//subscription pulls from the topic(queue) and send email with info gathered from the topic to the recepient.
public void DownloadEmailFromQueueAndSend()
{
SubscriberServiceApiClient client = SubscriberServiceApiClient.Create();
Subscription s = CreateGetSubscription(); //you must getSubscription before being able to read messages from Topic/Queue
PullResponse pullResponse = client.Pull(s.SubscriptionName, true, 1); //Reading the message on top (You can read more than just 1 at a time)
KeyRepository kr = new KeyRepository();
if (pullResponse != null)
{
if (pullResponse.ReceivedMessages.Count > 0)
{
//extracting the first message since in the previous line it was specified to read one at a time. (Loop required to read more than 1 item(The amount set in maxMessages from the Pull method))
string encryptedData = pullResponse.ReceivedMessages[0].Message.Data.ToStringUtf8();
string decryptedData = kr.Decrypt(encryptedData);
File deserialized = JsonSerializer.Deserialize <File>(decryptedData); //Deserializing since it was serialized when added to the queue
string htmlString = $"<html><b>{deserialized.FileOwner}</b> is sharing the file <b>{deserialized.FileTitle}</b> with you.<br/> <a href=\"{deserialized.Link}\">Click me to access file</a> </html>";
string encryptedRecepient = pullResponse.ReceivedMessages[0].Message.Attributes["recepient"];
string recepient = kr.Decrypt(encryptedRecepient);
//Dummy email was created to act as a "Company email which will send emails to users."
//Send Email with deserialized. Documentation: https://docs.microsoft.com/en-us/dotnet/api/system.net.mail.smtpclient?view=netframework-4.8
MailMessage message = new MailMessage();
SmtpClient smtp = new SmtpClient();
message.From = new MailAddress("*****@*****.**");
message.To.Add(new MailAddress(recepient));
message.Subject = "File";
message.IsBodyHtml = true; //to make message body as html
message.Body = htmlString;
smtp.Port = 587;
smtp.Host = "smtp.gmail.com"; //for gmail host
smtp.EnableSsl = true;
smtp.UseDefaultCredentials = false;
smtp.Credentials = new NetworkCredential("*****@*****.**", "passForpfc1234");
//go on googleaccount > Security > search for lesssecureapps > turn it to on
//Note: Google will automatically turn this setting OFF lesssecureapps if it’s not being used
smtp.DeliveryMethod = SmtpDeliveryMethod.Network;
smtp.Send(message);
List <string> acksIds = new List <string>();
//after the email is sent successfully you acknolwedge the message so it is confirmed that it was processed. (Message will be removed after acknowledge.)
acksIds.Add(pullResponse.ReceivedMessages[0].AckId);
client.Acknowledge(s.SubscriptionName, acksIds.AsEnumerable());
}
}
}
//Publish method: uploads a message to the queue.
public void AddToEmailQueue(File f, string recepient)
{
PublisherServiceApiClient client = PublisherServiceApiClient.Create();
Topic t = CreateGetTopic();
KeyRepository kr = new KeyRepository();
string serialized = JsonSerializer.Serialize(f, typeof(File));
// this list is used so that the method can take more than 1 message/item/file at a time.
List <PubsubMessage> messagesToAddToQueue = new List <PubsubMessage>();
PubsubMessage msg = new PubsubMessage();
//Encripting data and recepient values
string encryptedData = kr.Encrypt(serialized);
string encryptedRecepient = kr.Encrypt(recepient);
msg.Data = ByteString.CopyFromUtf8(encryptedData); //Stores email content.
msg.Attributes["recepient"] = encryptedRecepient; //stores recepient as a key-value attribute.
messagesToAddToQueue.Add(msg);
client.Publish(t.TopicName, messagesToAddToQueue); //committing to queue
}