From fd782219eff8016a00e87f0c8e44af3a3ba74be6 Mon Sep 17 00:00:00 2001
From: Max Isom <hi@maxisom.me>
Date: Sun, 19 Sep 2021 22:04:34 -0400
Subject: Move to ESM, use ytsr, implement caching

Closes #315
---
 src/services/cache.ts | 52 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 52 insertions(+)
 create mode 100644 src/services/cache.ts

(limited to 'src/services/cache.ts')

diff --git a/src/services/cache.ts b/src/services/cache.ts
new file mode 100644
index 0000000..d76eab9
--- /dev/null
+++ b/src/services/cache.ts
@@ -0,0 +1,52 @@
+import {injectable} from 'inversify';
+import {Cache} from '../models/index.js';
+import debug from '../utils/debug.js';
+
+type Seconds = number;
+
+type Options = {
+  expiresIn: Seconds;
+  key?: string;
+};
+
+const futureTimeToDate = (time: Seconds) => new Date(new Date().getTime() + (time * 1000));
+
+@injectable()
+export default class CacheProvider {
+  async wrap<T extends [...any[], Options], F>(func: (...options: any) => Promise<F>, ...options: T): Promise<F> {
+    if (options.length === 0) {
+      throw new Error('Missing cache options');
+    }
+
+    const functionArgs = options.slice(0, options.length - 1);
+
+    const {
+      key = JSON.stringify(functionArgs),
+      expiresIn
+    } = options[options.length - 1] as Options;
+
+    const cachedResult = await Cache.findByPk(key);
+
+    if (cachedResult) {
+      if (new Date() < cachedResult.expiresAt) {
+        debug(`Cache hit: ${key}`);
+        return JSON.parse(cachedResult.value);
+      }
+
+      await cachedResult.destroy();
+    }
+
+    debug(`Cache miss: ${key}`);
+
+    const result = await func(...options as any[]);
+
+    // Save result
+    await Cache.upsert({
+      key,
+      value: JSON.stringify(result),
+      expiresAt: futureTimeToDate(expiresIn)
+    });
+
+    return result;
+  }
+}
-- 
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