qcobjects/src/BackendMicroservice.ts

QCObjects is an Open-source framework that empowers full-stack developers to make micro-services and micro-frontends into an N-Tier architecture.

import { Http2Stream } from "http2";
import { Stream } from "stream";
import { _basePath_ } from "./basePath";
import { _DataStringify } from "./DataStringify";
import { _domain_ } from "./domain";
import { InheritClass } from "./InheritClass";
import { logger } from "./Logger";
import { Package } from "./Package";
import { IMicroservice } from "types";

export class BackendMicroservice extends InheritClass {
  stream: any;
  route: any;
  headers: any;
  request: any;

  constructor({
    domain = _domain_,
    basePath = _basePath_,
    body = null,
    stream = null,
    request = null
  }:IMicroservice) {
    super({
      domain,
      basePath,
      body,
      stream,
      request
    });
    logger.debug("Initializing BackendMicroservice...");
    const microservice = this;
    if (typeof this.body === "undefined") {
      this.body = null;
    }
    if (typeof body !== "undefined") {
      this.body = body;
    }
    this.cors();
    microservice.stream = stream;
    (stream as any)?.on("data", (data: any) => {
      // data from POST, GET
      const requestMethod = (request as any)?.method.toLowerCase();
      const supportedMethods = {
        "post": microservice.post.bind(microservice),
      };
      if (Object.hasOwn(supportedMethods, requestMethod)) {
        (supportedMethods as any)[requestMethod].call(microservice, data);
      }
    });

    // data from POST, GET
    const requestMethod = (request as any)?.method.toLowerCase();
    const supportedMethods = {
      "get": microservice.get.bind(microservice),
      "head": microservice.head.bind(microservice),
      "put": microservice.put.bind(microservice),
      "delete": microservice.delete.bind(microservice),
      "connect": microservice.connect.bind(microservice),
      "options": microservice.options.bind(microservice),
      "trace": microservice.trace.bind(microservice),
      "patch": microservice.patch.bind(microservice)
    };
    if (Object.hasOwn(supportedMethods, requestMethod)) {
      (supportedMethods as any)[requestMethod].call(microservice);
    }


  }

  cors():void {
    if (this.route.cors) {
      logger.debug("Validating CORS...");
      const {
        allow_origins,
        allow_credentials,
        allow_methods,
        allow_headers
      } = this.route.cors;
      const microservice = this;
      if (typeof microservice.headers !== "object") {
        microservice.headers = {};
      }
      if (typeof microservice.route.responseHeaders !== "object") {
        microservice.route.responseHeaders = {};
      }
      if (typeof allow_origins !== "undefined") {
        logger.debug("CORS: allow_origins available. Validating origins...");
        // an example of allow_origins is ['https://example.com','http://www.example.com']
        if (allow_origins === "*" || (typeof microservice.request.headers.origin === "undefined") || [...allow_origins].indexOf(microservice.request.headers.origin) !== -1) {
          // for compatibility with all browsers allways return a wildcard when the origin is allowed
          logger.debug("CORS: Adding header Access-Control-Allow-Origin=*");
          microservice.route.responseHeaders["Access-Control-Allow-Origin"] = "*";
        } else {
          logger.debug("CORS: Origin is not allowed: " + microservice.request.headers.origin);
          logger.debug("CORS: Forcing to finish the response...");
          this.body = {};
          try {
            this.done();
          } catch (e:any) {
            logger.debug(`It was not possible to finish the call to the microservice: ${e}`);
          }
        }
      } else {
        logger.debug("CORS: no allow_origins available. Allowing all origins...");
        logger.debug("CORS: Adding header Access-Control-Allow-Origin=*");
        microservice.route.responseHeaders["Access-Control-Allow-Origin"] = "*";
      }
      if (typeof allow_credentials !== "undefined") {
        logger.debug(`CORS: allow_credentials present. Allowing ${allow_credentials}...`);
        microservice.route.responseHeaders["Access-Control-Allow-Credentials"] = allow_credentials.toString();
      } else {
        logger.debug("CORS: No allow_credentials present. Allowing all credentials.");
        microservice.route.responseHeaders["Access-Control-Allow-Credentials"] = "true";
      }
      if (typeof allow_methods !== "undefined") {
        logger.debug(`CORS: allow_methods present. Allowing ${allow_methods}...`);
        microservice.route.responseHeaders["Access-Control-Allow-Methods"] = [...allow_methods].join(",");
      } else {
        logger.debug("CORS: No allow_methods present. Allowing only GET, OPTIONS and POST");
        microservice.route.responseHeaders["Access-Control-Allow-Methods"] = "GET, OPTIONS, POST";
      }
      if (typeof allow_headers !== "undefined") {
        logger.debug(`CORS: allow_headers present. Allowing ${allow_headers}...`);
        microservice.route.responseHeaders["Access-Control-Allow-Headers"] = [...allow_headers].join(",");
      } else {
        logger.debug("CORS: No allow_headers present. Allowing all headers...");
        microservice.route.responseHeaders["Access-Control-Allow-Headers"] = "*";
      }
    } else {
      logger.debug("No CORS validation available. You can specify cors in CONFIG.backend.routes[].cors");
    }
  }


