Add link to generate links in PDF mode

src/lib/links.ts

@@ -1,6 +1,15 @@
 import 'server-only';
 
 import { headers } from 'next/headers';
+import { RevisionPageDocument } from '@gitbook/api';
+
+export interface PageHrefContext {
+    /**
+     * If defined, we are generating a PDF of the specific page IDs,
+     * and these pages will be rendered in the same HTML output.
+     */
+    pdf?: string[];
+}
 
 /**
  * Return the base path for the current request.
@@ -10,9 +19,56 @@ export function basePath(): string {
     return headersList.get('x-gitbook-basepath') ?? '';
 }
 
+/**
+ * Create an absolute href in the current content.
+ */
+export function absoluteHref(href: string): string {
+    return `${basePath()}/${href.startsWith('/') ? href.slice(1) : href}`;
+}
+
 /**
  * Create a link to a page path in the current space.
  */
-export function pageHref(pagePath: string): string {
-    return `${basePath()}/${pagePath.startsWith('/') ? pagePath.slice(1) : pagePath}`;
+export function pageHref(
+    page: RevisionPageDocument,
+    context: PageHrefContext = {},
+    /** Anchor to link to in the page. */
+    anchor?: string,
+): string {
+    const { pdf } = context;
+
+    if (pdf) {
+        if (pdf.includes(page.id)) {
+            return '#' + pagePDFContainerId(page, anchor);
+        } else {
+            // Use an absolute URL to the page
+            // TODO: we need to extend RevisionPageDocument with "urls"
+            return page.urls?.published || '/todo';
+        }
+    }
+
+    return absoluteHref(page.path) + (anchor ? '#' + anchor : '');
+}
+
+/**
+ * Create the HTML ID for the container of a page during a PDF rendering.
+ */
+export function pagePDFContainerId(page: RevisionPageDocument, anchor?: string): string {
+    return `pdf-page-${page.id}` + (anchor ? `-${anchor}` : '');
+}
+
+/**
+ * Create an HTML ID for a block in a page.
+ * It ensures the ID is unique in the entire HTML page (in case we are generating a PDF with multiple pages).
+ */
+export function pageLocalId(
+    page: RevisionPageDocument,
+    localId: string,
+    context: PageHrefContext,
+): string {
+    if (!context.pdf?.length) {
+        return localId;
+    }
+
+    return pagePDFContainerId(page, localId);
 }

src/lib/references.ts

@@ -1,6 +1,6 @@
 import { ContentRef, Revision, RevisionPageDocument, Space } from '@gitbook/api';
 import { resolvePageId } from './pages';
-import { pageHref } from './links';
+import { pageHref, PageHrefContext } from './links';
 
 export interface ResolvedContentRef {
     /** Text to render in the content ref */
@@ -9,7 +9,7 @@ export interface ResolvedContentRef {
     href: string;
 }
 
-export interface ContentRefContext {
+export interface ContentRefContext extends PageHrefContext {
     space: Space;
     revision: Revision;
     page: RevisionPageDocument;
@@ -20,7 +20,7 @@ export interface ContentRefContext {
  */
 export async function resolveContentRef(
     contentRef: ContentRef,
-    { space, revision, page: activePage }: ContentRefContext,
+    { space, revision, page: activePage, ...linksContext }: ContentRefContext,
 ): Promise<ResolvedContentRef | null> {
     // Try to resolve a local ref in the current space
     if (contentRef.kind === 'url') {
@@ -49,13 +49,13 @@ export async function resolveContentRef(
 
         if (contentRef.kind === 'page') {
             return {
-                href: pageHref(page.path),
+                href: pageHref(page, linksContext),
                 text: page.title,
             };
         }
 
         return {
-            href: pageHref(page.path) + '#' + contentRef.anchor,
+            href: pageHref(page, linksContext, contentRef.anchor),
             text: page.title + '#' + contentRef.anchor,
         };
     } else if (contentRef.kind === 'space' && contentRef.space === space.id) {