From 4902a321ea2d5037e1faa02eb7118a06e34e15c9 Mon Sep 17 00:00:00 2001
From: Azgaar <maxganiev@yandex.ru>
Date: Fri, 23 Jul 2021 20:48:38 +0300
Subject: [PATCH] river type - memoize what is small size for river

---
 modules/river-generator.js | 23 ++++++++++++++---------
 modules/ui/tools.js        |  3 +--
 2 files changed, 15 insertions(+), 11 deletions(-)

diff --git a/modules/river-generator.js b/modules/river-generator.js
index 3859ec9d..e86b5c64 100644
--- a/modules/river-generator.js
+++ b/modules/river-generator.js
@@ -388,14 +388,11 @@
   const specify = function () {
     const rivers = pack.rivers;
     if (!rivers.length) return;
-    Math.random = aleaPRNG(seed);
-    const thresholdElement = Math.ceil(rivers.length * 0.15);
-    const smallLength = rivers.map(r => r.length || 0).sort((a, b) => a - b)[thresholdElement];
 
-    for (const r of rivers) {
-      r.basin = getBasin(r.i);
-      r.name = getName(r.mouth);
-      r.type = getType(r, r.length < smallLength);
+    for (const river of rivers) {
+      river.basin = getBasin(river.i);
+      river.name = getName(river.mouth);
+      river.type = getType(river);
     }
   };
 
@@ -414,8 +411,16 @@
       small: {Branch: 1}
     }
   };
-  const getType = function (river, isSmall) {
-    const isFork = each(3)(river.i) && river.parent && river.parent !== river.i;
+
+  let smallLength = null;
+  const getType = function ({i, length, parent}) {
+    if (smallLength === null) {
+      const threshold = Math.ceil(pack.rivers.length * 0.15);
+      smallLength = pack.rivers.map(r => r.length || 0).sort((a, b) => a - b)[threshold];
+    }
+
+    const isSmall = length < smallLength;
+    const isFork = each(3)(i) && parent && parent !== i;
     return rw(riverTypes[isFork ? "fork" : "main"][isSmall ? "small" : "big"]);
   };
 
diff --git a/modules/ui/tools.js b/modules/ui/tools.js
index f358d517..5c13b6e3 100644
--- a/modules/ui/tools.js
+++ b/modules/ui/tools.js
@@ -639,8 +639,7 @@ function addRiverOnClick() {
   } else {
     const basin = Rivers.getBasin(parent);
     const name = Rivers.getName(mouth);
-    const smallLength = rivers.map(r => r.length || 0).sort((a, b) => a - b)[Math.ceil(pack.rivers.length * 0.15)];
-    const type = length < smallLength ? rw({Creek: 9, River: 3, Brook: 3, Stream: 1}) : "River";
+    const type = Rivers.getType({i: riverId, length, parent});
 
     rivers.push({i: riverId, source, mouth, discharge, length, width, widthFactor, sourceWidth, parent, cells: riverCells, basin, name, type});
   }