Integrate Gmail into C# applications

AppendMessages.cs

using (IGmailClient client = GmailClient.GetInstance(clientId, clientSecret, refreshToken, email))
{
    // Create a message to append to the "Inbox"
    MailMessage message = new MailMessage("[email protected]", "[email protected]", "Subject for inbox message", "Body of the message");

    // Append the message to the inbox with the "INBOX" label
    string messageId = client.AppendMessage(message, "INBOX");
    Console.WriteLine($"Message appended to the Inbox. ID: {messageId}");
}

CreateAndListGmailFilters.cs

using (IGmailClient client = GmailClient.GetInstance(clientId, clientSecret, refreshToken, email))
{
    // Create a filter for messages with a specific subject
    Filter filter = new Filter
    {
        MatchingCriteria = new Criteria { Subject = "Important" },
        Action = new Action { AddLabelIds = new string[] { "IMPORTANT" } }
    };

    // Create a filter
    string filterId = client.CreateFilter(filter);
    Console.WriteLine($"Filter created! ID: {filterId}");

    // List all filters
    var filters = client.ListFilters();
    foreach (var f in filters)
    {
        Console.WriteLine($"Filter ID: {f.Id}");
    }
}

DeleteGmailFilters.cs

using (IGmailClient client = GmailClient.GetInstance(clientId, clientSecret, refreshToken, email))
{
    var filters = client.ListFilters();

    foreach (var filter in filters)
    {
        client.DeleteFilter(filter.Id);
        Console.WriteLine($"Filter ID: {filter.Id} deleted.");
    }
}

FetchAndDeleteGmailMessages.cs

using (IGmailClient client = GmailClient.GetInstance(clientId, clientSecret, refreshToken, email))
{
    // List all messages in the mailbox
    var messages = client.ListMessages();

    // Fetch and display the first 3 messages
    for (int i = 0; i < 3; i++)
    {
        var msg = client.FetchMessage(messages[i].Id);
        Console.WriteLine($"Message {i + 1}: Subject - {msg.Subject}, Body - {msg.Body}");

        // Delete the message by moving it to trash
        client.DeleteMessage(messages[i].Id, true);
        Console.WriteLine($"Message {i + 1} moved to trash.");
    }
}

GetAccessTokenByAuthCode.cs

// Obtain OAuth2 Token for Gmail Access
internal static TokenResponse GetAccessTokenByAuthCode(string authorizationCode)
{
    HttpWebRequest request = (HttpWebRequest)WebRequest.Create("https://oauth2.googleapis.com/token");
    request.CookieContainer = new CookieContainer();
    request.Method = "POST";
    request.ContentType = "application/x-www-form-urlencoded";

    string clientId = System.Web.HttpUtility.UrlEncode(userClientId);
    string clientSecret = System.Web.HttpUtility.UrlEncode(userClientSecret);
    string authCode = System.Web.HttpUtility.UrlEncode(authorizationCode);
    string redirectUri = System.Web.HttpUtility.UrlEncode("urn:ietf:wg:oauth:2.0:oob");
    string grantType = System.Web.HttpUtility.UrlEncode("authorization_code");

    string encodedParameters = $"client_id={clientId}&client_secret={clientSecret}&code={authCode}&redirect_uri={redirectUri}&grant_type={grantType}";
    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;
    using (TextReader reader = new StreamReader(response.GetResponseStream(), Encoding.ASCII))
        responseText = reader.ReadToEnd();

    TokenResponse tokensResponse = Newtonsoft.Json.JsonConvert.DeserializeObject<TokenResponse>(responseText);

    return tokensResponse;
}

SendMessages.cs

// Using the Gmail API to send an email with an attachment
using (IGmailClient client = GmailClient.GetInstance(clientId, clientSecret, refreshToken, email))
{
    // Create a new message 
    MailMessage message = new MailMessage("[email protected]", "[email protected]", "Weekly Report", "Attached is the weekly report.");

    // Add an attachment
    string attachmentPath = Path.Combine(TestUtil.GetTestDataPath(), "report.pdf");
    message.Attachments.Add(new Attachment(attachmentPath));

    // Send the message using Gmail Client
    string messageId = client.SendMessage(message);
    Console.WriteLine($"Message with attachment sent! ID: {messageId}");
}