From 5a5f7cb5cd02e3bfed25a485fb3df67bbf11235f Mon Sep 17 00:00:00 2001
From: Frank Noirot <frank@zoo.dev>
Date: Fri, 21 Jun 2024 11:49:45 -0400
Subject: [PATCH] Franknoirot/limit model loading (#139)

* Update guidance on local token in README

* Make items fetched per page a named const, add one for fetch ahead page count

* Refactor GenerationList to fetch only a few pages ahead and fetch more when scroll is near the bottom

* Add a Playwright test to verify this behavior

* Follow Svelte warning and put the initial fetch in an onMount handler

* Update persistence key so we reset localStorage for people
---
 README.md                            |   2 +-
 src/components/GenerationList.svelte | 107 +++++++++++++++++++--------
 src/lib/consts.ts                    |  11 ++-
 src/lib/endpoints.ts                 |   3 +-
 src/lib/stores.ts                    |   5 +-
 tests/e2e.playwright.ts              |  14 ++++
 6 files changed, 106 insertions(+), 36 deletions(-)

diff --git a/README.md b/README.md
index dda5cc0..1d36528 100644
--- a/README.md
+++ b/README.md
@@ -5,7 +5,7 @@ This repository is an open-source example of how to quickly get up and running w
 ## Developing
 
 1. Generate a dev API token from https://dev.zoo.dev
-2. Set the `VITE_TOKEN` environment variable in `./.env.development` to the generated dev API token
+2. Set the `VITE_TOKEN` environment variable in `./.env.development.local` to the generated dev API token
 3. Install yarn
 4. Install dependencies with `yarn global add vite` and `yarn install`
 5. Run the dev server with `yarn dev -- --open`
diff --git a/src/components/GenerationList.svelte b/src/components/GenerationList.svelte
index 99de7e5..c09a88d 100644
--- a/src/components/GenerationList.svelte
+++ b/src/components/GenerationList.svelte
@@ -1,33 +1,51 @@
 <script lang="ts">
 	import type { Models } from '@kittycad/lib'
+	import type { UIEventHandler } from 'svelte/elements'
 	import GenerationListItem from './GenerationListItem.svelte'
 	import { endpoints } from '$lib/endpoints'
 	import { page } from '$app/stores'
-	import { fetchedGenerations, generations, nextPageToken } from '$lib/stores'
+	import { fetchedGenerations, generations, nextPageTokens } from '$lib/stores'
 	import { sortTimeBuckets } from '$lib/time'
-	import { browser } from '$app/environment'
 	import Spinner from 'components/Icons/Spinner.svelte'
+	import { PAGES_AHEAD_TO_FETCH } from '$lib/consts'
+	import { onMount } from 'svelte'
 
-	let isFetching = false
 	let error: string | null = null
+	let pagesToFetch = PAGES_AHEAD_TO_FETCH
+	let scrolledPercentage = 0
+	let fetchPromise: Promise<void>
 
-	$: if (browser && $nextPageToken !== null) {
-		fetchData()
+	onMount(() => {
+		fetchPromise =
+			$nextPageTokens[$nextPageTokens.length - 1] === null ? Promise.resolve() : fetchData()
+	})
+
+	// Reset the pages to fetch counter if the user scrolls
+	// to the bottom of the generation list
+	const handleScroll: UIEventHandler<HTMLElement> = (e) => {
+		const { scrollTop, scrollHeight, clientHeight } = e.target as HTMLElement
+		scrolledPercentage = (scrollTop / (scrollHeight - clientHeight)) * 100
+		if (scrolledPercentage > 90) {
+			pagesToFetch = PAGES_AHEAD_TO_FETCH
+			fetchPromise = fetchData()
+		}
 	}
 
 	async function fetchData() {
-		if ($nextPageToken === null) return
-		isFetching = true
+		// If we're at the end of the list, don't fetch more
+		if ($nextPageTokens[$nextPageTokens.length - 1] === null) return
 
