fix(search): normalize geocoder bias across the antimeridian (#1272)

Keep geocoder viewport bias near the antimeridian and omit misleading wrapped viewboxes.

Contribution by @asturksever.

src/keylessGeocoder.js

@@ -206,12 +206,27 @@ export function photonSearchUrl(
   url.searchParams.set('limit', String(limit));
 
   const corners = String(bias ?? '').split('|');
-  if (corners.length === 2) {
-    const [swLat, swLng] = corners[0].split(',').map(Number);
-    const [neLat, neLng] = corners[1].split(',').map(Number);
-    if ([swLat, swLng, neLat, neLng].every(Number.isFinite)) {
+  const tokens = corners.flatMap((corner) => corner.split(','));
+  if (
+    corners.length === 2 &&
+    corners.every((corner) => corner.split(',').length === 2) &&
+    tokens.every((token) => token.trim() !== '')
+  ) {
+    const [swLat, swLng, neLat, neLng] = tokens.map(Number);
+    if (
+      [swLat, swLng, neLat, neLng].every(Number.isFinite) &&
+      Math.abs(swLat) <= 90 &&
+      Math.abs(neLat) <= 90 &&
+      swLat <= neLat &&
+      Math.abs(swLng) <= 180 &&
+      Math.abs(neLng) <= 180
+    ) {
+      const midpoint = (swLng + neLng + (swLng > neLng ? 360 : 0)) / 2;
       url.searchParams.set('lat', String((swLat + neLat) / 2));
-      url.searchParams.set('lon', String((swLng + neLng) / 2));
+      url.searchParams.set(
+        'lon',
+        String(midpoint > 180 ? midpoint - 360 : midpoint),
+      );
     }
   }
   return url.toString();

src/keylessGeocoder.test.mjs

@@ -452,3 +452,14 @@ function readGeocodingConsumer(file) {
     ? [file, 'annotations/resolver.js'] : [file];
   return files.map((name) => fs.readFileSync(path.join(ROOT, 'src', name), 'utf8')).join('\n');
 }
+
+
+test('wrapped view bias stays near the antimeridian and malformed coordinates are omitted', () => {
+  for (const [bias, expected] of [['-20,170|-10,-171', 179.5], ['50,175|60,-165', -175], ['0,180|10,-180', 180], ['0,-180|10,180', 0]]) {
+    const params = new URL(photonSearchUrl('island', { bias })).searchParams;
+    assert.equal(Number(params.get('lon')), expected);
+  }
+  for (const bias of ['-91,0|0,1', '0,181|1,0', '10,0|0,1', ',|,', '0,1,2|3,4', '0,1|Infinity,2']) {
+    assert.equal(new URL(photonSearchUrl('island', { bias })).searchParams.has('lon'), false);
+  }
+});

src/nominatimGeocode.js

@@ -166,6 +166,8 @@ export function nominatimViewboxFromBounds(bounds) {
   const neLat = nominatimLatitude(match[3]);
   const neLng = nominatimLongitude(match[4]);
   if ([swLat, swLng, neLat, neLng].some((value) => value === null)) return null;
-  if (swLat >= neLat) return null;
+  // One Nominatim viewbox cannot express a wrapped interval. Omit this soft
+  // preference rather than biasing the search toward the opposite hemisphere.
+  if (swLat >= neLat || swLng > neLng) return null;
   return `${swLng},${neLat},${neLng},${swLat}`;
 }

src/nominatimGeocode.test.mjs

@@ -173,3 +173,12 @@ test('a viewport hint is sent only when every edge is a real coordinate', () =>
       `${JSON.stringify(bounds)} must not become a viewbox`,
     );
 });
+
+test('wrapped viewports omit the Nominatim bias without rejecting the search', () => {
+  assert.equal(nominatimViewboxFromBounds('-20,170|-10,-171'), null);
+  assert.equal(nominatimViewboxFromBounds('50,175|60,-165'), null);
+  assert.equal(
+    nominatimViewboxFromBounds('-20,170|-10,180'),
+    '170,-10,180,-20',
+  );
+});