Refactored iCal parser to parse RRules

package.json

@@ -20,7 +20,8 @@
 		"format": "prettier --ignore-path .gitignore --write --plugin-search-dir=. ."
 	},
 	"dependencies": {
-		"rfs": "^9.0.6"
+		"rfs": "^9.0.6",
+		"rrule": "^2.6.8"
 	},
 	"devDependencies": {
 		"@sveltejs/adapter-static": "next",

src/lib/components/events/event-carousel.svelte

@@ -1,6 +1,6 @@
 <script lang="ts">
 	import EventItem from './event-item.svelte';
-	import type { AcmEvent } from '$lib/parse-ical-data';
+	import type { AcmEvent } from '$lib/ical/parse';
 
 	export let events: AcmEvent[] = [];
 
@@ -13,7 +13,7 @@
 	const scrollTheCarousel = (movementScalar: number, isSmooth: boolean = false) =>
 		carouselRef.scrollBy({
 			left: -movementScalar,
-			behavior: isSmooth ? 'smooth' : 'auto'
+			behavior: isSmooth ? 'smooth' : 'auto',
 		});
 	const scrollOnMouseMove = (event: MouseEvent) => isGrabbing && scrollTheCarousel(event.movementX);
 	const startGrabbing = () => (isGrabbing = true);
@@ -39,8 +39,7 @@
 			on:mousedown={startGrabbing}
 			on:mouseup={endGrabbing}
 			on:mouseleave={endGrabbing}
-			on:wheel={scrollHorizontally}
-		>
+			on:wheel={scrollHorizontally}>
 			<div class="event-item-buffer" />
 			{#each events as eventInfo}
 				<EventItem info={eventInfo} />

src/lib/components/events/event-item.svelte

@@ -1,13 +1,13 @@
 <script lang="ts">
 	import { onMount } from 'svelte';
-	import type { AcmEvent } from '$lib/parse-ical-data';
-	import { links } from '$lib/constants/links';
+	import type { AcmEvent } from '$lib/ical/parse';
 	import AcmButton from '$lib/components/utils/acm-button.svelte';
 
 	export let info: AcmEvent;
 
-	let isActive = false;
-	let isSuccessfullyCopied = false;
+	let isActive: boolean = false;
+	let isRecurring: boolean = info.recurring;
+	let isSuccessfullyCopied: boolean = false;
 	let anchor: HTMLDivElement;
 
 	const copyEventLink = (slug: string) => {
@@ -25,7 +25,7 @@
 			anchor.scrollIntoView({
 				behavior: 'smooth',
 				block: 'start',
-				inline: 'center'
+				inline: 'center',
 			});
 		}
 	});
@@ -39,12 +39,14 @@
 				{info.month}
 				{info.day}
 			</span>
+			{#if isRecurring}
+				<p class="event-recurring">RECURRING</p>
+			{/if}
 		</p>
 		<h3
 			class="headers"
 			class:copied={isSuccessfullyCopied}
-			on:click={() => copyEventLink(info.slug)}
-		>
+			on:click={() => copyEventLink(info.slug)}>
 			{info.summary}
 		</h3>
 		<div>
@@ -92,6 +94,12 @@
 		border-radius: 30px;
 	}
 
+	.event-recurring {
+		font-weight: 800;
+		color: var(--acm-blue);
+		font-size: 16px;
+	}
+
 	.event-card h3 {
 		position: relative;
 		width: 186px;

src/lib/constants/time.ts

@@ -0,0 +1,9 @@
+export enum Time {
+	Millisecond = 1,
+	Second = 1e3 * Millisecond,
+	Minute = 60 * Second,
+	Hour = 60 * Minute,
+	Day = 24 * Hour,
+}
+
+export const ACM_LOCALE = 'en-US';

