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602//! Email channel adapter (IMAP + SMTP).
//!
//! Polls IMAP for new emails and sends responses via SMTP using `lettre`.
//! Uses the subject line for agent routing (e.g., "\[coder\] Fix this bug").
use crate::types::{ChannelAdapter, ChannelContent, ChannelMessage, ChannelType, ChannelUser};
use async_trait::async_trait;
use chrono::Utc;
use dashmap::DashMap;
use futures::Stream;
use lettre::message::Mailbox;
use lettre::transport::smtp::authentication::Credentials;
use lettre::AsyncSmtpTransport;
use lettre::AsyncTransport;
use lettre::Tokio1Executor;
use std::pin::Pin;
use std::sync::Arc;
use std::time::Duration;
use tokio::sync::{mpsc, watch};
use tracing::{debug, error, info, warn};
use zeroize::Zeroizing;
/// Reply context for email threading (In-Reply-To / Subject continuity).
#[derive(Debug, Clone)]
struct ReplyCtx {
subject: String,
message_id: String,
}
/// Email channel adapter using IMAP for receiving and SMTP for sending.
pub struct EmailAdapter {
/// IMAP server host.
imap_host: String,
/// IMAP port (993 for TLS).
imap_port: u16,
/// SMTP server host.
smtp_host: String,
/// SMTP port (587 for STARTTLS, 465 for implicit TLS).
smtp_port: u16,
/// Email address (used for both IMAP and SMTP).
username: String,
/// SECURITY: Password is zeroized on drop.
password: Zeroizing<String>,
/// How often to check for new emails.
poll_interval: Duration,
/// Which IMAP folders to monitor.
folders: Vec<String>,
/// Only process emails from these senders (empty = all).
allowed_senders: Vec<String>,
/// Shutdown signal.
shutdown_tx: Arc<watch::Sender<bool>>,
shutdown_rx: watch::Receiver<bool>,
/// Tracks reply context per sender for email threading.
reply_ctx: Arc<DashMap<String, ReplyCtx>>,
}
impl EmailAdapter {
/// Create a new email adapter.
#[allow(clippy::too_many_arguments)]
pub fn new(
imap_host: String,
imap_port: u16,
smtp_host: String,
smtp_port: u16,
username: String,
password: String,
poll_interval_secs: u64,
folders: Vec<String>,
allowed_senders: Vec<String>,
) -> Self {
let (shutdown_tx, shutdown_rx) = watch::channel(false);
Self {
imap_host,
imap_port,
smtp_host,
smtp_port,
username,
password: Zeroizing::new(password),
poll_interval: Duration::from_secs(poll_interval_secs),
folders: if folders.is_empty() {
vec!["INBOX".to_string()]
} else {
folders
},
allowed_senders,
shutdown_tx: Arc::new(shutdown_tx),
shutdown_rx,
reply_ctx: Arc::new(DashMap::new()),
}
}
/// Check if a sender is in the allowlist (empty = allow all). Used in tests.
#[allow(dead_code)]
fn is_allowed_sender(&self, sender: &str) -> bool {
self.allowed_senders.is_empty() || self.allowed_senders.iter().any(|s| sender.contains(s))
}
/// Extract agent name from subject line brackets, e.g., "[coder] Fix the bug" -> Some("coder")
fn extract_agent_from_subject(subject: &str) -> Option<String> {
let subject = subject.trim();
if subject.starts_with('[') {
if let Some(end) = subject.find(']') {
let agent = &subject[1..end];
if !agent.is_empty() {
return Some(agent.to_string());
}
}
}
None
}
/// Strip the agent tag from a subject line.
fn strip_agent_tag(subject: &str) -> String {
let subject = subject.trim();
if subject.starts_with('[') {
if let Some(end) = subject.find(']') {
return subject[end + 1..].trim().to_string();
}
}
subject.to_string()
}
/// Build an async SMTP transport for sending emails.
async fn build_smtp_transport(
&self,
) -> Result<AsyncSmtpTransport<Tokio1Executor>, Box<dyn std::error::Error>> {
let creds =
Credentials::new(self.username.clone(), self.password.as_str().to_string());
let transport = if self.smtp_port == 465 {
// Implicit TLS (port 465)
AsyncSmtpTransport::<Tokio1Executor>::relay(&self.smtp_host)?
