lemmy/crates/utils/src/email.rs

use crate::{settings::structs::Settings, LemmyError};
use html2text;
use lettre::{
  message::{header, Mailbox, MultiPart, SinglePart},
  transport::smtp::{authentication::Credentials, extension::ClientId},
  Address,
  Message,
  SmtpTransport,
  Transport,
};
use std::str::FromStr;
use uuid::Uuid;

pub fn send_email(
  subject: &str,
  to_email: &str,
  to_username: &str,
  html: &str,
  settings: &Settings,
) -> Result<(), LemmyError> {
  let email_config = settings
    .email
    .to_owned()
    .ok_or_else(|| LemmyError::from_message("no_email_setup"))?;
  let domain = settings.hostname.to_owned();

  let (smtp_server, smtp_port) = {
    let email_and_port = email_config.smtp_server.split(':').collect::<Vec<&str>>();
    if email_and_port.len() == 1 {
      return Err(LemmyError::from_message(
        "email.smtp_server needs a port, IE smtp.xxx.com:465",
      ));
    }

    (
      email_and_port[0],
      email_and_port[1]
        .parse::<u16>()
        .expect("email needs a port"),
    )
  };

  // the message length before wrap, 78, is somewhat arbritary but looks good to me
  let plain_text = html2text::from_read(html.as_bytes(), 78);

  let email = Message::builder()
    .from(
      email_config
        .smtp_from_address
        .parse()
        .expect("email from address isn't valid"),
    )
    .to(Mailbox::new(
      Some(to_username.to_string()),
      Address::from_str(to_email).expect("email to address isn't valid"),
    ))
    .message_id(Some(format!("{}@{}", Uuid::new_v4(), settings.hostname)))
    .subject(subject)
    .multipart(
      MultiPart::mixed().multipart(
        MultiPart::alternative()
          .singlepart(
            SinglePart::builder()
              .header(header::ContentType::TEXT_PLAIN)
              .body(plain_text),
          )
          .multipart(
            MultiPart::related().singlepart(
              SinglePart::builder()
                .header(header::ContentType::TEXT_HTML)
                .body(html.to_string()),
            ),
          ),
      ),
    )
    .expect("email built incorrectly");

  // don't worry about 'dangeous'. it's just that leaving it at the default configuration
  // is bad.

  // Set the TLS
  let builder_dangerous = SmtpTransport::builder_dangerous(smtp_server).port(smtp_port);

  let mut builder = match email_config.tls_type.as_str() {
    "starttls" => SmtpTransport::starttls_relay(smtp_server)?,
    "tls" => SmtpTransport::relay(smtp_server)?,
    _ => builder_dangerous,
  };

  // Set the creds if they exist
  if let (Some(username), Some(password)) = (email_config.smtp_login, email_config.smtp_password) {
    builder = builder.credentials(Credentials::new(username, password));
  }

  let mailer = builder.hello_name(ClientId::Domain(domain)).build();

  let result = mailer.send(&email);

  match result {
    Ok(_) => Ok(()),
    Err(e) => Err(LemmyError::from_error_message(e, "email_send_failed")),
  }
}