feat: add event handlers

apps/backend/package.json

@@ -8,8 +8,8 @@
     "build:docker": "bun build --compile src/index.ts --target=bun --packages=external --sourcemap --outfile undb"
   },
   "dependencies": {
-    "@aws-sdk/client-s3": "^3.673.0",
-    "@aws-sdk/s3-request-presigner": "^3.673.0",
+    "@aws-sdk/client-s3": "^3.674.0",
+    "@aws-sdk/s3-request-presigner": "^3.674.0",
     "@elysiajs/cors": "1.1.0",
     "@elysiajs/cron": "1.1.0",
     "@elysiajs/html": "1.1.0",
@@ -25,6 +25,7 @@
     "@undb/authz": "workspace:*",
     "@undb/base": "workspace:*",
     "@undb/command-handlers": "workspace:*",
+    "@undb/event-handlers": "workspace:*",
     "@undb/context": "workspace:*",
     "@undb/cqrs": "workspace:*",
     "@undb/dashboard": "workspace:*",
@@ -41,7 +42,7 @@
     "@undb/trpc": "workspace:*",
     "@undb/webhook": "workspace:*",
     "arctic": "^1.9.2",
-    "bun": "^1.1.30",
+    "bun": "^1.1.31",
     "core-js": "^3.38.1",
     "elysia": "1.1.7",
     "got": "^14.4.3",

apps/backend/src/registry/index.ts

@@ -1,6 +1,7 @@
 import { registerCommands } from "@undb/command-handlers"
 import { registerQueries } from "@undb/query-handlers"
 
+import { registerEvents } from "@undb/event-handlers"
 import { registerWebhook } from "../modules"
 import { registerStorage } from "../modules/file/storage"
 import { registerMail } from "../modules/mail/mail.register"
@@ -13,6 +14,7 @@ export const register = () => {
   registerContext()
   registerDb()
   registerCommands()
+  registerEvents()
   registerQueries()
   registerWebhook()
 }

apps/frontend/package.json

@@ -27,8 +27,8 @@
     "@types/lodash.unzip": "^3.4.9",
     "@types/papaparse": "^5.3.14",
     "@types/sortablejs": "latest",
-    "@typescript-eslint/eslint-plugin": "^8.9.0",
-    "@typescript-eslint/parser": "^8.9.0",
+    "@typescript-eslint/eslint-plugin": "^8.10.0",
+    "@typescript-eslint/parser": "^8.10.0",
     "@undb/commands": "workspace:*",
     "@undb/domain": "workspace:*",
     "@undb/i18n": "workspace:*",

bunfig.toml

@@ -0,0 +1,3 @@
+[install]
+# set default registry as a string
+registry = "https://registry.npmmirror.com"

package.json

@@ -23,7 +23,7 @@
     "drizzle-kit": "^0.26.2",
     "husky": "^9.1.6",
     "lint-staged": "^15.2.10",
-    "npm-run-all2": "^6.2.3",
+    "npm-run-all2": "^6.2.4",
     "prettier": "^3.3.3",
     "turbo": "^2.1.3"
   },
@@ -33,7 +33,7 @@
   "engines": {
     "node": ">=18"
   },
-  "packageManager": "bun@1.1.30",
+  "packageManager": "bun@1.1.31",
   "workspaces": [
     "apps/*",
     "packages/*"

packages/cqrs/src/decorators/constants.ts

@@ -3,3 +3,6 @@ export const COMMAND_HANDLER_METADATA = Symbol.for("COMMAND_HANDLER")
 
 export const QUERY_METADATA = Symbol.for("QUERY")
 export const QUERY_HANDLER_METADATA = Symbol.for("QUERY_HANDLER")
+
+export const EVENT_METADATA = Symbol.for("EVENT")
+export const EVENT_HANDLER_METADATA = Symbol.for("EVENT_HANDLER")

packages/cqrs/src/decorators/event-handler.decorator.ts

@@ -0,0 +1,15 @@
+import "reflect-metadata"
+
+import type { BaseEvent } from "@undb/domain"
+import type { Class } from "type-fest"
+import { v4 } from "uuid"
+import { EVENT_HANDLER_METADATA, EVENT_METADATA } from "./constants"
+
+export const eventHandler = (event: Class<BaseEvent>): ClassDecorator => {
+  return (target: object) => {
+    if (!Reflect.hasOwnMetadata(EVENT_METADATA, event)) {
+      Reflect.defineMetadata(EVENT_METADATA, { id: v4() }, event)
+    }
+    Reflect.defineMetadata(EVENT_HANDLER_METADATA, event, target)
+  }
+}

packages/cqrs/src/decorators/index.ts

@@ -1,2 +1,3 @@
 export * from "./command-handler.decorator"
+export * from "./event-handler.decorator"
 export * from "./query-handler.decorator"

packages/cqrs/src/default-event-publisher.ts

@@ -0,0 +1,14 @@
+import type { BaseEvent, IEventPublisher } from "@undb/domain"
+import { Subject } from "rxjs"
+
+export class DefaultEventPubSub<E extends BaseEvent> implements IEventPublisher<E> {
+  constructor(public subject$: Subject<E>) {}
+
+  async publish(event: E): Promise<void> {
+    this.subject$.next(event)
+  }
+
+  async publishMany(events: E[]): Promise<void> {
+    events.forEach((event) => this.subject$.next(event))
+  }
+}

