lazy load history

apps/client/src/features/page-history/components/history-list.tsx

@@ -9,8 +9,16 @@ import {
   historyAtoms,
 } from "@/features/page-history/atoms/history-atoms";
 import { useAtom } from "jotai";
-import { useCallback, useEffect } from "react";
-import { Button, ScrollArea, Group, Divider, Text } from "@mantine/core";
+import { useCallback, useEffect, useMemo, useRef } from "react";
+import {
+  Button,
+  ScrollArea,
+  Group,
+  Divider,
+  Text,
+  Loader,
+  Center,
+} from "@mantine/core";
 import {
   pageEditorAtom,
   titleEditorAtom,
@@ -35,12 +43,22 @@ function HistoryList({ pageId }: Props) {
   const [activeHistoryId, setActiveHistoryId] = useAtom(activeHistoryIdAtom);
   const [, setActiveHistoryPrevId] = useAtom(activeHistoryPrevIdAtom);
   const {
-    data: pageHistoryList,
+    data: pageHistoryData,
     isLoading,
     isError,
+    fetchNextPage,
+    hasNextPage,
+    isFetchingNextPage,
   } = usePageHistoryListQuery(pageId);
   const { data: activeHistoryData } = usePageHistoryQuery(activeHistoryId);
 
+  const historyItems = useMemo(
+    () => pageHistoryData?.pages.flatMap((page) => page.items) ?? [],
+    [pageHistoryData],
+  );
+
+  const loadMoreRef = useRef<HTMLDivElement>(null);
+
   const [mainEditor] = useAtom(pageEditorAtom);
   const [mainEditorTitle] = useAtom(titleEditorAtom);
   const [, setHistoryModalOpen] = useAtom(historyAtoms);
@@ -82,15 +100,28 @@ function HistoryList({ pageId }: Props) {
   }, [activeHistoryData]);
 
   useEffect(() => {
-    if (
-      pageHistoryList &&
-      pageHistoryList.items.length > 0 &&
-      !activeHistoryId
-    ) {
-      setActiveHistoryId(pageHistoryList.items[0].id);
-      setActiveHistoryPrevId(pageHistoryList.items[1]?.id ?? "");
+    if (historyItems.length > 0 && !activeHistoryId) {
+      setActiveHistoryId(historyItems[0].id);
+      setActiveHistoryPrevId(historyItems[1]?.id ?? "");
     }
-  }, [pageHistoryList, activeHistoryId, setActiveHistoryId, setActiveHistoryPrevId]);
+  }, [historyItems, activeHistoryId, setActiveHistoryId, setActiveHistoryPrevId]);
+
+  useEffect(() => {
+    const sentinel = loadMoreRef.current;
+    if (!sentinel || !hasNextPage) return;
+
+    const observer = new IntersectionObserver(
+      (entries) => {
+        if (entries[0].isIntersecting && !isFetchingNextPage) {
+          fetchNextPage();
+        }
+      },
+      { threshold: 0.1 },
+    );
+
+    observer.observe(sentinel);
+    return () => observer.disconnect();
+  }, [fetchNextPage, hasNextPage, isFetchingNextPage]);
 
   if (isLoading) {
     return <></>;
@@ -100,27 +131,30 @@ function HistoryList({ pageId }: Props) {
     return <div>{t("Error loading page history.")}</div>;
   }
 
-  if (!pageHistoryList || pageHistoryList.items.length === 0) {
+  if (historyItems.length === 0) {
     return <>{t("No page history saved yet.")}</>;
   }
 
   return (
     <div>
       <ScrollArea h={620} w="100%" type="scroll" scrollbarSize={5}>
-        {pageHistoryList &&
-          pageHistoryList.items.map((historyItem, index) => (
-            <HistoryItem
-              key={historyItem.id}
-              historyItem={historyItem}
-              onSelect={(id) => {
-                setActiveHistoryId(id);
-                setActiveHistoryPrevId(
-                  pageHistoryList.items[index + 1]?.id ?? "",
-                );
-              }}
-              isActive={historyItem.id === activeHistoryId}
-            />
-          ))}
+        {historyItems.map((historyItem, index) => (
+          <HistoryItem
+            key={historyItem.id}
+            historyItem={historyItem}
+            onSelect={(id) => {
+              setActiveHistoryId(id);
+              setActiveHistoryPrevId(historyItems[index + 1]?.id ?? "");
+            }}
+            isActive={historyItem.id === activeHistoryId}
+          />
+        ))}
+        {hasNextPage && <div ref={loadMoreRef} style={{ height: 1 }} />}
+        {isFetchingNextPage && (
+          <Center py="sm">
+            <Loader size="sm" />
+          </Center>
+        )}
       </ScrollArea>
 
