added code

index.js

@@ -1,27 +1,85 @@
 const Router = require('./router')
+const aesjs = require('aes-js');
 
-/**
- * Example of how router can be used in an application
- *  */
 addEventListener('fetch', event => {
     event.respondWith(handleRequest(event.request))
 })
 
-function handler(request) {
-    const init = {
-        headers: { 'content-type': 'application/json' },
+const AESKEY = [106, 111, 54, 97, 101, 121, 54, 104, 97, 105, 100, 50, 84, 101, 105, 104]
+
+url_gen = {
+    "cipher": new aesjs.ModeOfOperation.ecb(AESKEY),
+    "resolve": async function(md5_origin, format, id, media_version) {  // Track URL generation function
+        result = [md5_origin, format, id, media_version].join('\xa4')
+
+        var buf = new ArrayBuffer(result.length);
+        var result_hash = new Uint8Array(buf);
+        for (var i=0; i < result.length; i++) {
+            result_hash[i] = result.charCodeAt(i);
+        }
+        result_hash = await crypto.subtle.digest('MD5', result_hash)
+        result_hash = Array.from(new Uint8Array(result_hash))
+        result_hash = result_hash.reduce(function(previous, current) {
+            return previous + "0".concat(current.toString(16)).substr(-2, 2);
+        }, ''),
+
+        result = result_hash + '\xa4' + result + '\xa4'
+
+        // padding
+        result += '\x00'.repeat(result.length % 16 ? 16 - result.length % 16 : 0)
+
+        // converting to array for encryption / hex string
+        result = Array.from(result).map(function(item) {
+            return item.charCodeAt(0);
+        })
+        // encryption / hex string
+        result = (result = url_gen.cipher.encrypt(result)).reduce(function(previous, current) {
+            return previous + "0".concat(current.toString(16)).substr(-2, 2);
+        }, '')
+
+        // cdn template with first character of md5 string + hash
+        return `https://e-cdns-proxy-${md5_origin[0]}.dzcdn.net/api/1/${result}`
     }
-    const body = JSON.stringify({ some: 'json' })
-    return new Response(body, init)
+}
+
+async function track(request) {
+    const id = request.url.split('/')[4]
+
+    if (id === "") {
+        return new Response("Track ID needs to be specified", {status: 400, headers: {'content-type': "text/plain"}})
+    }
+
+    access_token = await KV.get("access_token")
+    if (access_token === null) {
+        const response = await fetch("https://connect.deezer.com/oauth/access_token.php?grant_type=client_credentials&client_id=447462&client_secret=a83bf7f38ad2f137e444727cfc3775cf&output=json")
+        const json = await response.json()
+        if (json.error !== undefined) {
+            return new Response("Couldn't get access token from Deezer", {status: 500, headers: {'content-type': "text/plain"}})
+        }
+
+        access_token = json.access_token
+        await KV.put("access_token", access_token, {expirationTtl: Number(json.expires)})
+    }
+    
+    const response = await fetch(`https://api.deezer.com/track/${id}?access_token=${access_token}`)
+    const json = await response.json()
+    if (json.error !== undefined) {
+        return new Response(JSON.stringify(json.error), {status: 403, headers: {'content-type': "application/json"}})
+    }
+
+    const md5_origin = json.md5_origin
+    const format = "3"
+    const media_version = json.media_version
+
+    const url = await url_gen.resolve(md5_origin, format, id, media_version)
+
+    return new Response(null, {status: 302, headers: {'location': url}})
 }
 
 async function handleRequest(request) {
     const r = new Router()
     // Replace with the appropriate paths and handlers
-    r.get('.*/bar', () => new Response('responding for /bar'))
-    r.get('.*/foo', request => handler(request))
-    r.post('.*/foo.*', request => handler(request))
-    r.get('/demos/router/foo', request => fetch(request)) // return the response from the origin
+    r.get('/track/.*', () => track(request))
 
     r.get('/', () => new Response('Hello worker!')) // return a default message for the root route