From e93b98a2426b0e7375cf3b53c4e57c66121cbb57 Mon Sep 17 00:00:00 2001
From: slorber <lorber.sebastien@gmail.com>
Date: Mon, 25 May 2020 19:51:37 +0200
Subject: [PATCH] fix writeRedirectFiles

---
 .../src/collectRedirects.ts                   |  3 -
 .../src/index.ts                              |  2 +-
 .../src/writeRedirectFiles.ts                 | 59 +++++++++++++++----
 3 files changed, 48 insertions(+), 16 deletions(-)

diff --git a/packages/docusaurus-plugin-client-redirects/src/collectRedirects.ts b/packages/docusaurus-plugin-client-redirects/src/collectRedirects.ts
index 8e7a11abdd..89b36f9c03 100644
--- a/packages/docusaurus-plugin-client-redirects/src/collectRedirects.ts
+++ b/packages/docusaurus-plugin-client-redirects/src/collectRedirects.ts
@@ -5,7 +5,6 @@
  * LICENSE file in the root directory of this source tree.
  */
 
-import path from 'path';
 import {flatten, uniqBy} from 'lodash';
 import {
   RedirectsCreator,
@@ -13,8 +12,6 @@ import {
   RedirectMetadata,
   PluginOptions,
 } from './types';
-import createRedirectPageContent from './createRedirectPageContent';
-import {addTrailingSlash, getFilePathForRoutePath} from './utils';
 import {
   fromExtensionsRedirectCreator,
   toExtensionsRedirectCreator,
diff --git a/packages/docusaurus-plugin-client-redirects/src/index.ts b/packages/docusaurus-plugin-client-redirects/src/index.ts
index bc0b8d2a27..1253e2b768 100644
--- a/packages/docusaurus-plugin-client-redirects/src/index.ts
+++ b/packages/docusaurus-plugin-client-redirects/src/index.ts
@@ -31,7 +31,7 @@ export default function pluginClientRedirectsPages(
       const redirects: RedirectMetadata[] = collectRedirects(pluginContext);
 
       // Write files only at the end: make code more easy to test without IO
-      await writeRedirectFiles(redirects);
+      await writeRedirectFiles(redirects, pluginContext);
     },
   };
 }
diff --git a/packages/docusaurus-plugin-client-redirects/src/writeRedirectFiles.ts b/packages/docusaurus-plugin-client-redirects/src/writeRedirectFiles.ts
index 7dbda45323..f98e5a8ccf 100644
--- a/packages/docusaurus-plugin-client-redirects/src/writeRedirectFiles.ts
+++ b/packages/docusaurus-plugin-client-redirects/src/writeRedirectFiles.ts
@@ -6,23 +6,58 @@
  */
 
 import fs from 'fs-extra';
-import {RedirectMetadata} from './types';
+import path from 'path';
+import {memoize} from 'lodash';
 
-type RedirectFile = Pick<
-  RedirectMetadata,
-  'redirectAbsoluteFilePath' | 'redirectPageContent'
->;
+import {PluginContext, RedirectMetadata} from './types';
+import createRedirectPageContent from './createRedirectPageContent';
+import {addTrailingSlash, getFilePathForRoutePath} from './utils';
 
-export default async function writeRedirectFiles(redirects: RedirectFile[]) {
-  async function writeRedirectFile(redirect: RedirectFile) {
+type FileMetadata = RedirectMetadata & {
+  fileAbsolutePath: string;
+  fileContent: string;
+};
+
+function toFileMetadata(
+  redirects: RedirectMetadata[],
+  pluginContext: PluginContext,
+): FileMetadata[] {
+  // Perf: avoid rendering the template twice with the exact same "props"
+  // We might create multiple redirect pages for the same destination url
+  // note: the first fn arg is the cache key!
+  const createPageContentMemoized = memoize((toUrl: string) => {
+    return createRedirectPageContent({toUrl});
+  });
+
+  return redirects.map((redirect) => {
+    const fileAbsolutePath = path.join(
+      pluginContext.outDir,
+      getFilePathForRoutePath(redirect.fromRoutePath),
+    );
+    const toUrl = addTrailingSlash(
+      `${pluginContext.baseUrl}${redirect.toRoutePath}`,
+    );
+    const fileContent = createPageContentMemoized(toUrl);
+    return {
+      ...redirect,
+      fileAbsolutePath,
+      fileContent,
+    };
+  });
+}
+
+export default async function writeRedirectFiles(
+  redirects: RedirectMetadata[],
+  pluginContext: PluginContext,
+) {
+  async function writeFile(file: FileMetadata) {
     try {
-      await fs.writeFile(
-        redirect.redirectAbsoluteFilePath,
-        redirect.redirectPageContent,
-      );
+      await fs.writeFile(file.fileAbsolutePath, file.fileContent);
     } catch (err) {
       throw new Error(`Redirect file creation error: ${err}`);
     }
   }
-  await Promise.all(redirects.map(writeRedirectFile));
+
+  const files = toFileMetadata(redirects, pluginContext);
+  await Promise.all(files.map(writeFile));
 }