use super::{
    event::{Created, Event},
    Id, Login,
};
use crate::event::{Instant, Sequence};

#[derive(Clone, Debug, Eq, PartialEq)]
pub struct History {
    pub login: Login,
    pub created: Instant,
}

// State interface
impl History {
    pub fn id(&self) -> &Id {
        &self.login.id
    }

    // Snapshot of this login as it was when created. (Note to the future: it's okay
    // if this returns a redacted or modified version of the login. If we  implement
    // renames by redacting the original name, then this should return the edited
    // login, not the original, even if that's not how it was "as created.")
    pub fn as_created(&self) -> Login {
        self.login.clone()
    }

    pub fn as_of(&self, resume_point: Sequence) -> Option<Login> {
        self.events()
            .filter(Sequence::up_to(resume_point))
            .collect()
    }

    // Snapshot of this login, as of all events recorded in this history.
    pub fn as_snapshot(&self) -> Option<Login> {
        self.events().collect()
    }
}

// Events interface
impl History {
    fn created(&self) -> Event {
        Created {
            instant: self.created,
            login: self.login.clone(),
        }
        .into()
    }

    pub fn events(&self) -> impl Iterator<Item = Event> {
        [self.created()].into_iter()
    }
}