src/lib/ical/common.ts

@@ -0,0 +1,132 @@
+import RRule from 'rrule';
+
+interface IcalOutput {
+	[key: string]: string | string[] | IcalOutput[];
+}
+
+const cleanIcalKey = (key: string): string => {
+	if (key.startsWith('DTSTART')) return 'DTSTART';
+	if (key.startsWith('DTEND')) return 'DTEND';
+	return key;
+};
+
+/**
+ * The code in this function is derived from
+ * https://github.com/adrianlee44/ical2json.
+ * @param source The raw calendar data in ICAL format.
+ * @returns The parsed ICAL data.
+ */
+export const parseRawIcal = (source: string): IcalOutput => {
+	const output: IcalOutput = {};
+	const lines = source.split(/\r\n|\n|\r/);
+	const parents: IcalOutput[] = [];
+	let parent: IcalOutput = {};
+	let current: IcalOutput = output;
+	let currentKey = '';
+
+	for (const line of lines) {
+		let currentValue = '';
+		if (line.charAt(0) === ' ') {
+			current[currentKey] += line.substr(1);
+		} else {
+			const splitAt = line.indexOf(':');
+			if (splitAt < 0) {
+				continue;
+			}
+			currentKey = cleanIcalKey(line.substr(0, splitAt));
+			currentValue = line.substr(splitAt + 1);
+			switch (currentKey) {
+				case 'BEGIN':
+					parents.push(parent);
+					parent = current;
+					if (parent[currentValue] == null) {
+						parent[currentValue] = [];
+					}
+					// Create a new object, store the reference for future uses.
+					current = {};
+					(parent[currentValue] as IcalOutput[]).push(current);
+					break;
+				case 'END':
+					current = parent;
+					parent = parents.pop() as IcalOutput;
+					break;
+				default:
+					if (current[currentKey]) {
+						if (!Array.isArray(current[currentKey])) {
+							current[currentKey] = [current[currentKey]] as string[];
+						}
+						(current[currentKey] as string[]).push(currentValue);
+					} else {
+						(current[currentKey] as string) = currentValue;
+					}
+			}
+		}
+	}
+
+	return output;
+};
+
+/**
+ * This function parses the raw ICAL datetime string into a Date object.
+ * @param datetime Example: October 31st, 2021 = "20211031T000000"
+ * @returns The parsed Date object.
+ */
+const parseRawIcalDatetime = (datetime: string): Date => {
+	const fullYear = datetime.slice(0, 4);
+	const month = datetime.slice(4, 6);
+	const day = datetime.slice(6, 8);
+	const hours = datetime.slice(9, 11);
+	const minutes = datetime.slice(11, 13);
+	const seconds = datetime.slice(13, 15);
+	const date = new Date();
+	date.setFullYear(Number(fullYear), Number(month) - 1, Number(day));
+	date.setHours(Number(hours) - 7, Number(minutes), Number(seconds));
+	return date;
+};
+
+export const computeIcalDatetime = (event: any) => {
+	const rawDatetime = event['DTSTART'];
+	const rawRrule = event['RRULE'];
+	if (rawRrule !== undefined) {
+		try {
+			const ruleSrc = `DTSTART:${rawDatetime}Z\nRRULE:${rawRrule}`;
+			const recurrence = RRule.fromString(ruleSrc);
+			const date = recurrence.after(new Date());
+			date.setHours(date.getHours());
+			return date;
+		} catch {}
+	}
+	return parseRawIcalDatetime(rawDatetime);
+};
+
+export const slugifyEvent = (summary: string, month: string, day: number): string => {
+	const cleanedSummary = summary.replace(/[^\w\s\_]/g, '').replace(/(\s|\-|\_)+/g, '-');
+	const slug = [cleanedSummary, month, day].join('-').toLowerCase();
+	return slug;
+};
+
+export const checkForRecurrence = (raw?: string): boolean => {
+	if (raw === undefined) return false;
+	try {
+		const recurrence = RRule.fromString(raw);
+		return recurrence.isFullyConvertibleToText();
+	} catch {}
+	return false;
+};
+
+export const parseDescription = (content: string): Record<string, string> => {
+	const result = {};
+	for (const line of content.split('\n')) {
+		const [key, value] = line.split('=');
+		result[key.trim()] = value;
+	}
+	return result;
+};
+
+export const sortByDate = () => {
+	return ({ date: date1 }, { date: date2 }) => (date1.valueOf() > date2.valueOf() ? 1 : -1);
+};
+
+export const filterIfPassed = (now: number, offset: number = 0) => {
+	return ({ date }: { date: Date }) => date.valueOf() + offset > now;
+};