From 4e4770169d2e85df10283fc5f8e11f998b4c047d Mon Sep 17 00:00:00 2001
From: Eduardo San Martin Morote <posva13@gmail.com>
Date: Wed, 16 Sep 2020 11:55:17 +0200
Subject: [PATCH] refactor(server): add types and fix out of bounds
 next/previous

---
 src/client/app/composables/siteData.ts        |  4 +-
 .../components/NextAndPrevLinks.ts            |  5 ++-
 src/node/server.ts                            | 42 +++++++++++++------
 3 files changed, 35 insertions(+), 16 deletions(-)

diff --git a/src/client/app/composables/siteData.ts b/src/client/app/composables/siteData.ts
index 09b3ead3..f27f6c83 100644
--- a/src/client/app/composables/siteData.ts
+++ b/src/client/app/composables/siteData.ts
@@ -6,8 +6,8 @@ const parse = (data: string) => readonly(JSON.parse(data)) as SiteData
 
 export const siteDataRef: Ref<SiteData> = ref(parse(serialized))
 
-export function useSiteData() {
-  return siteDataRef
+export function useSiteData<T = any>() {
+  return siteDataRef as Ref<SiteData<T>>
 }
 
 // hmr
diff --git a/src/client/theme-default/components/NextAndPrevLinks.ts b/src/client/theme-default/components/NextAndPrevLinks.ts
index 0c0f0c85..387ef08b 100644
--- a/src/client/theme-default/components/NextAndPrevLinks.ts
+++ b/src/client/theme-default/components/NextAndPrevLinks.ts
@@ -1,12 +1,15 @@
 import { defineComponent, computed } from 'vue'
 import { usePageData, useSiteData } from 'vitepress'
+import { DefaultTheme } from '../config'
 
 export default defineComponent({
   setup() {
     const pageData = usePageData()
+    // TODO: could this be useSiteData<DefaultTheme.Config> or is the siteData
+    // resolved and has a different structure?
     const siteData = useSiteData()
     const resolveLink = (targetLink: string) => {
-      let target: any = undefined
+      let target: DefaultTheme.SideBarLink | undefined
       Object.keys(siteData.value.themeConfig.sidebar).some((k) => {
         return siteData.value.themeConfig.sidebar[k].some(
           (v: { children: any }) => {
diff --git a/src/node/server.ts b/src/node/server.ts
index 644d041a..9ca08a99 100644
--- a/src/node/server.ts
+++ b/src/node/server.ts
@@ -106,6 +106,7 @@ function createVitePressPlugin({
 
         const pageDataWithLinks = {
           ...pageData,
+          // TODO: this doesn't work with locales
           ...getNextAndPrev(siteData.themeConfig, ctx.path)
         }
         await next()
@@ -131,21 +132,31 @@ function createVitePressPlugin({
   }
 }
 
+// TODO: share types from SideBarLink, SideBarGroup, etc. We are also assuming
+// all themes follow this structure, in which case, we should expose the type
+// instead of having any for themeConfig or not nest `sidebar` inside
+// `themeConfig`, specially given it must be specified inside `locales` if there
+// are any
+interface SideBarLink {
+  text: string
+  link: string
+}
+
 function getNextAndPrev(themeConfig: any, pagePath: string) {
   if (!themeConfig.sidebar) {
     return
   }
   const sidebar = themeConfig.sidebar
-  let candidates: { text: string; link: string }[] = []
+  let candidates: SideBarLink[] = []
   Object.keys(sidebar).forEach((k) => {
     if (!pagePath.startsWith(k)) {
       return
     }
-    sidebar[k].forEach((sidebarItem: { [key: string]: any }) => {
+    sidebar[k].forEach((sidebarItem: { children?: SideBarLink[] }) => {
       if (!sidebarItem.children) {
         return
       }
-      sidebarItem.children.forEach((candidate: any) => {
+      sidebarItem.children.forEach((candidate) => {
         candidates.push(candidate)
       })
     })
@@ -153,17 +164,22 @@ function getNextAndPrev(themeConfig: any, pagePath: string) {
 
   const path = pagePath.replace(/\.(md|html)$/, '')
   const currentLinkIndex = candidates.findIndex((v) => v.link === path)
-  const hideNextLink = themeConfig.nextLinks === false
-  const hidePrevLink = themeConfig.prevLinks === false
-
-  return {
-    ...(currentLinkIndex !== -1 && !hideNextLink
-      ? { next: candidates[currentLinkIndex + 1] }
-      : {}),
-    ...(currentLinkIndex !== -1 && !hidePrevLink
-      ? { prev: candidates[currentLinkIndex - 1] }
-      : {})
+
+  const nextAndPrev: { prev?: SideBarLink; next?: SideBarLink } = {}
+
+  if (
+    themeConfig.nextLinks !== false &&
+    currentLinkIndex > -1 &&
+    currentLinkIndex < candidates.length - 1
+  ) {
+    nextAndPrev.next = candidates[currentLinkIndex + 1]
   }
+
+  if (themeConfig.prevLinks !== false && currentLinkIndex > 0) {
+    nextAndPrev.next = candidates[currentLinkIndex - 1]
+  }
+
+  return nextAndPrev
 }
 
 export async function createServer(options: ServerConfig = {}) {