import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import {
  BehaviorSubject,
  Observable,
  concat,
  distinctUntilChanged,
  map,
  tap,
} from 'rxjs';
import { User } from '../models/user.model';
import { Router } from '@angular/router';
import { environment } from 'src/environments/environment';

@Injectable({ providedIn: 'root' })
export class UserService {
  private currnetUserSubject = new BehaviorSubject<User | null>(null);
  public currentUser = this.currnetUserSubject
    .asObservable()
    .pipe(distinctUntilChanged());

  public isAuthenticated = this.currentUser.pipe(map((user) => !!user));

  constructor(
    private readonly http: HttpClient,
    private readonly router: Router
  ) {}

  logout(): void {
    this.purgeAuth();
    // post to api /revoke with cookie
    this.http
      .get(environment.api + '/auth/revoke', {
        withCredentials: true,
      })
      .subscribe({
        complete: () => this.router.navigateByUrl('/login'),
      });
  }

  getCurrentUser(): Observable<{ user: User }> {
    return this.http
      .get<{ user: User }>(environment.api + '/auth/user', {
        withCredentials: true,
      })
      .pipe(
        tap({
          next: ({ user }) => {
            this.setAuth(user);
          },
          error: () => this.purgeAuth(),
        })
      );
  }

  setAuth(user: User): void {
    void this.currnetUserSubject.next(user);
  }

  purgeAuth(): void {
    void this.currnetUserSubject.next(null);
  }
}