Azure Function for sending a mail as a user after authenticating using the Password Grant flow

MailDaemon.csx

#r "Newtonsoft.Json"
using System;
using System.Text;
using System.Threading.Tasks;
using System.Net.Http;
using Newtonsoft.Json;
using static System.Environment;
using System.Collections.Generic;

public async static void Run(string input, TraceWriter log)
{
    log.Info($"C# manually triggered function called with input: {input}");
    
    var domain = "contoso.onmicrosoft.com";
    var user = "[email protected]";
    var pw = "password";
    var clientId = "guid-from-portal";
    var resource = "https://graph.microsoft.com";
    HttpClient client = new HttpClient();

    string requestUrl = $"https://login.microsoftonline.com/{domain}/oauth2/token";

    string request_content = $"grant_type=password&resource={resource}&client_id={clientId}&username={user}&password={pw}&scope=openid+Mail.Send";

    HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Post, requestUrl);
    try
    {
        request.Content = new StringContent(request_content, Encoding.UTF8, "application/x-www-form-urlencoded");
    }
    catch (Exception x)
    {
        var msg = x.Message;
    }
    HttpResponseMessage response = await client.SendAsync(request);

    string responseString = await response.Content.ReadAsStringAsync();
    log.Info(responseString);
    GenericToken token = JsonConvert.DeserializeObject<GenericToken>(responseString);
    var at = token.access_token;

    var me = await GetUserInfo(at);

    log.Info($"Display Name:{me.displayName}{NewLine}Upn:{me.userPrincipalName}{NewLine}Preferred Language:{me.preferredLanguage}");

    await SendMail(at,log);
}

private static async Task<AADUser> GetUserInfo(string token)
{
    string graphRequest = $"https://graph.microsoft.com/v1.0/me/";
    var authHeader = "Bearer " + token;
    HttpClient client = new HttpClient();

    client.DefaultRequestHeaders.TryAddWithoutValidation("Authorization", authHeader);
    var response = await client.GetAsync(new Uri(graphRequest));

    string content = await response.Content.ReadAsStringAsync();
    var user = JsonConvert.DeserializeObject<AADUser>(content);
    return user;
}

private static async Task<MailMessage> SendMail(string token, TraceWriter log)
{
    //https://graph.microsoft.io/en-us/docs/api-reference/v1.0/api/user_sendmail
    HttpClient client = new HttpClient();
    var authHeader = "Bearer " + token;
    string requestUrl = $"https://graph.microsoft.com/v1.0/me/sendMail";

    var baseEmail = new EmailAddress { name = "Alice", address = "[email protected]" };
    var fromEmail = new EmailAddress { name = "Bob", address = "[email protected]" };
    var from = new From { emailAddress = fromEmail };
    var send = new Sender { emailAddress = fromEmail };

    var recList = new List<ToRecipient>();
    recList.Add(new ToRecipient { emailAddress = baseEmail });

    var replyAddress = new List<ReplyTo>();
    replyAddress.Add(new ReplyTo { emailAddress = fromEmail });

    var bcc = new List<BccRecipient>();
    var cc = new List<CcRecipient>();
    var cats = new List<string>();

    var body = new Body { contentType = "text", content = "Hello World" };

    var draft = new MailItem { toRecipients = recList,sender=send,from = from, bccRecipients=bcc,ccRecipients=cc, replyTo=replyAddress, categories=cats, body = body, subject = "Hello World" };

    var Message = new MailMessage { Message = draft, SaveToSentItems = "true" };

    string request_content = JsonConvert.SerializeObject(Message);

    HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Post, requestUrl);
    try
    {
        client.DefaultRequestHeaders.TryAddWithoutValidation("Authorization", authHeader);
        request.Content = new StringContent(request_content, Encoding.UTF8, "application/json");
    }
    catch (Exception x)
    {
        var exception = x.Message;
    }
    HttpResponseMessage response = await client.SendAsync(request);

    string responseString = await response.Content.ReadAsStringAsync();
    log.Info(responseString);
    MailMessage msg = JsonConvert.DeserializeObject<MailMessage>(responseString);
    return msg;
}

public class GenericToken
{
    public string token_type { get; set; }
    public string scope { get; set; }
    public string resource { get; set; }
    public string access_token { get; set; }
    public string refresh_token { get; set; }
    public string id_token { get; set; }
    public string expires_in { get; set; }
}

public class AADUser
{
    public string displayName { get; set; }
    public string givenName { get; set; }
    public string surname { get; set; }
    public string mail { get; set; }
    public string preferredLanguage { get; set; }
    public string userPrincipalName { get; set; }
    public string mobilePhone { get; set; }
}

public class MailMessage
{
    public MailItem Message { get; set; }
    public string SaveToSentItems { get; set; }
}

public class EmailAddress
{
    public string name { get; set; }
    public string address { get; set; }
}

public class BccRecipient
{
    public EmailAddress emailAddress { get; set; }
}

public class Body
{
    public string contentType { get; set; }
    public string content { get; set; }
}

public class CcRecipient
{
    public EmailAddress emailAddress { get; set; }
}

public class From
{
    public EmailAddress emailAddress { get; set; }
}

public class ReplyTo
{
    public EmailAddress emailAddress { get; set; }
}

public class Sender
{
    public EmailAddress emailAddress { get; set; }
}

public class ToRecipient
{
    public EmailAddress emailAddress { get; set; }
}

public class UniqueBody
{
    public string contentType { get; set; }
    public string content { get; set; }
}

public class MailItem
{
    public List<BccRecipient> bccRecipients { get; set; }
    public Body body { get; set; }
    public string bodyPreview { get; set; }
    public List<string> categories { get; set; }
    public List<CcRecipient> ccRecipients { get; set; }
    public string changeKey { get; set; }
    public string conversationId { get; set; }
    public string createdDateTime { get; set; }
    public From from { get; set; }
    public bool hasAttachments { get; set; }
    public string id { get; set; }
    public string importance { get; set; }
    public string inferenceClassification { get; set; }
    public string internetMessageId { get; set; }
    public bool isDeliveryReceiptRequested { get; set; }
    public bool isDraft { get; set; }
    public bool isRead { get; set; }
    public bool isReadReceiptRequested { get; set; }
    public string lastModifiedDateTime { get; set; }
    public string parentFolderId { get; set; }
    public string receivedDateTime { get; set; }
    public List<ReplyTo> replyTo { get; set; }
    public Sender sender { get; set; }
    public string sentDateTime { get; set; }
    public string subject { get; set; }
    public List<ToRecipient> toRecipients { get; set; }
    public UniqueBody uniqueBody { get; set; }
    public string webLink { get; set; }
}