import { HttpClient } from '@angular/common/http';
import { Injectable } from '@angular/core';
import { environment } from '@dafa-environment';
import { Participant } from '@dafa-models/participant.model';
import { SortBy } from '@dafa-models/sort-by.model';
import { BehaviorSubject, combineLatest, Observable } from 'rxjs';
import { map } from 'rxjs/operators';

@Injectable({
  providedIn: 'root',
})
export class ParticipantsService {
  private _participants$: Observable<Participant[]> = this.httpClient.get<Participant[]>(
    `${environment.apiBase}/participants`
  );
  private _sortBy$ = new BehaviorSubject<SortBy | null>({ key: 'service', reverse: false });
  public sortBy$: Observable<SortBy> = this._sortBy$.asObservable();

  public participants$: Observable<Participant[]> = combineLatest([this._sortBy$, this._participants$]).pipe(
    map(([sortBy, participants]) => {
      if (sortBy) {
        const reverse = sortBy.reverse ? -1 : 1;
        return [...participants].sort((a, b) => {
          const first = a[sortBy.key];
          const second = b[sortBy.key];
          return reverse * +(first > second) - +(second > first);
        });
      }
      return participants;
    })
  );

  public setSortKey(key: keyof Participant) {
    const currentSortBy = this._sortBy$.getValue();
    let reverse = false;

    if (currentSortBy?.key === key) {
      reverse = !currentSortBy.reverse;
    }

    this._sortBy$.next({ key, reverse });
  }

  constructor(private httpClient: HttpClient) {}
}