From 92d9946f597c2b06552b23ba370708aea86575c0 Mon Sep 17 00:00:00 2001
From: tamaina <tamaina@hotmail.co.jp>
Date: Wed, 5 Jul 2023 00:59:37 +0900
Subject: [PATCH] enhance(frontend): Better Timeline(MkPagination) Experience
 (#11066)
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* enhance(frontend): Better MkPagination Appearance

* fix

* fix

* 新規投稿が空でも先頭に戻ったらunshiftItemsする

* use Map

* refactor, 型エラー潰し

* refactor
---
 .../frontend/src/components/MkPagination.vue  | 170 +++++++++++++-----
 packages/frontend/src/pages/admin/abuses.vue  |   2 +-
 .../src/pages/custom-emojis-manager.vue       |   2 +-
 3 files changed, 127 insertions(+), 47 deletions(-)

diff --git a/packages/frontend/src/components/MkPagination.vue b/packages/frontend/src/components/MkPagination.vue
index 598529bf58..b361d568e8 100644
--- a/packages/frontend/src/components/MkPagination.vue
+++ b/packages/frontend/src/components/MkPagination.vue
@@ -21,14 +21,14 @@
 
 	<div v-else ref="rootEl">
 		<div v-show="pagination.reversed && more" key="_more_" class="_margin">
-			<MkButton v-if="!moreFetching" v-appear="(enableInfiniteScroll && !props.disableAutoLoad) ? fetchMoreAhead : null" :class="$style.more" :disabled="moreFetching" :style="{ cursor: moreFetching ? 'wait' : 'pointer' }" primary rounded @click="fetchMoreAhead">
+			<MkButton v-if="!moreFetching" v-appear="(enableInfiniteScroll && !props.disableAutoLoad) ? appearFetchMoreAhead : null" :class="$style.more" :disabled="moreFetching" :style="{ cursor: moreFetching ? 'wait' : 'pointer' }" primary rounded @click="fetchMoreAhead">
 				{{ i18n.ts.loadMore }}
 			</MkButton>
 			<MkLoading v-else class="loading"/>
 		</div>
-		<slot :items="items" :fetching="fetching || moreFetching"></slot>
+		<slot :items="Array.from(items.values())" :fetching="fetching || moreFetching"></slot>
 		<div v-show="!pagination.reversed && more" key="_more_" class="_margin">
-			<MkButton v-if="!moreFetching" v-appear="(enableInfiniteScroll && !props.disableAutoLoad) ? fetchMore : null" :class="$style.more" :disabled="moreFetching" :style="{ cursor: moreFetching ? 'wait' : 'pointer' }" primary rounded @click="fetchMore">
+			<MkButton v-if="!moreFetching" v-appear="(enableInfiniteScroll && !props.disableAutoLoad) ? appearFetchMore : null" :class="$style.more" :disabled="moreFetching" :style="{ cursor: moreFetching ? 'wait' : 'pointer' }" primary rounded @click="fetchMore">
 				{{ i18n.ts.loadMore }}
 			</MkButton>
 			<MkLoading v-else class="loading"/>
@@ -50,6 +50,7 @@ import { i18n } from '@/i18n';
 
 const SECOND_FETCH_LIMIT = 30;
 const TOLERANCE = 16;
+const APPEAR_MINIMUM_INTERVAL = 600;
 
 export type Paging<E extends keyof misskey.Endpoints = keyof misskey.Endpoints> = {
 	endpoint: E;
@@ -71,6 +72,16 @@ export type Paging<E extends keyof misskey.Endpoints = keyof misskey.Endpoints>
 
 	pageEl?: HTMLElement;
 };
+
+type MisskeyEntityMap = Map<string, MisskeyEntity>;
+
+function arrayToEntries(entities: MisskeyEntity[]): [string, MisskeyEntity][] {
+	return entities.map(en => [en.id, en]);
+}
+
+function concatMapWithArray(map: MisskeyEntityMap, entities: MisskeyEntity[]): MisskeyEntityMap {
+	return new Map([...map, ...arrayToEntries(entities)]);
+}
 </script>
 <script lang="ts" setup>
 import { infoImageUrl } from '@/instance';
@@ -94,21 +105,38 @@ let backed = $ref(false);
 
 let scrollRemove = $ref<(() => void) | null>(null);
 
