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use std::error::Error as StdError;
use std::fmt;
use crate::login::Credentials;
use crate::mail::Mailbox;
pub struct User {
pub name: String,
pub creds: Credentials,
}
#[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(User),
Selected(User, Mailbox),
Logout,
}
pub enum Transition {
None,
Authenticate(User),
Select(Mailbox),
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), Transition::Select(m)) => Ok(State::Selected(u, m)),
(State::Selected(u, _), Transition::Unselect) => Ok(State::Authenticated(u)),
(_, Transition::Logout) => Ok(State::Logout),
_ => Err(Error::ForbiddenTransition),
}
}
}
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