iOSGiphyCodeChallenge/LiveLikeGiphyChallenge/GiphyViewModel.swift

//
//  GiphyViewModel.swift
//  LiveLikeGiphyChallenge
//
//  Created by Arbnor Tefiki on 6.2.22.
//

import Foundation

class GiphyViewModel {
  typealias FetchCompleted = (_ finish: Bool) -> Void

  var searchTerm: String = "" {
    didSet {
      fetchGiphyImages(resetSearch: true)
    }
  }
  var trendingImages: [String] = []
  var searchedImages: [String] = []
  var items: [String] { return isSearchActive ? searchedImages : trendingImages }

  var canLoadList: Bool = true
  var isLoadingList: Bool = false
  var page = 0
  var didFinishLoadingData: FetchCompleted?
  var isSearchActive: Bool {
    return !searchTerm.isEmpty
  }

  func fetchGiphyImages(resetSearch: Bool = false) {
    isLoadingList = true
    let request = GiphyRequest(searchTerm: searchTerm, fetchType: fetchType, page: page)
    APIManager.fetchGifs(request: request) { response in
      self.isLoadingList = false
      guard let response = response, response.meta?.msg == "OK" else {
        return
      }
      if resetSearch {
        self.resetSearch()
      }
      self.loadData(response: response)
    }
  }

  func loadData(response: GiphyModel) {
    let allGifUrls = response.gifs.map({ $0.getGifURL() })

    if fetchType == .trending {
      trendingImages.append(contentsOf: allGifUrls)
    } else {
      searchedImages.append(contentsOf: allGifUrls)
    }
    canLoadList = response.pagination?.totalCount ?? 0 > items.count
    if canLoadList {
      page += 1
    }
    didFinishLoadingData?(true)
  }

  func tryToLoadMore(row: Int) {
    if items.count - 1 == row && canLoadList && !isLoadingList {
      fetchGiphyImages()
    }
  }

  private var fetchType: GiphyRequest.FetchType {
    return isSearchActive ? .search : .trending
  }

  func resetSearch() {
    page = 0
    canLoadList = false
    trendingImages.removeAll()
    searchedImages.removeAll()
  }

}