From ad37edf6814b4fb61c17e8313eae2027eef0a459 Mon Sep 17 00:00:00 2001
From: infiinte-persistence <inf.persistence@gmail.com>
Date: Tue, 23 Jun 2020 21:08:06 +0800
Subject: [PATCH] Inf-scroll: Fix scroll not working when navigating back from
 claim.

## Fixes:
3071: "Infinite scroll stops working when navigating to file page / back"

## The Issue:
In the POP operation, the `page` value is back to 1 due to the initializer `useState(1)`. If the results cache already contained more than 1 page's worth, then the rest of the logic thinks there's nothing to do.

## The Fix:
Previous fixes to Inf-Scroll added a "page correction" code to handle the mismatch. This fix simply adds this scenario to the list of scenarios to perform the correction.
---
 ui/component/claimListDiscover/view.jsx | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/ui/component/claimListDiscover/view.jsx b/ui/component/claimListDiscover/view.jsx
index 4c427e050..54869502c 100644
--- a/ui/component/claimListDiscover/view.jsx
+++ b/ui/component/claimListDiscover/view.jsx
@@ -296,9 +296,10 @@ function ClaimListDiscover(props: Props) {
   const claimSearchCacheQuery = createNormalizedClaimSearchKey(options);
   const claimSearchResult = claimSearchByQuery[claimSearchCacheQuery];
 
-  const [prevOptions, setPrevOptions] = useState(options);
+  const [prevOptions, setPrevOptions] = useState(null);
 
   if (!isJustScrollingToNewPage(prevOptions, options)) {
+    // --- New search, or search options changed.
     setPrevOptions(options);
 
     if (didNavigateForward) {
@@ -306,7 +307,7 @@ function ClaimListDiscover(props: Props) {
       window.scrollTo(0, 0); // Prevents onScrollBottom() from re-hitting while waiting for doClaimQuery():
       options.page = 1;
       setPage(options.page);
-    } else {
+    } else if (claimSearchResult) {
       // --- Update 'page' based on retrieved 'claimSearchResult'.
       options.page = Math.ceil(claimSearchResult.length / CS.PAGE_SIZE);
       if (options.page !== page) {
@@ -359,6 +360,11 @@ function ClaimListDiscover(props: Props) {
   // Returns true if the change in 'options' indicate that we are simply scrolling
   // down to a new page; false otherwise.
   function isJustScrollingToNewPage(prevOptions, options) {
+    if (!prevOptions) {
+      // It's a new search, or we just popped back from a different view.
+      return false;
+    }
+
     // Compare every field except for 'page' and 'release_time'.
     // There might be better ways to achieve this.
     let tmpPrevOptions = { ...prevOptions };