-const items = ref<MisskeyEntity[]>([]);
-const queue = ref<MisskeyEntity[]>([]);
+/**
+ * 表示するアイテムのソース
+ * 最新が0番目
+ */
+const items = ref<MisskeyEntityMap>(new Map());
+
+/**
+ * タブが非アクティブなどの場合に更新を貯めておく
+ * 最新が0番目
+ */
+const queue = ref<MisskeyEntityMap>(new Map());
+
 const offset = ref(0);
+
+/**
+ * 初期化中かどうか（trueならMkLoadingで全て隠す）
+ */
 const fetching = ref(true);
+
 const moreFetching = ref(false);
 const more = ref(false);
+const preventAppearFetchMore = ref(false);
+const preventAppearFetchMoreTimer = ref<number | null>(null);
 const isBackTop = ref(false);
-const empty = computed(() => items.value.length === 0);
+const empty = computed(() => items.value.size === 0);
 const error = ref(false);
 const {
 	enableInfiniteScroll,
 } = defaultStore.reactiveState;
 
 const contentEl = $computed(() => props.pagination.pageEl ?? rootEl);
-const scrollableElement = $computed(() => getScrollContainer(contentEl));
+const scrollableElement = $computed(() => contentEl ? getScrollContainer(contentEl) : document.body);
 
 const visibility = useDocumentVisibility();
 
@@ -133,9 +161,9 @@ watch([() => props.pagination.reversed, $$(scrollableElement)], () => {
 }, { immediate: true });
 
 watch($$(rootEl), () => {
-	scrollObserver.disconnect();
+	scrollObserver?.disconnect();
 	nextTick(() => {
-		if (rootEl) scrollObserver.observe(rootEl);
+		if (rootEl) scrollObserver?.observe(rootEl);
 	});
 });
 
@@ -155,12 +183,12 @@ if (props.pagination.params && isRef(props.pagination.params)) {
 }
 
 watch(queue, (a, b) => {
-	if (a.length === 0 && b.length === 0) return;
-	emit('queue', queue.value.length);
+	if (a.size === 0 && b.size === 0) return;
+	emit('queue', queue.value.size);
 }, { deep: true });
 
 async function init(): Promise<void> {
-	queue.value = [];
+	queue.value = new Map();
 	fetching.value = true;
 	const params = props.pagination.params ? isRef(props.pagination.params) ? props.pagination.params.value : props.pagination.params : {};
 	await os.api(props.pagination.endpoint, {
@@ -173,11 +201,11 @@ async function init(): Promise<void> {
 		}
 
 		if (res.length === 0 || props.pagination.noPaging) {
-			items.value = res;
+			concatItems(res);
 			more.value = false;
 		} else {
 			if (props.pagination.reversed) moreFetching.value = true;
-			items.value = res;
+			concatItems(res);
 			more.value = true;
 		}
 
@@ -191,12 +219,13 @@ async function init(): Promise<void> {
 }
 
 const reload = (): Promise<void> => {
-	items.value = [];
+	items.value = new Map();
+	queue.value = new Map();
 	return init();
 };
 
 const fetchMore = async (): Promise<void> => {
-	if (!more.value || fetching.value || moreFetching.value || items.value.length === 0) return;
+	if (!more.value || fetching.value || moreFetching.value || items.value.size === 0) return;
 	moreFetching.value = true;
 	const params = props.pagination.params ? isRef(props.pagination.params) ? props.pagination.params.value : props.pagination.params : {};
 	await os.api(props.pagination.endpoint, {
@@ -205,7 +234,7 @@ const fetchMore = async (): Promise<void> => {
 		...(props.pagination.offsetMode ? {
 			offset: offset.value,
 		} : {
-			untilId: items.value[items.value.length - 1].id,
+			untilId: Array.from(items.value.keys())[items.value.size - 1],
 		}),
 	}).then(res => {
 		for (let i = 0; i < res.length; i++) {
@@ -217,7 +246,7 @@ const fetchMore = async (): Promise<void> => {
 			const oldHeight = scrollableElement ? scrollableElement.scrollHeight : getBodyScrollHeight();
 			const oldScroll = scrollableElement ? scrollableElement.scrollTop : window.scrollY;
 
