From b83f464f12166191bef2fa85e33e07360da0df3b Mon Sep 17 00:00:00 2001
From: OneEuroQuestion <mike@oneeuroquestion.com>
Date: Thu, 4 Jan 2024 17:23:03 +0200
Subject: [PATCH] adding missing file

---
 src/queryCache.ts | 77 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 77 insertions(+)
 create mode 100644 src/queryCache.ts

diff --git a/src/queryCache.ts b/src/queryCache.ts
new file mode 100644
index 0000000..a29b530
--- /dev/null
+++ b/src/queryCache.ts
@@ -0,0 +1,77 @@
+// src/queryCache.ts
+
+import { FastifyRequest, FastifyReply } from 'fastify';
+import url from 'url';
+
+interface CacheEntry {
+    isFetching: boolean;
+    data: any;
+    expiry: number;
+}
+
+class RequestCache {
+    cache: Record<string, CacheEntry> = {};
+
+    async getOrFetchData(request: FastifyRequest, reply: FastifyReply, handler: (request: FastifyRequest, reply: FastifyReply) => Promise<any>) {
+        const key = url.parse(request.url).pathname || request.url;
+
+        if (key === '') {
+            console.error('QueryCache: Error: Key is an empty string');
+            throw new Error('Key cannot be an empty string');
+        }
+
+        if (!this.cache[key]) {
+            console.log(`QueryCache: No cache entry for ${key}. Fetching data...`);
+            await this.tryFetchData(key, request, reply, handler);
+
+        } else if (this.cache[key].isFetching) {
+            console.log(`QueryCache: Data for ${key} is currently being fetched...`);
+
+        } else if (Date.now() > this.cache[key].expiry) {
+            console.log(`QueryCache: Cache entry for ${key} has expired. Refreshing...`);
+            this.tryFetchData(key, request, reply, handler);
+        }
+
+        return this.cache[key]?.data || {};
+    }
+
+    async tryFetchData(key: string, request: FastifyRequest, reply: FastifyReply, handler: (request: FastifyRequest, reply: FastifyReply) => Promise<any>, retryCount: number = 0) {
+        if (this.cache[key]) {
+            // If the key exists, only update the properties
+            this.cache[key].isFetching = true;
+            this.cache[key].expiry = Date.now() + Math.floor(Math.random() * (25 - 15 + 1) + 15) * 1000; // Random number between 15 and 25 seconds
+        } else {
+            // If the key doesn't exist, create a new entry
+            this.cache[key] = {
+                isFetching: true,
+                data: {},
+                expiry: Date.now() + Math.floor(Math.random() * (25 - 15 + 1) + 15) * 1000, // Random number between 15 and 25 seconds
+            };
+        }
+
+        try {
+            console.time(`QueryCache: handler execution time for ${key}`);
+            const data = await handler(request, reply);
+            console.timeEnd(`QueryCache: handler execution time for ${key}`);
+            this.cache[key].data = data;
+            this.cache[key].isFetching = false;
+            console.log(`QueryCache: Data fetched for ${key}`);
+        } catch (error) {
+            console.log(`QueryCache: Error fetching data for ${key} on attempt ${retryCount + 1}`);
+            this.cache[key].isFetching = false;
+            if (retryCount < 2) { // If it's not the last attempt
+                setTimeout(() => {
+                    this.tryFetchData(key, request, reply, handler, retryCount + 1); 
+                }, 1000);
+            }
+        }
+    }
+
+    handleRequestWithCache(handler: (request: FastifyRequest, reply: FastifyReply) => Promise<any>): (request: FastifyRequest, reply: FastifyReply) => Promise<any> {
+        return async (request: FastifyRequest, reply: FastifyReply) => {
+            return await this.getOrFetchData(request, reply, handler);
+        };
+    }
+}
+
+export default RequestCache;
\ No newline at end of file