Auth0 impersonation for SharePoint

impersonate.cs

var domain = "YOUR_DOMAIN.auth0.com";
var globalClientId = "YOUR_GLOBAL_CLIENT_ID";
var globalClientSecret = "YOUR_GLOBAL_CLIENT_SECRET";

var impersonatorId = "USER_ID_OF_THE_IMPERSONATOR";
var targetUserId = "USER_ID_OF_THE_USER_YOU_ARE_TRYING_TO_IMPERSONATE";
var targetClientId = "CLIENT_ID_OF_THE_APPLICATION_YOU_WANT_TO_LOGIN_TO";
var callbackUrl = "SHAREPOINT_URL/_trust/";
var impersonationLinkLifetime = 30; // seconds

// Authenticate.
var client = new HttpClient();
var message = client.PostAsync(String.Format("https://{0}/oauth/token", domain), 
    new StringContent(JsonConvert.SerializeObject(new { client_id = globalClientId, client_secret = globalClientSecret, grant_type = "client_credentials" }), Encoding.UTF8, "application/json")).Result;
var tokenString = JsonConvert.DeserializeObject<Dictionary<string,string>>(message.Content.ReadAsStringAsync().Result);
var token = tokenString["access_token"];

// Get the impersonation url.
var impersonationBody = new
{
    ttl = impersonationLinkLifetime,
    protocol = "wsfed",
    impersonator_id = impersonatorId,
    client_id = targetClientId,
    additionalParameters = new {
        callback_url = callbackUrl,
        wctx = "/"
    }
};

var request = new HttpRequestMessage() { RequestUri = new Uri(String.Format("https://{0}/users/{1}/impersonate", domain, targetUserId)),  Method = HttpMethod.Post };
request.Headers.Authorization = new System.Net.Http.Headers.AuthenticationHeaderValue("Bearer", token);
request.Content = new StringContent(JsonConvert.SerializeObject(impersonationBody), Encoding.UTF8, "application/json");

var url = client.SendAsync(request).Result.Content.ReadAsStringAsync().Result;
Console.WriteLine(url);