mastodon-ios/Mastodon/Scene/Search/SearchResult/SearchResultViewModel.swift

126 lines
4.5 KiB
Swift

//
// SearchResultViewModel.swift
// Mastodon
//
// Created by MainasuK Cirno on 2021-7-14.
//
import Foundation
import Combine
import CoreData
import CoreDataStack
import GameplayKit
final class SearchResultViewModel {
var disposeBag = Set<AnyCancellable>()
// input
let context: AppContext
let searchScope: SearchDetailViewModel.SearchScope
let searchText = CurrentValueSubject<String, Never>("")
let statusFetchedResultsController: StatusFetchedResultsController
let viewDidAppear = CurrentValueSubject<Bool, Never>(false)
// output
private(set) lazy var stateMachine: GKStateMachine = {
let stateMachine = GKStateMachine(states: [
State.Initial(viewModel: self),
State.Loading(viewModel: self),
State.Fail(viewModel: self),
State.Idle(viewModel: self),
State.NoMore(viewModel: self),
])
stateMachine.enter(State.Initial.self)
return stateMachine
}()
let items = CurrentValueSubject<[SearchResultItem], Never>([])
var diffableDataSource: UITableViewDiffableDataSource<SearchResultSection, SearchResultItem>!
let didDataSourceUpdate = PassthroughSubject<Void, Never>()
init(context: AppContext, searchScope: SearchDetailViewModel.SearchScope) {
self.context = context
self.searchScope = searchScope
self.statusFetchedResultsController = StatusFetchedResultsController(
managedObjectContext: context.managedObjectContext,
domain: nil,
additionalTweetPredicate: nil
)
context.authenticationService.activeMastodonAuthenticationBox
.map { $0?.domain }
.assign(to: \.value, on: statusFetchedResultsController.domain)
.store(in: &disposeBag)
Publishers.CombineLatest(
items,
statusFetchedResultsController.objectIDs.removeDuplicates()
)
.receive(on: DispatchQueue.main)
.sink { [weak self] items, statusObjectIDs in
guard let self = self else { return }
guard let diffableDataSource = self.diffableDataSource else { return }
var snapshot = NSDiffableDataSourceSnapshot<SearchResultSection, SearchResultItem>()
snapshot.appendSections([.main])
// append account & hashtag items
snapshot.appendItems(items, toSection: .main)
var oldSnapshotAttributeDict: [NSManagedObjectID : Item.StatusAttribute] = [:]
let oldSnapshot = diffableDataSource.snapshot()
for item in oldSnapshot.itemIdentifiers {
guard case let .status(objectID, attribute) = item else { continue }
oldSnapshotAttributeDict[objectID] = attribute
}
// append statuses
var statusItems: [SearchResultItem] = []
for objectID in statusObjectIDs {
let attribute = oldSnapshotAttributeDict[objectID] ?? Item.StatusAttribute()
statusItems.append(.status(statusObjectID: objectID, attribute: attribute))
}
snapshot.appendItems(statusItems, toSection: .main)
if let currentState = self.stateMachine.currentState {
switch currentState {
case is State.Loading, is State.Fail, is State.Fail:
snapshot.appendItems([.bottomLoader], toSection: .main)
case is State.NoMore:
break
default:
break
}
}
diffableDataSource.defaultRowAnimation = .fade
diffableDataSource.apply(snapshot, animatingDifferences: true) { [weak self] in
guard let self = self else { return }
self.didDataSourceUpdate.send()
}
}
.store(in: &disposeBag)
}
}
extension SearchResultViewModel {
func setupDiffableDataSource(
tableView: UITableView,
dependency: NeedsDependency,
statusTableViewCellDelegate: StatusTableViewCellDelegate
) {
diffableDataSource = SearchResultSection.tableViewDiffableDataSource(
for: tableView,
dependency: dependency,
statusTableViewCellDelegate: statusTableViewCellDelegate
)
var snapshot = NSDiffableDataSourceSnapshot<SearchResultSection, SearchResultItem>()
snapshot.appendSections([.main])
snapshot.appendItems(self.items.value, toSection: .main) // with initial items
diffableDataSource.apply(snapshot, animatingDifferences: false)
}
}