feat(deploy): add cloudflare context to platform object

Example usage from a server component:

```ts
import { unstable_getPlatformObject } from 'waku/server';

const getData = async () => {
  const { env, executionCtx } = unstable_getPlatformObject() as { env: Env; executionCtx: ExecutionContext };
  executionCtx?.waitUntil(
    new Promise<void>((resolve) => {
      console.log("Waiting for 5 seconds");
      setTimeout(() => {
        console.log("OK, done waiting");
        resolve();
      }, 5000);
    }),
  );
  const { results } = await env.DB.prepare(
    "SELECT * FROM users WHERE user_id = ?",
  )
    .bind(userId)
    .all();
  return results;
};
```

packages/waku/package.json

@@ -87,6 +87,7 @@
     "vite": "5.4.4"
   },
   "devDependencies": {
+    "@cloudflare/workers-types": "^4.20240909.0",
     "@netlify/functions": "^2.8.1",
     "@swc/cli": "^0.4.0",
     "rollup": "^4.21.3",

packages/waku/src/lib/builder/serve-cloudflare.ts

@@ -1,41 +1,77 @@
 import { Hono } from 'hono';
+import { unstable_getPlatformObject } from 'waku/server';
 import { runner } from '../hono/runner.js';
+import type {
+  ExportedHandler,
+  fetch,
+  Request as CloudflareRequest,
+  Response as CloudflareResponse,
+} from '@cloudflare/workers-types/experimental';
 
 const loadEntries = () => import(import.meta.env.WAKU_ENTRIES_FILE!);
 let serveWaku: ReturnType<typeof runner> | undefined;
 
 export interface CloudflareEnv {
   ASSETS: {
-    fetch: (input: RequestInit | URL, init?: RequestInit) => Promise<Response>;
+    fetch: typeof fetch;
   };
 }
 
 export const app = new Hono<{
   Bindings: CloudflareEnv & { [k: string]: unknown };
 }>();
-app.use('*', (c, next) => serveWaku!(c, next));
+app.use('*', (c, next) => {
+  if (!serveWaku) {
+    throw new Error('serveWaku is not initialized');
+  }
+  const platform = unstable_getPlatformObject();
+  platform.honoContext = c;
+  platform.cf = (c.req.raw as unknown as CloudflareRequest).cf;
+  platform.env = c.env;
+  platform.executionContext = c.executionCtx;
+  return serveWaku(c, next);
+});
 app.notFound(async (c) => {
   const assetsFetcher = c.env.ASSETS;
   const url = new URL(c.req.raw.url);
   const errorHtmlUrl = `${url.origin}/404.html`;
-  const notFoundStaticAssetResponse = await assetsFetcher.fetch(
+  const notFoundStaticAssetResponse = (await assetsFetcher.fetch(
     new URL(errorHtmlUrl),
-  );
+  )) as unknown as Response;
   if (notFoundStaticAssetResponse && notFoundStaticAssetResponse.status < 400) {
     return c.body(notFoundStaticAssetResponse.body, 404);
   }
   return c.text('404 Not Found', 404);
 });
 
-export default {
-  async fetch(
-    request: Request,
-    env: Record<string, string>,
-    ctx: Parameters<typeof app.fetch>[2],
-  ) {
+// Waku getEnv only supports strings
+// Cloudflare injects bindings to env and JSON
+// Use unstable_getPlatformObject() to access cloudflare env and execution context
+// https://developers.cloudflare.com/workers/configuration/environment-variables/#add-environment-variables-via-wrangler
+// https://developers.cloudflare.com/workers/runtime-apis/bindings/
+const extractWakuEnv = (env: Record<string, unknown>): Record<string, string> =>
+  Object.fromEntries(
+    Object.entries(env).filter(([, value]) => typeof value === 'string'),
+  ) as Record<string, string>;
+
+const handler: ExportedHandler<CloudflareEnv & { [k: string]: never }> = {
+  async fetch(request, env, ctx) {
     if (!serveWaku) {
-      serveWaku = runner({ cmd: 'start', loadEntries, env });
+      serveWaku = runner({
+        cmd: 'start',
+        loadEntries,
+        env: extractWakuEnv(env),
+      });
     }
-    return app.fetch(request, env, ctx);
+    return app.fetch(
+      request as unknown as Request,
+      env,
+      ctx,
+    ) as unknown as CloudflareResponse;
   },
+  // It might be useful to have a way to populate other handlers tail, trace, scheduled, email, queue
+  // But it's not hard to create a separate worker with those handlers and access it via
+  // service bindings. https://developers.cloudflare.com/pages/functions/bindings/#service-bindings
 };
+
+export default handler;

packages/waku/src/server.ts

@@ -147,8 +147,11 @@ export function unstable_getHeaders(): Record<string, string> {
   >;
 }
 
-type PlatformObject = {
-  buildData?: Record<string, unknown>; // must be JSON serializable
+type PlatformObject<
+  T = Record<string, unknown>,
+  BuildData = Record<string, unknown>,
+> = {
+  buildData?: BuildData; // must be JSON serializable
   buildOptions?: {
     deploy?:
       | 'vercel-static'
@@ -167,11 +170,13 @@ type PlatformObject = {
       | 'buildClientBundle'
       | 'buildDeploy';
   };
-} & Record<string, unknown>;
+} & T;
 
 (globalThis as any).__WAKU_PLATFORM_OBJECT__ ||= {};
 
 // TODO tentative name
-export function unstable_getPlatformObject(): PlatformObject {
+export function unstable_getPlatformObject<
+  T = Record<string, unknown>,
+>(): PlatformObject<T> {
   return (globalThis as any).__WAKU_PLATFORM_OBJECT__;
 }