Fix shuffling locations bugs and update World map to remove invalid locations

Author: codergautam

api/map/mapHome.js

@@ -2,6 +2,7 @@ import sendableMap from "../../components/utils/sendableMap.js";
 import Map from "../../models/Map.js";
 import User from "../../models/User.js";
 import officialCountryMaps from '../../public/officialCountryMaps.json' with { type: "json" };
+import shuffle from "../../utils/shuffle.js";
 
 let mapCache = {
   popular: {
@@ -160,7 +161,7 @@ export default async function handler(req, res) {
 
       // for spotlight randomize the order
       if(method === "spotlight") {
-        response[method] = response[method].sort(() => Math.random() - 0.5);
+        response[method] = shuffle(response[method]);
       }
     } else {
       // retrieve from db
@@ -208,7 +209,7 @@ export default async function handler(req, res) {
       response[method] = sendableMaps;
       // if spotlight, randomize the order
       if(method === "spotlight") {
-        response[method] = response[method].sort(() => Math.random() - 0.5);
+        response[method] = shuffle(response[method]);
       }
 
       mapCache[method].data = sendableMaps;

components/home.js

@@ -8,6 +8,7 @@ import { useEffect, useState, useRef } from "react";
 import Navbar from "@/components/ui/navbar";
 import GameUI from "@/components/gameUI";
 import BannerText from "@/components/bannerText";
+import shuffle from "@/utils/shuffle";
 // findLatLongRandom is dynamically imported when needed to avoid loading Google Maps API on page load
 import Link from "next/link";
 import MultiplayerHome from "@/components/multiplayerHome";
@@ -2088,7 +2089,7 @@ export default function Home({ }) {
             let options = JSON.parse(JSON.stringify(onboarding.locations[onboarding.round - 1].otherOptions));
             options.push(onboarding.locations[onboarding.round - 1].country)
             // shuffle
-            options = options.sort(() => Math.random() - 0.5)
+            options = shuffle(options)
             setOtherOptions(options)
         } else {
             async function defaultMethod() {
@@ -2129,8 +2130,11 @@ export default function Home({ }) {
                             }
                         }
 
-                        // shuffle data.locations
-                        data.locations = data.locations.sort(() => Math.random() - 0.5)
+                        // Fisher-Yates shuffle (unbiased)
+                        for (let i = data.locations.length - 1; i > 0; i--) {
+                            const j = Math.floor(Math.random() * (i + 1));
+                            [data.locations[i], data.locations[j]] = [data.locations[j], data.locations[i]];
+                        }
 
 
                         setAllLocsArray(data.locations)
@@ -2185,24 +2189,18 @@ export default function Home({ }) {
                 if ((locIndex === -1) || allLocsArray.length === 1) {
                     fetchMethod()
                 } else {
-                    if (gameOptions.location === "all") {
-                        const loc = allLocsArray[locIndex + 1] ?? allLocsArray[0];
-                        setLatLong(loc);
-                    } else {
-                        // prevent repeats: remove the prev location from the array
-                        setAllLocsArray((prev) => {
-                            const newArr = prev.filter((l) => l.lat !== latLong.lat && l.long !== latLong.long)
-
-
-                            // community maps are randomized
-                            const loc = newArr[Math.floor(Math.random() * newArr.length)];
+                    // prevent repeats: remove the prev location from the array (for both all and community maps)
+                    setAllLocsArray((prev) => {
+                        const newArr = prev.filter((l) => l.lat !== latLong.lat || l.long !== latLong.long);
 
+                        // Pick next location
+                        const loc = gameOptions.location === "all"
+                            ? newArr[0]  // World map: take first from shuffled remaining
+                            : newArr[Math.floor(Math.random() * newArr.length)];  // Community: random
 
-                            setLatLong(loc);
-                            return newArr;
-                        })
-
-                    }
+                        setLatLong(loc);
+                        return newArr;
+                    })
                 }
 
             }

cron.js

@@ -595,7 +595,7 @@ app.get('/clueCountries.json', (req, res) => {
   if (clueLocations.length === 0) {
     return res.json({ ready: false });
   } else {
-    return res.json({ ready: true, locations: clueLocations.sort(() => Math.random() - 0.5) });
+    return res.json({ ready: true, locations: shuffle([...clueLocations]) });
   }
 });
 

public/world-main.json

@@ -31,6 +31,7 @@ import countries from './public/countries.json' with { type: "json" };
 
 // colors
 import colors from 'colors';
+import shuffle from './utils/shuffle.js';
 
 // express
 import express from 'express';
@@ -212,7 +213,7 @@ app.get('/countryLocations/:country', (req, res) => {
   } else {
 
     if( rawOverrides[req.params.country]) {
-      countryLocations[req.params.country].locations = rawOverrides[req.params.country].customCoordinates.sort(() => Math.random() - 0.5).slice(0, 1000).map(loc => {
+      countryLocations[req.params.country].locations = shuffle(rawOverrides[req.params.country].customCoordinates).slice(0, 1000).map(loc => {
         return {
           lat: loc.lat,
           long: loc.lng,

server.js

@@ -0,0 +1,10 @@
+// Fisher-Yates shuffle (unbiased)
+// Returns a new shuffled array without modifying the original
+export default function shuffle(arr) {
+  const result = [...arr];
+  for (let i = result.length - 1; i > 0; i--) {
+    const j = Math.floor(Math.random() * (i + 1));
+    [result[i], result[j]] = [result[j], result[i]];
+  }
+  return result;
+}

utils/shuffle.js

@@ -15,6 +15,7 @@ import { setElo } from "../../api/eloRank.js";
 import GameModel from "../../models/Game.js";
 import User from "../../models/User.js";
 import UserStatsService from "../../components/utils/userStatsService.js";
+import shuffle from "../../utils/shuffle.js";
 
 export default class Game {
   constructor(id, publicLobby, location="all", rounds=5, allLocations, isDuel=false) {
@@ -611,7 +612,7 @@ export default class Game {
           key: 'notEnoughLocationsInMap'
         });
       }
-      locs = locs.sort(() => Math.random() - 0.5).slice(0, this.rounds).map((loc) => ({
+      locs = shuffle(locs).slice(0, this.rounds).map((loc) => ({
         // lng -> long
         ...loc,
         long: loc.lng,