Import Contacts from Gmail Account in C# .NET

readme.md

Learn how to import contacts from Gmail account in C#: https://blog.aspose.com/2022/01/19/import-contacts-from-gmail-in-csharp-net/

GoogleOAuthHelper.cs

using System; 
using System.Diagnostics;
using System.IO; 
using System.Net;
using System.Text;
using System.Threading; 
using System.Windows.Forms;

namespace Aspose.Email
{
    internal class GoogleOAuthHelper
    {
        public const string TOKEN_REQUEST_URL = "https://accounts.google.com/o/oauth2/token";
        public const string SCOPE = "https%3A%2F%2Fwww.googleapis.com%2Fauth%2Fcalendar" + "+" + "https%3A%2F%2Fwww.google.com%2Fm8%2Ffeeds%2F" + "+" + "https%3A%2F%2Fmail.google.com%2F"; // IMAP & SMTP
        public const string REDIRECT_URI = "urn:ietf:wg:oauth:2.0:oob";
        public const string REDIRECT_TYPE = "code";

        internal static string GetAccessToken(TestUser user)
        {
            return GetAccessToken((GoogleUser)user);
        }

        internal static string GetAccessToken(GoogleUser user)
        {
            string access_token;
            string token_type;
            int expires_in;
            GetAccessToken(user, out access_token, out token_type, out expires_in);
            return access_token;
        }

        internal static void GetAccessToken(GoogleUser user, out string access_token, out string token_type, out int expires_in)
        {
            access_token = null;
            token_type = null;
            expires_in = 0;
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(TOKEN_REQUEST_URL);
            request.CookieContainer = new CookieContainer();
            request.Method = "POST";
            request.ContentType = "application/x-www-form-urlencoded";
            string encodedParameters = string.Format("client_id={0}&client_secret={1}&refresh_token={2}&grant_type={3}",
            System.Web.HttpUtility.UrlEncode(user.ClientId), System.Web.HttpUtility.UrlEncode(user.ClientSecret), System.Web.HttpUtility.UrlEncode(user.RefreshToken), System.Web.HttpUtility.UrlEncode(GrantTypes.refresh_token.ToString()));
            byte[] requestData = Encoding.UTF8.GetBytes(encodedParameters);
            request.ContentLength = requestData.Length;
            if (requestData.Length > 0)
                using (Stream stream = request.GetRequestStream())
                    stream.Write(requestData, 0, requestData.Length);
            HttpWebResponse response = (HttpWebResponse)request.GetResponse();
            string responseText = null;
            using (TextReader reader = new StreamReader(response.GetResponseStream(), Encoding.ASCII))
                responseText = reader.ReadToEnd();
            foreach (string sPair in responseText.Replace("{", "").Replace("}", "").Replace("\"", "").Split(new string[] { ",\n" }, StringSplitOptions.None))
            {
                string[] pair = sPair.Split(':');
                string name = pair[0].Trim().ToLower();
                string value = System.Web.HttpUtility.UrlDecode(pair[1].Trim());
                switch (name)
                {
                    case "access_token":
                        access_token = value;
                        break;
                    case "token_type":
                        token_type = value;
                        break;

                    case "expires_in":
                        expires_in = Convert.ToInt32(value);
                        break;
                }
            }
            Debug.WriteLine("");
            Debug.WriteLine("---------------------------------------------------------");
            Debug.WriteLine("-----------OAuth 2.0 authorization information-----------");
            Debug.WriteLine("---------------------------------------------------------");
            Debug.WriteLine(string.Format("Login: '{0}'", user.EMail));
            Debug.WriteLine(string.Format("Access token: '{0}'", access_token));
            Debug.WriteLine(string.Format("Token type: '{0}'", token_type));
            Debug.WriteLine(string.Format("Expires in: '{0}'", expires_in));
            Debug.WriteLine("---------------------------------------------------------");
            Debug.WriteLine("");
        }

