From a679024f55afdec1bee450502939274d38790567 Mon Sep 17 00:00:00 2001
From: Anton Maminov <anton.linux@gmail.com>
Date: Thu, 11 Apr 2024 11:07:26 +0300
Subject: [PATCH] Calculates the location of a destination coord

---
 README.md                 | 13 +++++++++++++
 shard.yml                 |  2 +-
 spec/geo/distance_spec.cr |  7 +++++++
 src/geo/distance.cr       |  7 +++++++
 4 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/README.md b/README.md
index d6fc590..126bde0 100644
--- a/README.md
+++ b/README.md
@@ -171,6 +171,19 @@ new_york.distance(london).to_kilometers
 # => 5570.4744596620685
 ```
 
+### Calculates the location of a destination coord
+
+```crystal
+require "geo"
+require "geo/distance"
+
+point = Geo::Coord.new(39, -75)
+
+point.destination(5000, 90, :kilometers)
+# Geo::Coord(@lat=26.440010707631124, @lng=-22.885355549364313)
+```
+
+
 ## Contributing
 
 1. Fork it (<https://github.com/geocrystal/geo/fork>)
diff --git a/shard.yml b/shard.yml
index 19556b5..8f6e5ef 100644
--- a/shard.yml
+++ b/shard.yml
@@ -6,7 +6,7 @@ crystal: ">= 1.0.0"
 dependencies:
   haversine:
     github: geocrystal/haversine
-    version: ">= 0.4.0"
+    version: ">= 0.5.0"
   convex_hull:
     github: geocrystal/convex_hull
     version: ">= 0.6.0"
diff --git a/spec/geo/distance_spec.cr b/spec/geo/distance_spec.cr
index 142ab54..b98a2a3 100644
--- a/spec/geo/distance_spec.cr
+++ b/spec/geo/distance_spec.cr
@@ -4,6 +4,7 @@ require "../../src/geo/distance"
 describe Geo::Coord do
   london = Geo::Coord.new(51.500153, -0.126236)
   new_york = Geo::Coord.new(40.714268, -74.005974)
+  point = Geo::Coord.new(39, -75)
 
   context "distance" do
     context "calculates distance (by haversine formula)" do
@@ -11,4 +12,10 @@ describe Geo::Coord do
       it { new_york.distance(london).to_kilometers.should eq(5570.482153929098) }
     end
   end
+
+  context "destination" do
+    context "Calculates the location of a destination point (by haversine formula)" do
+      it { point.destination(5000, 90, :kilometers).should eq(Geo::Coord.new(26.440010707631124, -22.885355549364313)) }
+    end
+  end
 end
diff --git a/src/geo/distance.cr b/src/geo/distance.cr
index 55a960a..932924f 100644
--- a/src/geo/distance.cr
+++ b/src/geo/distance.cr
@@ -7,5 +7,12 @@ module Geo
     def distance(other : Geo::Coord) : Haversine::Distance
       Haversine.distance(self.ll, other.ll)
     end
+
+    # Calculates the location of a destination point
+    def destination(distance : Number, bearing : Number, unit : Symbol = :kilometers) : Geo::Coord
+      point = Haversine.destination(self.ll, distance, bearing, unit)
+
+      Geo::Coord.new(point[0], point[1])
+    end
   end
 end