Merge pull request #41 from exstake/add-persisted-state-hook

add persisted state hook

app/javascript/src/hooks/usePersistedState.ts

@@ -0,0 +1,58 @@
+import type { SetStateAction, Dispatch } from "react";
+import { useState, useEffect, useCallback } from "react";
+
+export const usePersistedState = <S>(
+  key: string,
+  initialValue: S,
+  ttl?: number
+): [S, Dispatch<SetStateAction<S>>] => {
+  type PersistedStatePaylaod = {
+    value: S;
+    expiry?: number;
+  };
+
+  const [state, setState] = useState<S>(() => {
+    try {
+      const localStorageRaw = localStorage.getItem(key);
+
+      if (localStorageRaw === null) return initialValue;
+
+      const payload: PersistedStatePaylaod = JSON.parse(localStorageRaw);
+
+      if (!payload.expiry) return payload.value;
+
+      const expired = new Date().getTime() > payload.expiry;
+
+      if (expired) return initialValue;
+
+      return payload.value;
+    } catch {
+      return initialValue;
+    }
+  });
+
+  const setLocalStorage = useCallback(
+    (value) => {
+      try {
+        const expiry = ttl ? new Date().getTime() + ttl : undefined;
+        const payload: PersistedStatePaylaod = { value, expiry };
+
+        localStorage.setItem(key, JSON.stringify(payload));
+      } catch {
+        localStorage.removeItem(key);
+      }
+    },
+    [key]
+  );
+
+  const setLocalStorageAndState: Dispatch<SetStateAction<S>> = (newState) => {
+    setLocalStorage(newState);
+    setState(newState);
+  };
+
+  useEffect(() => {
+    setLocalStorage(state);
+  }, [setLocalStorage, state]);
+
+  return [state, setLocalStorageAndState];
+};

app/javascript/src/pages/Home/PoolListing.tsx

@@ -12,10 +12,16 @@ import { getEndBlock } from "../../utils/getEndBlock";
 import type { PoolListingQuery } from "./__generated__/PoolListingQuery.graphql";
 import { notEmpty } from "../../utils/notEmpty";
 import { Spinner } from "../../components";
+import { usePersistedState } from "../../hooks/usePersistedState";
 
 export const PoolListing = () => {
   const { provider } = useBsc();
-  const [validPools, setValidPools] = useState<PoolConfig[]>([]);
+  const [validPools, setValidPools] = usePersistedState<PoolConfig[]>(
+    "validPools",
+    [],
+    1200000 // 20 minutes
+  );
+
   const [isLoadingPools, setIsLoadingPools] = useState(true);
 
   const { currentUser } = useLazyLoadQuery<PoolListingQuery>(
@@ -35,6 +41,8 @@ export const PoolListing = () => {
 
   useEffect(() => {
     (async () => {
+      if (validPools.length) return;
+
       const blockNumber = await provider.getBlockNumber();
 
       const getChef = (pool: PoolConfig) => {
@@ -67,9 +75,9 @@ export const PoolListing = () => {
         setValidPools(pools.filter(notEmpty));
       });
     })();
-  }, [provider]);
+  }, [provider, setValidPools, validPools.length]);
 
-  if (isLoadingPools) {
+  if (isLoadingPools && !validPools.length) {
     return (
       <div className="w-full grid place-items-center mt-12">
         <Spinner />