Salvage dungeons (#14520)

Content.Server/NPC/Pathfinding/PathfindingSystem.Helper.cs

@@ -0,0 +1,74 @@
+namespace Content.Server.NPC.Pathfinding;
+
+public sealed partial class PathfindingSystem
+{
+    /// <summary>
+    /// Finds a generic path from start to end.
+    /// </summary>
+    public List<Vector2i> GetPath(Vector2i start, Vector2i end, bool diagonal = false)
+    {
+        if (start == end)
+        {
+            return new List<Vector2i>();
+        }
+
+        var frontier = new PriorityQueue<Vector2i, float>();
+        frontier.Enqueue(start, 0f);
+        var cameFrom = new Dictionary<Vector2i, Vector2i>();
+        var node = start;
+
+        while (frontier.TryDequeue(out node, out _))
+        {
+            if (node == end)
+            {
+                break;
+            }
+
+            if (diagonal)
+            {
+                for (var i = 0; i < 8; i++)
+                {
+                    var direction = (DirectionFlag) i;
+                    var neighbor = node + direction.AsDir().ToIntVec();
+
+                    if (!cameFrom.TryAdd(neighbor, node))
+                        continue;
+
+                    var gScore = OctileDistance(neighbor, end);
+                    frontier.Enqueue(neighbor, gScore);
+                }
+            }
+            else
+            {
+                for (var i = 0; i < 4; i++)
+                {
+                    var direction = (DirectionFlag) Math.Pow(2, i);
+                    var neighbor = node + direction.AsDir().ToIntVec();
+
+                    if (!cameFrom.TryAdd(neighbor, node))
+                        continue;
+
+                    frontier.Enqueue(neighbor, ManhattanDistance(neighbor, end));
+                }
+            }
+        }
+
+        if (node != end)
+        {
+            return new List<Vector2i>();
+        }
+
+        var path = new List<Vector2i>();
+
+        do
+        {
+            path.Add(node);
+            var before = cameFrom[node];
+            node = before;
+        } while (node != start);
+
+        path.Add(start);
+        path.Reverse();
+        return path;
+    }
+}