-			items.value = items.value.concat(_res);
+			items.value = concatMapWithArray(items.value, _res);
 
 			return nextTick(() => {
 				if (scrollableElement) {
@@ -237,7 +266,7 @@ const fetchMore = async (): Promise<void> => {
 					moreFetching.value = false;
 				});
 			} else {
-				items.value = items.value.concat(res);
+				items.value = concatMapWithArray(items.value, res);
 				more.value = false;
 				moreFetching.value = false;
 			}
@@ -248,7 +277,7 @@ const fetchMore = async (): Promise<void> => {
 					moreFetching.value = false;
 				});
 			} else {
-				items.value = items.value.concat(res);
+				items.value = concatMapWithArray(items.value, res);
 				more.value = true;
 				moreFetching.value = false;
 			}
@@ -260,7 +289,7 @@ const fetchMore = async (): Promise<void> => {
 };
 
 const fetchMoreAhead = async (): Promise<void> => {
-	if (!more.value || fetching.value || moreFetching.value || items.value.length === 0) return;
+	if (!more.value || fetching.value || moreFetching.value || items.value.size === 0) return;
 	moreFetching.value = true;
 	const params = props.pagination.params ? isRef(props.pagination.params) ? props.pagination.params.value : props.pagination.params : {};
 	await os.api(props.pagination.endpoint, {
@@ -269,14 +298,14 @@ const fetchMoreAhead = async (): Promise<void> => {
 		...(props.pagination.offsetMode ? {
 			offset: offset.value,
 		} : {
-			sinceId: items.value[items.value.length - 1].id,
+			sinceId: Array.from(items.value.keys())[items.value.size - 1],
 		}),
 	}).then(res => {
 		if (res.length === 0) {
-			items.value = items.value.concat(res);
+			items.value = concatMapWithArray(items.value, res);
 			more.value = false;
 		} else {
-			items.value = items.value.concat(res);
+			items.value = concatMapWithArray(items.value, res);
 			more.value = true;
 		}
 		offset.value += res.length;
@@ -286,7 +315,32 @@ const fetchMoreAhead = async (): Promise<void> => {
 	});
 };
 
-const isTop = (): boolean => isBackTop.value || (props.pagination.reversed ? isBottomVisible : isTopVisible)(contentEl, TOLERANCE);
+/**
+ * Appear（IntersectionObserver）によってfetchMoreが呼ばれる場合、
+ * APPEAR_MINIMUM_INTERVALミリ秒以内に2回fetchMoreが呼ばれるのを防ぐ
+ */
+const fetchMoreApperTimeoutFn = (): void => {
+	preventAppearFetchMore.value = false;
+	preventAppearFetchMoreTimer.value = null;
+};
+const fetchMoreAppearTimeout = (): void => {
+	preventAppearFetchMore.value = true;
+	preventAppearFetchMoreTimer.value = window.setTimeout(fetchMoreApperTimeoutFn, APPEAR_MINIMUM_INTERVAL);
+};
+
+const appearFetchMore = async (): Promise<void> => {
+	if (preventAppearFetchMore.value) return;
+	await fetchMore();
+	fetchMoreAppearTimeout();
+};
+
+const appearFetchMoreAhead = async (): Promise<void> => {
+	if (preventAppearFetchMore.value) return;
+	await fetchMoreAhead();
+	fetchMoreAppearTimeout();
+};
+
+const isTop = (): boolean => isBackTop.value || (props.pagination.reversed ? isBottomVisible : isTopVisible)(contentEl!, TOLERANCE);
 
 watch(visibility, () => {
 	if (visibility.value === 'hidden') {
@@ -308,10 +362,15 @@ watch(visibility, () => {
 	}
 });
 
+/**
+ * 最新のものとして1つだけアイテムを追加する
+ * ストリーミングから降ってきたアイテムはこれで追加する
+ * @param item アイテム
+ */
 const prepend = (item: MisskeyEntity): void => {
-	// 初回表示時はunshiftだけでOK
-	if (!rootEl) {
-		items.value.unshift(item);
+	if (items.value.size === 0) {
+		items.value.set(item.id, item);
+		fetching.value = false;
 		return;
 	}
 
@@ -319,38 +378,55 @@ const prepend = (item: MisskeyEntity): void => {
 	else prependQueue(item);
 };
 
