feat(scripts): implement dist-tags caching for prepare-release

Add caching to improve speed of dist-tags fetch. Enable cache path via an
environment variable. Cache results in JSON format.

Issue: DX-1201

Co-authored-by: llm-git <[email protected]>

Author: OttoAllmendinger

scripts/prepareRelease/distTags.ts

@@ -1,4 +1,4 @@
-import { readFileSync } from 'fs';
+import { readFileSync, writeFileSync, existsSync } from 'fs';
 import * as path from 'path';
 
 export type DistTags = Record<string, string>;
@@ -16,8 +16,24 @@ export async function getDistTags(packageName: string): Promise<DistTags> {
   return response.json();
 }
 
+// Add this function to read from cache
+export function getDistTagsCache(): string | undefined {
+  return process.env.BITGO_PREPARE_RELEASE_CACHE_DIST_TAGS;
+}
+
 export async function getDistTagsForModuleNames(moduleNames: string[]): Promise<Map<string, DistTags>> {
-  return new Map(
+  const cachePath = getDistTagsCache();
+
+  // If cache path is set and file exists, read from cache
+  if (cachePath && existsSync(cachePath)) {
+    console.log(`Reading dist tags from cache: ${cachePath}`);
+    const cacheContent = readFileSync(cachePath, { encoding: 'utf-8' });
+    const cachedTags = JSON.parse(cacheContent);
+    return new Map(Object.entries(cachedTags));
+  }
+
+  // Otherwise fetch from npm
+  const tagsMap = new Map(
     (
       await Promise.all(
         moduleNames.map(async (moduleName): Promise<[string, DistTags][]> => {
@@ -38,6 +54,19 @@ export async function getDistTagsForModuleNames(moduleNames: string[]): Promise<
       )
     ).flat()
   );
+
+  // If cache path is set but file doesn't exist, write to cache
+  if (cachePath) {
+    console.log(`Writing dist tags to cache: ${cachePath}`);
+    const cacheDir = path.dirname(cachePath);
+    if (!existsSync(cacheDir)) {
+      const { mkdirSync } = require('fs');
+      mkdirSync(cacheDir, { recursive: true });
+    }
+    writeFileSync(cachePath, JSON.stringify(Object.fromEntries(tagsMap), null, 2), { encoding: 'utf-8' });
+  }
+
+  return tagsMap;
 }
 
 export async function getDistTagsForModuleLocations(moduleLocations: string[]): Promise<(DistTags | undefined)[]> {