From f898404157e1aebe802dc028422ab96478f8e97f Mon Sep 17 00:00:00 2001
From: Yuchao <yuchao.sydneyuni@gmail.com>
Date: Wed, 28 Jun 2023 04:42:41 +1000
Subject: [PATCH] fix(VInfiniteScroll): persist load logic until is intersected
 (#17475)

fixes #17358

Co-authored-by: John Leider <john@vuetifyjs.com>
---
 .../labs/VInfiniteScroll/VInfiniteScroll.tsx  | 31 ++++++++++++++++---
 .../__tests__/VInfiniteScroll.spec.cy.tsx     | 26 ++++++++++++++++
 2 files changed, 53 insertions(+), 4 deletions(-)

diff --git a/packages/vuetify/src/labs/VInfiniteScroll/VInfiniteScroll.tsx b/packages/vuetify/src/labs/VInfiniteScroll/VInfiniteScroll.tsx
index b3f7d7b3e2c..37fa8dfce77 100644
--- a/packages/vuetify/src/labs/VInfiniteScroll/VInfiniteScroll.tsx
+++ b/packages/vuetify/src/labs/VInfiniteScroll/VInfiniteScroll.tsx
@@ -78,7 +78,7 @@ export const VInfiniteScrollIntersect = defineComponent({
   },
 
   emits: {
-    intersect: (side: InfiniteScrollSide) => true,
+    intersect: (side: InfiniteScrollSide, isIntersecting: boolean) => true,
   },
 
   setup (props, { emit }) {
@@ -89,7 +89,7 @@ export const VInfiniteScrollIntersect = defineComponent({
     } : undefined)
 
     watch(isIntersecting, async val => {
-      if (val) emit('intersect', props.side)
+      emit('intersect', props.side, val)
     })
 
     useRender(() => (
@@ -114,6 +114,7 @@ export const VInfiniteScroll = genericComponent<VInfiniteScrollSlots>()({
     const startStatus = ref<InfiniteScrollStatus>('ok')
     const endStatus = ref<InfiniteScrollStatus>('ok')
     const margin = computed(() => convertToUnit(props.margin))
+    const isIntersecting = ref(false)
 
     function setScrollAmount (amount: number) {
       if (!rootEl.value) return
@@ -166,7 +167,16 @@ export const VInfiniteScroll = genericComponent<VInfiniteScrollSlots>()({
     }
 
     let previousScrollSize = 0
-    function handleIntersect (side: InfiniteScrollSide) {
+    function handleIntersect (side: InfiniteScrollSide, _isIntersecting: boolean) {
+      isIntersecting.value = _isIntersecting
+      if (isIntersecting.value) {
+        intersecting(side)
+      }
+    }
+
+    function intersecting (side: InfiniteScrollSide) {
+      if (props.mode !== 'manual' && !isIntersecting.value) return
+
       const status = getStatus(side)
       if (!rootEl.value || status === 'loading') return
 
@@ -177,9 +187,22 @@ export const VInfiniteScroll = genericComponent<VInfiniteScrollSlots>()({
         setStatus(side, status)
 
         nextTick(() => {
+          if (status === 'empty' || status === 'error') return
+
           if (status === 'ok' && side === 'start') {
             setScrollAmount(getScrollSize() - previousScrollSize + getScrollAmount())
           }
+          if (props.mode !== 'manual') {
+            nextTick(() => {
+              window.requestAnimationFrame(() => {
+                window.requestAnimationFrame(() => {
+                  window.requestAnimationFrame(() => {
+                    intersecting(side)
+                  })
+                })
+              })
+            })
+          }
         })
       }
 
@@ -191,7 +214,7 @@ export const VInfiniteScroll = genericComponent<VInfiniteScrollSlots>()({
     function renderSide (side: InfiniteScrollSide, status: InfiniteScrollStatus) {
       if (props.side !== side && props.side !== 'both') return
 
-      const onClick = () => handleIntersect(side)
+      const onClick = () => intersecting(side)
       const slotProps = { side, props: { onClick, color: props.color } }
 
       if (status === 'error') return slots.error?.(slotProps)
diff --git a/packages/vuetify/src/labs/VInfiniteScroll/__tests__/VInfiniteScroll.spec.cy.tsx b/packages/vuetify/src/labs/VInfiniteScroll/__tests__/VInfiniteScroll.spec.cy.tsx
index 3272e7bd25e..91d8fadab54 100644
--- a/packages/vuetify/src/labs/VInfiniteScroll/__tests__/VInfiniteScroll.spec.cy.tsx
+++ b/packages/vuetify/src/labs/VInfiniteScroll/__tests__/VInfiniteScroll.spec.cy.tsx
@@ -4,6 +4,7 @@
 import { VInfiniteScroll } from '../VInfiniteScroll'
 
 // Utilities
+import { ref } from 'vue'
 import { createRange } from '@/util'
 
 // Constants
@@ -76,4 +77,29 @@ describe('VInfiniteScroll', () => {
       .get('.v-infinite-scroll .v-progress-circular').should('exist')
       .get('@load').should('have.been.calledOnce')
   })
+
+  // https://github.com/vuetifyjs/vuetify/issues/17358
+  it('should keep triggering load logic until VInfiniteScrollIntersect disappears', () => {
+    const loadTracker = cy.spy().as('loadTracker')
+    const items = ref(Array.from({ length: 3 }, (k, v) => v + 1))
+
+    const load = async ({ done }: any) => {
+      setTimeout(() => {
+        items.value.push(...Array.from({ length: 3 }, (k, v) => v + items.value.at(-1)! + 1))
+        loadTracker()
+        done('ok')
+      }, 100)
+    }
+
+    cy.viewport(400, 200)
+      .mount(() => (
+        <VInfiniteScroll onLoad={ load } mode="intersect">
+          { items.value.map(item => (
+            <div>Item #{ item }</div>
+          ))}
+        </VInfiniteScroll>
+      ))
+      .get('.v-infinite-scroll .v-progress-circular').should('exist')
+      .get('@loadTracker').should('have.been.calledTwice')
+  })
 })