+/**
+ * 新着アイテムをitemsの先頭に追加し、displayLimitを適用する
+ * @param newItems 新しいアイテムの配列
+ */
 function unshiftItems(newItems: MisskeyEntity[]) {
-	const length = newItems.length + items.value.length;
-	items.value = [...newItems, ...items.value].slice(0, props.displayLimit);
+	const length = newItems.length + items.value.size;
+	items.value = new Map([...arrayToEntries(newItems), ...items.value].slice(0, props.displayLimit));
+
+	if (length >= props.displayLimit) more.value = true;
+}
+
+/**
+ * 古いアイテムをitemsの末尾に追加し、displayLimitを適用する
+ * @param oldItems 古いアイテムの配列
+ */
+function concatItems(oldItems: MisskeyEntity[]) {
+	const length = oldItems.length + items.value.size;
+	items.value = new Map([...items.value, ...arrayToEntries(oldItems)].slice(0, props.displayLimit));
 
 	if (length >= props.displayLimit) more.value = true;
 }
 
 function executeQueue() {
-	if (queue.value.length === 0) return;
-	unshiftItems(queue.value);
-	queue.value = [];
+	unshiftItems(Array.from(queue.value.values()));
+	queue.value = new Map();
 }
 
 function prependQueue(newItem: MisskeyEntity) {
-	queue.value.unshift(newItem);
-	if (queue.value.length >= props.displayLimit) {
-		queue.value.pop();
-	}
+	queue.value = new Map([[newItem.id, newItem], ...queue.value].slice(0, props.displayLimit) as [string, MisskeyEntity][]);
 }
 
+/*
+ * アイテムを末尾に追加する（使うの？）
+ */
 const appendItem = (item: MisskeyEntity): void => {
-	items.value.push(item);
+	items.value.set(item.id, item);
 };
 
-const removeItem = (finder: (item: MisskeyEntity) => boolean) => {
-	const i = items.value.findIndex(finder);
-	items.value.splice(i, 1);
+const removeItem = (id: string) => {
+	items.value.delete(id);
+	queue.value.delete(id);
 };
 
 const updateItem = (id: MisskeyEntity['id'], replacer: (old: MisskeyEntity) => MisskeyEntity): void => {
-	const i = items.value.findIndex(item => item.id === id);
-	items.value[i] = replacer(items.value[i]);
+	const item = items.value.get(id);
+	if (item) items.value.set(id, replacer(item));
+
+	const queueItem = queue.value.get(id);
+	if (queueItem) queue.value.set(id, replacer(queueItem));
 };
 
 const inited = init();
@@ -364,7 +440,7 @@ onDeactivated(() => {
 });
 
 function toBottom() {
-	scrollToBottom(contentEl);
+	scrollToBottom(contentEl!);
 }
 
 onMounted(() => {
@@ -388,7 +464,11 @@ onBeforeUnmount(() => {
 		clearTimeout(timerForSetPause);
 		timerForSetPause = null;
 	}
-	scrollObserver.disconnect();
+	if (preventAppearFetchMoreTimer.value) {
+		clearTimeout(preventAppearFetchMoreTimer.value);
+		preventAppearFetchMoreTimer.value = null;
+	}
+	scrollObserver?.disconnect();
 });
 
 defineExpose({
diff --git a/packages/frontend/src/pages/admin/abuses.vue b/packages/frontend/src/pages/admin/abuses.vue
index 3bc5ee9723..9cf96d3d04 100644
--- a/packages/frontend/src/pages/admin/abuses.vue
+++ b/packages/frontend/src/pages/admin/abuses.vue
@@ -75,7 +75,7 @@ const pagination = {
 };
 
 function resolved(reportId) {
-	reports.removeItem(item => item.id === reportId);
+	reports.removeItem(reportId);
 }
 
 const headerActions = $computed(() => []);
diff --git a/packages/frontend/src/pages/custom-emojis-manager.vue b/packages/frontend/src/pages/custom-emojis-manager.vue
index 3da6a0d9cb..901fbc1eea 100644
--- a/packages/frontend/src/pages/custom-emojis-manager.vue
+++ b/packages/frontend/src/pages/custom-emojis-manager.vue
@@ -144,7 +144,7 @@ const edit = (emoji) => {
 					...result.updated,
 				}));
 			} else if (result.deleted) {
-				emojisPaginationComponent.value.removeItem((item) => item.id === emoji.id);
+				emojisPaginationComponent.value.removeItem(emoji.id);
 			}
 		},
 	}, 'closed');