From 10cdd2c77ebc464a58507227a2f1f5462cd80161 Mon Sep 17 00:00:00 2001
From: Paul Chavard <paul.chavard@beta.gouv.fr>
Date: Wed, 16 Jun 2021 09:28:07 +0200
Subject: [PATCH] Apply suggestions from code review

Co-authored-by: Pierre de La Morinerie <kemenaran@gmail.com>
---
 app/javascript/components/ComboCommunesSearch.jsx | 12 ++++++++++--
 app/javascript/components/shared/queryClient.js   |  8 ++++++--
 2 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/app/javascript/components/ComboCommunesSearch.jsx b/app/javascript/components/ComboCommunesSearch.jsx
index 81d9e1d9d..5216bae03 100644
--- a/app/javascript/components/ComboCommunesSearch.jsx
+++ b/app/javascript/components/ComboCommunesSearch.jsx
@@ -3,16 +3,24 @@ import { QueryClientProvider } from 'react-query';
 import { matchSorter } from 'match-sorter';
 
 import ComboSearch from './ComboSearch';
-import { queryClient } from './shared/queryClient';
+import { queryClient, searchResultsLimit } from './shared/queryClient';
 
 function expandResultsWithMultiplePostalCodes(term, results) {
+  // A single result may have several associated postal codes.
+  // To make the search results more precise, we want to generate
+  // an actual result for each postal code.
   const expandedResults = results.flatMap((result) =>
     result.codesPostaux.map((codePostal) => ({
       ...result,
       codesPostaux: [codePostal]
     }))
   );
-  const limit = term.length > 5 ? 10 : 5;
+
+  // Some very large cities (like Paris) have A LOT of associated postal codes.
+  // As we generated one result per postal code, we now have a lot of results
+  // for the same city. If the number of results is above the threshold, we use
+  // local search to narrow the results.
+  const limit = searchResultsLimit(term);
   if (expandedResults.length > limit) {
     return matchSorter(expandedResults, term, {
       keys: [(item) => `${item.nom} (${item.codesPostaux[0]})`, 'code'],
diff --git a/app/javascript/components/shared/queryClient.js b/app/javascript/components/shared/queryClient.js
index a39b37fc9..b651dc22a 100644
--- a/app/javascript/components/shared/queryClient.js
+++ b/app/javascript/components/shared/queryClient.js
@@ -13,6 +13,11 @@ export const queryClient = new QueryClient({
   }
 });
 
+// Avoid hiding similar matches for precise queries (like "Sainte Marie")
+export function searchResultsLimit(term) {
+  return term.length > 5 ? 10 : 5;
+}
+
 function buildURL(scope, term) {
   term = encodeURIComponent(term.replace(/\(|\)/g, ''));
   if (scope === 'adresse') {
@@ -23,8 +28,7 @@ function buildURL(scope, term) {
     if (isNumeric(term)) {
       return `${api_geo_url}/communes?codePostal=${term}&limit=5`;
     }
-    // Avoid hiding similar matches for precise queries (like "Sainte Marie")
-    const limit = term.length > 5 ? 10 : 5;
+    const limit = searchResultsLimit(term);
     return `${api_geo_url}/communes?nom=${term}&boost=population&limit=${limit}`;
   } else if (isNumeric(term)) {
     const code = term.padStart(2, '0');