-		const response = await fetch(endpoints.list({ page_token: $nextPageToken }), {
-			headers: {
-				'Content-Type': 'application/json',
-				Authorization: 'Bearer ' + $page.data.token
+		const response = await fetch(
+			endpoints.list({ page_token: $nextPageTokens[$nextPageTokens.length - 1] }),
+			{
+				headers: {
+					'Content-Type': 'application/json',
+					Authorization: 'Bearer ' + $page.data.token
+				}
 			}
-		})
-
+		)
 		if (!response.ok) {
-			isFetching = false
+			error = 'Failed to fetch your creations'
 			return
 		}
 
@@ -35,9 +53,23 @@
 
 		// If we see that one of fetched generations has an id that matches one of the
 		// generations in the store, we know we can stop fetching
-		const shouldKeepFetching = updateFetchedGenerations(nextBatchPayload)
-		$nextPageToken = shouldKeepFetching ? nextBatchPayload?.next_page ?? null : null
-		isFetching = false
+		const hasNoDuplicateGenerations = updateFetchedGenerations(nextBatchPayload)
+
+		if (nextBatchPayload?.next_page === null) {
+			$nextPageTokens = [...$nextPageTokens, null]
+			pagesToFetch = 0
+		} else if (hasNoDuplicateGenerations) {
+			$nextPageTokens = [...$nextPageTokens, nextBatchPayload?.next_page ?? null]
+			pagesToFetch = pagesToFetch - 1
+		} else {
+			pagesToFetch = 0
+		}
+
+		// If we have more pages to fetch, fetch them
+		// and "keep the promise alive"
+		if (pagesToFetch > 0) {
+			return fetchData()
+		}
 	}
 
 	function updateFetchedGenerations(payload: Models['TextToCadResultsPage_type']): boolean {
@@ -60,8 +92,14 @@
 	}
 </script>
 
-<section class="overflow-y-auto max-h-full px-2 lg:pr-4 pt-6">
-	{#if Object.keys($generations).length > 0}
+<section
+	on:scroll={handleScroll}
+	class="overflow-y-auto max-h-full px-2 lg:pr-4 pt-6"
+	data-testid="generation-list"
+>
+	{#if error}
+		<p class="text-red mt-2">{error}</p>
+	{:else if Object.keys($generations).length > 0}
 		{#each Object.entries($generations).toSorted(sortTimeBuckets) as [category, items]}
 			<div class="first-of-type:mt-0 mt-12">
 				<h2 class="pl-2 lg:pl-4 text-xl">{category}</h2>
@@ -74,19 +112,24 @@
 				</ul>
 			</div>
 		{/each}
-	{/if}
-	{#if isFetching}
-		<p
-			class={'flex gap-4 m-2 text-sm tracking-wide text-chalkboard-100 dark:text-chalkboard-30' +
-				(Object.keys($generations).length > 0 ? ' pt-8 border-t' : '')}
-		>
-			<span class="flex-grow">Fetching your creations</span>
-			<Spinner class="w-5 h-5 animate-spin inline-block mr-2" />
-		</p>
-	{:else if Object.keys($generations).length === 0}
+		{#await fetchPromise}
+			<p
+				class={'flex gap-4 m-2 text-sm tracking-wide text-chalkboard-100 dark:text-chalkboard-30' +
+					(Object.keys($generations).length > 0 ? ' pt-8 border-t' : '')}
+			>
+				<span class="flex-grow">Fetching your creations</span>
+				<Spinner class="w-5 h-5 animate-spin inline-block mr-2" />
+			</p>
+		{:then}
+			{#if $nextPageTokens[$nextPageTokens.length - 1] === null}
+				<p
+					class="text-chalkboard-100 dark:text-chalkboard-30 text-sm tracking-wide m-2 py-6 border-t"
+				>
+					You've reached the end of your creations 🎉
+				</p>
+			{/if}
+		{/await}
+	{:else}
 		<p>You'll see your creations here once you submit your first prompt</p>
 	{/if}
-	{#if error}
-		<p class="text-red mt-2">{error}</p>
-	{/if}
 </section>
diff --git a/src/lib/consts.ts b/src/lib/consts.ts
index 2f35ccf..75734c0 100644
--- a/src/lib/consts.ts
+++ b/src/lib/consts.ts
@@ -1,6 +1,6 @@
 import { msSinceStartOfDay, msSinceStartOfMonth, msSinceAWeekAgo, msSinceStartOfYear } from './time'
 
