From 935290328a34379d802357f54fec3dbe1d3093df Mon Sep 17 00:00:00 2001
From: Maciej Olejnik <maciekolej@gmail.com>
Date: Fri, 13 Jan 2023 21:29:28 +0100
Subject: [PATCH] feat: add support for first render

---
 src/__tests__/events.test.tsx |  45 ++++++++++++
 src/events.ts                 | 127 ++++++++++++----------------------
 2 files changed, 90 insertions(+), 82 deletions(-)

diff --git a/src/__tests__/events.test.tsx b/src/__tests__/events.test.tsx
index 5745d01..64318b1 100644
--- a/src/__tests__/events.test.tsx
+++ b/src/__tests__/events.test.tsx
@@ -281,3 +281,48 @@ test('Static usage', () => {
   expect(staticAliceListener).toBeCalledTimes(2)
   expect(staticBobListener).toBeCalledTimes(1) // should not changed
 })
+
+test('Fresh binding', () => {
+  const aliceListener = jest.fn()
+  const bobListener = jest.fn()
+
+  const [Provider, useEvents] = events({
+    onAlice: () => {},
+    onBob: () => {}
+  })
+
+  const Alice = () => {
+    const { onBob } = useEvents({
+      onAlice: aliceListener
+    })
+
+    React.useEffect(() => {
+      onBob()
+    }, [])
+
+    return <></>
+  }
+
+  const Bob = () => {
+    useEvents({
+      onBob: bobListener
+    })
+
+    return <></>
+  }
+
+  const App = () => (
+    <Provider>
+      <Alice />
+      <Bob />
+    </Provider>
+  )
+
+  expect(aliceListener).toBeCalledTimes(0)
+  expect(bobListener).toBeCalledTimes(0)
+
+  render(<App />)
+
+  expect(aliceListener).toBeCalledTimes(0)
+  expect(bobListener).toBeCalledTimes(1)
+})
diff --git a/src/events.ts b/src/events.ts
index 9501bdf..209fdc1 100644
--- a/src/events.ts
+++ b/src/events.ts
@@ -4,13 +4,11 @@ import {
   unstable_runWithPriority as runWithPriority
 } from 'scheduler'
 
-import { isDev, useIsomorphicLayoutEffect } from './common'
+import { useIsomorphicLayoutEffect } from './common'
 
 /**
  * Types
  */
-type ContextListener<Value> = (value: Readonly<Value>) => void
-
 type EventKey = string | number | symbol
 
 type EventMiddleware<In extends Readonly<unknown>[], Out> = (
@@ -24,20 +22,7 @@ type EventRegistry<
   Event extends EventMiddleware<any, any>
 > = Record<Key, Event>
 
-type EventState = Readonly<{ type: EventKey; payloadArgs: any[] }>
-
-type EventDispatcher = (event: EventState) => void
-
-/**
- * Constants
- */
-
-const EVENT_DISPATCHED_NULL: EventDispatcher = () => {
-  /* istanbul ignore next */
-  if (isDev) {
-    console.warn('Tried to dispatch event without Provider')
-  }
-}
+type EventRecord = Readonly<{ key: EventKey; payload: any[] }>
 
 export default function events<
   Key extends EventKey,
@@ -48,110 +33,88 @@ export default function events<
     [key in keyof Partial<Registry>]: EventListener<ReturnType<Registry[key]>>
   }
 
-  const dispatcher: { current: EventDispatcher } = {
-    current: EVENT_DISPATCHED_NULL
+  const isBinded = { current: false }
+  const listeners: ListenerRegistry[] = []
+  const records: EventRecord[] = []
+
+  const informListeners = (
+    listeners: ListenerRegistry[],
+    record: EventRecord
+  ) => {
+    listeners.forEach((registry) =>
+      registry[record.key]?.(middlewares[record.key](...record.payload))
+    )
   }
-  const contextListeners: ContextListener<EventState>[] = []
 
