aerogramme/src/imap/flow.rs

59 lines
1.7 KiB
Rust

use std::error::Error as StdError;
use std::fmt;
use std::sync::Arc;
use crate::imap::mailbox_view::MailboxView;
use crate::mail::user::User;
#[derive(Debug)]
pub enum Error {
ForbiddenTransition,
}
impl fmt::Display for Error {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
write!(f, "Forbidden Transition")
}
}
impl StdError for Error {}
pub enum State {
NotAuthenticated,
Authenticated(Arc<User>),
Selected(Arc<User>, MailboxView),
// Examined is like Selected, but indicates that the mailbox is read-only
Examined(Arc<User>, MailboxView),
Logout,
}
pub enum Transition {
None,
Authenticate(Arc<User>),
Examine(MailboxView),
Select(MailboxView),
Unselect,
Logout,
}
// See RFC3501 section 3.
// https://datatracker.ietf.org/doc/html/rfc3501#page-13
impl State {
pub fn apply(self, tr: Transition) -> Result<Self, Error> {
match (self, tr) {
(s, Transition::None) => Ok(s),
(State::NotAuthenticated, Transition::Authenticate(u)) => Ok(State::Authenticated(u)),
(
State::Authenticated(u) | State::Selected(u, _) | State::Examined(u, _),
Transition::Select(m),
) => Ok(State::Selected(u, m)),
(
State::Authenticated(u) | State::Selected(u, _) | State::Examined(u, _),
Transition::Examine(m),
) => Ok(State::Examined(u, m)),
(State::Selected(u, _), Transition::Unselect) => Ok(State::Authenticated(u)),
(State::Examined(u, _), Transition::Unselect) => Ok(State::Authenticated(u)),
(_, Transition::Logout) => Ok(State::Logout),
_ => Err(Error::ForbiddenTransition),
}
}
}