import { Injectable } from '@angular/core';
import { BehaviorSubject, Observable, of, Subject } from 'rxjs';
import { map } from 'rxjs/operators';
import { Story } from './story';
import { SupaService } from './supa.service';

@Injectable({
  providedIn: 'root'
})
export class StoryService {
  // storyMap: Map<number, Story> = new Map();
  storyMap = {};
  stories: BehaviorSubject<any> = new BehaviorSubject([]);
  subscribedStandUpIds: number[] = [];
  isListening: boolean = false;

  constructor(
    private supa: SupaService,
  ) { }

  /**
   * Get Storys from local store.
   * Requests data if store is emtpy.
   * @param standup_id 
   * @returns Observable<Story[]>
   */
  getStories(standup_id: number): Observable<Story[]> {
    if (!this.subscribedStandUpIds.includes(standup_id)) {
      this.subscribeToStories(standup_id);
      console.log('getStories - REFRESH', standup_id)
      this.supa.client.from<Story>('story').select()
      .filter(<never>'standup_id', 'eq', standup_id)      
      .then(
        data => {
          this.updateStore(data.body);
        },
        error => {
          console.error(error);
        }
      );
    } else {      
      console.log('getStories - LOCAL', standup_id)
    }
    return this.stories.asObservable().pipe(
      map(stories => stories.filter(e => e.standup_id === standup_id))
    );
  }

  /**
   * Listen to realtime events from story db.
   */
  subscribeToStories(standup_id: number) {
    // TODO check for this.subscribedStandUpIds.includes(standup_id)
    if (!this.isListening) {
      this.subscribedStandUpIds.push(standup_id);
      this.supa.client.from<Story>('story').on('*', payload => {
        console.log('subscribeToStories - REALTIME EVENT', payload)
        if ((payload.eventType === 'INSERT') || (payload.eventType === 'UPDATE')) {
          this.storyMap[payload.new.id] = payload.new;
        } else {
          delete this.storyMap[payload.old.id];
        }
        this.next();
      }).subscribe();
    }
  }

  /** 
   * Requests up to date data from API.
   * Returns the local copy.
   * @returns Observable<Story>
   */
  // refreshStorys(): Observable<Story[]> {
  //   this.subscribeToStories();
  //   this.supa.client.from<Story>('story').select()
  //     .then(stories => this.updateStore(stories.body))
  //     .catch(error => console.log('Error: ', error));
  //   return this.stories.asObservable();
  // }

  /**
   * Update the local store with provided stories
   * @param stories 
   */
  updateStore(stories: Story[]) {
    stories.forEach(e => {
      // this.storyMap.set(e.id, e);
      this.storyMap[e.id] = e;
    });
    console.log('update stories', this.storyMap)
    this.next();
  }

  /**
   * Emits local store.
   */
  next = () => {
    console.log('next', Object.values(this.storyMap))
    this.stories.next(Object.values(this.storyMap))
  };

  /**
   * Retrieve story from local store.
   * @param id 
   */
  getOne(id: number) {
    if (this.storyMap[id]) {
      return of(this.storyMap[id]);
    } else {
      const subject: Subject<Story> = new Subject();
      this.supa.client.from<Story>('story').select('id, name, description')
      .filter(<never>'id', 'eq', id)      
      .then(
        data => {
          this.updateStore([data.body[0]]);
          subject.next(data.body[0]);
          subject.complete();
        },
        error => {
          subject.error(error);
          subject.complete();
        }
      );
      return subject.asObservable();
    }
  }

  /**
   * 
   * @param story 
   */
  updateOne(story: Story): Observable<Story> {
    const subject: Subject<Story> = new Subject();
    this.supa.client.from<Story>('story').update(story)
      .match({ id: story.id })
      .then(
        data => {
          subject.next(data.body[0]);
          subject.complete();
        },
        error => {
          subject.error(error);
          subject.complete();
        }
      );
    return subject.asObservable();
  }


  /**
   * Removes one story from db.
   * @param story 
   */
  deleteOne(story: Story): Observable<Story> {
    const subject: Subject<Story> = new Subject();
    this.supa.client.from<Story>('story').delete()
      .match({ id: story.id })
      .then(
        data => {
          subject.next(story);
          subject.complete();
        },
        error => {
          subject.error(error);
          subject.complete();
        }
      );
    return subject.asObservable();
  }

  /**
   * Creates a story on the db.
   * @param story 
   */
  addOne(story: Story): Observable<Story> {
    const subject: Subject<Story> = new Subject();
    this.supa.client.from<Story>('story').insert(story)
      .then(
        data => {
          subject.next(data.body[0]);
          subject.complete();
        },
        error => {
          subject.error(error);
          subject.complete();
      }
      );
    return subject.asObservable();
  }

}