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|
use std::collections::BTreeMap;
use crate::{
clock::DateTime,
repo::{
channel::{self, Channel},
login::Login,
message,
},
};
#[derive(
Debug,
Default,
Eq,
Ord,
PartialEq,
PartialOrd,
Clone,
Copy,
serde::Serialize,
serde::Deserialize,
sqlx::Type,
)]
#[serde(transparent)]
#[sqlx(transparent)]
pub struct Sequence(i64);
impl Sequence {
pub fn next(self) -> Self {
let Self(current) = self;
Self(current + 1)
}
}
// For the purposes of event replay, a resume point is a vector of resume
// elements. A resume element associates a channel (by ID) with the latest event
// seen in that channel so far. Replaying the event stream can restart at a
// predictable point - hence the name. These values can be serialized and sent
// to the client as JSON dicts, then rehydrated to recover the resume point at a
// later time.
//
// Using a sorted map ensures that there is a canonical representation for
// each resume point.
#[derive(Clone, Debug, Default, PartialEq, PartialOrd, serde::Deserialize, serde::Serialize)]
#[serde(transparent)]
pub struct ResumePoint(BTreeMap<channel::Id, Sequence>);
impl ResumePoint {
pub fn advance<'e>(&mut self, event: impl Into<ResumeElement<'e>>) {
let Self(elements) = self;
let ResumeElement(channel, sequence) = event.into();
elements.insert(channel.clone(), sequence);
}
pub fn forget<'e>(&mut self, event: impl Into<ResumeElement<'e>>) {
let Self(elements) = self;
let ResumeElement(channel, _) = event.into();
elements.remove(channel);
}
pub fn get(&self, channel: &channel::Id) -> Option<Sequence> {
let Self(elements) = self;
elements.get(channel).copied()
}
pub fn not_after<'e>(&self, event: impl Into<ResumeElement<'e>>) -> bool {
let Self(elements) = self;
let ResumeElement(channel, sequence) = event.into();
elements
.get(channel)
.map_or(true, |resume_at| resume_at < &sequence)
}
}
pub struct ResumeElement<'i>(&'i channel::Id, Sequence);
#[derive(Clone, Debug)]
pub struct ResumableEvent(pub ResumePoint, pub ChannelEvent);
#[derive(Clone, Debug, Eq, PartialEq, serde::Serialize)]
pub struct ChannelEvent {
#[serde(skip)]
pub sequence: Sequence,
pub at: DateTime,
#[serde(flatten)]
pub data: ChannelEventData,
}
impl ChannelEvent {
pub fn created(channel: Channel) -> Self {
Self {
at: channel.created_at,
sequence: Sequence::default(),
data: CreatedEvent { channel }.into(),
}
}
pub fn channel_id(&self) -> &channel::Id {
match &self.data {
ChannelEventData::Created(event) => &event.channel.id,
ChannelEventData::Message(event) => &event.channel.id,
ChannelEventData::MessageDeleted(event) => &event.channel.id,
ChannelEventData::Deleted(event) => &event.channel,
}
}
}
impl<'c> From<&'c ChannelEvent> for ResumeElement<'c> {
fn from(event: &'c ChannelEvent) -> Self {
Self(event.channel_id(), event.sequence)
}
}
#[derive(Clone, Debug, Eq, PartialEq, serde::Serialize)]
#[serde(tag = "type", rename_all = "snake_case")]
pub enum ChannelEventData {
Created(CreatedEvent),
Message(MessageEvent),
MessageDeleted(MessageDeletedEvent),
Deleted(DeletedEvent),
}
#[derive(Clone, Debug, Eq, PartialEq, serde::Serialize)]
pub struct CreatedEvent {
pub channel: Channel,
}
impl From<CreatedEvent> for ChannelEventData {
fn from(event: CreatedEvent) -> Self {
Self::Created(event)
}
}
#[derive(Clone, Debug, Eq, PartialEq, serde::Serialize)]
pub struct MessageEvent {
pub channel: Channel,
pub sender: Login,
pub message: message::Message,
}
impl From<MessageEvent> for ChannelEventData {
fn from(event: MessageEvent) -> Self {
Self::Message(event)
}
}
#[derive(Clone, Debug, Eq, PartialEq, serde::Serialize)]
pub struct MessageDeletedEvent {
pub channel: Channel,
pub message: message::Id,
}
impl From<MessageDeletedEvent> for ChannelEventData {
fn from(event: MessageDeletedEvent) -> Self {
Self::MessageDeleted(event)
}
}
#[derive(Clone, Debug, Eq, PartialEq, serde::Serialize)]
pub struct DeletedEvent {
pub channel: channel::Id,
}
impl From<DeletedEvent> for ChannelEventData {
fn from(event: DeletedEvent) -> Self {
Self::Deleted(event)
}
}
|
