Embed apps in Sharepoint

public async getUrl(): Promise<string> {

	// Get currently logged-in Sharepoint user (for SSO in Peliqan app)
	const user = this.context.pageContext.user;
  const userEmail: string = user.email;
  const userName: string = user.displayName;

  // Update these app settings
  const appId = 123;
  const secretKey = "xxx"; // See App Embed Secret Key
  let appUrl = "https://app.eu.peliqan.io/apps/UnVGZW...lONA==/?embed=true";

  const timestamp = Math.floor(Date.now() / 1000);
  const message = `${appId}_${timestamp}`;
  const enc = new TextEncoder();
  const key = await crypto.subtle.importKey("raw", enc.encode(secretKey), { name: "HMAC", hash: { name: "SHA-1" } }, false, ["sign"]);
  const signature = await crypto.subtle.sign("HMAC", key, enc.encode(message));
  const digestBase64 = btoa(String.fromCharCode(...new Uint8Array(signature)));
  const token = { digest: digestBase64, timestamp };
  const tokenJson = JSON.stringify(token).replace(/:/g, ': ').replace(/,/g, ', ');
  const sessionToken = btoa(unescape(encodeURIComponent(tokenJson)));
  appUrl += `&session_token=${sessionToken}`;
  appUrl += `&userEmail=${userEmail}&userName=${userName}`;
  return appUrl;
  
  // Note: in the Peliqan app, use st.query_params.get("userEmail")
  // to read the currently logged-in Sharepoint user for SSO
}

public render(): void {
  this.getUrl().then( (appUrl) => {  
     this.domElement.innerHTML = `
      <div style="width:100%; height:400px;">
        <iframe src="${appUrl}" 
                width="100%" 
                height="100%" 
                style="border:1px solid black;" 
                frameborder="0" 
                scrolling="yes"></iframe>
      </div>
    `;
  } ).catch( (e) => { console.log(e) } );
}

{
  "compilerOptions": {
    "target": "es2015",
     "downlevelIteration": true
  },
  "lib": [
    "es2015",
    "dom",
    "es2015.collection",
    "es2015.promise"
  ]
}