Early work for token cache implementation

TokenCache.ts

@@ -0,0 +1,42 @@
+import * as fs from 'fs';
+const jwtDecode = require('jwt-decode');
+
+export class TokenCache {
+
+    public Read(): string | null {
+        let token = null;
+        try {
+            token = fs.readFileSync(".token_cache", "utf8");
+        }
+        catch (e) {
+            console.error(e);
+            
+            return null;
+        }
+
+        interface Jwt {
+            [key: string]: any
+        }
+
+        const decodedJwt: Jwt = jwtDecode(token);
+
+        let now = Math.floor(Date.now() / 1000);
+        let exp = decodedJwt["exp"];
+        let timeLeft = exp - now;
+
+        if (timeLeft < 120) {
+            return null;
+        }
+
+        return token;
+    }
+
+    public Write(token: string): void {
+        fs.writeFile(".token_cache", token, (err: any) => {
+            if (err) {
+                return console.error(err);
+            }
+            console.log("Fresh access token dropped into .token_cache");
+        });
+    }
+}