feat: support geo query

Storage/Storage.Test/GeoTest.cs

@@ -1,4 +1,6 @@
 using NUnit.Framework;
+using System;
+using System.Threading.Tasks;
 using LeanCloud.Storage;
 
 namespace Storage.Test {
@@ -19,5 +21,32 @@ namespace Storage.Test {
             TestContext.WriteLine(radians);
             Assert.Less(radians - 0.0005, 0.0001);
         }
+
+        [Test]
+        public async Task Query() {
+            LCObject geoObj = new LCObject("GeoObj");
+            Random random = new Random();
+            LCGeoPoint p1 = new LCGeoPoint(-90 + random.NextDouble() * 180, -180 + random.NextDouble() * 360);
+            geoObj["location"] = p1;
+            await geoObj.Save();
+
+            LCGeoPoint p2 = new LCGeoPoint(p1.Latitude + 0.01, p1.Longitude + 0.01);
+
+            double km = p1.KilometersTo(p2);
+            TestContext.WriteLine($"km: {km}, {Math.Ceiling(km)}");
+            LCQuery<LCObject> query = new LCQuery<LCObject>("GeoObj");
+            query.WhereWithinKilometers("location", p2, Math.Ceiling(km));
+            Assert.Greater((await query.Find()).Count, 0);
+
+            double miles = p1.MilesTo(p2);
+            query = new LCQuery<LCObject>("GeoObj");
+            query.WhereWithinMiles("location", p2, Math.Ceiling(miles));
+            Assert.Greater((await query.Find()).Count, 0);
+
+            double radians = p1.RadiansTo(p2);
+            query = new LCQuery<LCObject>("GeoObj");
+            query.WhereWithinRadians("location", p2, Math.Ceiling(radians));
+            Assert.Greater((await query.Find()).Count, 0);
+        }
     }
 }

Storage/Storage/Internal/Query/LCCompositionalCondition.cs

@@ -94,6 +94,14 @@ namespace LeanCloud.Storage.Internal.Query {
             AddOperation(key, "$within", value);
         }
 
+        public void WhereWithinRadians(string key, LCGeoPoint point, double maxDistance) {
+            Dictionary<string, object> value = new Dictionary<string, object> {
+                { "$nearSphere", point },
+                { "$maxDistance", maxDistance }
+            };
+            Add(new LCEqualCondition(key, value));
+        }
+
         public void WhereRelatedTo(LCObject parent, string key) {
             Add(new LCRelatedCondition(parent, key));
         }

Storage/Storage/Public/LCQuery.cs

@@ -205,6 +205,19 @@ namespace LeanCloud.Storage {
             return this;
         }
 
+        public LCQuery<T> WhereWithinRadians(string key, LCGeoPoint point, double maxDistance) {
+            Condition.WhereWithinRadians(key, point, maxDistance);
+            return this;
+        }
+
+        public LCQuery<T> WhereWithinMiles(string key, LCGeoPoint point, double maxDistance) {
+            return WhereWithinRadians(key, point, maxDistance / 3958.8);
+        }
+
+        public LCQuery<T> WhereWithinKilometers(string key, LCGeoPoint point, double maxDistance) {
+            return WhereWithinRadians(key, point, maxDistance / 6371.0);
+        }
+
         /// <summary>
         ///  The value corresponding to key is related to the parent.
         /// </summary>