client/src/app/videos/recommendations/recent-videos-recommendation.service.ts

   1 import { Injectable } from '@angular/core'
   2 import { RecommendationService } from '@app/videos/recommendations/recommendations.service'
   3 import { Video } from '@app/shared/video/video.model'
   4 import { RecommendationInfo } from '@app/shared/video/recommendation-info.model'
   5 import { VideoService } from '@app/shared/video/video.service'
   6 import { map, switchMap } from 'rxjs/operators'
   7 import { Observable, of } from 'rxjs'
   8 import { SearchService } from '@app/search/search.service'
   9 import { AdvancedSearch } from '@app/search/advanced-search.model'
  10
  11 /**
  12  * Provides "recommendations" by providing the most recently uploaded videos.
  13  */
  14 @Injectable()
  15 export class RecentVideosRecommendationService implements RecommendationService {
  16   readonly pageSize = 5
  17
  18   constructor (
  19     private videos: VideoService,
  20     private searchService: SearchService
  21   ) { }
  22
  23   getRecommendations (recommendation: RecommendationInfo): Observable<Video[]> {
  24     return this.fetchPage(1, recommendation)
  25       .pipe(
  26         map(videos => {
  27           const otherVideos = videos.filter(v => v.uuid !== recommendation.uuid)
  28           return otherVideos.slice(0, this.pageSize)
  29         })
  30       )
  31   }
  32
  33   private fetchPage (page: number, recommendation: RecommendationInfo): Observable<Video[]> {
  34     const pagination = { currentPage: page, itemsPerPage: this.pageSize + 1 }
  35     const defaultSubscription = this.videos.getVideos(pagination, '-createdAt')
  36                                     .pipe(map(v => v.videos))
  37
  38     if (!recommendation.tags || recommendation.tags.length === 0) return defaultSubscription
  39
  40     return this.searchService.searchVideos('',
  41       pagination,
  42       new AdvancedSearch({ tagsOneOf: recommendation.tags.join(','), sort: '-createdAt' })
  43     ).pipe(
  44       map(v => v.videos),
  45       switchMap(videos => {
  46         if (videos.length <= 1) return defaultSubscription
  47
  48         return of(videos)
  49       })
  50     )
  51   }
  52 }