.port(self.smtp_port)
.credentials(creds)
.build()
} else {
// STARTTLS (port 587 or other)
AsyncSmtpTransport::<Tokio1Executor>::starttls_relay(&self.smtp_host)?
.port(self.smtp_port)
.credentials(creds)
.build()
};
Ok(transport)
}
}
/// Extract `user@domain` from a potentially formatted email string like `"Name <user@domain>"`.
fn extract_email_addr(raw: &str) -> String {
let raw = raw.trim();
if let Some(start) = raw.find('<') {
if let Some(end) = raw.find('>') {
if end > start {
return raw[start + 1..end].trim().to_string();
}
}
}
raw.to_string()
}
/// Get a specific header value from a parsed email.
fn get_header(parsed: &mailparse::ParsedMail<'_>, name: &str) -> Option<String> {
parsed
.headers
.iter()
.find(|h| h.get_key().eq_ignore_ascii_case(name))
.map(|h| h.get_value())
}
/// Extract the text/plain body from a parsed email (handles multipart).
fn extract_text_body(parsed: &mailparse::ParsedMail<'_>) -> String {
if parsed.subparts.is_empty() {
return parsed.get_body().unwrap_or_default();
}
// Walk subparts looking for text/plain
for part in &parsed.subparts {
let ct = part.ctype.mimetype.to_lowercase();
if ct == "text/plain" {
return part.get_body().unwrap_or_default();
}
}
// Fallback: first subpart body
parsed
.subparts
.first()
.and_then(|p| p.get_body().ok())
.unwrap_or_default()
}
/// Fetch unseen emails from IMAP using blocking I/O.
/// Returns a Vec of (from_addr, subject, message_id, body).
fn fetch_unseen_emails(
host: &str,
port: u16,
username: &str,
password: &str,
folders: &[String],
) -> Result<Vec<(String, String, String, String)>, String> {
let tls = native_tls::TlsConnector::builder()
.build()
.map_err(|e| format!("TLS connector error: {e}"))?;
let client = imap::connect((host, port), host, &tls)
.map_err(|e| format!("IMAP connect failed: {e}"))?;
let mut session = client
.login(username, password)
.map_err(|(e, _)| format!("IMAP login failed: {e}"))?;
let mut results = Vec::new();
for folder in folders {
if let Err(e) = session.select(folder) {
warn!(folder, error = %e, "IMAP SELECT failed, skipping folder");
continue;
}
let uids = match session.uid_search("UNSEEN") {
Ok(uids) => uids,
Err(e) => {
warn!(folder, error = %e, "IMAP SEARCH UNSEEN failed");
continue;
}
};
if uids.is_empty() {
debug!(folder, "No unseen emails");
continue;
}
// Fetch in batches of up to 50 to avoid huge responses
let uid_list: Vec<u32> = uids.into_iter().take(50).collect();
let uid_set: String = uid_list
.iter()
.map(|u| u.to_string())
.collect::<Vec<_>>()
.join(",");
let fetches = match session.uid_fetch(&uid_set, "RFC822") {
Ok(f) => f,
Err(e) => {
warn!(folder, error = %e, "IMAP FETCH failed");
continue;
}
};
for fetch in fetches.iter() {
let body_bytes = match fetch.body() {
Some(b) => b,
None => continue,
};
let parsed = match mailparse::parse_mail(body_bytes) {
Ok(p) => p,
Err(e) => {
warn!(error = %e, "Failed to parse email");
continue;
}
};
let from = get_header(&parsed, "From").unwrap_or_default();
let subject = get_header(&parsed, "Subject").unwrap_or_default();
let message_id = get_header(&parsed, "Message-ID").unwrap_or_default();
let text_body = extract_text_body(&parsed);
let from_addr = extract_email_addr(&from);
results.push((from_addr, subject, message_id, text_body));
}
// Mark fetched messages as Seen
if let Err(e) = session.uid_store(&uid_set, "+FLAGS (\\Seen)") {
warn!(error = %e, "Failed to mark emails as Seen");
}
}
let _ = session.logout();
Ok(results)
}
#[async_trait]
