Example plugin for Spotify top artist

examples/spotify/config.json

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+{
+    "title": "Spotify Top Artist",
+    "description": "Notarize your favorite artist on Spotify",
+    "steps": [
+        {
+            "title": "Visit Spotify webplayer",
+            "cta": "Go",
+            "action": "start"
+        },
+        {
+            "title": "Collect credentials",
+            "description": "Login to your account if you haven't already",
+            "cta": "Go",
+            "action": "two"
+        },
+        {
+            "title": "Notarize",
+            "cta": "Notarize",
+            "action": "three",
+            "prover": true
+        }
+    ],
+    "hostFunctions": [
+        "redirect",
+        "notarize"
+    ],
+    "cookies": [],
+    "headers": [
+        "api.spotify.com"
+    ],
+    "requests": [
+        {
+            "url": "https://api.spotify.com/v1/me/top/artists?time_range=medium_term&limit=1",
+            "method": "GET"
+        }
+    ]
+}

examples/spotify/esbuild.js

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+const esbuild = require('esbuild');
+const path = require('path');
+const { name } = require('./package.json');
+const { execSync } = require('child_process');
+
+const outputDir = 'dist';
+const entryFile = 'src/index.ts';
+const outputFile = path.join(outputDir, 'index.js');
+const outputWasm = path.join(outputDir, `${name}.tlsn.wasm`);
+
+async function build() {
+  try {
+    await esbuild.build({
+      entryPoints: [entryFile],
+      bundle: true,
+      outdir: outputDir, // Use outdir for directory output
+      sourcemap: true,
+      minify: false, // might want to use true for production build
+      format: 'cjs', // needs to be CJS for now
+      target: ['es2020'], // don't go over es2020 because quickjs doesn't support it
+      loader: {'.png': 'dataurl'}
+    });
+
+    console.log('esbuild completed successfully.');
+
+    // Run extism-js to generate the wasm file
+    const extismCommand = `extism-js ${outputFile} -i src/index.d.ts -o ${outputWasm}`;
+    execSync(extismCommand, { stdio: 'inherit' });
+    console.log('extism-js completed successfully.');
+  } catch (error) {
+    console.error('Build process failed:', error);
+    process.exit(1);
+  }
+}
+
+build();

examples/spotify/package.json

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+{
+  "name": "spotify_top_artist",
+  "version": "1.0.0",
+  "description": "Demo TLSNotary plugin to notarize your top artist on Spotify",
+  "main": "src/index.ts",
+  "scripts": {
+    "build": "node esbuild.js"
+  },
+  "keywords": [],
+  "author": "TLSNotary",
+  "license": "MIT",
+  "devDependencies": {
+    "@extism/js-pdk": "^1.0.1",
+    "esbuild": "^0.19.6",
+    "typescript": "^5.3.2"
+  }
+}

examples/spotify/src/index.d.ts

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+declare module 'main' {
+    // Extism exports take no params and return an I32
+    export function start(): I32;
+    export function two(): I32;
+    export function three(): I32;
+    export function config(): I32;
+}
+
+declare module 'extism:host' {
+    interface user {
+        redirect(ptr: I64): void;
+        notarize(ptr: I64): I64;
+    }
+}

examples/spotify/src/index.ts

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+import icon from '../assets/icon.png';
+import config_json from '../config.json';
+import { redirect, notarize, outputJSON, getCookiesByHost, getHeadersByHost } from './utils/hf.js';
+
+/**
+ * Plugin configuration
+ * This configurations defines the plugin, most importantly:
+ *  * the different steps
+ *  * the user data (headers, cookies) it will access
+ *  * the web requests it will query (or notarize)
+ */
+export function config() {
+  outputJSON({
+    ...config_json,
+    icon: icon
+  });
+}
+
+function isValidHost(urlString: string) {
+  const url = new URL(urlString);
+  return url.hostname === 'open.spotify.com';
+}
+
+/**
+ * Implementation of the first (start) plugin step
+  */
+export function start() {
+  if (!isValidHost(Config.get('tabUrl'))) {
+    redirect('https://open.spotify.com');
+    outputJSON(false);
+    return;
+  }
+  outputJSON(true);
+}
+
+/**
+ * Implementation of step "two".
+ * This step collects and validates authentication cookies and headers for 'api.x.com'.
+ * If all required information, it creates the request object.
+ * Note that the url needs to be specified in the `config` too, otherwise the request will be refused.
+ */
+export function two() {
+  const headers = getHeadersByHost('api.spotify.com');
+
+  if (
+    !headers['authorization']
+  ) {
+    outputJSON(false);
+    return;
+  }
+
+  outputJSON({
+    url: 'https://api.spotify.com/v1/me/top/artists?time_range=medium_term&limit=1',
+    method: 'GET',
+    headers: {
+      'x-twitter-client-language': 'en',
+      'x-csrf-token': headers['x-csrf-token'],
+      Host: 'api.x.com',
+      authorization: headers.authorization,
+      Connection: 'close',
+    },
+    secretHeaders: [
+      `authorization: ${headers.authorization}`,
+    ],
+  });
+}
+
+/**
+ * Step 3: calls the `notarize` host function
+ */
+export function three() {
+  const params = JSON.parse(Host.inputString());
+
+  if (!params) {
+    outputJSON(false);
+  } else {
+    const id = notarize({
+      ...params,
+    });
+    outputJSON(id);
+  }
+}

examples/spotify/src/utils/hf.js

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+function redirect(url) {
+  const { redirect } = Host.getFunctions();
+  const mem = Memory.fromString(url);
+  redirect(mem.offset);
+}
+
+function notarize(options) {
+  const { notarize } = Host.getFunctions();
+  const mem = Memory.fromString(JSON.stringify(options));
+  const idOffset = notarize(mem.offset);
+  const id = Memory.find(idOffset).readString();
+  return id;
+}
+
+function outputJSON(json) {
+  Host.outputString(
+    JSON.stringify(json),
+  );
+}
+
+function getCookiesByHost(hostname) {
+  const cookies = JSON.parse(Config.get('cookies'));
+  if (!cookies[hostname]) throw new Error(`cannot find cookies for ${hostname}`);
+  return cookies[hostname];
+}
+
+function getHeadersByHost(hostname) {
+  const headers = JSON.parse(Config.get('headers'));
+  if (!headers[hostname]) throw new Error(`cannot find headers for ${hostname}`);
+  return headers[hostname];
+}
+
+module.exports = {
+  redirect,
+  notarize,
+  outputJSON,
+  getCookiesByHost,
+  getHeadersByHost,
+};

examples/spotify/tsconfig.json

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+{
+    "compilerOptions": {
+        "lib": [],
+        "types": [
+            "@extism/js-pdk"
+        ],
+        "noEmit": true,
+        "resolveJsonModule": true,
+        "esModuleInterop": true,
+    },
+    "include": [
+        "src/**/*"
+    ]
+}