Fix Dijkstra

src/Avans.FlatGalaxy.Models/CelestialBodies/CelestialBody.cs

@@ -56,6 +56,8 @@ public void Collide(CelestialBody other)
             CollisionState.Collide(this, other);
         }
 
+        public double DistanceTo(CelestialBody target) => Math.Pow(CenterX - target.CenterX, 2) + Math.Pow(CenterY - target.CenterY, 2);
+
         public IDisposable Subscribe(IObserver<CelestialBody> observer)
         {
             _observers.Add(observer);

src/Avans.FlatGalaxy.Presentation/SimulationWindow.xaml.cs

@@ -10,7 +10,6 @@
 using Avans.FlatGalaxy.Presentation.Extensions;
 using Avans.FlatGalaxy.Simulation;
 using Avans.FlatGalaxy.Simulation.Data;
-using Color=System.Drawing.Color;
 
 namespace Avans.FlatGalaxy.Presentation
 {

src/Avans.FlatGalaxy.Simulation/PathFinding/BreadthFirstPathFinder.cs

@@ -5,7 +5,7 @@ namespace Avans.FlatGalaxy.Simulation.PathFinding
 {
     public class BreadthFirstPathFinder : PathFinder
     {
-        protected override List<Planet> Find(Planet start, Planet end)
+        protected override List<Planet> Find(Planet start, Planet end, List<Planet> planets)
         {
             var previous = new Dictionary<Planet, Planet>();
             var queue = new Queue<Planet>();

src/Avans.FlatGalaxy.Simulation/PathFinding/Data/DijkstraEdge.cs

@@ -0,0 +1,15 @@
+namespace Avans.FlatGalaxy.Simulation.PathFinding.Data
+{
+    public class DijkstraEdge
+    {
+        public DijkstraNode Node { get; set; }
+
+        public double Weight { get; set; }
+
+        public DijkstraEdge(DijkstraNode node, double weight)
+        {
+            Node = node;
+            Weight = weight;
+        }
+    }
+}

src/Avans.FlatGalaxy.Simulation/PathFinding/Data/DijkstraGraph.cs

@@ -0,0 +1,26 @@
+using System.Collections.Generic;
+using System.Linq;
+using Avans.FlatGalaxy.Models.CelestialBodies;
+
+namespace Avans.FlatGalaxy.Simulation.PathFinding.Data
+{
+    public class DijkstraGraph
+    {
+        public List<DijkstraNode> Nodes { get; }
+
+        public DijkstraGraph(List<Planet> planets)
+        {
+            Nodes = planets.Select(planet => new DijkstraNode(planet)).ToList();
+
+            foreach (var node in Nodes)
+            {
+                foreach (var neighbour in node.Planet.Neighbours)
+                {
+                    var neighbourNode = Nodes.First(node1 => node1.Planet == neighbour);
+
+                    node.Neighbours.Add(new(neighbourNode, node.Planet.DistanceTo(neighbour)));
+                }
+            }
+        }
+    }
+}

src/Avans.FlatGalaxy.Simulation/PathFinding/Data/DijkstraNode.cs

@@ -0,0 +1,24 @@
+using System;
+using System.Collections.Generic;
+using Avans.FlatGalaxy.Models.CelestialBodies;
+
+namespace Avans.FlatGalaxy.Simulation.PathFinding.Data
+{
+    public class DijkstraNode
+    {
+        public Planet Planet { get; }
+
+        public KeyValuePair<Planet, double> Weight { get; set; }
+
+        public List<DijkstraEdge> Neighbours { get; }
+
+        public bool Visited { get; set; }
+
+        public DijkstraNode(Planet planet)
+        {
+            Neighbours = new();
+            Weight = new(null, double.PositiveInfinity);
+            Planet = planet;
+        }
+    }
+}

src/Avans.FlatGalaxy.Simulation/PathFinding/DijkstraPathFinder.cs

@@ -1,16 +1,48 @@
-using System;
-using System.Collections.Generic;
+using System.Collections.Generic;
+using System.Linq;
 using Avans.FlatGalaxy.Models.CelestialBodies;
+using Avans.FlatGalaxy.Simulation.PathFinding.Data;
 
 namespace Avans.FlatGalaxy.Simulation.PathFinding
 {
     public class DijkstraPathFinder : PathFinder
     {
-        protected override List<Planet> Find(Planet start, Planet end)
+        protected override List<Planet> Find(Planet start, Planet end, List<Planet> planets)
         {
-            return null;
-        }
+            var graph = new DijkstraGraph(planets);
+            var startNode = graph.Nodes.First(node => node.Planet == start);
+            startNode.Weight = new(null, 0);
+            var unvisited = new List<DijkstraNode> { startNode };
+
+            while (unvisited.Any())
+            {
+                var node = unvisited.OrderBy(node1 => node1.Weight.Value).First();
+
+                foreach (var neighbour in node.Neighbours)
+                {
+                    if (neighbour.Weight + node.Weight.Value < neighbour.Node.Weight.Value)
+                    {
+                        neighbour.Node.Weight = new(node.Planet, neighbour.Weight + node.Weight.Value);
 
-        private static double GetDistance(Planet origin, Planet target) => Math.Pow(origin.CenterX - target.CenterX, 2) + Math.Pow(origin.CenterY - target.CenterY, 2);
+                        if (!unvisited.Contains(neighbour.Node) && !neighbour.Node.Visited)
+                        {
+                            unvisited.Add(neighbour.Node);
+                        }
+                    }
+                }
+                node.Visited = true;
+                unvisited.Remove(node);
+            }
+
+            var endNode = graph.Nodes.First(node => node.Planet == end);
+            var path = new List<DijkstraNode> { endNode };
+            while (endNode.Weight.Key != null)
+            {
+                endNode = endNode.Neighbours.OrderBy(edge => edge.Node.Weight.Value).First().Node;
+                path.Add(endNode);
+            }
+
+            return path.Select(node => node.Planet).ToList();
+        }
     }
 }

src/Avans.FlatGalaxy.Simulation/PathFinding/PathFinder.cs

@@ -6,12 +6,13 @@ namespace Avans.FlatGalaxy.Simulation.PathFinding
 {
     public abstract class PathFinder
     {
-        protected abstract List<Planet> Find(Planet start, Planet end);
+        protected abstract List<Planet> Find(Planet start, Planet end, List<Planet> planets);
 
         public List<Planet> Get(ISimulator simulator)
         {
-            var stepPlanets = simulator.Galaxy.CelestialBodies.OfType<Planet>().OrderByDescending(planet => planet.Radius).ToList();
-            return stepPlanets.Count < 2 ? null : Find(stepPlanets[0], stepPlanets[1]);
+            var planets = simulator.Galaxy.CelestialBodies.OfType<Planet>().ToList();
+            var planets2 = planets.OrderByDescending(planet => planet.Radius).ToList();
+            return planets2.Count < 2 ? null : Find(planets2[0], planets2[1], planets);
         }
     }
 }

src/Avans.FlatGalaxy.Simulation/Simulator.cs

@@ -122,8 +122,8 @@ private void Tick(CancellationToken token)
 
                     _collisionHandler.Detect(this);
 
-                    PathSteps = new BreadthFirstPathFinder().Get(this);
-                    // PathSteps = new CheapestPathFinder().Get(this);
+                    // PathSteps = new BreadthFirstPathFinder().Get(this);
+                    PathSteps = new DijkstraPathFinder().Get(this);
 
                     _lastTick = DateTime.UtcNow;
                     if ((DateTime.UtcNow - _lastBookmark).TotalSeconds >= ISimulator.BookmarkTime)