import {Injectable} from '@angular/core';
import {BehaviorSubject, combineLatest, Observable, ReplaySubject} from 'rxjs';
import {StateService} from '@app/state.service';
import {GraphData} from './graph-data';
import {filter, shareReplay, switchMap, takeUntil} from 'rxjs/operators';
import {IssueGraphApiService} from './issue-graph-api.service';
import {FilterState} from '@app/graphs/shared';

@Injectable({
  providedIn: 'root'
})
export class IssueGraphStateService {
  state$: Observable<GraphData>;

  constructor(private apiService: IssueGraphApiService, private ss: StateService) {}

  /**
   * Maps an observable of the state of the graph filters (toggles and queries in search bar) onto an observable
   * emitting graph state for these filters retrieved from the backend.
   * @param filter$ an observable emitting a sequence of values describing the state of the filter bar above the graph
   * @param reload$ an observable emitting irrelevant values to signal a reload is required, after a manipulation of graph data
   * @param destroy$ used to signal that the caller is no longer interested. On emission the returned observable finishes.
   * @returns observable emitting sequence of graph states containing e.g. components and interfaces. It will emit new values when
   * the filter$ or reload$ observables emit a value.
   */
  graphDataForFilter(
    filter$: BehaviorSubject<FilterState>,
    reload$: BehaviorSubject<void>,
    destroy$: ReplaySubject<void>
  ): Observable<GraphData> {
    // Whenever a new value arrives from reload$, loadIssueGraphData is executed
    this.state$ = combineLatest([this.ss.state$, filter$, reload$]).pipe(
      takeUntil(destroy$),
      filter(([appState]) => appState.project?.node.id != null),
      switchMap(([appState, filterState]) =>
        this.apiService.loadIssueGraphData(
          appState.project.node.id,
          filterState.selectedCategories,
          filterState.selectedFilter.labels,
          filterState.selectedFilter.texts
        )
      ),
      shareReplay(1)
    );
    return this.state$;
  }

  /**
   * Make the interface with interfaceId a consumed interface of the component with id componentId
   */
  addConsumedInterface(componentId: string, interfaceId: string): Observable<any> {
    return this.apiService.addConsumedInterface(componentId, interfaceId);
  }

  /**
   * Remove the interface with interfaceId from consumed interfaces of the component with id componentId
   */
  removeConsumedInterface(componentId: string, interfaceId: string): Observable<any> {
    return this.apiService.removeConsumedInterface(componentId, interfaceId);
  }
}