MireaFrontend/src/api/api.service.ts

import {
  BehaviorSubject,
  catchError,
  distinctUntilChanged,
  filter,
  first,
  Observable,
  of,
  ReplaySubject,
  switchMap
} from "rxjs";
import {HttpClient, HttpErrorResponse} from "@angular/common/http";
import {environment} from "@environment";
import {Router} from "@angular/router";
import {Injectable} from "@angular/core";
import {RequestBuilder, RequestData} from "@api/RequestBuilder";
import {ToastrService} from "ngx-toastr";
import {AuthRoles} from "@model/AuthRoles";

export enum AvailableVersion {
  v1
}

@Injectable()
export default abstract class ApiService {
  constructor(protected http: HttpClient, protected notify: ToastrService, private router: Router) {
  }

  private apiUrl = environment.apiUrl;
  private static isRefreshingToken: BehaviorSubject<boolean> = new BehaviorSubject<boolean>(false);
  private static refreshTokenSubject: ReplaySubject<any> = new ReplaySubject(1);

  protected abstract basePath: string;
  protected abstract version: AvailableVersion;

  private static addQuery(endpoint: string, queryParams?: Record<string, string | number | boolean | Array<any> | null> | null): string {
    const url = new URL(endpoint);

    if (queryParams) {
      Object.keys(queryParams).forEach(key => {
        const value = queryParams[key];
        if (value !== null && value !== undefined) {
          if (typeof (value) === typeof (Array)) {
            (value as Array<any>).forEach(x => url.searchParams.append(key, x.toString()));
          } else
            url.searchParams.append(key, value.toString());
        }
      });
    }

    return url.href;
  }

  private static combineUrls(...parts: string[]): string {
    return parts.map(part => part.replace(/(^\/+|\/+$)/g, '')).join('/');
  }

  protected combinedUrl(request: RequestData) {
    return ApiService.addQuery(ApiService.combineUrls(this.apiUrl, AvailableVersion[this.version], this.basePath, request.endpoint), request.queryParams);
  }

  private sendHttpRequest<Type>(method: 'get' | 'post' | 'delete' | 'put', request: RequestData, secondTry: boolean = false): Observable<Type> {
    const doneEndpoint = this.combinedUrl(request);

    return this.http.request<Type>(method, doneEndpoint, {
      withCredentials: request.withCredentials,
      headers: request.httpHeaders,
      body: request.data,
    }).pipe(
      catchError(error => {
        if (!secondTry && error.status === 401)
          return this.handle401Error().pipe(
            switchMap(() => this.sendHttpRequest<Type>(method, request, true))
          );
        else {
          if (!request.silenceMode)
            this.handleError(error);

          throw error;
        }
      })
    );
  }

  private refreshToken(): Observable<AuthRoles> {
    return this.http.get<AuthRoles>(ApiService.combineUrls(this.apiUrl, AvailableVersion[AvailableVersion.v1], 'Auth', 'ReLogin'), {
      withCredentials: true
    });
  }

  private handle401Error(): Observable<any> {
    if (ApiService.isRefreshingToken.value)
      return ApiService.refreshTokenSubject.asObservable();

    ApiService.isRefreshingToken.next(true);
    return this.refreshToken().pipe(
      switchMap(_ => {
        ApiService.isRefreshingToken.next(false);
        ApiService.refreshTokenSubject.next(null);
        return of(null);
      }),
      catchError(err => {
        ApiService.isRefreshingToken.next(false);
        ApiService.refreshTokenSubject.error(err);
        ApiService.refreshTokenSubject = new ReplaySubject(1);
        throw err;
      })
    );
  }

  private makeHttpRequest<Type>(method: 'get' | 'post' | 'delete' | 'put', request: RequestData): Observable<Type> {
    if (request.needAuth) {
      return ApiService.isRefreshingToken.pipe(
        distinctUntilChanged(),
        filter(isRefreshing => !isRefreshing),
        first(),
        switchMap(() => this.sendHttpRequest<Type>(method, request))
      );
    } else {
      return this.sendHttpRequest<Type>(method, request);
    }
  }

  private getRequest(request: RequestData | string | null): RequestData {
    if (request === null)
      return this.createRequestBuilder().build;
    if (typeof request === 'string')
      return this.createRequestBuilder().setEndpoint(request as string).build;

    return request as RequestData;
  }

  public createRequestBuilder() {
    return new RequestBuilder();
  }

  public get<Type>(request: RequestData | string | null = null): Observable<Type> {
    return this.makeHttpRequest<Type>('get', this.getRequest(request));
  }

  public post<Type>(request: RequestData | string | null = null): Observable<Type> {
    return this.makeHttpRequest<Type>('post', this.getRequest(request));
  }

  public put<Type>(request: RequestData | string | null = null): Observable<Type> {
    return this.makeHttpRequest<Type>('put', this.getRequest(request));
  }

  public delete<Type>(request: RequestData | string | null = null): Observable<Type> {
    return this.makeHttpRequest<Type>('delete', this.getRequest(request));
  }

  public addAuth(request: RequestData) {
    request.needAuth = true;
    request.withCredentials = true;
    return this;
  }

  private handleError(error: HttpErrorResponse): void {
    // todo: change to Retry-After condition
    if (error.error && error.error.toString().includes("setup")) {
      this.router.navigate(['/setup/']).then();
      return;
    }

    let title: string;
    let message: string | undefined = undefined;
    if (error.error instanceof ErrorEvent) {
      title = `Произошла ошибка: ${error.error.message}`;
    } else {
      switch (error.status) {
        case 0:
          title = 'Неизвестная ошибка. Пожалуйста, попробуйте позже.';
          break;
        case 400:
          title = 'Ошибка запроса. Пожалуйста, проверьте отправленные данные.';
          break;
        case 401:
          this.router.navigate(['/login/']).then();
          title = 'Ошибка авторизации. Пожалуйста, выполните вход с правильными учетными данными.';
          break;
        case 403:
          title = 'Отказано в доступе. У вас нет разрешения на выполнение этого действия.';
          break;
        case 404:
          title = 'Запрашиваемый ресурс не найден.';
          break;
        case 500:
          title = 'Внутренняя ошибка сервера. Пожалуйста, попробуйте позже.';
          break;
        case 503:
          title = 'Сервер на обслуживании. Пожалуйста, попробуйте позже.';
          break;
        default:
          title = `Сервер вернул код ошибки: ${error.status}`;
          break;
      }
      if (error.error?.Error)
        message = error.error.Error;
      else if (error.error instanceof String)
        message = error.error.toString();
      else
        message = error.error.statusMessage;
    }
    this.notify.error(message == '' ? undefined : message, title);
  }
}