        internal static void GetAccessToken(TestUser user, out string access_token, out string refresh_token)
        {
            GetAccessToken((GoogleUser)user, out access_token, out refresh_token);
        }

        internal static void GetAccessToken(GoogleUser user, out string access_token, out string refresh_token)
        {
            string token_type;
            int expires_in;
            GoogleOAuthHelper.GetAccessToken(user, out access_token, out refresh_token, out token_type, out expires_in);
        }

        internal static void GetAccessToken(TestUser user, out string access_token, out string refresh_token, out string token_type, out int expires_in)
        {
            GetAccessToken((GoogleUser)user, out access_token, out refresh_token, out token_type, out expires_in);
        }

        internal static void GetAccessToken(GoogleUser user, out string access_token, out string refresh_token, out string token_type, out int expires_in)
        {
            string authorizationCode = GoogleOAuthHelper.GetAuthorizationCode(user, GoogleOAuthHelper.SCOPE, GoogleOAuthHelper.REDIRECT_URI, GoogleOAuthHelper.REDIRECT_TYPE);
            GoogleOAuthHelper.GetAccessToken(authorizationCode, user, out access_token, out token_type, out expires_in, out refresh_token);
        }

        internal static void GetAccessToken(string authorizationCode, TestUser user, out string access_token, out string token_type, out int expires_in, out string refresh_token)
        {
            GetAccessToken(authorizationCode, (GoogleUser)user, out access_token, out token_type, out expires_in, out refresh_token);
        }

        internal static void GetAccessToken(string authorizationCode, GoogleUser user, out string access_token, out string token_type, out int expires_in, out string refresh_token)
        {
            access_token = null;
            token_type = null;
            expires_in = 0;
            refresh_token = null;
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(TOKEN_REQUEST_URL);
            request.CookieContainer = new CookieContainer();
            request.Method = "POST";
            request.ContentType = "application/x-www-form-urlencoded";
            string encodedParameters = string.Format("client_id={0}&code={1}&client_secret={2}&redirect_uri={3}&grant_type={4}", System.Web.HttpUtility.UrlEncode(user.ClientId), System.Web.HttpUtility.UrlEncode(authorizationCode), System.Web.HttpUtility.UrlEncode(user.ClientSecret), System.Web.HttpUtility.UrlEncode(REDIRECT_URI), System.Web.HttpUtility.UrlEncode(GrantTypes.authorization_code.ToString()));
            byte[] requestData = Encoding.UTF8.GetBytes(encodedParameters);
            request.ContentLength = requestData.Length;
            if (requestData.Length > 0)
                using (Stream stream = request.GetRequestStream())
                    stream.Write(requestData, 0, requestData.Length);
            HttpWebResponse response = (HttpWebResponse)request.GetResponse();
            string responseText = null;
            using (TextReader reader = new StreamReader(response.GetResponseStream(), Encoding.ASCII))
                responseText = reader.ReadToEnd();
            foreach (string sPair in responseText.Replace("{", "").Replace("}", "").Replace("\"", "").Split(new string[] { ",\n" }, StringSplitOptions.None))
            {
                string[] pair = sPair.Split(':');
                string name = pair[0].Trim().ToLower();
                string value = System.Web.HttpUtility.UrlDecode(pair[1].Trim());
                switch (name)
                {
                    case "access_token":
                        access_token = value;
                        break;
                    case "token_type":
                        token_type = value;
                        break;

                    case "expires_in":
                        expires_in = Convert.ToInt32(value);
                        break;

                    case "refresh_token":
                        refresh_token = value;
                        break;
                }
            }

