feat: frontend vers. support & improved in-memory caching logic

web/src/app.css

@@ -262,6 +262,47 @@
 		@apply text-[var(--dark-text)]/60;
 	}
 
+	/* Versions dropdown */
+	.versions-dropdown {
+		@apply absolute right-0 z-10 mt-2 w-52 origin-top-right space-y-0.5 rounded-md bg-[var(--light-foreground)] shadow-lg ring-1 ring-[var(--light-foreground)]/10 focus:outline-none;
+	}
+
+	.dark .versions-dropdown {
+		@apply bg-[var(--dark-foreground)] ring-[var(--dark-foreground)]/10;
+	}
+
+	.versions-dropdown-item {
+		@apply w-full cursor-pointer bg-[var(--light-foreground)] p-3 transition-colors hover:bg-[var(--light-background)];
+	}
+
+	.dark .versions-dropdown-item {
+		@apply bg-[var(--dark-foreground)] hover:bg-[var(--dark-background)];
+	}
+
+	.versions-dropdown-item-active {
+		@apply bg-[var(--light-accent)]/20;
+	}
+
+	.dark .versions-dropdown-item-active {
+		@apply bg-[var(--dark-accent)]/20;
+	}
+
+	.versions-dropdown-item-text {
+		@apply text-xs text-[var(--light-text)]/60;
+	}
+
+	.dark .versions-dropdown-item-text {
+		@apply text-[var(--dark-text)]/60;
+	}
+
+	.versions-dropdown-divider {
+		@apply divide-y divide-[var(--light-text)]/20;
+	}
+
+	.dark .versions-dropdown-divider {
+		@apply divide-[var(--dark-text)]/20;
+	}
+
 	/* Note editor */
 	.note-title-input {
 		@apply w-full rounded-2xl border-b border-[var(--light-text)]/20 bg-transparent pb-2 text-2xl font-bold focus:border-[var(--light-accent)];

web/src/lib/client.ts

@@ -26,6 +26,7 @@ export interface FullNote {
 	content: string
 	versionNumber: number
 	versionCreatedAt: Date
+	isActiveVersion: boolean
 	noteCreatedAt: Date
 	noteUpdatedAt: Date
 }
@@ -60,23 +61,34 @@ interface NewNoteResponse {
 	content: string
 }
 
-interface VersionMetadataResponse {
+interface VersionMetadata {
 	versionID: string
 	title: string
+	versionNumber: number
+	isActive: boolean
+	createdAt: Date
 }
 
-interface FullVersionResponse {
-	versionID: string
+interface ApiVersionMetadataResponse {
+	version_id: string
+	title: string
+	version_number: number
+	created_at: string
+}
+
+interface ApiFullVersionResponse {
+	version_id: string
 	title: string
 	content: string
-	versionNumber: number
-	createdAt: Date
+	version_number: number
+	created_at: string
 }
 
 // Some of these could just be local variables as they're not used globally
 export const currentUser: Writable<User | null> = writable(null)
 export const currentFullNote: Writable<FullNote | null> = writable(null)
 export const availableNotes: Writable<NoteMetadata[] | null> = writable(null)
+export const versionHistory: Writable<VersionMetadata[] | null> = writable(null)
 export const accessToken: Writable<string | null> = writable(null)
 export const csrfToken: Writable<string | null> = writable(null)
 export const isPending: Writable<boolean> = writable(false)
@@ -88,8 +100,10 @@ class ApiClient {
 	private lastAtUpdate = new Date(0)
 	private lastCsrfUpdate = new Date(0)
 	private refreshInProgress = false
+	private activeVersion = -1
 	private loadedNotesCache = new Map<string, FullNote>()
-	// TODO: private loadedVersionsCache = new Map<string, FullVersion>()
+	private loadedHistoryCache = new Map<string, VersionMetadata[]>()
+	private loadedVersionsCache = new Map<string, FullNote>() // Key: noteID + versionID
 
 	constructor(baseUrl: string) {
 		this.baseUrl = baseUrl
@@ -293,11 +307,50 @@ class ApiClient {
 			content: apiResponse.content,
 			versionNumber: apiResponse.version_number,
 			versionCreatedAt: new Date(apiResponse.version_created_at),
+			isActiveVersion: true, // This endpoint serves only the latest version
 			noteCreatedAt: new Date(apiResponse.note_created_at),
 			noteUpdatedAt: new Date(apiResponse.note_updated_at)
 		}
 	}
 