impl ChannelAdapter for EmailAdapter {
fn name(&self) -> &str {
"email"
}
fn channel_type(&self) -> ChannelType {
ChannelType::Email
}
async fn start(
&self,
) -> Result<Pin<Box<dyn Stream<Item = ChannelMessage> + Send>>, Box<dyn std::error::Error>>
{
let (tx, rx) = mpsc::channel::<ChannelMessage>(256);
let poll_interval = self.poll_interval;
let imap_host = self.imap_host.clone();
let imap_port = self.imap_port;
let username = self.username.clone();
let password = self.password.clone();
let folders = self.folders.clone();
let allowed_senders = self.allowed_senders.clone();
let mut shutdown_rx = self.shutdown_rx.clone();
let reply_ctx = self.reply_ctx.clone();
info!(
"Starting email adapter (IMAP: {}:{}, SMTP: {}:{}, polling every {:?})",
imap_host, imap_port, self.smtp_host, self.smtp_port, poll_interval
);
tokio::spawn(async move {
loop {
tokio::select! {
_ = shutdown_rx.changed() => {
info!("Email adapter shutting down");
break;
}
_ = tokio::time::sleep(poll_interval) => {}
}
// IMAP operations are blocking I/O — run in spawn_blocking
let host = imap_host.clone();
let port = imap_port;
let user = username.clone();
let pass = password.clone();
let fldrs = folders.clone();
let emails = tokio::task::spawn_blocking(move || {
fetch_unseen_emails(&host, port, &user, pass.as_str(), &fldrs)
})
.await;
let emails = match emails {
Ok(Ok(emails)) => emails,
Ok(Err(e)) => {
error!("IMAP poll error: {e}");
continue;
}
Err(e) => {
error!("IMAP spawn_blocking panic: {e}");
continue;
}
};
for (from_addr, subject, message_id, body) in emails {
// Check allowed senders
if !allowed_senders.is_empty()
&& !allowed_senders.iter().any(|s| from_addr.contains(s))
{
debug!(from = %from_addr, "Email from non-allowed sender, skipping");
continue;
}
// Store reply context for threading
if !message_id.is_empty() {
reply_ctx.insert(
from_addr.clone(),
ReplyCtx {
subject: subject.clone(),
message_id: message_id.clone(),
},
);
}
// Extract target agent from subject brackets (stored in metadata for router)
let _target_agent =
EmailAdapter::extract_agent_from_subject(&subject);
let clean_subject = EmailAdapter::strip_agent_tag(&subject);
// Build the message body: prepend subject context
let text = if clean_subject.is_empty() {
body.trim().to_string()
} else {
format!("Subject: {clean_subject}\n\n{}", body.trim())
};
let msg = ChannelMessage {
channel: ChannelType::Email,
platform_message_id: message_id.clone(),
sender: ChannelUser {
platform_id: from_addr.clone(),
display_name: from_addr.clone(),
openfang_user: None,
},
content: ChannelContent::Text(text),
target_agent: None, // Routing handled by bridge AgentRouter
timestamp: Utc::now(),
is_group: false,
thread_id: None,
metadata: std::collections::HashMap::new(),
};
if tx.send(msg).await.is_err() {
info!("Email channel receiver dropped, stopping poll");
return;
}
}
}
});
Ok(Box::pin(tokio_stream::wrappers::ReceiverStream::new(rx)))
}
async fn send(
&self,
user: &ChannelUser,
content: ChannelContent,
) -> Result<(), Box<dyn std::error::Error>> {
match content {
ChannelContent::Text(text) => {
// Parse recipient address
let to_addr = extract_email_addr(&user.platform_id);
let to_mailbox: Mailbox = to_addr
.parse()
.map_err(|e| format!("Invalid recipient email '{}': {}", to_addr, e))?;
let from_mailbox: Mailbox = self
.username
.parse()
.map_err(|e| format!("Invalid sender email '{}': {}", self.username, e))?;
// Extract subject from text body convention: "Subject: ...\n\n..."