packages/cqrs/src/event-bus.ts

@@ -0,0 +1,74 @@
+import { container, singleton } from "@undb/di"
+import type { BaseEvent, EventMetadata, IEventBus, IEventHandler, IEventPublisher } from "@undb/domain"
+import { Subject } from "rxjs"
+import type { Class } from "type-fest"
+import { EVENT_HANDLER_METADATA, EVENT_METADATA } from "./decorators/constants"
+import { DefaultEventPubSub } from "./default-event-publisher"
+import { EventHandlerNotFoundException } from "./exceptions/event-handler-not-found.exception"
+import { InvalidEventHandlerException } from "./exceptions/invalid-event-handler.exception"
+
+export type EventHandlerType = Class<IEventHandler<BaseEvent, any>>
+
+@singleton()
+export class EventBus<TEvent extends BaseEvent = BaseEvent> implements IEventBus<TEvent> {
+  private subject = new Subject<TEvent>()
+  private readonly publisher: IEventPublisher = new DefaultEventPubSub(this.subject)
+
+  #handlers = new Map<string, IEventHandler<TEvent, any>>()
+
+  async publish(event: TEvent): Promise<void> {
+    console.log("publish event", event)
+    const eventId = this.getEventId(event)
+    const handler = this.#handlers.get(eventId)
+    if (!handler) {
+      const eventName = this.getEventName(event)
+      throw new EventHandlerNotFoundException(eventName)
+    }
+    this.publisher.publish(event)
+    return handler.handle(event)
+  }
+
+  async publishMany(events: TEvent[]): Promise<void> {
+    await Promise.all(events.map((event) => this.publish(event)))
+  }
+
+  register(handlers: EventHandlerType[]) {
+    handlers.forEach((handler) => this.registerHandler(handler))
+  }
+
+  private bind<T extends TEvent>(handler: IEventHandler<T, any>, id: string) {
+    this.#handlers.set(id, handler)
+  }
+
+  protected registerHandler(handler: EventHandlerType) {
+    const instance = container.resolve(handler)
+    if (!instance) {
+      return
+    }
+    const target = this.reflectEventId(handler)
+    if (!target) {
+      throw new InvalidEventHandlerException()
+    }
+    this.bind(instance as IEventHandler<TEvent, any>, target)
+  }
+
+  private reflectEventId(handler: EventHandlerType): string | undefined {
+    const event: BaseEvent = Reflect.getMetadata(EVENT_HANDLER_METADATA, handler)
+    const eventMetadata: EventMetadata = Reflect.getMetadata(EVENT_METADATA, event)
+    return eventMetadata.id
+  }
+
+  private getEventId(event: TEvent): string {
+    const { constructor: eventType } = Object.getPrototypeOf(event)
+    const eventMetadata: EventMetadata = Reflect.getMetadata(EVENT_METADATA, eventType)
+    if (!eventMetadata) {
+      throw new EventHandlerNotFoundException(eventType.name)
+    }
+    return eventMetadata.id
+  }
+
+  private getEventName(event: TEvent): string {
+    const { constructor } = Object.getPrototypeOf(event)
+    return constructor.name as string
+  }
+}

packages/cqrs/src/exceptions/event-handler-not-found.exception.ts

@@ -0,0 +1,5 @@
+export class EventHandlerNotFoundException extends Error {
+  constructor(eventId: string) {
+    super(`The event handler for the "${eventId}" event was not found!`)
+  }
+}

packages/cqrs/src/exceptions/invalid-event-handler.exception.ts

@@ -0,0 +1,5 @@
+export class InvalidEventHandlerException extends Error {
+  constructor() {
+    super(`Invalid event handler exception (missing @eventHandler() decorator?)`)
+  }
+}

packages/cqrs/src/index.ts

@@ -1,3 +1,4 @@
 export * from "./command-bus"
 export * from "./decorators"
+export * from "./event-bus"
 export * from "./query-bus"

packages/domain/src/event-bus.ts

@@ -0,0 +1,6 @@
+import type { BaseEvent } from "./event.js"
+
+export interface IEventBus<TEvent extends BaseEvent = BaseEvent> {
+  publish(event: TEvent): Promise<void>
+  publishMany(events: TEvent[]): Promise<void>
+}

packages/domain/src/event-metadata.ts

@@ -0,0 +1,3 @@
+export interface EventMetadata {
+  id: string
+}

packages/domain/src/event-publisher.ts

@@ -0,0 +1,6 @@
+import type { BaseEvent } from "./event"
+
+export interface IEventPublisher<TEvent extends BaseEvent = BaseEvent> {
+  publish(event: TEvent): Promise<void>
+  publishMany(events: TEvent[]): Promise<void>
+}

packages/domain/src/index.ts

@@ -8,7 +8,10 @@ export * from "./command.js"
 export * from "./date.vo.js"
 export * from "./email.vo.js"
 export * from "./entity.base.js"
+export * from "./event-bus.js"
 export * from "./event-handler.js"
+export * from "./event-metadata.js"
+export * from "./event-publisher.js"
 export * from "./event.js"
 export * from "./exception.base.js"
 export * from "./exceptions"