  head(formData: any):void {
    logger.debug(`[BackendMicroservice.head] Data received: ${_DataStringify(formData)}`);
    this.done();
  }

  get(formData: any):void {
    logger.debug(`[BackendMicroservice.get] Data received: ${_DataStringify(formData)}`);
    this.done();
  }

  post(formData: any):void {
    logger.debug(`[BackendMicroservice.post] Data received: ${_DataStringify(formData)}`);
    this.done();
  }

  put(formData: any):void {
    logger.debug(`[BackendMicroservice.put] Data received: ${_DataStringify(formData)}`);
    this.done();
  }

  delete(formData: any):void {
    logger.debug(`[BackendMicroservice.delete] Data received: ${_DataStringify(formData)}`);
    this.done();
  }

  connect(formData: any):void {
    logger.debug(`[BackendMicroservice.connect] Data received: ${_DataStringify(formData)}`);
    this.done();
  }

  options(formData: any):void {
    logger.debug(`[BackendMicroservice.options] Data received: ${_DataStringify(formData)}`);
    this.done();
  }

  trace(formData: any):void {
    logger.debug(`[BackendMicroservice.trace] Data received: ${_DataStringify(formData)}`);
    this.done();
  }

  patch(formData: any):void {
    logger.debug(`[BackendMicroservice.patch] Data received: ${_DataStringify(formData)}`);
    this.done();
  }

  finishWithBody(stream?: Http2Stream | Stream):void {
    try {
      logger.debug("[BackendMicroservice.finishWithBody] Ending the stream...");
      logger.debug(`[BackendMicroservice.finishWithBody] type of body is: ${typeof this.body}`);
      if (typeof this.body !== "string") {
        this.body = _DataStringify(this.body);
      }
      logger.debug(`[BackendMicroservice.finishWithBody] \n body: ${this.body} `);
      (stream as any)?.write(this.body);
      (stream as any)?.end();
      logger.debug("[BackendMicroservice.finishWithBody] Stream ended.");
    } catch (e:any) {
      logger.debug(`[BackendMicroservice.finishWithBody] Something went wrong ending the stream: ${e}`);
    }
  }

  done():void {
    logger.debug("[BackendMicroservice.done] Finalizing the response...");
    const microservice = this;
    const stream = microservice.stream;
    try {
      logger.debug("[BackendMicroservice.done] Sending response headers...");
      if (microservice.route.responseHeaders) {
        logger.debug(`[BackendMicroservice.done] Response headers present: ${Object.keys(microservice.route.responseHeaders).join(",")}`);
        stream.respond(microservice.route.responseHeaders);
      } else {
        throw Error("[BackendMicroservice.done] No headers present.");
      }
    } catch (e:any) {
      logger.debug(`[BackendMicroservice.done] Something went wrong sending response headers: ${e}`);
    }
    if (microservice.body !== null) {
      try {
        logger.debug("[BackendMicroservice.done] A body of message is present. Finalizing the response...");
        microservice.finishWithBody.call(microservice, stream);
      } catch (e:any) {
        logger.debug(`[BackendMicroservice.done] Something went wrong finalizing the response: ${e}`);
      }
    } else {
      logger.debug("[BackendMicroservice.done] No body present. Ending stream...");
      stream.end();
    }
  }


}

Package("com.qcobjects.api", [
  BackendMicroservice
]);