http.ts

import type { IncomingMessage, ServerResponse } from 'http';
import {
  createHandler as createRawHandler,
  HandlerOptions as RawHandlerOptions,
  Request as RawRequest,
  parseRequestParams as rawParseRequestParams,
  OperationContext,
} from '../handler';
import { RequestParams } from '../common';

/**
 * The context in the request for the handler.
 *
 * @category Server/http
 */
export interface RequestContext {
  res: ServerResponse;
}

/**
 * The GraphQL over HTTP spec compliant request parser for an incoming GraphQL request.
 *
 * If the HTTP request _is not_ a [well-formatted GraphQL over HTTP request](https://graphql.github.io/graphql-over-http/draft/#sec-Request), the function will respond
 * on the `ServerResponse` argument and return `null`.
 *
 * If the HTTP request _is_ a [well-formatted GraphQL over HTTP request](https://graphql.github.io/graphql-over-http/draft/#sec-Request), but is invalid or malformed,
 * the function will throw an error and it is up to the user to handle and respond as they see fit.
 *
 * ```js
 * import http from 'http';
 * import { parseRequestParams } from 'graphql-http/lib/use/http';
 *
 * const server = http.createServer(async (req, res) => {
 *   if (req.url.startsWith('/graphql')) {
 *     try {
 *       const maybeParams = await parseRequestParams(req, res);
 *       if (!maybeParams) {
 *         // not a well-formatted GraphQL over HTTP request,
 *         // parser responded and there's nothing else to do
 *         return;
 *       }
 *
 *       // well-formatted GraphQL over HTTP request,
 *       // with valid parameters
 *       res.writeHead(200).end(JSON.stringify(maybeParams, null, '  '));
 *     } catch (err) {
 *       // well-formatted GraphQL over HTTP request,
 *       // but with invalid parameters
 *       res.writeHead(400).end(err.message);
 *     }
 *   } else {
 *     res.writeHead(404).end();
 *   }
 * });
 *
 * server.listen(4000);
 * console.log('Listening to port 4000');
 * ```
 *
 * @category Server/http
 */
export async function parseRequestParams(
  req: IncomingMessage,
  res: ServerResponse,
): Promise<RequestParams | null> {
  const rawReq = toRequest(req, res);
  const paramsOrRes = await rawParseRequestParams(rawReq);
  if (!('query' in paramsOrRes)) {
    const [body, init] = paramsOrRes;
    res.writeHead(init.status, init.statusText, init.headers).end(body);
    return null;
  }
  return paramsOrRes;
}

/**
 * Handler options when using the http adapter.
 *
 * @category Server/http
 */
export type HandlerOptions<Context extends OperationContext = undefined> =
  RawHandlerOptions<IncomingMessage, RequestContext, Context>;

/**
 * Create a GraphQL over HTTP spec compliant request handler for
 * the Node environment http module.
 *
 * ```js
 * import http from 'http';
 * import { createHandler } from 'graphql-http/lib/use/http';
 * import { schema } from './my-graphql-schema';
 *
 * const server = http.createServer(createHandler({ schema }));
 *
 * server.listen(4000);
 * console.log('Listening to port 4000');
 * ```
 *
 * @category Server/http
 */
export function createHandler<Context extends OperationContext = undefined>(
  options: HandlerOptions<Context>,
): (req: IncomingMessage, res: ServerResponse) => Promise<void> {
  const handle = createRawHandler(options);
  return async function requestListener(req, res) {
    try {
      if (!req.url) {
        throw new Error('Missing request URL');
      }
      if (!req.method) {
        throw new Error('Missing request method');
      }
      const [body, init] = await handle(toRequest(req, res));
      res.writeHead(init.status, init.statusText, init.headers).end(body);
    } catch (err) {
      // The handler shouldnt throw errors.
      // If you wish to handle them differently, consider implementing your own request handler.
      console.error(
        'Internal error occurred during request handling. ' +
          'Please check your implementation.',
        err,
      );
      res.writeHead(500).end();
    }
  };
}

function toRequest(
  req: IncomingMessage,
  res: ServerResponse,
): RawRequest<IncomingMessage, RequestContext> {
  if (!req.url) {
    throw new Error('Missing request URL');
  }
  if (!req.method) {
    throw new Error('Missing request method');
  }
  return {
    url: req.url,
    method: req.method,
    headers: req.headers,
    body: () =>
      new Promise<string>((resolve) => {
        let body = '';
        req.setEncoding('utf-8');
        req.on('data', (chunk) => (body += chunk));
        req.on('end', () => resolve(body));
      }),
    raw: req,
    context: { res },
  };
}