-  /**
-   * Proxy Dispatcher for easier use
-   * @param event
-   * @param payload
-   */
   type Dispatcher = {
     [key in keyof Registry]: (...payload: Parameters<Registry[key]>) => void
   }
-  const proxyDispatcher = new Proxy(dispatcher, {
-    get: ({ current: targetDispatcher }, type) => {
-      return (...payloadArgs: unknown[]) =>
-        targetDispatcher({ type, payloadArgs })
+  const dispatcher = new Proxy(listeners, {
+    get: (thisListeners, eventKey) => {
+      return (...payload: unknown[]) => {
+        if (isBinded.current) {
+          // Dispatch immediately
+          informListeners(thisListeners, { key: eventKey, payload })
+        } else {
+          // Dispatch after the first render
+          records.push({ key: eventKey, payload })
+        }
+      }
     }
   }) as unknown as Dispatcher
 
-  /**
-   * Informat
-   * @param eventListeners ListenerRegistry
-   * @returns void
-   */
-  const informant: (
-    eventListeners?: ListenerRegistry
-  ) => ContextListener<EventState> =
-    (eventListeners?: ListenerRegistry) => (event: EventState) => {
-      eventListeners?.[event.type]?.(
-        middlewares[event.type](...event.payloadArgs)
-      )
-    }
-
   /**
    * Provider
    */
   const BindProvider: React.FC = (props) => {
-    // setEvent is never updated
-    const [events, setEvents] = React.useState<EventState[]>([])
-    dispatcher.current = React.useCallback(
-      (event: EventState) => setEvents((oldEvents) => [...oldEvents, event]),
-      [setEvents]
-    )
-
     useIsomorphicLayoutEffect(() => {
       runWithPriority(NormalPriority, () => {
-        contextListeners.forEach((listener) => {
-          events.forEach((event) => listener(event))
-        })
-      })
+        // Informing listeners
+        records.forEach((record) => informListeners(listeners, record))
+        records.splice(0, records.length)
 
-      // Removing events without render
-      events.splice(0, events.length)
-    }, [events])
+        isBinded.current = true
+      })
+    }, [])
 
     return React.createElement(React.Fragment, props)
   }
 
   /**
    * useEvent hook
-   * @param eventListeners List of subscribed events
+   * @param newListeners List of subscribed events
    * @returns Dispatch function
    */
-  const useEvent = (eventListeners?: ListenerRegistry) => {
-    // EventListener caller
-    const update = React.useCallback(informant(eventListeners), [
-      eventListeners
-    ])
-
-    // Adding listener on component initialization
+  const useEvent = (newListeners?: ListenerRegistry) => {
     useIsomorphicLayoutEffect(() => {
-      contextListeners.push(update)
+      if (!newListeners) {
+        return
+      }
+
+      listeners.push(newListeners)
 
       return () => {
-        const index = contextListeners.indexOf(update)
-        contextListeners.splice(index, 1)
+        listeners.splice(listeners.indexOf(newListeners), 1)
       }
-    }, [contextListeners])
+    }, [newListeners])
 
-    return proxyDispatcher
+    return dispatcher
   }
 
   /**
    * Subscriber for non-hook aproaches
-   * @param eventListeners List of subscribed events
+   * @param newListeners List of subscribed events
    * @returns Subscriber with unsubscribe method
    */
-  const subscribe = (eventListeners: ListenerRegistry) => {
-    const subscriber: ContextListener<EventState> = informant(eventListeners)
-
-    contextListeners.push(subscriber)
+  const subscribe = (newListeners: ListenerRegistry) => {
+    listeners.push(newListeners)
 
     const unsubscribe = () => {
-      const index = contextListeners.indexOf(subscriber)
-      contextListeners.splice(index, 1)
+      listeners.splice(listeners.indexOf(newListeners), 1)
     }
 
     return { unsubscribe }
   }
 
-  return [
-    BindProvider,
-    useEvent,
-    { subscribe, dispatcher: proxyDispatcher }
-  ] as const
+  return [BindProvider, useEvent, { subscribe, dispatcher }] as const
 }