let (subject, body) = if text.starts_with("Subject: ") {
if let Some(pos) = text.find("\n\n") {
let subj = text[9..pos].trim().to_string();
let body = text[pos + 2..].to_string();
(subj, body)
} else {
("OpenFang Reply".to_string(), text)
}
} else {
// Check reply context for subject continuity
let subj = self
.reply_ctx
.get(&to_addr)
.map(|ctx| format!("Re: {}", ctx.subject))
.unwrap_or_else(|| "OpenFang Reply".to_string());
(subj, text)
};
// Build email message
let mut builder = lettre::Message::builder()
.from(from_mailbox)
.to(to_mailbox)
.subject(&subject);
// Add In-Reply-To header for threading
if let Some(ctx) = self.reply_ctx.get(&to_addr) {
if !ctx.message_id.is_empty() {
builder = builder.in_reply_to(ctx.message_id.clone());
}
}
let email = builder
.body(body)
.map_err(|e| format!("Failed to build email: {e}"))?;
// Send via SMTP
let transport = self.build_smtp_transport().await?;
transport
.send(email)
.await
.map_err(|e| format!("SMTP send failed: {e}"))?;
info!(
to = %to_addr,
subject = %subject,
"Email sent successfully via SMTP"
);
}
_ => {
warn!(
"Unsupported email content type for {}, only text is supported",
user.platform_id
);
}
}
Ok(())
}
async fn stop(&self) -> Result<(), Box<dyn std::error::Error>> {
let _ = self.shutdown_tx.send(true);
Ok(())
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_email_adapter_creation() {
let adapter = EmailAdapter::new(
"imap.gmail.com".to_string(),
993,
"smtp.gmail.com".to_string(),
587,
"user@gmail.com".to_string(),
"password".to_string(),
30,
vec![],
vec![],
);
assert_eq!(adapter.name(), "email");
assert_eq!(adapter.folders, vec!["INBOX".to_string()]);
}
#[test]
fn test_allowed_senders() {
let adapter = EmailAdapter::new(
"imap.example.com".to_string(),
993,
"smtp.example.com".to_string(),
587,
"bot@example.com".to_string(),
"pass".to_string(),
30,
vec![],
vec!["boss@company.com".to_string()],
);
assert!(adapter.is_allowed_sender("boss@company.com"));
assert!(!adapter.is_allowed_sender("random@other.com"));
let open = EmailAdapter::new(
"imap.example.com".to_string(),
993,
"smtp.example.com".to_string(),
587,
"bot@example.com".to_string(),
"pass".to_string(),
30,
vec![],
vec![],
);
assert!(open.is_allowed_sender("anyone@anywhere.com"));
}
#[test]
fn test_extract_agent_from_subject() {
assert_eq!(
EmailAdapter::extract_agent_from_subject("[coder] Fix the bug"),
Some("coder".to_string())
);
assert_eq!(
EmailAdapter::extract_agent_from_subject("[researcher] Find papers on AI"),
Some("researcher".to_string())
);
assert_eq!(
EmailAdapter::extract_agent_from_subject("No brackets here"),
None
);
assert_eq!(
EmailAdapter::extract_agent_from_subject("[] Empty brackets"),
None
);
}
#[test]
fn test_strip_agent_tag() {
assert_eq!(
EmailAdapter::strip_agent_tag("[coder] Fix the bug"),
"Fix the bug"
);
assert_eq!(EmailAdapter::strip_agent_tag("No brackets"), "No brackets");
}
#[test]
fn test_extract_email_addr() {
assert_eq!(
extract_email_addr("John Doe <john@example.com>"),
"john@example.com"
);
assert_eq!(extract_email_addr("user@example.com"), "user@example.com");
assert_eq!(extract_email_addr("<user@test.com>"), "user@test.com");
}
#[test]
fn test_subject_extraction_from_body() {
let text = "Subject: Test Subject\n\nThis is the body.";
assert!(text.starts_with("Subject: "));
let pos = text.find("\n\n").unwrap();
let subject = &text[9..pos];
let body = &text[pos + 2..];
assert_eq!(subject, "Test Subject");
assert_eq!(body, "This is the body.");
}
#[test]
fn test_reply_ctx_threading() {
let ctx_map: DashMap<String, ReplyCtx> = DashMap::new();
ctx_map.insert(
"user@test.com".to_string(),
ReplyCtx {
subject: "Original Subject".to_string(),
message_id: "<msg-123@test.com>".to_string(),
},
);
let ctx = ctx_map.get("user@test.com").unwrap();
assert_eq!(ctx.subject, "Original Subject");
assert_eq!(ctx.message_id, "<msg-123@test.com>");
}
}