            Debug.WriteLine(string.Format("Authorization code: '{0}'", authorizationCode));
            Debug.WriteLine(string.Format("Access token: '{0}'", access_token));
            Debug.WriteLine(string.Format("Refresh token: '{0}'", refresh_token));
            Debug.WriteLine(string.Format("Token type: '{0}'", token_type));
            Debug.WriteLine(string.Format("Expires in: '{0}'", expires_in));
            Debug.WriteLine("---------------------------------------------------------");
            Debug.WriteLine("");
        }

        internal static string GetAuthorizationCode(TestUser acc, string scope, string redirectUri, string responseType)
        {
            return GetAuthorizationCode((GoogleUser)acc, scope, redirectUri, responseType);
        }

        internal static string GetAuthorizationCode(GoogleUser acc, string scope, string redirectUri, string responseType)
        {
            Debug.WriteLine("");
            Debug.WriteLine("---------------------------------------------------------");
            Debug.WriteLine("-----------OAuth 2.0 authorization information-----------");
            Debug.WriteLine("---------------------------------------------------------");
            Debug.WriteLine(string.Format("Login: '{0}'", acc.EMail));
            string authorizationCode = null;
            string error = null;
            string approveUrl = string.Format("https://accounts.google.com/o/oauth2/auth?redirect_uri={0}&response_type={1}&client_id={2}&scope={3}", redirectUri, responseType, acc.ClientId, scope);

            AutoResetEvent are0 = new AutoResetEvent(false);
            Thread t = new Thread(delegate ()
            {
                bool doEvents = true;
                WebBrowser browser = new WebBrowser();
                browser.AllowNavigation = true;
                browser.DocumentCompleted += delegate (object sender, WebBrowserDocumentCompletedEventArgs e) { doEvents = false; };
                Form f = new Form();
                f.FormBorderStyle = FormBorderStyle.FixedToolWindow;
                f.ShowInTaskbar = false;
                f.StartPosition = FormStartPosition.Manual;
                f.Location = new System.Drawing.Point(-2000, -2000);
                f.Size = new System.Drawing.Size(1, 1);
                f.Controls.Add(browser);
                f.Load += delegate (object sender, EventArgs e)
                {
                    try
                    {
                        browser.Navigate("https://accounts.google.com/Logout");
                        doEvents = true;
                        while (doEvents) Application.DoEvents();
                        browser.Navigate("https://accounts.google.com/ServiceLogin?sacu=1");
                        doEvents = true;
                        while (doEvents) Application.DoEvents();
                        HtmlElement loginForm = browser.Document.Forms["gaia_loginform"];
                        if (loginForm != null)
                        {
                            HtmlElement userName = browser.Document.All["Email"];

                            userName.SetAttribute("value", acc.EMail);
                            loginForm.InvokeMember("submit");
                            doEvents = true;
                            while (doEvents)
                                Application.DoEvents();

                            loginForm = browser.Document.Forms["gaia_loginform"];
                            HtmlElement passwd = browser.Document.All["Passwd"];
                            passwd.SetAttribute("value", acc.Password);

                            loginForm.InvokeMember("submit");
                            doEvents = true;
                            while (doEvents)
                                Application.DoEvents();
                        }
                        else
                        {
                            error = "Login form is not found in \n" + browser.Document.Body.InnerHtml;
                            return;
                        }
                        browser.Navigate(approveUrl);
                        doEvents = true;
                        while (doEvents) Application.DoEvents();
                        HtmlElement approveForm = browser.Document.Forms["connect-approve"];
                        if (approveForm != null)
                        {
                            HtmlElement submitAccess = browser.Document.All["submit_access"];
                            submitAccess.SetAttribute("value", "true");
                            approveForm.InvokeMember("submit");
                            doEvents = true;
                            while (doEvents)
                                Application.DoEvents();
                        }
                        else
                        {
                            error = "Approve form is not found in \n" + browser.Document.Body.InnerHtml;
                            return;
                        }
                        HtmlElement code = browser.Document.All["code"];
                        if (code != null)
                            authorizationCode = code.GetAttribute("value");
                        else
                            error = "Authorization code is not found in \n" + browser.Document.Body.InnerHtml;
                    }
                    catch (Exception ex)
                    {
                        error = ex.Message;
                    }
                    finally
                    {
                        f.Close();
                    }
                };
                Application.Run(f);
                are0.Set();
            });
            t.SetApartmentState(ApartmentState.STA);
            t.Start();
            are0.WaitOne();
            if (error != null)
                throw new Exception(error);
            return authorizationCode;
        }
    }
}

