Build 6000 initial pages. Skip them in revalidation

Closes #390

src/lib/services/dictionary.ts

@@ -21,6 +21,7 @@ export interface AlphabetLetter {
 }
 
 let dictionaryCache: DictionaryEntry[] | null = null
+let cachedInitialPages: string[] | null = null
 
 const addSlugs = (words: RawDictionaryEntry[]): DictionaryEntry[] => {
   const existingSlugs = {}
@@ -106,6 +107,25 @@ export const getAlphabet = (): AlphabetLetter[] => {
   return formattedLetters
 }
 
+/**
+ * Initial word pages to build are basically 6000
+ * headword pages based on modulus. Larger number
+ * can not be deployed in one go.
+ */
+export const getInitialWordsToBuild = (): string[] => {
+  if (cachedInitialPages) return cachedInitialPages
+
+  const allWords = getAllWords()
+
+  const result: string[] = []
+  for (let i = 0; i < allWords.length; i += 5) {
+    result.push(allWords[i].slug);
+  }
+
+  cachedInitialPages = result
+  return cachedInitialPages
+}
+
 export default {
   getAllWords,
   getByLetter,

src/pages/api/revalidate.ts

@@ -1,6 +1,6 @@
-import { NextApiRequest, NextApiResponse } from 'next'
+import type { NextApiRequest, NextApiResponse } from 'next'
 
-import { getAllWords } from 'lib/services/dictionary'
+import { getAllWords, getInitialWordsToBuild } from 'lib/services/dictionary'
 import { getWordPath } from 'lib/utils/links'
 
 export default async function handler(req: NextApiRequest, res: NextApiResponse) {
@@ -18,9 +18,12 @@ export default async function handler(req: NextApiRequest, res: NextApiResponse)
 
   try {
     const words = getAllWords()
+    const initialWords = getInitialWordsToBuild()
+
     const { start, end: givenEnd } = req.query
     const end = parseInt(givenEnd, 10) <= words.length ? parseInt(givenEnd, 10) : words.length - 1
     const revalidates = words
+      .filter((word) => !initialWords.includes(word.slug))
       .sort((a, b) => a.slug.localeCompare(b.slug))
       .map((word) => getWordPath(word))
       .slice(parseInt(start, 10), end)

src/pages/word/[word].tsx

@@ -3,6 +3,7 @@ import { useRouter } from 'next/router'
 // Services.
 import {
   getWord, getAlphabet, type DictionaryEntry, type AlphabetLetter,
+  getInitialWordsToBuild,
 } from 'lib/services/dictionary'
 import { getAbbreviations } from 'lib/services/abbreviations'
 import { youngerFuthark } from 'riimut'
@@ -29,9 +30,31 @@ interface WordPageProps {
   runes: string,
 }
 
-export async function getStaticPaths() {
+interface WordPath{
+  params: {
+      word: string
+  }
+}
+
+interface WordPageStaticPathsResponseSchema{
+  paths: WordPath[]
+  fallback: string | boolean
+}
+
+/**
+ * There are too many word paths for Vercel to build.
+ * It hits 16 000 file limit.
+ *
+ * Build around 6000 pages initially and rest as they are accessed
+ * or remotely revalidated via API.
+ */
+export async function getStaticPaths(): Promise<WordPageStaticPathsResponseSchema> {
+  const initialPages = getInitialWordsToBuild()
+
   return {
-    paths: [],
+    paths: initialPages.map((slug) => ({
+      params: { word: slug },
+    })),
     fallback: 'blocking',
   }
 }

tests/unit/lib/services/dictionary.test.ts

@@ -3,6 +3,7 @@ import { isArray } from 'volva'
 import { matchesSchema } from 'jafningjar'
 import {
   getAllWords, getByLetter, getWord, getAlphabet,
+  getInitialWordsToBuild,
 } from 'lib/services/dictionary'
 
 describe('Dictionary tests', () => {
@@ -109,4 +110,21 @@ describe('Dictionary tests', () => {
 
     expect(foundÖ).toBeTruthy();
   })
+
+  test('Returns initial batch of pages to build', () => {
+    const wordsToBuild = getInitialWordsToBuild()
+
+    // Correct amount sampled.
+    expect(wordsToBuild.length).toEqual(5991)
+
+    // Deterministic entry slugs, roughly spread through dictionary.
+    expect(wordsToBuild[0]).toEqual('a')
+    expect(wordsToBuild[10]).toEqual('afflutningr')
+    expect(wordsToBuild[100]).toEqual('allfamennr')
+    expect(wordsToBuild[1000]).toEqual('dvala')
+    expect(wordsToBuild[2000]).toEqual('handargagn')
+    expect(wordsToBuild[3000]).toEqual('lausliga')
+    expect(wordsToBuild[4000]).toEqual('sem')
+    expect(wordsToBuild[5000]).toEqual('undanhald')
+  })
 })

tests/unit/pages/word.test.tsx

@@ -113,14 +113,12 @@ describe('Word page: render & usage', () => {
 
 describe('Word page: data fetching', () => {
   test('getStaticPaths works', async () => {
-    const expected = {
-      paths: [],
-      fallback: 'blocking',
-    }
-
     const result = await getStaticPaths()
 
-    expect(result).toMatchObject(expected)
+    expect(result.fallback).toBe('blocking')
+
+    // Should build initial pages.
+    expect(result.paths.length).toBe(5991)
   })
 
   test('getStaticProps works', async () => {