       {spaceAbility.cannot(

apps/client/src/features/page-history/queries/page-history-query.ts

@@ -1,4 +1,10 @@
-import { useQuery, UseQueryResult } from "@tanstack/react-query";
+import {
+  InfiniteData,
+  useInfiniteQuery,
+  UseInfiniteQueryResult,
+  useQuery,
+  UseQueryResult,
+} from "@tanstack/react-query";
 import {
   getPageHistoryById,
   getPageHistoryList,
@@ -8,12 +14,14 @@ import { IPagination } from "@/lib/types.ts";
 
 export function usePageHistoryListQuery(
   pageId: string,
-): UseQueryResult<IPagination<IPageHistory>, Error> {
-  return useQuery({
+): UseInfiniteQueryResult<InfiniteData<IPagination<IPageHistory>, unknown>> {
+  return useInfiniteQuery({
     queryKey: ["page-history-list", pageId],
-    queryFn: () => getPageHistoryList(pageId),
+    queryFn: ({ pageParam }) => getPageHistoryList(pageId, pageParam),
     enabled: !!pageId,
     gcTime: 0,
+    initialPageParam: undefined,
+    getNextPageParam: (lastPage) => lastPage.meta?.nextCursor ?? undefined,
   });
 }
 

apps/client/src/features/page-history/services/page-history-service.ts

@@ -4,9 +4,11 @@ import { IPagination } from "@/lib/types.ts";
 
 export async function getPageHistoryList(
   pageId: string,
+  cursor?: string,
 ): Promise<IPagination<IPageHistory>> {
   const req = await api.post("/pages/history", {
     pageId,
+    cursor,
   });
   return req.data;
 }

