Bug fix on submap with rivers with river.parent not visible in the new map (#1431)

* fixing issue 1411

* bug fix : getBasin() does not check if the river parent exists. added a getParent() function that retuns the current river id of the parent does not exists.
bug fix : submap removes rivers not visible in the new map but does not modify river.parent of children rivers. This fix forces river.parent and river.basin to river.i in that case

Author: EltakaTrollBait

src/modules/resample.ts

@@ -184,6 +184,7 @@ class Resampler {
       .filter((river) => river !== null);
 
     pack.rivers.forEach((river) => {
+      river.parent = Rivers.getParent(river.i);
       river.basin = Rivers.getBasin(river.i);
       river.length = Rivers.getApproximateLength(river.points);
     });

src/modules/river-generator.ts

@@ -558,6 +558,7 @@ class RiverModule {
     if (!rivers.length) return;
 
     for (const river of rivers) {
+      river.parent = this.getParent(river.i);
       river.basin = this.getBasin(river.i);
       river.name = this.getName(river.mouth);
       river.type = this.getType(river);
@@ -616,11 +617,18 @@ class RiverModule {
     pack.rivers = pack.rivers.filter((r) => !riversToRemove.includes(r.i));
   }
 
+  getParent(r: number): number {
+    const parent = pack.rivers.find(river => river.i === r)?.parent;
+    if (!parent || parent === r) return r;
+    if (!pack.rivers.some(river => river.i === parent)) return r;
+    return parent;
+  };
+
   getBasin(r: number): number {
-    const parent = pack.rivers.find((river) => river.i === r)?.parent;
-    if (!parent || r === parent) return r;
+    const parent = this.getParent(r);
+    if (parent === r) return r;
     return this.getBasin(parent);
-  }
+  };
 
   getNextId(rivers: { i: number }[]) {
     return rivers.length ? Math.max(...rivers.map((r) => r.i)) + 1 : 1;