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// Copyright (c) 2024 Cloudflare, Inc.
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// Licensed under the Apache 2.0 license found in the LICENSE file or at:
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//     https://opensource.org/licenses/Apache-2.0
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import {
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  portMapper,
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  type FetchHandler as Fetcher,
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} from 'cloudflare-internal:http';
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interface ServerDescriptor {
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  port?: number | null | undefined;
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}
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interface NodeStyleServer {
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  listen(...args: unknown[]): this;
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  address(): { port?: number | null | undefined };
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}
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function validatePort(port: unknown): number {
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  if (
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    !Number.isFinite(port) ||
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    (port as number) < 0 ||
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    (port as number) > 65535
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  ) {
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    throw new Error('Failed to determine port for server');
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  }
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  return port as number;
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}
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export async function handleAsNodeRequest(
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  desc: number | ServerDescriptor,
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  request: Request,
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  env?: unknown,
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  ctx?: unknown
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): Promise<Response> {
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  if (typeof desc === 'number') {
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    desc = { port: desc };
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  }
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  // While TypeScript will complain if `desc` is null or undefined,
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  // JavaScript does not enforce this, so we need to check at runtime.
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  // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
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  const port = validatePort(desc?.port);
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  const instance = portMapper.get(port);
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  if (!instance) {
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    const error = new Error(
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      `Http server with port ${port} not found. This is likely a bug with your code. ` +
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        `You should check if server.listen() was called with the same port (${port})`
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    );
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    // @ts-expect-error TS2339 We're imitating Node.js errors.
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    error.code = 'ERR_INVALID_ARG_VALUE';
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    throw error;
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  }
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  return await instance.fetch(request, env, ctx);
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}
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export function httpServerHandler(
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  desc: number | ServerDescriptor | NodeStyleServer
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): Fetcher {
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  if (typeof desc === 'number') {
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    desc = { port: desc };
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  }
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  // While the TypeScript type system prevents `desc` from being null or undefined,
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  // JavaScript does not, so we need to check for it at runtime.
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  // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
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  if (desc == null) {
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    throw new Error('Server descriptor cannot be null or undefined');
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  }
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  // The desc can be a ServerDescriptor or a Server (where "Server" is defined
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  // as a type that has a "listen()" method and an "address()" method).
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  let port: number | null = null;
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  // If there is no port defined and desc has a listen method, we will try to
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  // access it as a Server, calling listen() if necessary to determine the port.
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  if (
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    (desc as ServerDescriptor).port == null &&
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    typeof (desc as NodeStyleServer).listen === 'function'
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  ) {
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    const server = desc as NodeStyleServer;
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    // First, let's see if the server-like thing already has a port.
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    // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
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    let serverPort = server.address()?.port;
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    if (typeof serverPort === 'number') {
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      // Nice, we're already bound to a port.
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      port = serverPort;
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    } else {
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      // We're not yet bound to a port. Try calling listen() to start the server
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      // and determine the port.
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      server.listen();
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      // Did it work? We do expect the listen in this case to synchronously
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      // assign the port so we can check it immediately.
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      // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
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      serverPort = server.address()?.port;
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      if (typeof serverPort === 'number') {
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        // Nice. We've got a port now.
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        port = serverPort;
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      }
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    }
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  } else if (typeof (desc as ServerDescriptor).port === 'number') {
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    // We're a ServerDescriptor with a port defined.
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    port = (desc as ServerDescriptor).port as number;
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  }
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  port = validatePort(port);
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  return {
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    async fetch(req: Request, env?: unknown, ctx?: unknown): Promise<Response> {
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      return await handleAsNodeRequest(
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        { port: validatePort(port) },
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        req,
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        env,
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        ctx
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      );
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    },
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  };
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}