From 60a5d9300435dfb7ca4aa5fd3dff7b5d7d96520d Mon Sep 17 00:00:00 2001
From: Eric Ribeiro <ericribeiro@outlook.com.br>
Date: Sat, 17 Apr 2021 16:43:15 -0700
Subject: [PATCH] fix: Fix automatic sort of `Composite` items in fixed
 containers

---
 .../__utils/useSortBasedOnDOMPosition.ts      | 25 ++++++++++++++-----
 1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/packages/reakit/src/Composite/__utils/useSortBasedOnDOMPosition.ts b/packages/reakit/src/Composite/__utils/useSortBasedOnDOMPosition.ts
index b308b909..771e6f73 100644
--- a/packages/reakit/src/Composite/__utils/useSortBasedOnDOMPosition.ts
+++ b/packages/reakit/src/Composite/__utils/useSortBasedOnDOMPosition.ts
@@ -1,16 +1,30 @@
 import * as React from "react";
+import { getDocument } from "reakit-utils/getDocument";
 import { sortBasedOnDOMPosition } from "./sortBasedOnDOMPosition";
 import { Item } from "./types";
 
 type SetItems = (items: Item[]) => void;
 
-function setItemsBasedOnDOMPosition(items: Item[], setItems: SetItems) {
+function mutateItemsBasedOnDOMPosition(items: Item[], setItems: SetItems) {
   const sortedItems = sortBasedOnDOMPosition(items);
   if (items !== sortedItems) {
     setItems(sortedItems);
   }
 }
 
+function getCommonParent(items: Item[]) {
+  const [firstItem, ...nextItems] = items;
+  let parentElement = firstItem?.ref.current?.parentElement;
+  while (parentElement) {
+    const parent = parentElement;
+    if (nextItems.every((item) => parent.contains(item.ref.current))) {
+      return parentElement;
+    }
+    parentElement = parentElement.parentElement;
+  }
+  return getDocument(parentElement).body;
+}
+
 // istanbul ignore next: JSDOM doesn't support IntersectionObverser
 // See https://github.com/jsdom/jsdom/issues/2032
 function useIntersectionObserver(items: Item[], setItems: SetItems) {
@@ -21,13 +35,12 @@ function useIntersectionObserver(items: Item[], setItems: SetItems) {
       const hasPreviousItems = !!previousItems.current.length;
       // We don't want to sort items if items have been just registered.
       if (hasPreviousItems) {
-        setItemsBasedOnDOMPosition(items, setItems);
+        mutateItemsBasedOnDOMPosition(items, setItems);
       }
       previousItems.current = items;
     };
-    const observer = new IntersectionObserver(callback, {
-      root: document.body,
-    });
+    const root = getCommonParent(items);
+    const observer = new IntersectionObserver(callback, { root });
     for (const item of items) {
       if (item.ref.current) {
         observer.observe(item.ref.current);
@@ -41,7 +54,7 @@ function useIntersectionObserver(items: Item[], setItems: SetItems) {
 
 function useTimeoutObserver(items: Item[], setItems: SetItems) {
   React.useEffect(() => {
-    const callback = () => setItemsBasedOnDOMPosition(items, setItems);
+    const callback = () => mutateItemsBasedOnDOMPosition(items, setItems);
     const timeout = setTimeout(callback, 250);
     return () => clearTimeout(timeout);
   });