Add Term type

components/ArchivePage.tsx

@@ -1,6 +1,6 @@
 import React from "react";
 
-import { capitalize } from "@/utils";
+import { capitalize, Term } from "@/utils";
 
 import { Link } from "./Link";
 import {
@@ -16,7 +16,7 @@ export interface Props {
   type: "news" | "events";
   items: {
     year: string;
-    terms: string[];
+    terms: Term[];
   }[];
 }
 

lib/events.ts

@@ -7,10 +7,11 @@ import matter from "gray-matter";
 import { MDXRemoteSerializeResult } from "next-mdx-remote";
 import { serialize } from "next-mdx-remote/serialize";
 
+import { Term, TERMS, isTerm } from "@/utils";
+
 import type { Props } from "../pages/events/[year]/[term]/index";
 
 const EVENTS_PATH = path.join("content", "events");
-export const TERMS = ["winter", "spring", "fall"];
 
 export async function getEventYears(): Promise<string[]> {
   return (await fs.readdir(EVENTS_PATH, { withFileTypes: true }))
@@ -19,12 +20,12 @@ export async function getEventYears(): Promise<string[]> {
     .sort();
 }
 
-export async function getEventTermsByYear(year: string): Promise<string[]> {
+export async function getEventTermsByYear(year: string): Promise<Term[]> {
   return (
     await fs.readdir(path.join(EVENTS_PATH, year), { withFileTypes: true })
   )
-    .filter((dirent) => dirent.isDirectory() && TERMS.includes(dirent.name))
-    .map((dirent) => dirent.name)
+    .filter((dirent) => dirent.isDirectory() && isTerm(dirent.name))
+    .map((dirent) => dirent.name as Term)
     .sort((a, b) => TERMS.indexOf(a) - TERMS.indexOf(b));
 }
 
@@ -58,7 +59,7 @@ export const DATE_FORMAT = "MMMM dd yyyy HH:mm";
 
 export async function getEventBySlug(
   year: string,
-  term: string,
+  term: Term,
   slug: string
 ): Promise<Event> {
   const file = await fs.readFile(
@@ -84,7 +85,7 @@ export async function getEventBySlug(
 
 export async function getEventsByTerm(
   year: string,
-  term: string
+  term: Term
 ): Promise<string[]> {
   try {
     return (await fs.readdir(path.join(EVENTS_PATH, year, term)))
@@ -149,7 +150,7 @@ export async function getEventsPageProps({
   term,
 }: {
   year: string;
-  term: string;
+  term: Term;
 }): Promise<Props> {
   const eventNames = await getEventsByTerm(year, term);
 
@@ -177,7 +178,7 @@ export async function getEventsPageProps({
   const eventYears = await getEventYears();
 
   const minYear = eventYears[0];
-  const pastTerms: { year: string; term: string }[] = [];
+  const pastTerms: { year: string; term: Term }[] = [];
   let curPastYear = year;
   let curPastTerm = term;
   while (parseInt(curPastYear) >= parseInt(minYear) && pastTerms.length < 2) {
@@ -191,7 +192,7 @@ export async function getEventsPageProps({
   pastTerms.reverse();
 
   const maxYear = eventYears[eventYears.length - 1];
-  const futureTerms: { year: string; term: string }[] = [];
+  const futureTerms: { year: string; term: Term }[] = [];
   let curFutureYear = year;
   let curFutureTerm = term;
   while (
@@ -217,7 +218,7 @@ export async function getEventsPageProps({
   };
 }
 
-export function getCurrentTerm() {
+export function getCurrentTerm(): { year: string; term: Term } {
   const today = new Date().toLocaleDateString("en-CA", {
     timeZone: "EST",
     year: "numeric",
@@ -241,17 +242,14 @@ export function getCurrentTerm() {
     term = "fall";
   }
 
-  if (term === "") {
+  if (!isTerm(term)) {
     throw new Error("Error setting the current term");
   }
 
   return { year, term };
 }
 
-function getPastTerm(
-  year: string,
-  term: string
-): { year: string; term: string } {
+function getPastTerm(year: string, term: Term): { year: string; term: Term } {
   const index = TERMS.indexOf(term);
 
   if (index === -1) {
@@ -269,10 +267,7 @@ function getPastTerm(
       };
 }
 
-function getFutureTerm(
-  year: string,
-  term: string
-): { year: string; term: string } {
+function getFutureTerm(year: string, term: Term): { year: string; term: Term } {
   const index = TERMS.indexOf(term);
 
   if (index === -1) {

lib/news.ts

@@ -6,10 +6,11 @@ import matter from "gray-matter";
 import { MDXRemoteSerializeResult } from "next-mdx-remote";
 import { serialize } from "next-mdx-remote/serialize";
 
+import { isTerm, Term, TERMS } from "@/utils";
+
 import { DATE_FORMAT, getLocalDateFromEST } from "./events";
 
 export const NEWS_PATH = path.join("content", "news");
-const TERMS = ["winter", "spring", "fall"];
 
 export interface Metadata {
   author: string;
@@ -28,14 +29,14 @@ export async function getNewsYears(): Promise<string[]> {
     .sort();
 }
 