+	private deserializeVersionMetadatas(
+		apiResponses: ApiVersionMetadataResponse[]
+	): VersionMetadata[] {
+		return apiResponses.map((res) => {
+			return {
+				versionID: res.version_id,
+				title: res.title,
+				versionNumber: res.version_number,
+				isActive: this.activeVersion === res.version_number,
+				createdAt: new Date(res.created_at)
+			}
+		})
+	}
+
+	private joinDeserializedVersion(
+		noteID: string,
+		apiResponse: ApiFullVersionResponse
+	): FullNote | undefined {
+		// Cache lookups are safe here due to this always being called *after* fetching the actual `FullNote`
+		const cachedNote = this.loadedNotesCache.get(noteID)
+
+		if (!cachedNote) {
+			return
+		}
+
+		return {
+			id: cachedNote.id,
+			owner: cachedNote.owner,
+			title: apiResponse.title,
+			content: apiResponse.content,
+			versionNumber: apiResponse.version_number,
+			versionCreatedAt: new Date(apiResponse.created_at),
+			isActiveVersion: cachedNote.versionNumber === apiResponse.version_number,
+			noteCreatedAt: cachedNote.noteCreatedAt,
+			noteUpdatedAt: cachedNote.noteUpdatedAt
+		}
+	}
+
 	public async register(username: string, password: string): Promise<void> {
 		return this.handleRequest(
 			async () => {
@@ -541,15 +594,22 @@ class ApiClient {
 		)
 	}
 
-	public async getFullNote(noteID: string): Promise<FullNote | undefined> {
+	public async getActiveFullNote(
+		noteID: string,
+		fetchRemote: boolean
+	): Promise<FullNote | undefined> {
 		if (!UUID_REGEX.test(noteID)) {
 			throw new Error("Invalid note ID format.")
 		}
 
-		const cachedNote = this.loadedNotesCache.get(noteID)
-		if (cachedNote != null) {
-			console.log(`cache hit ${noteID}`)
-			return cachedNote
+		// Attempt cache lookup only if we didn't just push new updates
+		if (!fetchRemote) {
+			const cachedNote = this.loadedNotesCache.get(noteID)
+			if (cachedNote != null) {
+				// console.log(`full note cache hit ${noteID}`)
+				this.activeVersion = cachedNote.versionNumber
+				return cachedNote
+			}
 		}
 
 		return this.handleRequest(
@@ -567,6 +627,7 @@ class ApiClient {
 
 				console.log(`caching ${noteID}`)
 				this.loadedNotesCache.set(noteID, note)
+				this.activeVersion = note.versionNumber
 
 				return note
 			},
@@ -599,11 +660,22 @@ class ApiClient {
 		)
 	}
 
-	public async getNoteHistory(noteID: string): Promise<VersionMetadataResponse[] | undefined> {
+	public async getNoteHistory(
+		noteID: string,
+		fetchRemote: boolean
+	): Promise<VersionMetadata[] | undefined> {
 		if (!UUID_REGEX.test(noteID)) {
 			throw new Error("Invalid note ID format.")
 		}
 
+		if (!fetchRemote) {
+			const cachedVersions = this.loadedHistoryCache.get(noteID)
+			if (cachedVersions != null) {
+				// console.log(`full version cache hit ${noteID}`)
+				return cachedVersions
+			}
+		}
+
 		return this.handleRequest(
 			async () => {
 				const response = await fetch(`${this.baseUrl}/notes/${noteID}/versions`, {
@@ -612,10 +684,13 @@ class ApiClient {
 					}
 				})
 
-				const versions = await this.handleResponse<VersionMetadataResponse[]>(response, {
+				const data = await this.handleResponse<ApiVersionMetadataResponse[]>(response, {
 					useBearerAuth: false
 				})
-				console.log(`got ${versions.length} version metadata results`)
+				const versions = this.deserializeVersionMetadatas(data)
+
+				console.log(`got ${versions.length} version metadata results, caching ${noteID}`)
+				this.loadedHistoryCache.set(noteID, versions)
 
 				return versions
 			},
@@ -652,10 +727,7 @@ class ApiClient {
 		)
 	}
 
-	public async getFullVersion(
-		noteID: string,
-		versionID: string
-	): Promise<FullVersionResponse | undefined> {
+	public async getFullVersion(noteID: string, versionID: string): Promise<FullNote | undefined> {
 		if (!UUID_REGEX.test(noteID)) {
 			throw new Error("Invalid note ID format.")
 		}
@@ -664,6 +736,18 @@ class ApiClient {
 			throw new Error("Invalid version ID format.")
 		}
 
