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), Selected(Arc, MailboxView, MailboxPerm), Idle(Arc, MailboxView, MailboxPerm), Logout, } #[derive(Clone)] pub enum MailboxPerm { ReadOnly, ReadWrite, } pub enum Transition { None, Authenticate(Arc), Select(MailboxView, MailboxPerm), Idle, UnIdle, Unselect, Logout, } // See RFC3501 section 3. // https://datatracker.ietf.org/doc/html/rfc3501#page-13 impl State { pub fn apply(&mut self, tr: Transition) -> Result<(), Error> { let new_state = match (std::mem::replace(self, State::NotAuthenticated), tr) { (_s, Transition::None) => return Ok(()), (State::NotAuthenticated, Transition::Authenticate(u)) => State::Authenticated(u), ( State::Authenticated(u) | State::Selected(u, _, _), Transition::Select(m, p), ) => State::Selected(u, m, p), (State::Selected(u, _, _) , Transition::Unselect) => { State::Authenticated(u.clone()) } (State::Selected(u, m, p), Transition::Idle) => { State::Idle(u, m, p) }, (State::Idle(u, m, p), Transition::UnIdle) => { State::Selected(u, m, p) }, (_, Transition::Logout) => State::Logout, _ => return Err(Error::ForbiddenTransition), }; *self = new_state; Ok(()) } }