apps/client/src/features/page-history/utils/history-diff.ts

@@ -1,183 +0,0 @@
-import type { Node as PMNode } from "@tiptap/pm/model";
-
-function stableStringify(value: unknown): string {
-  if (value === null || typeof value !== "object") {
-    return JSON.stringify(value);
-  }
-
-  if (Array.isArray(value)) {
-    return `[${value.map(stableStringify).join(",")}]`;
-  }
-
-  const obj = value as Record<string, unknown>;
-  const keys = Object.keys(obj).sort();
-  return `{${keys
-    .map((k) => `${JSON.stringify(k)}:${stableStringify(obj[k])}`)
-    .join(",")}}`;
-}
-
-type DiffOp =
-  | { type: "equal"; aIndex: number; bIndex: number }
-  | { type: "insert"; bIndex: number }
-  | { type: "delete"; aIndex: number };
-
-function myersDiff(a: string[], b: string[]): DiffOp[] {
-  const N = a.length;
-  const M = b.length;
-  const max = N + M;
-
-  let v = new Map<number, number>();
-  v.set(1, 0);
-  const trace: Array<Map<number, number>> = [];
-
-  for (let d = 0; d <= max; d += 1) {
-    const vNew = new Map<number, number>();
-    for (let k = -d; k <= d; k += 2) {
-      const vKMinus = v.get(k - 1) ?? 0;
-      const vKPlus = v.get(k + 1) ?? 0;
-
-      let x: number;
-      if (k === -d || (k !== d && vKMinus < vKPlus)) {
-        x = vKPlus;
-      } else {
-        x = vKMinus + 1;
-      }
-
-      let y = x - k;
-      while (x < N && y < M && a[x] === b[y]) {
-        x += 1;
-        y += 1;
-      }
-      vNew.set(k, x);
-
-      if (x >= N && y >= M) {
-        trace.push(vNew);
-        return backtrack(trace, a, b);
-      }
-    }
-    trace.push(vNew);
-    v = vNew;
-  }
-
-  return [];
-}
-
-function backtrack(trace: Array<Map<number, number>>, a: string[], b: string[]) {
-  let x = a.length;
-  let y = b.length;
-  const ops: DiffOp[] = [];
-
-  for (let d = trace.length - 1; d > 0; d -= 1) {
-    const v = trace[d];
-    const prevV = trace[d - 1];
-
-    const k = x - y;
-
-    const prevK =
-      k === -d || (k !== d && (prevV.get(k - 1) ?? 0) < (prevV.get(k + 1) ?? 0))
-        ? k + 1
-        : k - 1;
-
-    const prevX = prevV.get(prevK) ?? 0;
-    const prevY = prevX - prevK;
-
-    while (x > prevX && y > prevY) {
-      ops.push({ type: "equal", aIndex: x - 1, bIndex: y - 1 });
-      x -= 1;
-      y -= 1;
-    }
-
-    if (x === prevX) {
-      ops.push({ type: "insert", bIndex: y - 1 });
-      y -= 1;
-    } else {
-      ops.push({ type: "delete", aIndex: x - 1 });
-      x -= 1;
-    }
-  }
-
-  while (x > 0 && y > 0) {
-    ops.push({ type: "equal", aIndex: x - 1, bIndex: y - 1 });
-    x -= 1;
-    y -= 1;
-  }
-  while (x > 0) {
-    ops.push({ type: "delete", aIndex: x - 1 });
-    x -= 1;
-  }
-  while (y > 0) {
-    ops.push({ type: "insert", bIndex: y - 1 });
-    y -= 1;
-  }
-
-  ops.reverse();
-  return ops;
-}
-
-export interface HistoryBlockDiffResult {
-  diffDoc: PMNode;
-  addedNodeRanges: Array<{ from: number; to: number }>;
-  deletedNodeRanges: Array<{ from: number; to: number }>;
-  addedCount: number;
-  deletedCount: number;
-}
-
-export function computeHistoryBlockDiff(
-  currentDoc: PMNode,
-  prevDoc: PMNode,
-): HistoryBlockDiffResult {
-  const currentTop = Array.from({ length: currentDoc.childCount }, (_, i) =>
-    currentDoc.child(i),
-  );
-  const prevTop = Array.from({ length: prevDoc.childCount }, (_, i) =>
-    prevDoc.child(i),
-  );
-
-  const currentHashes = currentTop.map((n) => stableStringify(n.toJSON()));
-  const prevHashes = prevTop.map((n) => stableStringify(n.toJSON()));
-
-  const ops = myersDiff(prevHashes, currentHashes);
-
-  const nodes: PMNode[] = [];
-  const addedIndices: number[] = [];
-  const deletedIndices: number[] = [];
-
-  for (const op of ops) {
-    if (op.type === "equal") {
-      nodes.push(currentTop[op.bIndex]);
-      continue;
-    }
-    if (op.type === "insert") {
-      addedIndices.push(nodes.length);
-      nodes.push(currentTop[op.bIndex]);
-      continue;
-    }
-    deletedIndices.push(nodes.length);
-    nodes.push(prevTop[op.aIndex]);
-  }
-
-  const diffDoc = currentDoc.type.create(null, nodes);
-
-  const addedNodeRanges: Array<{ from: number; to: number }> = [];
-  const deletedNodeRanges: Array<{ from: number; to: number }> = [];
-
-  let pos = 0;
-  for (let i = 0; i < nodes.length; i += 1) {
-    const node = nodes[i];
-    const from = pos;
-    const to = pos + node.nodeSize;
-    if (addedIndices.includes(i)) addedNodeRanges.push({ from, to });
-    if (deletedIndices.includes(i)) deletedNodeRanges.push({ from, to });
-    pos = to;
-  }
-
-  return {
-    diffDoc,
-    addedNodeRanges,
-    deletedNodeRanges,
-    addedCount: addedIndices.length,
-    deletedCount: deletedIndices.length,
-  };
-}
-
-