+		// NOTE: Versions aren't editable so we don't need to prevent the system from attempting
+		//       to locate each request's contents first from the cache
+
+		const cachedVersion = this.loadedVersionsCache.get(noteID + versionID)
+		if (cachedVersion != null) {
+			// console.log(`full version cache hit [${noteID}, ${versionID}]`)
+			return cachedVersion
+		}
+
+		// TODO: check if the requested version is the current version -> use `loadedNotesCache`
+		// (we probably have to modify the caching mechanism so we can look the regular note items up using versionID)
+
 		return this.handleRequest(
 			async () => {
 				const response = await fetch(`${this.baseUrl}/notes/${noteID}/${versionID}`, {
@@ -671,7 +755,20 @@ class ApiClient {
 						...this.getAuthHeader()
 					}
 				})
-				return await this.handleResponse<FullVersionResponse>(response, { useBearerAuth: false })
+
+				const data = await this.handleResponse<ApiFullVersionResponse>(response, {
+					useBearerAuth: false
+				})
+				const version = this.joinDeserializedVersion(noteID, data)
+
+				if (!version) {
+					return
+				}
+
+				console.log(`caching [${noteID}, ${versionID}]`)
+				this.loadedVersionsCache.set(noteID + versionID, version)
+
+				return version
 			},
 			{ useBearerAuth: true }
 		)

web/src/lib/components/NoteEditor.svelte

@@ -2,7 +2,7 @@
 	import { onMount } from "svelte"
 	import { marked } from "marked"
 	import { TITLE_MAX_LENGTH } from "$lib/const"
-	import type { FullNote } from "$lib/client"
+	import { apiClient, type FullNote } from "$lib/client"
 
 	// Props
 	export let note: FullNote
@@ -138,7 +138,7 @@
 				{editableTitle.length}/{TITLE_MAX_LENGTH} characters
 			</div>
 			<div class="note-char-count ml-3">
-				Last updated: {new Date(note.noteUpdatedAt).toLocaleString()}
+				Last updated: {new Date(note.versionCreatedAt).toLocaleString()}
 				{#if !isEditing}
 					<!-- Minus 1 due to versioning beginning at 2 in the DB -->
 					• Version: {note.versionNumber - 1}
@@ -149,7 +149,7 @@
 				{note.title || "Untitled Note"}
 			</h1>
 			<div class="note-char-count">
-				Last updated: {new Date(note.noteUpdatedAt).toLocaleString()}
+				Last updated: {new Date(note.versionCreatedAt).toLocaleString()}
 				{#if !isEditing}
 					<!-- Minus 1 due to versioning beginning at 2 in the DB -->
 					• Version: {note.versionNumber - 1}

web/src/lib/components/NoteView.svelte

@@ -8,19 +8,22 @@
 	import {
 		apiClient,
 		currentUser,
-		// isPending,
 		currentFullNote,
 		availableNotes,
-		cError
+		versionHistory,
+		cError,
+		type FullNote
 	} from "$lib/client"
 	import ToggleSidebar from "$lib/icons/ToggleSidebar.svelte"
+	import VersionArrow from "$lib/icons/VersionArrow.svelte"
 
 	// Props
 	export let isLoading = false
 
 	// State
-	let sidebarOpen = false
+	let sidebarOpen = window.innerWidth > 768
 	let showSettings = false
+	let showVersionsDropdown = false
 	let isEditing = false
 
 	onMount(async (): Promise<any> => {
@@ -66,11 +69,14 @@
 		const notes = await apiClient.listNotes()
 
 		if (notes) {
-			console.log(notes)
 			availableNotes.set(notes)
 		}
 	}
 
+	const toggleVersionDropdown = () => {
+		showVersionsDropdown = !showVersionsDropdown
+	}
+
 	const toggleSidebar = () => {
 		sidebarOpen = !sidebarOpen
 	}
@@ -94,24 +100,58 @@
 			// (we need to find the ID from the updated `availableNotes`)
 			if ($availableNotes && $availableNotes.length > 0) {
 				const latestNote = $availableNotes[0] // Assuming the latest note is first
-				await selectNote(latestNote.id)
+				await selectNote(latestNote.id, true)
 			}
 
 			isEditing = true // Open brand new notes in edit mode by default
 		}
 	}
 
-	const selectNote = async (noteId: string) => {
-		const note = await apiClient.getFullNote(noteId)
+	const isLatestVersion = (note: FullNote | null) => {
+		if (!note) {
+			return true
+		}
+
+		return note.isActiveVersion
+	}
+
+	const selectNote = async (noteID: string, fetchRemote: boolean) => {
+		const note = await apiClient.getActiveFullNote(noteID, fetchRemote)
 
 		if (note) {
 			currentFullNote.set(note)
 			isEditing = false
 		}
+
+		const history = await apiClient.getNoteHistory(noteID, fetchRemote)
+
+		if (history) {
+			versionHistory.set(history)
+		}
+
+		// MOBILE: Close sidebar when selecting a note from the list
+		if (window.innerWidth < 768) {
+			closeSidebar()
+		}
+	}
+
+	const selectVersion = async (versionID: string) => {
+		if ($currentFullNote) {
+			const note = await apiClient.getFullVersion($currentFullNote.id, versionID)
+
+			if (note) {
+				currentFullNote.set(note)
+				showVersionsDropdown = false
+			}
+		}
 	}
 
 	const toggleEditMode = () => {
-		isEditing = !isEditing
+		if (isLatestVersion($currentFullNote)) {
+			isEditing = !isEditing
+		} else {
+			cError.set("Editing historical versions is prohibited.")
+		}
 	}
 
 	const saveNote = async (title: string, content: string) => {
@@ -119,7 +159,7 @@
 			await apiClient.createVersion($currentFullNote.id, title, content)
 
