feat: add support for user import maps (#6)

* refactor: rename variable * feat: add support for user import maps
netlify · Mar 15, 2022 · 9067956 · 9067956
1 parent c5fa05e
commit 9067956
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Showing 3 changed files with 31 additions and 14 deletions.
diff --git a/src/bundler.ts b/src/bundler.ts
@@ -11,7 +11,7 @@ import type { Declaration } from './declaration.js'
 import { getESZIPBundler } from './eszip.js'
 import { findHandlers } from './finder.js'
 import { Handler } from './handler.js'
-import { ImportMap } from './import_map.js'
+import { ImportMap, ImportMapFile } from './import_map.js'
 import { generateManifest } from './manifest.js'
 import { getFileHash } from './utils/sha256.js'
 
@@ -21,7 +21,8 @@ interface HandlerLine {
 }
 
 interface BundleOptions {
-  importMapPath?: string
+  distImportMapPath?: string
+  importMaps?: ImportMapFile[]
   onAfterDownload?: LifecycleHook
   onBeforeDownload?: LifecycleHook
 }
@@ -38,7 +39,7 @@ const bundle = async (
   sourceDirectories: string[],
   distDirectory: string,
   declarations: Declaration[] = [],
-  { importMapPath, onAfterDownload, onBeforeDownload }: BundleOptions = {},
+  { distImportMapPath, importMaps, onAfterDownload, onBeforeDownload }: BundleOptions = {},
 ) => {
   const deno = new DenoBridge({
     onAfterDownload,
@@ -49,7 +50,10 @@ const bundle = async (
   // compute until we run the bundle process. For now, we'll use a random ID
   // to create the bundle artifacts and rename them later.
   const buildID = uuidv4()
-  const importMap = new ImportMap()
+
+  // Creating an ImportMap instance with any import maps supplied by the user,
+  // if any.
+  const importMap = new ImportMap(importMaps)
   const { handlers, preBundlePath } = await preBundle(sourceDirectories, distDirectory, `${buildID}-pre.js`)
   const bundleAlternates: BundleAlternate[] = ['js']
   const bundleOps = [bundleJS({ buildID, deno, distDirectory, importMap, preBundlePath })]
@@ -70,8 +74,8 @@ const bundle = async (
 
   await fs.unlink(preBundlePath)
 
-  if (importMapPath) {
-    await importMap.writeToFile(importMapPath)
+  if (distImportMapPath) {
+    await importMap.writeToFile(distImportMapPath)
   }
 
   return { handlers, manifest, preBundlePath }

diff --git a/src/import_map.ts b/src/import_map.ts
@@ -6,11 +6,20 @@ const DEFAULT_IMPORTS = {
   'netlify:edge': 'https://dinosaurs:are-the-future!@edge-bootstrap.netlify.app/v1/index.ts',
 }
 
+interface ImportMapFile {
+  imports: Record<string, string>
+  scopes?: Record<string, string>
+}
+
 class ImportMap {
   imports: Record<string, string>
 
-  constructor() {
-    this.imports = DEFAULT_IMPORTS
+  constructor(input: ImportMapFile[] = []) {
+    const inputImports = input.reduce((acc, { imports }) => ({ ...acc, ...imports }), {})
+
+    // `DEFAULT_IMPORTS` must come last because we want our internal imports to
+    // take precedence.
+    this.imports = { ...inputImports, ...DEFAULT_IMPORTS }
   }
 
   getContents() {
@@ -37,3 +46,4 @@ class ImportMap {
 }
 
 export { ImportMap }
+export type { ImportMapFile }
diff --git a/src/server.ts b/src/server.ts
@@ -3,19 +3,20 @@ import { tmpName } from 'tmp-promise'
 import { DenoBridge, LifecycleHook } from './bridge.js'
 import { preBundle } from './bundler.js'
 import type { Declaration } from './declaration.js'
-import { ImportMap } from './import_map.js'
+import { ImportMap, ImportMapFile } from './import_map.js'
 import { generateManifest } from './manifest.js'
 
 interface ServeOptions {
-  importMapPath?: string
+  distImportMapPath?: string
+  importMaps?: ImportMapFile[]
   onAfterDownload?: LifecycleHook
   onBeforeDownload?: LifecycleHook
 }
 
 const serve = async (
   port: number,
   sourceDirectories: string[],
-  { importMapPath, onAfterDownload, onBeforeDownload }: ServeOptions = {},
+  { distImportMapPath, importMaps, onAfterDownload, onBeforeDownload }: ServeOptions = {},
 ) => {
   const deno = new DenoBridge({
     onAfterDownload,
@@ -29,13 +30,15 @@ const serve = async (
   // Wait for the binary to be downloaded if needed.
   await deno.getBinaryPath()
 
-  const importMap = new ImportMap()
+  // Creating an ImportMap instance with any import maps supplied by the user,
+  // if any.
+  const importMap = new ImportMap(importMaps)
   const flags = ['-A', '--unstable', '--no-clear-screen', '--watch', `--import-map=${importMap.toDataURL()}`]
 
   deno.run(['run', ...flags, preBundlePath, port.toString()], { wait: false })
 
-  if (importMapPath) {
-    await importMap.writeToFile(importMapPath)
+  if (distImportMapPath) {
+    await importMap.writeToFile(distImportMapPath)
   }
 
   return {