use std::num::NonZeroU32;
use std::sync::Arc;
use anyhow::{Error, Result};
use boitalettres::proto::res::body::Data as Body;
use imap_codec::types::core::Atom;
use imap_codec::types::flag::Flag;
use imap_codec::types::response::{Code, Data, MessageAttribute, Status};
use crate::mail::mailbox::Mailbox;
use crate::mail::uidindex::UidIndex;
const DEFAULT_FLAGS: [Flag; 5] = [
Flag::Seen,
Flag::Answered,
Flag::Flagged,
Flag::Deleted,
Flag::Draft,
];
/// A MailboxView is responsible for giving the client the information
/// it needs about a mailbox, such as an initial summary of the mailbox's
/// content and continuous updates indicating when the content
/// of the mailbox has been changed.
/// To do this, it keeps a variable `known_state` that corresponds to
/// what the client knows, and produces IMAP messages to be sent to the
/// client that go along updates to `known_state`.
pub struct MailboxView {
mailbox: Arc<Mailbox>,
known_state: UidIndex,
}
impl MailboxView {
/// Creates a new IMAP view into a mailbox.
/// Generates the necessary IMAP messages so that the client
/// has a satisfactory summary of the current mailbox's state.
/// These are the messages that are sent in response to a SELECT command.
pub async fn new(mailbox: Arc<Mailbox>) -> Result<(Self, Vec<Body>)> {
// TODO THIS IS JUST A TEST REMOVE LATER
mailbox.test().await?;
let state = mailbox.current_uid_index().await;
let new_view = Self {
mailbox,
known_state: state,
};
let mut data = Vec::<Body>::new();
data.push(new_view.exists()?);
data.push(new_view.recent()?);
data.extend(new_view.flags()?.into_iter());
data.push(new_view.uidvalidity()?);
data.push(new_view.uidnext()?);
if let Some(unseen) = new_view.unseen()? {
data.push(unseen);
}
Ok((new_view, data))
}
/// Looks up state changes in the mailbox and produces a set of IMAP
/// responses describing the new state.
pub async fn update(&mut self) -> Result<Vec<Body>> {
self.mailbox.sync().await?;
// TODO THIS IS JUST A TEST REMOVE LATER
self.mailbox.test().await?;
let new_view = MailboxView {
mailbox: self.mailbox.clone(),
known_state: self.mailbox.current_uid_index().await,
};
let mut data = Vec::<Body>::new();
if new_view.known_state.uidvalidity != self.known_state.uidvalidity {
// TODO: do we want to push less/more info than this?
data.push(new_view.uidvalidity()?);
data.push(new_view.exists()?);
data.push(new_view.uidnext()?);
} else {
// Calculate diff between two mailbox states
// See example in IMAP RFC in section on NOOP command:
// we want to produce something like this:
// C: a047 NOOP
// S: * 22 EXPUNGE
// S: * 23 EXISTS
// S: * 14 FETCH (UID 1305 FLAGS (\Seen \Deleted))
// S: a047 OK Noop completed
// In other words:
// - notify client of expunged mails
// - if new mails arrived, notify client of number of existing mails
// - if flags changed for existing mails, tell client
// - notify client of expunged mails
let mut n_expunge = 0;
for (i, (uid, uuid)) in self.known_state.idx_by_uid.iter().enumerate() {
if !new_view.known_state.table.contains_key(uuid) {
data.push(Body::Data(Data::Expunge(
NonZeroU32::try_from((i + 1 - n_expunge) as u32).unwrap(),
)));
n_expunge += 1;
}
}
// - if new mails arrived, notify client of number of existing mails
if new_view.known_state.table.len() != self.known_state.table.len() - n_expunge {
data.push(new_view.exists()?);
}
// - if flags changed for existing mails, tell client
for (i, (uid, uuid)) in new_view.known_state.idx_by_uid.iter().enumerate() {
let old_mail = self.known_state.table.get(uuid);
let new_mail = new_view.known_state.table.get(uuid);
if old_mail.is_some() && old_mail != new_mail {
if let Some((uid, flags)) = new_mail {
data.push(Body::Data(Data::Fetch {
seq_or_uid: NonZeroU32::try_from((i + 1) as u32).unwrap(),
attributes: vec![
MessageAttribute::Uid((*uid).try_into().unwrap()),
MessageAttribute::Flags(
flags.iter().filter_map(|f| string_to_flag(f)).collect(),
),
],
}));
}
}
}
}
*self = new_view;
Ok(data)
}
// ----
/// Produce an OK [UIDVALIDITY _] message corresponding to `known_state`
fn uidvalidity(&self) -> Result<Body> {
let uid_validity = Status::ok(
None,
Some(Code::UidValidity(self.known_state.uidvalidity)),
"UIDs valid",
)
.map_err(Error::msg)?;
Ok(Body::Status(uid_validity))
}
/// Produce an OK [UIDNEXT _] message corresponding to `known_state`
fn uidnext(&self) -> Result<Body> {
let next_uid = Status::ok(
None,
Some(Code::UidNext(self.known_state.uidnext)),
"Predict next UID",
)
.map_err(Error::msg)?;
Ok(Body::Status(next_uid))
}
/// Produces an UNSEEN message (if relevant) corresponding to the
/// first unseen message id in `known_state`
fn unseen(&self) -> Result<Option<Body>> {
let unseen = self
.known_state
.idx_by_flag
.get(&"$unseen".to_string())
.and_then(|os| os.get_min())
.cloned();
if let Some(unseen) = unseen {
let status_unseen =
Status::ok(None, Some(Code::Unseen(unseen.clone())), "First unseen UID")
.map_err(Error::msg)?;
Ok(Some(Body::Status(status_unseen)))
} else {
Ok(None)
}
}
/// Produce an EXISTS message corresponding to the number of mails
/// in `known_state`
fn exists(&self) -> Result<Body> {
let exists = u32::try_from(self.known_state.idx_by_uid.len())?;
Ok(Body::Data(Data::Exists(exists)))
}
/// Produce a RECENT message corresponding to the number of
/// recent mails in `known_state`
fn recent(&self) -> Result<Body> {
let recent = self
.known_state
.idx_by_flag
.get(&"\\Recent".to_string())
.map(|os| os.len())
.unwrap_or(0);
let recent = u32::try_from(recent)?;
Ok(Body::Data(Data::Recent(recent)))
}
/// Produce a FLAGS and a PERMANENTFLAGS message that indicates
/// the flags that are in `known_state` + default flags
fn flags(&self) -> Result<Vec<Body>> {
let mut flags: Vec<Flag> = self
.known_state
.idx_by_flag
.flags()
.map(|f| string_to_flag(f))
.flatten()
.collect();
for f in DEFAULT_FLAGS.iter() {
if !flags.contains(f) {
flags.push(f.clone());
}
}
let mut ret = vec![Body::Data(Data::Flags(flags.clone()))];
flags.push(Flag::Permanent);
let permanent_flags =
Status::ok(None, Some(Code::PermanentFlags(flags)), "Flags permitted")
.map_err(Error::msg)?;
ret.push(Body::Status(permanent_flags));
Ok(ret)
}
}
fn string_to_flag(f: &str) -> Option<Flag> {
match f.chars().next() {
Some('\\') => None,
Some('$') if f == "$unseen" => None,
Some(_) => match Atom::try_from(f.clone()) {
Err(_) => {
tracing::error!(flag=%f, "Unable to encode flag as IMAP atom");
None
}
Ok(a) => Some(Flag::Keyword(a)),
},
None => None,
}
}
