fix: lazy shims (#912)

_tasks/dnt.ts

@@ -102,6 +102,7 @@ await Promise.all([
         name: "ws",
         version: "8.13.0",
       },
+      "./deps/shims/shim-deno.ts": "@deno/shim-deno",
       "./deps/shims/upgradeWebSocket.ts": "./deps/shims/upgradeWebSocket.node.ts",
       "./deps/shims/register.ts": "./deps/shims/register.node.ts",
       "./deps/std/http.ts": "./deps/std/http.node.ts",
@@ -136,8 +137,21 @@ await Promise.all([
   fs.copy("server/static/", path.join(outDir, "esm/server/static/")),
 ])
 
-await Deno.writeTextFile(
-  "target/npm/esm/main.js",
-  (await Deno.readTextFile("target/npm/esm/main.js"))
-    .replace(/^#!.+/, "#!/usr/bin/env -S node --loader ts-node/esm"),
-)
+await Promise.all([
+  editFile(
+    "target/npm/esm/main.js",
+    (content) =>
+      content
+        .replace(/^#!.+/, "#!/usr/bin/env -S node --loader ts-node/esm"),
+  ),
+  editFile(
+    "target/npm/esm/_dnt.shims.js",
+    (content) =>
+      content
+        .replace(/"@deno\/shim-deno"/g, `"./deps/shims/Deno.node.js"`),
+  ),
+])
+
+async function editFile(path: string, modify: (content: string) => string) {
+  await Deno.writeTextFile(path, modify(await Deno.readTextFile(path)))
+}

deps/shims/Deno.node.ts

@@ -0,0 +1,34 @@
+import { Command } from "./command.node.ts"
+
+declare const process: { env: Record<string, string> }
+let _deno = {
+  errors: {
+    NotFound: class NotFound extends Error {},
+    AlreadyExists: class AlreadyExists extends Error {},
+  },
+  env: {
+    // @ts-ignore .
+    get: (key: string) => process.env[key],
+    set: (key: string, value: string) => {
+      process.env[key] = value
+    },
+    has: (key: string) => key in process.env,
+    delete: (key: string) => {
+      delete process.env[key]
+    },
+    toObject: () => ({ ...process.env }),
+  },
+} as any as typeof globalThis.Deno
+
+export const Deno = new Proxy(
+  {},
+  new Proxy(Reflect, {
+    // @ts-ignore .
+    get: (_, key) => (_, ...x) => Reflect[key](_deno, ...x),
+  }),
+)
+
+export function register(newDeno: typeof globalThis.Deno) {
+  _deno = newDeno
+  _deno.Command = Command
+}

deps/shims/command.node.ts

@@ -1,6 +1,6 @@
 import { readableStreamFromReader, writableStreamFromWriter } from "../std/streams.ts"
 
-class Command implements Deno.Command {
+export class Command implements Deno.Command {
   #command
   #options
   constructor(command: string, options?: Deno.CommandOptions) {
@@ -128,7 +128,3 @@ class ChildProcess implements Deno.ChildProcess {
     }
   }
 }
-
-if (!("Command" in Deno)) {
-  Deno.Command = Command
-}

deps/shims/register.node.ts

@@ -1 +1,3 @@
-import "./command.node.ts"
+import { register } from "./Deno.node.ts"
+import { Deno } from "./shim-deno.ts"
+register(Deno)

deps/shims/shim-deno.ts

@@ -0,0 +1,3 @@
+// This will be shimmed to the `@deno/shim-deno` npm package by DNT
+
+export declare const Deno: typeof globalThis.Deno