From 6919a819b67edcbccae6ee5dff5c27520ca3798a Mon Sep 17 00:00:00 2001
From: Pablo Baleztena <pablo@ultharsoftware.com>
Date: Sat, 12 Oct 2024 15:39:51 -0300
Subject: [PATCH] [fabric/domain] Refactor event store and event stream
 interfaces

---
 .../fabric/domain/src/events/event-store.ts   | 42 +++++++------------
 .../fabric/domain/src/events/event-stream.ts  | 16 +++++++
 packages/fabric/domain/src/events/event.ts    | 18 +++-----
 packages/fabric/domain/src/events/index.ts    |  2 +
 .../fabric/domain/src/events/stored-event.ts  | 10 +++++
 5 files changed, 49 insertions(+), 39 deletions(-)
 create mode 100644 packages/fabric/domain/src/events/event-stream.ts
 create mode 100644 packages/fabric/domain/src/events/stored-event.ts

diff --git a/packages/fabric/domain/src/events/event-store.ts b/packages/fabric/domain/src/events/event-store.ts
index c58102b..0e31fc1 100644
--- a/packages/fabric/domain/src/events/event-store.ts
+++ b/packages/fabric/domain/src/events/event-store.ts
@@ -1,36 +1,26 @@
-import { AsyncResult, MaybePromise, PosixDate } from "@fabric/core";
+import { AsyncResult, PosixDate } from "@fabric/core";
 import { StoreQueryError } from "../errors/query-error.js";
-import { UUID } from "../types/uuid.js";
-import { Event, StoredEvent } from "./event.js";
+import { EventsFromStream, EventStream } from "./event-stream.js";
+import { StoredEvent } from "./stored-event.js";
 
-export interface EventStore<TEvent extends Event = Event> {
-  getStream<TEventStreamEvent extends TEvent>(
-    streamId: UUID,
-  ): AsyncResult<EventStream<TEventStreamEvent>, StoreQueryError>;
-
-  appendToStream<TEvent extends Event>(
-    streamId: UUID,
-    events: TEvent,
-  ): AsyncResult<void, StoreQueryError>;
-}
-
-export interface EventStream<TEvent extends Event = Event> {
-  getCurrentVersion(): bigint;
-
-  append(events: TEvent): AsyncResult<StoredEvent<TEvent>, StoreQueryError>;
-
-  subscribe(callback: (event: StoredEvent<TEvent>) => MaybePromise<void>): void;
-
-  getEvents(
-    opts?: EventFilterOptions,
-  ): AsyncResult<StoredEvent<TEvent>[], StoreQueryError>;
+export interface EventStore<TEventStream extends EventStream> {
+  /**
+   * Store a new event in the event store.
+   */
+  append<
+    TStreamKey extends TEventStream["name"],
+    T extends EventsFromStream<TEventStream, TStreamKey>,
+  >(
+    streamName: TStreamKey,
+    event: T,
+  ): AsyncResult<StoredEvent<T>, StoreQueryError>;
 }
 
 export interface EventFilterOptions {
   fromDate?: PosixDate;
   toDate?: PosixDate;
-  fromVersion?: number;
-  toVersion?: number;
+  fromVersion?: bigint;
+  toVersion?: bigint;
   limit?: number;
   offset?: number;
 }
diff --git a/packages/fabric/domain/src/events/event-stream.ts b/packages/fabric/domain/src/events/event-stream.ts
new file mode 100644
index 0000000..9b70954
--- /dev/null
+++ b/packages/fabric/domain/src/events/event-stream.ts
@@ -0,0 +1,16 @@
+import { AsyncResult } from "@fabric/core";
+import { UUID } from "../types/uuid.js";
+import { Event } from "./event.js";
+import { StoredEvent } from "./stored-event.js";
+
+export interface EventStream<
+  TName extends string = string,
+  TEvent extends Event = Event,
+> {
+  id: UUID;
+  name: TName;
+  append<T extends TEvent>(event: Event): AsyncResult<StoredEvent<T>>;
+}
+
+export type EventsFromStream<T extends EventStream, TKey extends string> =
+  T extends EventStream<TKey, infer TEvent> ? TEvent : never;
diff --git a/packages/fabric/domain/src/events/event.ts b/packages/fabric/domain/src/events/event.ts
index be843d1..e314103 100644
--- a/packages/fabric/domain/src/events/event.ts
+++ b/packages/fabric/domain/src/events/event.ts
@@ -1,20 +1,12 @@
 /* eslint-disable @typescript-eslint/no-explicit-any */
-import { PosixDate, TaggedVariant } from "@fabric/core";
 import { UUID } from "../types/uuid.js";
 
 /**
  * An event is a tagged variant with a payload and a timestamp.
  */
-export interface Event<TTag extends string = string, TPayload = any>
-  extends TaggedVariant<TTag> {
-  streamId: UUID;
-  payload: TPayload;
+export interface Event<TTag extends string = string, TPayload = any> {
+  readonly type: TTag;
+  readonly id: UUID;
+  readonly streamId: UUID;
+  readonly payload: TPayload;
 }
-
-/**
- * A stored event is an inmutable event, already stored, with it's version in the stream and timestamp.
- */
-export type StoredEvent<TEvent extends Event> = Readonly<TEvent> & {
-  readonly version: number;
-  readonly timestamp: PosixDate;
-};
diff --git a/packages/fabric/domain/src/events/index.ts b/packages/fabric/domain/src/events/index.ts
index a28ecf2..7b181cc 100644
--- a/packages/fabric/domain/src/events/index.ts
+++ b/packages/fabric/domain/src/events/index.ts
@@ -1,2 +1,4 @@
 export * from "./event-store.js";
+export * from "./event-stream.js";
 export * from "./event.js";
+export * from "./stored-event.js";
diff --git a/packages/fabric/domain/src/events/stored-event.ts b/packages/fabric/domain/src/events/stored-event.ts
new file mode 100644
index 0000000..e0a33eb
--- /dev/null
+++ b/packages/fabric/domain/src/events/stored-event.ts
@@ -0,0 +1,10 @@
+import { PosixDate } from "@fabric/core";
+import { Event } from "./event.js";
+
+/**
+ * A stored event is an inmutable event, already stored, with it's version in the stream and timestamp.
+ */
+export type StoredEvent<TEvent extends Event> = TEvent & {
+  readonly version: bigint;
+  readonly timestamp: PosixDate;
+};