From fa548b31e1ce27dd6b40f0c223191efae3d86ae6 Mon Sep 17 00:00:00 2001
From: kartikvirendrar <kartikrajput357@gmail.com>
Date: Sat, 20 Jul 2024 17:30:16 +0530
Subject: [PATCH] added caching mechanism for suggestions

---
 package.json                 |  2 +-
 src/index.tsx                |  8 ++--
 src/util/suggestions-util.ts | 88 ++++++++++++++++++++++++++++++++----
 3 files changed, 84 insertions(+), 14 deletions(-)

diff --git a/package.json b/package.json
index c70ec92..ed2916f 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@ai4bharat/indic-transliterate",
-  "version": "1.3.3",
+  "version": "1.3.4",
   "description": "Transliterate component for React",
   "author": "AI4Bharat",
   "license": "MIT",
diff --git a/src/index.tsx b/src/index.tsx
index 8221e8a..e07594d 100644
--- a/src/index.tsx
+++ b/src/index.tsx
@@ -135,12 +135,12 @@ export const IndicTransliterate = ({
     // fetch suggestion from api
     // const url = `https://www.google.com/inputtools/request?ime=transliteration_en_${lang}&num=5&cp=0&cs=0&ie=utf-8&oe=utf-8&app=jsapi&text=${lastWord}`;
 
-    const numOptions = showCurrentWordAsLastSuggestion
-      ? maxOptions - 1
-      : maxOptions;
+    // const numOptions = showCurrentWordAsLastSuggestion
+    //   ? maxOptions - 1
+    //   : maxOptions;
 
     const data = await getTransliterateSuggestions(lastWord, customApiURL, {
-      numOptions,
+      // numOptions,
       showCurrentWordAsLastSuggestion,
       lang,
     });
diff --git a/src/util/suggestions-util.ts b/src/util/suggestions-util.ts
index b22e483..c80e249 100644
--- a/src/util/suggestions-util.ts
+++ b/src/util/suggestions-util.ts
@@ -1,26 +1,70 @@
 import { Language } from "../types/Language";
 
 type Config = {
-  numOptions?: number;
+  // numOptions?: number;
   showCurrentWordAsLastSuggestion?: boolean;
   lang?: Language;
 };
 
+type CacheEntry = {
+  suggestions: string[];
+  frequency: number;
+};
+
+const MAX_CACHE_SIZE = 1000;
+const SAVE_THRESHOLD = 20;
+const CACHE_KEY = 'transliterateCache';
+
+const cache: Record<string, Record<string, CacheEntry>> = loadCacheFromLocalStorage();
+let newEntriesCount = 0;
+
+function loadCacheFromLocalStorage(): Record<string, Record<string, CacheEntry>> {
+  const cachedData = localStorage.getItem(CACHE_KEY);
+  return cachedData ? JSON.parse(cachedData) : {};
+}
+
+function saveCacheToLocalStorage() {
+  localStorage.setItem(CACHE_KEY, JSON.stringify(cache));
+}
+
+const getWordWithLowestFrequency = (dictionary: Record<string, CacheEntry>): string | null => {
+  let lowestFreqWord: string | null = null;
+  let lowestFreq = Infinity;
+
+  for (const word in dictionary) {
+    if (dictionary[word].frequency < lowestFreq) {
+      lowestFreq = dictionary[word].frequency;
+      lowestFreqWord = word;
+    }
+  }
+
+  return lowestFreqWord;
+};
+
 export const getTransliterateSuggestions = async (
   word: string,
   customApiURL: string,
   config?: Config,
 ): Promise<string[] | undefined> => {
-  const { showCurrentWordAsLastSuggestion, lang } = config || {
-    numOptions: 5,
-    showCurrentWordAsLastSuggestion: true,
-    lang: "hi",
-  };
+  const {
+    // numOptions = 5,
+    showCurrentWordAsLastSuggestion = true,
+    lang = "hi",
+  } = config || {};
   // fetch suggestion from api
   // const url = `https://www.google.com/inputtools/request?ime=transliteration_en_${lang}&num=5&cp=0&cs=0&ie=utf-8&oe=utf-8&app=jsapi&text=${word}`;
   // let myHeaders = new Headers();
   // myHeaders.append("Content-Type", "application/json");
 
+  if (!cache[lang]) {
+    cache[lang] = {};
+  }
+
+  if (cache[lang][word]) {
+    cache[lang][word].frequency += 1;
+    return cache[lang][word].suggestions;
+  }
+
   const requestOptions = {
     method: "GET",
   };
@@ -37,17 +81,41 @@ export const getTransliterateSuggestions = async (
     );
     let data = await res.json();
     console.log("library data", data);
-    if(!customApiURL.includes("xlit-api")){
+    if (!customApiURL.includes("xlit-api")) {
       data.result = data.output[0].target;
     }
     if (data && data.result.length > 0) {
       const found = showCurrentWordAsLastSuggestion
         ? [...data.result, word]
         : data.result;
+
+      if (Object.keys(cache[lang]).length >= MAX_CACHE_SIZE) {
+        const lowestFreqWord = getWordWithLowestFrequency(cache[lang]);
+        if (lowestFreqWord) {
+          delete cache[lang][lowestFreqWord];
+        }
+      }
+
+      cache[lang][word] = {
+        suggestions: found,
+        frequency: 1,
+      };
+
+      newEntriesCount += 1;
+      if (newEntriesCount >= SAVE_THRESHOLD) {
+        saveCacheToLocalStorage();
+        newEntriesCount = 0;
+      }
+
       return found;
     } else {
       if (showCurrentWordAsLastSuggestion) {
-        return [word];
+        const fallback = [word];
+        cache[lang][word] = {
+          suggestions: fallback,
+          frequency: 1,
+        };
+        return fallback;
       }
       return [];
     }
@@ -56,4 +124,6 @@ export const getTransliterateSuggestions = async (
     console.error("There was an error with transliteration", e);
     return [];
   }
-};
\ No newline at end of file
+};
+
+window.addEventListener('beforeunload', saveCacheToLocalStorage);
\ No newline at end of file