UI Server: factor out responses handling logic in abstract class

[e-mobility-charging-stations-simulator.git] / src / charging-station / ui-server / UIHttpServer.ts

import type { IncomingMessage, RequestListener, ServerResponse } from 'http';

import { StatusCodes } from 'http-status-codes';

import BaseError from '../../exception/BaseError';
import type { UIServerConfiguration } from '../../types/ConfigurationData';
import {
  ProcedureName,
  Protocol,
  ProtocolRequest,
  ProtocolResponse,
  ProtocolVersion,
  RequestPayload,
  ResponseStatus,
} from '../../types/UIProtocol';
import logger from '../../utils/Logger';
import Utils from '../../utils/Utils';
import { AbstractUIServer } from './AbstractUIServer';
import { UIServiceUtils } from './ui-services/UIServiceUtils';

const moduleName = 'UIHttpServer';

export default class UIHttpServer extends AbstractUIServer {
  public constructor(protected readonly uiServerConfiguration: UIServerConfiguration) {
    super(uiServerConfiguration);
  }

  public start(): void {
    this.httpServer.on('request', this.requestListener.bind(this) as RequestListener);
    if (this.httpServer.listening === false) {
      this.httpServer.listen(this.uiServerConfiguration.options);
    }
  }

  // eslint-disable-next-line @typescript-eslint/no-unused-vars
  public sendRequest(request: ProtocolRequest): void {
    // This is intentionally left blank
  }

  public sendResponse(response: ProtocolResponse): void {
    const [uuid, payload] = response;
    if (this.responseHandlers.has(uuid) === true) {
      const res = this.responseHandlers.get(uuid) as ServerResponse;
      res.writeHead(this.responseStatusToStatusCode(payload.status), {
        'Content-Type': 'application/json',
      });
      res.end(JSON.stringify(payload));
      this.responseHandlers.delete(uuid);
    } else {
      logger.error(
        `${this.logPrefix(moduleName, 'sendResponse')} Response for unknown request id: ${uuid}`
      );
    }
  }

  public logPrefix(modName?: string, methodName?: string, prefixSuffix?: string): string {
    const logMsgPrefix = prefixSuffix ? `UI HTTP Server ${prefixSuffix}` : 'UI HTTP Server';
    const logMsg =
      modName && methodName ? ` ${logMsgPrefix} | ${modName}.${methodName}:` : ` ${logMsgPrefix} |`;
    return Utils.logPrefix(logMsg);
  }

  private requestListener(req: IncomingMessage, res: ServerResponse): void {
    if (this.authenticate(req) === false) {
      res.setHeader('Content-Type', 'text/plain');
      res.setHeader('WWW-Authenticate', 'Basic realm=users');
      res.writeHead(StatusCodes.UNAUTHORIZED);
      res.end(`${StatusCodes.UNAUTHORIZED} Unauthorized`);
      return;
    }
    // Expected request URL pathname: /ui/:version/:procedureName
    const [protocol, version, procedureName] = req.url?.split('/').slice(1) as [
      Protocol,
      ProtocolVersion,
      ProcedureName
    ];
    const uuid = Utils.generateUUID();
    this.responseHandlers.set(uuid, res);
    try {
      if (UIServiceUtils.isProtocolAndVersionSupported(protocol, version) === false) {
        throw new BaseError(`Unsupported UI protocol version: '/${protocol}/${version}'`);
      }
      this.registerProtocolVersionUIService(version);
      req.on('error', (error) => {
        logger.error(
          `${this.logPrefix(moduleName, 'requestListener.req.onerror')} Error on HTTP request:`,
          error
        );
      });
      if (req.method === 'POST') {
        const bodyBuffer = [];
        req
          .on('data', (chunk) => {
            bodyBuffer.push(chunk);
          })
          .on('end', () => {
            const body = JSON.parse(Buffer.concat(bodyBuffer).toString()) as RequestPayload;
            this.uiServices
              .get(version)
              .requestHandler(this.buildProtocolRequest(uuid, procedureName, body ?? {}))
              .catch(() => {
                this.sendResponse(
                  this.buildProtocolResponse(uuid, { status: ResponseStatus.FAILURE })
                );
              });
          });
      } else {
        throw new BaseError(`Unsupported HTTP method: '${req.method}'`);
      }
    } catch (error) {
      logger.error(
        `${this.logPrefix(moduleName, 'requestListener')} Handle HTTP request error:`,
        error
      );
      this.sendResponse(this.buildProtocolResponse(uuid, { status: ResponseStatus.FAILURE }));
    }
  }

  private authenticate(req: IncomingMessage): boolean {
    if (this.isBasicAuthEnabled() === true) {
      if (this.isValidBasicAuth(req) === true) {
        return true;
      }
      return false;
    }
    return true;
  }

  private responseStatusToStatusCode(status: ResponseStatus): StatusCodes {
    switch (status) {
      case ResponseStatus.SUCCESS:
        return StatusCodes.OK;
      case ResponseStatus.FAILURE:
        return StatusCodes.BAD_REQUEST;
      default:
        return StatusCodes.INTERNAL_SERVER_ERROR;
    }
  }
}