fix: cached paths skip the start cell and are no longer shared between maps (2.1.1)

src/NosCore.PathFinder/NosCore.PathFinder.csproj

@@ -12,7 +12,7 @@
 		<RepositoryUrl>https://github.com/NosCoreIO/NosCore.PathFinder.git</RepositoryUrl>
 		<PackageIconUrl></PackageIconUrl>
 		<PackageTags>nostale, noscore, nostale private server source, nostale emulator</PackageTags>
-		<Version>2.1.0</Version>
+		<Version>2.1.1</Version>
 		<PackageRequireLicenseAcceptance>false</PackageRequireLicenseAcceptance>
 		<Description>NosCore's PathFinder</Description>
 		<PackageLicenseExpression></PackageLicenseExpression>

src/NosCore.PathFinder/Pathfinder/GoalBasedPathfinder.cs

@@ -27,7 +27,7 @@ public GoalBasedPathfinder(IMapGrid mapGrid, IHeuristic heuristic)
 
         public GoalBasedPathfinder(IMapGrid mapGrid, IHeuristic heuristic, BrushFire brushfire) : this(mapGrid, heuristic)
         {
-            BrushFirecache.Set(brushfire.Origin, brushfire, DateTimeOffset.Now.AddSeconds(10));
+            BrushFirecache.Set((mapGrid, brushfire.Origin), brushfire, DateTimeOffset.Now.AddSeconds(10));
         }
 
         public IEnumerable<(short X, short Y)> FindPath((short X, short Y) start, (short X, short Y) end)
@@ -39,10 +39,10 @@ public GoalBasedPathfinder(IMapGrid mapGrid, IHeuristic heuristic, BrushFire bru
                 return list;
             }
 
-            if (!BrushFirecache.TryGetValue(end, out BrushFire brushFire))
+            if (!BrushFirecache.TryGetValue((_mapGrid, end), out BrushFire brushFire))
             {
                 brushFire = _mapGrid.LoadBrushFire(end, _heuristic);
-                BrushFirecache.Set(end, brushFire, DateTimeOffset.Now.AddSeconds(10));
+                BrushFirecache.Set((_mapGrid, end), brushFire, DateTimeOffset.Now.AddSeconds(10));
             }
 
             if (!brushFire.Distances.ContainsKey(start))

src/NosCore.PathFinder/Pathfinder/JumpPointSearchPathfinder.cs

@@ -59,15 +59,16 @@ public JumpPointSearchPathfinder(IMapGrid mapGrid, IHeuristic heuristic)
 
         public IEnumerable<(short X, short Y)> FindPath((short X, short Y) start, (short X, short Y) end)
         {
-            if (Cache.TryGetValue((start, end), out IEnumerable<(short X, short Y)>? cachedList))
+            // Keyed by grid too: the cache is shared by every pathfinder instance, one per map.
+            if (Cache.TryGetValue((_mapGrid, start, end), out IEnumerable<(short X, short Y)>? cachedList))
             {
                 return cachedList ?? Array.Empty<(short X, short Y)>();
             }
 
             var path = BuildFullPath(GetJumpList(start, end).ToList());
             for (var i = 0; i < path.Count; i++)
             {
-                Cache.Set((path[i], end), path.Skip(i), DateTimeOffset.Now.AddSeconds(10));
+                Cache.Set((_mapGrid, path[i], end), path.Skip(i + 1), DateTimeOffset.Now.AddSeconds(10));
             }
             return path;
         }

test/NosCore.PathFinder.Tests/JumpPointSearchPathfinderTests.cs

@@ -53,5 +53,51 @@ public void Test_JumpPointSearchPathfinder()
 
             TestHelper.VerifyFile("jump-point-search-pathfinder.png", image, listPixel, "Jump Point Search Pathfinder (break at walls)");
         }
+
+        [TestMethod]
+        public void ACachedPathStartsOnTheFirstStepLikeAFreshOne()
+        {
+            var pathfinder = new JumpPointSearchPathfinder(Walled(new[]
+            {
+                new byte[] { 0, 0, 0, 0, 0, 0 },
+            }), new OctileDistanceHeuristic());
+            var fresh = pathfinder.FindPath((1, 1), (6, 1)).ToList();
+
+            var cached = pathfinder.FindPath(fresh[0], (6, 1)).ToList();
+
+            CollectionAssert.AreEqual(fresh.Skip(1).ToList(), cached);
+        }
+
+        [TestMethod]
+        public void TwoMapsDoNotShareCachedPaths()
+        {
+            var open = new JumpPointSearchPathfinder(Walled(new[]
+            {
+                new byte[] { 0, 0, 0, 0, 0 },
+                new byte[] { 0, 0, 0, 0, 0 },
+            }), new OctileDistanceHeuristic());
+            var blocked = new JumpPointSearchPathfinder(Walled(new[]
+            {
+                new byte[] { 0, 0, 1, 0, 0 },
+                new byte[] { 0, 0, 0, 0, 0 },
+            }), new OctileDistanceHeuristic());
+
+            var straight = open.FindPath((1, 1), (5, 1)).ToList();
+            var around = blocked.FindPath(straight[0], (5, 1)).ToList();
+
+            Assert.Contains(((short)3, (short)1), straight);
+            Assert.DoesNotContain(((short)3, (short)1), around, "the blocked map must not reuse the open map's path through its wall");
+            Assert.AreEqual(((short)5, (short)1), around.Last());
+        }
+
+        private static TestMap Walled(byte[][] inside)
+        {
+            var width = inside[0].Length + 2;
+            var wall = Enumerable.Repeat((byte)1, width).ToArray();
+            return new TestMap(new[] { wall }
+                .Concat(inside.Select(row => new byte[] { 1 }.Concat(row).Append((byte)1).ToArray()))
+                .Append(wall)
+                .ToArray());
+        }
     }
 }