From 9e1c0d8b958a048db7fdbb297c24ed3c2dc25e54 Mon Sep 17 00:00:00 2001
From: memoyil <2213635+memoyil@users.noreply.github.com>
Date: Tue, 6 Aug 2024 11:45:52 +0200
Subject: [PATCH] perf: Make history manager provider render only with
 subscribe

---
 apps/web/src/contexts/HistoryContext.tsx | 72 ++++++++++++++++++++----
 1 file changed, 62 insertions(+), 10 deletions(-)

diff --git a/apps/web/src/contexts/HistoryContext.tsx b/apps/web/src/contexts/HistoryContext.tsx
index 485b965e860a0b..d76e9902b9de39 100644
--- a/apps/web/src/contexts/HistoryContext.tsx
+++ b/apps/web/src/contexts/HistoryContext.tsx
@@ -1,28 +1,66 @@
 import { useRouter } from 'next/router'
-import { createContext, useContext, useEffect, useMemo, useState } from 'react'
+import { createContext, useCallback, useContext, useEffect, useMemo, useRef, useState } from 'react'
 
-const historyManagerContext = createContext<ReturnType<typeof useHistoryManager> | null>(null)
+interface HistoryManagerContext {
+  history: string[]
+  canGoBack: () => boolean
+  subscribe: (subscriber: Subscriber) => void
+  unsubscribe: (subscriber: Subscriber) => void
+}
+
+interface Subscriber {
+  setState: React.Dispatch<React.SetStateAction<any>>
+}
 
-export function HistoryManagerProvider({ children }) {
+const historyManagerContext = createContext<HistoryManagerContext | null>(null)
+
+export function HistoryManagerProvider({ children }: { children: React.ReactNode }) {
   const value = useHistoryManager()
   return <historyManagerContext.Provider value={value}>{children}</historyManagerContext.Provider>
 }
 
-export const useHistory = () => useContext(historyManagerContext)
+export const useHistory = () => {
+  const context = useContext(historyManagerContext)
+  if (!context) {
+    throw new Error('useHistory must be used within a HistoryManagerProvider')
+  }
+
+  const [, setState] = useState()
+
+  useEffect(() => {
+    const subscriber = { setState }
+    context.subscribe(subscriber)
+
+    return () => {
+      context.unsubscribe(subscriber)
+    }
+  }, [context])
 
-function useHistoryManager() {
+  return context
+}
+
+function useHistoryManager(): HistoryManagerContext {
   const router = useRouter()
   const [history, setHistory] = useState<string[]>(() => [router?.asPath])
+  const subscribersRef = useRef<Subscriber[]>([])
 
   useEffect(() => {
-    const handleRouteChange = (url, { shallow }) => {
+    const handleRouteChange = (url: string, { shallow }: { shallow: boolean }) => {
       if (!shallow) {
-        setHistory((prevState) => [...prevState, url])
+        setHistory((prevState) => {
+          const newHistory = [...prevState, url]
+          notifySubscribers(newHistory)
+          return newHistory
+        })
       }
     }
 
     router.beforePopState(() => {
-      setHistory((prevState) => prevState.slice(0, -2))
+      setHistory((prevState) => {
+        const newHistory = prevState.slice(0, -2)
+        notifySubscribers(newHistory)
+        return newHistory
+      })
       return true
     })
 
@@ -34,7 +72,21 @@ function useHistoryManager() {
     // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [])
 
+  const notifySubscribers = useCallback((newHistory: string[]) => {
+    subscribersRef.current.forEach((subscriber) => {
+      subscriber.setState(newHistory)
+    })
+  }, [])
+
+  const subscribe = useCallback((subscriber: Subscriber) => {
+    subscribersRef.current.push(subscriber)
+  }, [])
+
+  const unsubscribe = useCallback((subscriber: Subscriber) => {
+    subscribersRef.current = subscribersRef.current.filter((sub) => sub !== subscriber)
+  }, [])
+
   return useMemo(() => {
-    return { history, canGoBack: () => history.length > 1 }
-  }, [history])
+    return { history, canGoBack: () => history.length > 1, subscribe, unsubscribe }
+  }, [history, subscribe, unsubscribe])
 }