 			// Refresh the current note to get the latest version (+ assure that client and server are synced)
-			await selectNote($currentFullNote.id)
+			await selectNote($currentFullNote.id, true)
 
 			// Refresh the notes list to update any changes (ordering based on `updatedAt` field)
 			await loadNotes()
@@ -174,9 +214,49 @@
 
 			<div class="flex items-center space-x-4 pl-2">
 				{#if $currentFullNote}
-					<button on:click={toggleEditMode} class="btn-primary rounded-full">
-						{isEditing ? "Preview" : "Edit"}
-					</button>
+					<!-- Note edit/preview button (only shown for latest version) -->
+					{#if isLatestVersion($currentFullNote)}
+						<button on:click={toggleEditMode} class="btn-primary rounded-full">
+							{isEditing ? "Preview" : "Edit"}
+						</button>
+					{:else}
+						<button disabled class="btn-primary cursor-not-allowed rounded-full opacity-40">
+							Edit
+						</button>
+					{/if}
+
+					<!-- Version history dropdown menu -->
+					<div class="relative">
+						<button
+							on:click={toggleVersionDropdown}
+							class="btn-secondary flex items-center rounded-full"
+						>
+							<span>Versions</span>
+							<VersionArrow />
+						</button>
+
+						{#if showVersionsDropdown && $versionHistory && $versionHistory.length > 0}
+							<div class="versions-dropdown">
+								{#each $versionHistory as version}
+									<button
+										on:click={() => selectVersion(version.versionID)}
+										class="versions-dropdown-item {$currentFullNote.versionNumber ===
+										version.versionNumber
+											? 'versions-dropdown-item-active'
+											: ''}"
+									>
+										<p class="versions-dropdown-item-text truncate font-bold">{version.title}</p>
+										<span class="versions-dropdown-item-text"
+											>{version.createdAt.toLocaleString()}</span
+										>
+										{#if version.isActive}<span class="versions-dropdown-item-text ml-2 opacity-70"
+												>(active)</span
+											>{/if}
+									</button>
+								{/each}
+							</div>
+						{/if}
+					</div>
 				{/if}
 			</div>
 

web/src/lib/components/Sidebar.svelte

@@ -13,7 +13,7 @@
 	export let toggleSettings: () => void
 	export let logout: () => Promise<void>
 	export let createNewNote: () => Promise<void>
-	export let selectNote: (noteId: string) => Promise<void>
+	export let selectNote: (noteId: string, fetchRemote: boolean) => Promise<void>
 
 	const formatDate = (dateString: string | Date): string => {
 		if (!dateString) {
@@ -38,7 +38,7 @@
 	const handleNoteKeydown = (event: KeyboardEvent, noteID: string) => {
 		if (event.key === "Enter" || event.key === " ") {
 			event.preventDefault() // Prevent page scroll on space
-			selectNote(noteID)
+			selectNote(noteID, true) // Sync with API due to pushing updates
 		}
 	}
 
@@ -50,6 +50,7 @@
 </script>
 
 <!-- TODO: add admin modal button (+ component similar to the settings modal) if the user is an admin -->
+<!-- TODO: component-level paging support (via the implementation in `pages.ts`) -->
 
 <aside
 	class="sidebar z-10"
@@ -96,7 +97,7 @@
 					<li
 						class="sidebar-item"
 						class:sidebar-item-active={currentNote && note.id === currentNote.id}
-						on:click={() => selectNote(note.id)}
+						on:click={() => selectNote(note.id, false)}
 						on:keydown={(e) => handleNoteKeydown(e, note.id)}
 						tabindex="0"
 						role="option"

web/src/lib/icons/VersionArrow.svelte

@@ -0,0 +1,7 @@
+<svg class="ml-0.5 h-5 w-5" viewBox="0 0 20 20" fill="currentColor">
+	<path
+		fill-rule="evenodd"
+		d="M5.293 7.293a1 1 0 011.414 0L10 10.586l3.293-3.293a1 1 0 111.414 1.414l-4 4a1 1 0 01-1.414 0l-4-4a1 1 0 010-1.414z"
+		clip-rule="evenodd"
+	/>
+</svg>