use std::error::Error as StdError; use std::fmt; use std::sync::Arc; use tokio::sync::Notify; use crate::imap::mailbox_view::MailboxView; use crate::mail::user::User; use imap_codec::imap_types::core::Tag; #[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, Tag<'static>, Arc, ), Logout, } impl fmt::Display for State { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { use State::*; match self { NotAuthenticated => write!(f, "NotAuthenticated"), Authenticated(..) => write!(f, "Authenticated"), Selected(..) => write!(f, "Selected"), Idle(..) => write!(f, "Idle"), Logout => write!(f, "Logout"), } } } #[derive(Clone)] pub enum MailboxPerm { ReadOnly, ReadWrite, } pub enum Transition { None, Authenticate(Arc), Select(MailboxView, MailboxPerm), Idle(Tag<'static>, Notify), UnIdle, Unselect, Logout, } impl fmt::Display for Transition { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { use Transition::*; match self { None => write!(f, "None"), Authenticate(..) => write!(f, "Authenticated"), Select(..) => write!(f, "Selected"), Idle(..) => write!(f, "Idle"), UnIdle => write!(f, "UnIdle"), Unselect => write!(f, "Unselect"), Logout => write!(f, "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> { tracing::debug!(state=%self, transition=%tr, "try change state"); let new_state = match (std::mem::replace(self, State::Logout), tr) { (s, Transition::None) => s, (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(t, s)) => { State::Idle(u, m, p, t, Arc::new(s)) } (State::Idle(u, m, p, _, _), Transition::UnIdle) => State::Selected(u, m, p), (_, Transition::Logout) => State::Logout, (s, t) => { tracing::error!(state=%s, transition=%t, "forbidden transition"); return Err(Error::ForbiddenTransition); } }; *self = new_state; tracing::debug!(state=%self, "transition succeeded"); Ok(()) } }