-export const PERSIST_KEY_VERSION = '2023-01-09'
+export const PERSIST_KEY_VERSION = '2024-06-21'
 export const PERSIST_KEY_GENERATIONS = 'TEXT_TO_CAD_GENERATIONS'
 export const PERSIST_KEY_UNREAD = 'TEXT_TO_CAD_UNREAD'
 
@@ -41,3 +41,12 @@ export const TIME_BUCKETS = [
 		test: (then: Date, now: Date) => now.getTime() - then.getTime() < msSinceStartOfYear(now)
 	}
 ] as const
+
+/**
+ * The number of pages to fetch ahead of the current page
+ */
+export const PAGES_AHEAD_TO_FETCH = 5
+/**
+ * The number of items to fetch per request
+ */
+export const ITEMS_PER_PAGE = 5
diff --git a/src/lib/endpoints.ts b/src/lib/endpoints.ts
index 42481ce..a4813ab 100644
--- a/src/lib/endpoints.ts
+++ b/src/lib/endpoints.ts
@@ -1,4 +1,5 @@
 import type { Models } from '@kittycad/lib'
+import { ITEMS_PER_PAGE } from './consts'
 
 export type CADFormat = Models['FileExportFormat_type']
 
@@ -23,7 +24,7 @@ export const endpoints = {
 		`${import.meta.env.VITE_API_BASE_URL}/file/conversion/gltf/${output_format}`,
 	feedback: (id: string, feedback: Models['TextToCad_type']['feedback']) =>
 		`${import.meta.env.VITE_API_BASE_URL}/user/text-to-cad/${id}?feedback=${feedback}`,
-	list: ({ limit = 5, page_token }: ListParams) =>
+	list: ({ limit = ITEMS_PER_PAGE, page_token }: ListParams) =>
 		`${import.meta.env.VITE_API_BASE_URL}/user/text-to-cad?no_models=true&limit=${limit}${
 			page_token ? `&page_token=${page_token}` : ''
 		}`,
diff --git a/src/lib/stores.ts b/src/lib/stores.ts
index ea9dd14..0c9cade 100644
--- a/src/lib/stores.ts
+++ b/src/lib/stores.ts
@@ -55,7 +55,10 @@ export const generations = derived([combinedGenerations], ([$combinedGenerations
 	return groupBy($combinedGenerations, ({ created_at }) => bucketByTime(created_at))
 })
 
-export const nextPageToken = writable<string | null | undefined>(undefined)
+const NEXT_PAGE_TOKENS_KEY = 'nextPageTokens'
+export const nextPageTokensInitial = fromLocalStorage<string[]>(NEXT_PAGE_TOKENS_KEY, [])
+export const nextPageTokens = writable(nextPageTokensInitial)
+toLocalStorage(nextPageTokens, NEXT_PAGE_TOKENS_KEY)
 
 type UserSettings = {
 	autoRotateModels: boolean
diff --git a/tests/e2e.playwright.ts b/tests/e2e.playwright.ts
index 6a0cbd0..0d39599 100644
--- a/tests/e2e.playwright.ts
+++ b/tests/e2e.playwright.ts
@@ -1,3 +1,4 @@
+import { ITEMS_PER_PAGE, PAGES_AHEAD_TO_FETCH } from '../src/lib/consts'
 import { expect, test } from '@playwright/test'
 
 test('Redirects to the dashboard from home when logged-in', async ({ page }) => {
@@ -24,3 +25,16 @@ test('Prompt input is visible and usable on mobile', async ({ page }) => {
 	await expect(page.locator('textarea')).toBeInViewport()
 	await expect(page.locator('textarea')).toBeFocused()
 })
+
+test('Sidebar only loads set number of pages of results initially', async ({ page }) => {
+	// Go to the home page
+	await page.goto('https://localhost:3000')
+
+	// Assert that we are now on the dashboard
+	await page.waitForURL('**/dashboard', { waitUntil: 'networkidle' })
+
+	// Assert that only 5 pages of results are loaded initially
+	await expect(page.getByTestId('generation-list').getByRole('link')).toHaveCount(
+		PAGES_AHEAD_TO_FETCH * ITEMS_PER_PAGE
+	)
+})