import {catchError, distinctUntilChanged, filter, first, mergeMap, Observable, retryWhen, switchMap, timer} from "rxjs";
import {HttpClient, HttpErrorResponse} from "@angular/common/http";
import {NotifyColor, OpenNotifyService} from "@service/open-notify.service";
import {environment} from "@environment";
import {Router} from "@angular/router";
import {Injectable} from "@angular/core";
import {RequestBuilder, RequestData} from "@api/RequestBuilder";
import {TokenRefreshService} from "@service/token-refresh.service";
import {AuthToken} from "@service/auth.service";

export function retryWithInterval<T>(): (source: Observable<T>) => Observable<T> {
  return (source: Observable<T>) =>
    source.pipe(
      retryWhen((errors: Observable<any>) =>
        errors.pipe(
          mergeMap((error, index) => {
            if (index < (environment.maxRetry < 0 ? Infinity : environment.maxRetry - 1) && !error.status.toString().startsWith('4') && !error.status.toString().startsWith('5')) {
              console.log(`Retrying after ${environment.retryDelay}ms...`);
              return timer(environment.retryDelay);
            } else {
              if (error.status.toString().startsWith('4'))
                console.error(`Server returned a client code error`);
              else
                console.error(`Exceeded maximum retries (${environment.maxRetry})`);

              throw error;
            }
          })
        )
      )
    );
}

export enum AvailableVersion {
  v1
}

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

  private apiUrl = environment.apiUrl;

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

  public static readonly tokenKey = 'auth_token';

  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): Observable<Type> {
    const doneEndpoint = this.combinedUrl(request);

    return this.http.request<Type>(method, doneEndpoint, {
      withCredentials: request.withCredentials,
      headers: request.httpHeaders,
      body: request.data
    }).pipe(
      retryWithInterval<Type>(),
      catchError(error => {
        if (!request.silenceMode)
          this.handleError(error);

        throw error;
      })
    );
  }

  private makeHttpRequest<Type>(method: 'get' | 'post' | 'delete' | 'put', request: RequestData): Observable<Type> {
    if (request.needAuth)
      return this.tokenRefreshService.getTokenRefreshing$().pipe(
        distinctUntilChanged(),
        filter(isRefreshing => !isRefreshing),
        first(),
        switchMap(() => {
          const token = localStorage.getItem(ApiService.tokenKey);

          if (token) {
            const authToken = AuthToken.httpHeader((JSON.parse(token) as AuthToken));
            authToken.keys().forEach(key => request.httpHeaders = request.httpHeaders.append(key, authToken.get(key) ?? ''));
          }

          return this.sendHttpRequest<Type>(method, request);
        })
      );

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