From ba2bfb12ee1dd2ef2f41a4369dbccdc177dce4b3 Mon Sep 17 00:00:00 2001
From: Willian Mitsuda <wmitsuda@gmail.com>
Date: Fri, 30 Jul 2021 05:05:31 -0300
Subject: [PATCH] Preload prev blocks on page reload

---
 src/special/london/Blocks.tsx | 27 ++++++++++++++++++++++++++-
 1 file changed, 26 insertions(+), 1 deletion(-)

diff --git a/src/special/london/Blocks.tsx b/src/special/london/Blocks.tsx
index e510d5d..e94f01e 100644
--- a/src/special/london/Blocks.tsx
+++ b/src/special/london/Blocks.tsx
@@ -22,6 +22,8 @@ import { RuntimeContext } from "../../useRuntime";
 
 const MAX_BLOCK_HISTORY = 20;
 
+const PREV_BLOCK_COUNT = 15;
+
 const options: ChartOptions = {
   animation: false,
   plugins: {
@@ -67,6 +69,11 @@ const Blocks: React.FC<BlocksProps> = ({ latestBlock, targetBlockNumber }) => {
         return;
       }
 
+      // Skip blocks before the hard fork during the transition
+      if (blockNumber < targetBlockNumber) {
+        return;
+      }
+
       const extBlock = await readBlock(provider, blockNumber.toString());
       setNow(Date.now());
       setBlock((_blocks) => {
@@ -85,7 +92,7 @@ const Blocks: React.FC<BlocksProps> = ({ latestBlock, targetBlockNumber }) => {
         return newBlocks;
       });
     },
-    [provider]
+    [provider, targetBlockNumber]
   );
 
   useEffect(() => {
@@ -110,6 +117,24 @@ const Blocks: React.FC<BlocksProps> = ({ latestBlock, targetBlockNumber }) => {
     };
   }, [blocks]);
 
+  // On page reload, pre-populate the last N blocks
+  useEffect(
+    () => {
+      const addPreviousBlocks = async () => {
+        for (
+          let i = latestBlock.number - PREV_BLOCK_COUNT;
+          i < latestBlock.number;
+          i++
+        ) {
+          await addBlock(i);
+        }
+      };
+      addPreviousBlocks();
+    },
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+    []
+  );
+
   return (
     <div className="w-full mb-auto">
       <div className="px-9 pt-3 pb-12 divide-y-2">