-export async function getNewsTermsByYear(year: string): Promise<string[]> {
+export async function getNewsTermsByYear(year: string): Promise<Term[]> {
   return (
     await fs.readdir(path.join(NEWS_PATH, year), {
       withFileTypes: true,
     })
   )
-    .filter((dirent) => dirent.isDirectory() && TERMS.includes(dirent.name))
-    .map((dirent) => dirent.name)
+    .filter((dirent) => dirent.isDirectory() && isTerm(dirent.name))
+    .map((dirent) => dirent.name as Term)
     .sort((a, b) => TERMS.indexOf(a) - TERMS.indexOf(b));
 }
 

pages/events/[year]/[term]/[event].tsx

@@ -18,7 +18,7 @@ import {
   getEventsByTerm,
   getEventBySlug,
 } from "@/lib/events";
-import { capitalize } from "@/utils";
+import { capitalize, Term } from "@/utils";
 
 export default function EventInfoPage({ year, term, event }: Props) {
   return (
@@ -43,13 +43,13 @@ EventInfoPage.getShapesConfig = ((width, height) => {
 
 interface Props {
   year: string;
-  term: string;
+  term: Term;
   event: Event;
 }
 
 interface Params extends ParsedUrlQuery {
   year: string;
-  term: string;
+  term: Term;
   event: string;
 }
 

pages/events/[year]/[term]/index.tsx

@@ -14,21 +14,21 @@ import {
   getEventYears,
   getEventTermsByYear,
 } from "@/lib/events";
-import { capitalize } from "@/utils";
+import { capitalize, Term } from "@/utils";
 
 import styles from "./index.module.css";
 
 export interface Props {
   year: string;
-  term: string;
+  term: Term;
   pastEvents: Event[];
   futureEvents: Event[];
   isCurrentTerm: boolean;
-  pastTerms: { year: string; term: string }[];
-  futureTerms: { year: string; term: string }[];
+  pastTerms: { year: string; term: Term }[];
+  futureTerms: { year: string; term: Term }[];
 }
 
-export default function Term(props: Props) {
+export default function TermPage(props: Props) {
   let headerTerms = [{ year: props.year, term: props.term }];
 
   // p, Current, f
@@ -120,7 +120,7 @@ export default function Term(props: Props) {
 
 function HeaderLink(props: {
   year: string;
-  term: string;
+  term: Term;
   isCurrentTerm?: boolean;
 }) {
   return (
@@ -134,7 +134,7 @@ function HeaderLink(props: {
 
 interface Params extends ParsedUrlQuery {
   year: string;
-  term: string;
+  term: Term;
 }
 
 export const getStaticProps: GetStaticProps<Props, Params> = async (

pages/events/[year]/index.tsx

@@ -6,12 +6,13 @@ import React from "react";
 import { Link } from "@/components/Link";
 import { Title } from "@/components/Title";
 import { getEventYears, getEventTermsByYear } from "@/lib/events";
+import { Term } from "@/utils";
 
 import styles from "./index.module.css";
 
 interface Props {
   year: string;
-  terms: string[];
+  terms: Term[];
 }
 
 export default function Year(props: Props) {

pages/events/index.tsx

@@ -2,9 +2,9 @@ import { GetStaticProps } from "next";
 
 import { getCurrentTerm, getEventsPageProps } from "@/lib/events";
 
-import Term, { Props } from "./[year]/[term]";
+import TermEvent, { Props } from "./[year]/[term]";
 
-export default Term;
+export default TermEvent;
 
 export const getStaticProps: GetStaticProps<Props> = async () => {
   return { props: await getEventsPageProps(getCurrentTerm()) };

pages/news/[year]/[term].tsx

@@ -18,13 +18,13 @@ import {
   getNewsYears,
   News,
 } from "@/lib/news";
-import { capitalize } from "@/utils";
+import { capitalize, Term } from "@/utils";
 
 import styles from "./[term].module.css";
 
 interface Props {
   year: string;
-  term: string;
+  term: Term;
   news: News[];
 }
 
@@ -75,7 +75,7 @@ export const getStaticProps: GetStaticProps<Props, Params> = async (
 
 interface Params extends ParsedUrlQuery {
   year: string;
-  term: string;
+  term: Term;
 }
 
 export const getStaticPaths: GetStaticPaths<Params> = async () => {

utils.ts

@@ -1,3 +1,11 @@
+export const TERMS = ["winter", "spring", "fall"] as const;
+export type Term = typeof TERMS[number];
+
+// https://www.typescriptlang.org/docs/handbook/2/narrowing.html#using-type-predicates
+export function isTerm(x: string): x is Term {
+  return x === "winter" || x === "spring" || x === "fall";
+}
+
 export function capitalize(str: string) {
   return str.slice(0, 1).toUpperCase() + str.slice(1);
 }