GoogleUser.cs

using System;

namespace Aspose.Email
{
    internal enum GrantTypes
    {
        authorization_code,
        refresh_token
    }

    public class TestUser
    {
        internal TestUser(string name, string eMail, string password, string domain)
        {
            Name = name;
            EMail = eMail;
            Password = password;
            Domain = domain;
        }

        public readonly string Name;
        public readonly string EMail;
        public readonly string Password;
        public readonly string Domain;

        public static bool operator ==(TestUser x, TestUser y)
        {
            if ((object)x != null)
                return x.Equals(y);
            if ((object)y != null)
                return y.Equals(x);
            return true;
        }

        public static bool operator !=(TestUser x, TestUser y)
        {
            return !(x == y);
        }

        public static implicit operator string(TestUser user)
        {
            return user == null ? null : user.Name;
        }

        public override int GetHashCode()
        {
            return ToString().GetHashCode();
        }

        public override bool Equals(object obj)
        {
            return obj != null && obj is TestUser && this.ToString().Equals(obj.ToString(), StringComparison.OrdinalIgnoreCase);
        }

        public override string ToString()
        {
            return string.IsNullOrEmpty(Domain) ? Name : string.Format("{0}/{1}", Domain, Name);
        }
    }
    public class GoogleUser : TestUser
    {
        public GoogleUser(string name, string eMail, string password)
            : this(name, eMail, password, null, null, null)
        { }

        public GoogleUser(string name, string eMail, string password, string clientId, string clientSecret)
            : this(name, eMail, password, clientId, clientSecret, null)
        { }

        public GoogleUser(string name, string eMail, string password, string clientId, string clientSecret, string refreshToken)
            : base(name, eMail, password, "gmail.com")
        {
            ClientId = clientId;
            ClientSecret = clientSecret;
            RefreshToken = refreshToken;
        }
        public readonly string ClientId;
        public readonly string ClientSecret;
        public readonly string RefreshToken;
    }
}

Import-Gmail-Contacts-From-Group.cs

// Create a Google user
GoogleUser User = new GoogleUser("user", "email address", "password", "clientId", "client secret");
string accessToken;
string refreshToken;

// Get access token
GoogleOAuthHelper.GetAccessToken(User, out accessToken, out refreshToken);

// Get IGmailclient
using (IGmailClient client = GmailClient.GetInstance(accessToken, User.EMail))
{
    // Fetch contacts from a specific group
    ContactGroupCollection groups = client.GetAllGroups();
    GoogleContactGroup group = null;
    foreach (GoogleContactGroup g in groups)
        switch (g.Title)
        {
            case "TestGroup":
                group = g;
                break;
        }

    // Retrieve contacts from the Group
    if (group != null)
    {
        Contact[] contacts2 = client.GetContactsFromGroup(group.Id);
        foreach (Contact con in contacts2)
            Console.WriteLine(con.DisplayName + "," + con.EmailAddresses[0].ToString());
    }
}

Import-Gmail-Contacts.cs

// Create a Google user
GoogleUser User = new GoogleUser("user", "email address", "password", "clientId", "client secret");
string accessToken;
string refreshToken;

// Get access token
GoogleOAuthHelper.GetAccessToken(User, out accessToken, out refreshToken);

// Get IGmailclient
using (IGmailClient client = GmailClient.GetInstance(accessToken, User.EMail))
{
    // Access contacts
    Contact[] contacts = client.GetAllContacts();
    foreach (Contact contact in contacts)
        Console.WriteLine(contact.DisplayName + ", " + contact.EmailAddresses[0]);
}