From 85a9f4b948523b2b9dfb698d108660bda775c61b Mon Sep 17 00:00:00 2001
From: Marc Emmanuel <marc.emmanuel@tado.com>
Date: Sun, 25 Jan 2026 19:35:48 +0100
Subject: [PATCH] refactor: update shoreline calculation and improve type
 imports in PackedGraph

---
 src/modules/features.ts  | 10 +++++++---
 src/types/PackedGraph.ts |  6 +++---
 src/utils/polyfills.ts   |  2 +-
 3 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/src/modules/features.ts b/src/modules/features.ts
index c85931f3..bedb48ff 100644
--- a/src/modules/features.ts
+++ b/src/modules/features.ts
@@ -1,4 +1,4 @@
-import { clipPoly, connectVertices, createTypedArray, distanceSquared, isLand, isWater, rn, TYPED_ARRAY_MAX_VALUES,unique } from "../utils";
+import { clipPoly, connectVertices, createTypedArray, distanceSquared, isLand, isWater, rn, TYPED_ARRAY_MAX_VALUES, unique } from "../utils";
 import Alea from "alea";
 import { polygonArea } from "d3";
 
@@ -194,7 +194,12 @@ class FeatureModule {
 
       if (type === "lake") {
         if (area > 0) feature.vertices = (feature.vertices as number[]).reverse();
-        feature.shoreline = unique((feature.vertices as number[]).map(vertex => vertices.c[vertex].filter((index: number) => isLand(index, pack))).flat() || []);
+        feature.shoreline = unique(
+          (feature.vertices as number[])
+            .flatMap(
+              vertexIndex => vertices.c[vertexIndex].filter((index) => isLand(index, pack))
+            )
+        );
         feature.height = Lakes.getHeight(feature as PackedGraphFeature);
       }
 
@@ -228,7 +233,6 @@ class FeatureModule {
       while (queue.length) {
         const cellId = queue.pop() as number;
         if (borderCells[cellId]) border = true;
-        if (!border && borderCells[cellId]) border = true;
 
         for (const neighborId of neighbors[cellId]) {
           const isNeibLand = isLand(neighborId, pack);
diff --git a/src/types/PackedGraph.ts b/src/types/PackedGraph.ts
index c058520e..23f464df 100644
--- a/src/types/PackedGraph.ts
+++ b/src/types/PackedGraph.ts
@@ -1,5 +1,5 @@
-import { PackedGraphFeature } from "../modules/features";
-import { River } from "../modules/river-generator";
+import type { PackedGraphFeature } from "../modules/features";
+import type { River } from "../modules/river-generator";
 
 
 type TypedArray = Uint8Array | Uint16Array | Uint32Array | Int8Array | Int16Array | Float32Array | Float64Array;
@@ -25,7 +25,7 @@ export interface PackedGraph {
   };
   vertices: {
     i: number[]; // vertex indices
-    c: number[][]; // neighboring cells
+    c: [number, number, number][]; // neighboring cells
     v: number[][]; // neighboring vertices
     x: number[]; // x coordinates
     y: number[]; // y coordinates
diff --git a/src/utils/polyfills.ts b/src/utils/polyfills.ts
index 89a0d2d9..18f5f1bd 100644
--- a/src/utils/polyfills.ts
+++ b/src/utils/polyfills.ts
@@ -44,7 +44,7 @@ declare global {
   }
 
   interface Array<T> {
-    flat(depth?: number): T;
+    flat(depth?: number): T[];
     at(index: number): T | undefined;
   }