomRightLon; lon += actualWidthDegreesPerHash) {
+                hashes.add(encodeHashToLong(lat, to180(lon), length));
             }
         }
         // ensure have the borders covered
         for (double lat = bottomRightLat; lat <= topLeftLat; lat += actualHeightDegreesPerHash) {
-            hashes.add(encodeHashToLong(lat, maxLon, length));
+            hashes.add(encodeHashToLong(lat, to180(bottomRightLon), length));
         }
-        for (double lon = topLeftLon; lon <= maxLon; lon += actualWidthDegreesPerHash) {
-            hashes.add(encodeHashToLong(topLeftLat, lon, length));
+        for (double lon = topLeftLon; lon <= bottomRightLon; lon += actualWidthDegreesPerHash) {
+            hashes.add(encodeHashToLong(topLeftLat, to180(lon), length));
         }
         // ensure that the topRight corner is covered
-        hashes.add(encodeHashToLong(topLeftLat, maxLon, length));
+        hashes.add(encodeHashToLong(topLeftLat, to180(bottomRightLon), length));
 
         double areaDegrees = diff * (topLeftLat - bottomRightLat);
         double coverageAreaDegrees = hashes.count * widthDegrees(length) * heightDegrees(length);

geo/src/test/java/com/github/davidmoten/geo/CoverageTest.java

@@ -1,6 +1,7 @@
 package com.github.davidmoten.geo;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
 
 import org.junit.Test;
 
@@ -28,4 +29,84 @@ public void testCoverageOfAnAreaThatCantBeCoveredWithHashOfLengthOne() {
         assertEquals(1, coverage.getHashLength());
         assertEquals(Sets.newHashSet("q", "r"), coverage.getHashes());
     }
+
+    /**
+     * test copied from https://github.com/davidmoten/geo/pull/25/files to validate bug fix
+     */
+    @Test
+    public void testWideCoverage() {
+        double top = -1;
+        double left = -26;
+        double bottom = -2;
+        double right = 175;
+
+        Coverage coverage = GeoHash.coverBoundingBox(top, left, bottom, right, 1);
+        assertTrue(coverage.getHashes().contains("r"));
+    }
+
+    /**
+     * test copied from https://github.com/davidmoten/geo/issues/34 to validate bug fix
+     */
+    @Test
+    public void testCoverageAllWorld() {
+        double topLeftLat = 90d;
+        double topLeftLon = -179d;
+        double bottomRightLat = -90d;
+        double bottomRightLon = 180d;
+        Coverage coverage = GeoHash.coverBoundingBox(topLeftLat, topLeftLon, bottomRightLat, bottomRightLon, 1);
+        assertEquals(Sets.newHashSet("0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "b", "c", "d", "e", "f", "g", "h", "j", "k", "m", "n", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"),
+                coverage.getHashes());
+    }
+
+    @Test
+    public void testCoverageAllWorldLeaflet() {
+        double topLeftLat = 90;
+        double topLeftLon = -703;
+        double bottomRightLat = -90;
+        double bottomRightLon = 624;
+        Coverage coverage = GeoHash.coverBoundingBox(topLeftLat, topLeftLon, bottomRightLat, bottomRightLon, 1);
+        assertEquals(Sets.newHashSet("0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "b", "c", "d", "e", "f", "g", "h", "j", "k", "m", "n", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"),
+                coverage.getHashes());
+    }
+
+    @Test
+    public void testCoverageAntimeridianGoogleMaps() {
+        double topLeftLat = 39;
+        double topLeftLon = 156;
+        double bottomRightLat = 3;
+        double bottomRightLon = -118;
+        Coverage coverage = GeoHash.coverBoundingBox(topLeftLat, topLeftLon, bottomRightLat, bottomRightLon, 1);
+        assertEquals(Sets.newHashSet("x", "8", "9"), coverage.getHashes());
+    }
+
+    @Test
+    public void testCoverageAntimeridianLeaflet() {
+        double topLeftLat = 39;
+        double topLeftLon = -204;
+        double bottomRightLat = 2;
+        double bottomRightLon = -121;
+        Coverage coverage = GeoHash.coverBoundingBox(topLeftLat, topLeftLon, bottomRightLat, bottomRightLon, 1);
+        assertEquals(Sets.newHashSet("x", "8", "9"), coverage.getHashes());
+    }
+
+    @Test
+    public void testCoverageAntimeridianLeaflet2() {
+        double topLeftLat = 44;
+        double topLeftLon = 110;
+        double bottomRightLat = 9;
+        double bottomRightLon = 194;
+        Coverage coverage = GeoHash.coverBoundingBox(topLeftLat, topLeftLon, bottomRightLat, bottomRightLon, 1);
+        assertEquals(Sets.newHashSet("w", "x", "8"), coverage.getHashes());
+    }
+
+    @Test
+    public void testCoverageMaxHashes() {
+        double topLeftLat = 50.1112;
+        double topLeftLon = -6.8167;
+        double bottomRightLat = 46.6997;
+        double bottomRightLon = 3.7301;
+        Coverage coverage = GeoHash.coverBoundingBoxMaxHashes(topLeftLat, topLeftLon, bottomRightLat, bottomRightLon, 64);
+        assertEquals(3, coverage.getHashLength());
+        assertEquals(24, coverage.getHashes().size());
+    }
 }

geo/src/test/java/com/github/davidmoten/geo/GeoHashTest.java

@@ -618,8 +618,4 @@ public void testCoverBoundingBoxPreconditionLat() {
         GeoHash.coverBoundingBox(0, 100, 10, 120);
     }
 
-    @Test(expected=IllegalArgumentException.class)
-    public void testCoverBoundingBoxPreconditionLon() {
-        GeoHash.coverBoundingBox(10, 120, 0, 100);
-    }
 }