From 93febae9b1746ef70ab58e5ffaec20b439034dff Mon Sep 17 00:00:00 2001
From: Duc Nguyen Thanh <58723762+ngtduc693@users.noreply.github.com>
Date: Sat, 26 Oct 2024 03:21:26 +0700
Subject: [PATCH] Add Geofencing (#487)

---
 Algorithms.Tests/Other/GeofenceTests.cs | 66 +++++++++++++++++++++++++
 Algorithms/Other/Geofence.cs            | 37 ++++++++++++++
 README.md                               |  1 +
 3 files changed, 104 insertions(+)
 create mode 100644 Algorithms.Tests/Other/GeofenceTests.cs
 create mode 100644 Algorithms/Other/Geofence.cs

diff --git a/Algorithms.Tests/Other/GeofenceTests.cs b/Algorithms.Tests/Other/GeofenceTests.cs
new file mode 100644
index 00000000..30dcfff4
--- /dev/null
+++ b/Algorithms.Tests/Other/GeofenceTests.cs
@@ -0,0 +1,66 @@
+using Algorithms.Other;
+using NUnit.Framework;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Algorithms.Tests.Other
+{
+    [TestFixture]
+    public class GeofenceTests
+    {
+        private Geofence? geofence;
+
+        [SetUp]
+        public void Setup()
+        {
+            geofence = new Geofence(10.8231, 106.6297, 500);
+        }
+
+        [Test]
+        public void IsInside_ShouldReturnTrue_WhenUserIsInsideGeofence()
+        {
+            double userLat = 10.8221;
+            double userLon = 106.6289;
+
+            bool? result = geofence?.IsInside(userLat, userLon);
+
+            Assert.That(result, Is.True);
+        }
+
+        [Test]
+        public void IsInside_ShouldReturnFalse_WhenUserIsOutsideGeofence()
+        {
+            double userLat = 10.8300;
+            double userLon = 106.6400;
+
+            bool? result = geofence?.IsInside(userLat, userLon);
+
+            Assert.That(result, Is.False);
+        }
+
+        [Test]
+        public void IsInside_ShouldReturnTrue_WhenUserIsExactlyOnGeofenceBoundary()
+        {
+            double userLat = 10.8231;
+            double userLon = 106.6297;
+
+            bool? result = geofence?.IsInside(userLat, userLon);
+
+            Assert.That(result, Is.True);
+        }
+
+        [Test]
+        public void IsInside_ShouldReturnFalse_WhenUserIsFarFromGeofence()
+        {
+            double userLat = 20.0000;
+            double userLon = 100.0000;
+
+            bool? result = geofence?.IsInside(userLat, userLon);
+
+            Assert.That(result, Is.False);
+        }
+    }
+}
diff --git a/Algorithms/Other/Geofence.cs b/Algorithms/Other/Geofence.cs
new file mode 100644
index 00000000..90fb9626
--- /dev/null
+++ b/Algorithms/Other/Geofence.cs
@@ -0,0 +1,37 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Algorithms.Other
+{
+    public class Geofence
+    {
+        public double Latitude { get; set; }
+
+        public double Longitude { get; set; }
+
+        public double RadiusInMeters { get; set; }
+
+        public Geofence(double latitude, double longitude, double radiusInMeters)
+        {
+            Latitude = latitude;
+            Longitude = longitude;
+            RadiusInMeters = radiusInMeters;
+        }
+
+        /// <summary>
+        /// Checks whether the provided user location (latitude and longitude) is within the geofence boundary.
+        /// The geofence is defined by a center point (latitude, longitude) and a radius in meters.
+        /// </summary>
+        /// <param name="userLatitude">The latitude of the user's current location.</param>
+        /// <param name="userLongitude">The longitude of the user's current location.</param>
+        /// <returns>Returns true if the user is inside the geofence, otherwise returns false.</returns>
+        public bool IsInside(double userLatitude, double userLongitude)
+        {
+            double distance = GeoLocation.CalculateDistanceFromLatLng(Latitude, Longitude, userLatitude, userLongitude);
+            return distance <= RadiusInMeters;
+        }
+    }
+}
diff --git a/README.md b/README.md
index a4d4663f..8085ccab 100644
--- a/README.md
+++ b/README.md
@@ -223,6 +223,7 @@ find more than one implementation for the same objective but using different alg
     * [Julian Easter](./Algorithms/Other/JulianEaster.cs)
     * [Pollard's Rho](./Algorithms/Other/PollardsRhoFactorizing.cs)
     * [GeoLocation Hash](./Algorithms/Other/Geohash.cs)
+    * [Geofencing](./Algorithms/Other/Geofence.cs)
     * [Triangulation Algorithm](./Algorithms/Other/Triangulator.cs)
   * [Problems](./Algorithms/Problems)
     * [Stable Marriage](./Algorithms/Problems/StableMarriage)