Kurdtvs-Live-Kurdish-TV-Kur.../Mastodon/Scene/Profile/Favorite/FavoriteViewModel.swift

102 lines
3.9 KiB
Swift

//
// FavoriteViewModel.swift
// Mastodon
//
// Created by MainasuK Cirno on 2021-4-6.
//
import UIKit
import Combine
import CoreData
import CoreDataStack
import GameplayKit
final class FavoriteViewModel {
var disposeBag = Set<AnyCancellable>()
// input
let context: AppContext
let activeMastodonAuthenticationBox: CurrentValueSubject<AuthenticationService.MastodonAuthenticationBox?, Never>
let statusFetchedResultsController: StatusFetchedResultsController
let cellFrameCache = NSCache<NSNumber, NSValue>()
// output
var diffableDataSource: UITableViewDiffableDataSource<StatusSection, Item>?
private(set) lazy var stateMachine: GKStateMachine = {
let stateMachine = GKStateMachine(states: [
State.Initial(viewModel: self),
State.Reloading(viewModel: self),
State.Fail(viewModel: self),
State.Idle(viewModel: self),
State.Loading(viewModel: self),
State.NoMore(viewModel: self),
])
stateMachine.enter(State.Initial.self)
return stateMachine
}()
init(context: AppContext) {
self.context = context
self.activeMastodonAuthenticationBox = CurrentValueSubject(context.authenticationService.activeMastodonAuthenticationBox.value)
self.statusFetchedResultsController = StatusFetchedResultsController(
managedObjectContext: context.managedObjectContext,
domain: nil,
additionalTweetPredicate: Status.notDeleted()
)
context.authenticationService.activeMastodonAuthenticationBox
.assign(to: \.value, on: activeMastodonAuthenticationBox)
.store(in: &disposeBag)
activeMastodonAuthenticationBox
.map { $0?.domain }
.assign(to: \.value, on: statusFetchedResultsController.domain)
.store(in: &disposeBag)
statusFetchedResultsController.objectIDs
.receive(on: DispatchQueue.main)
.sink { [weak self] objectIDs in
guard let self = self else { return }
guard let diffableDataSource = self.diffableDataSource else { return }
var items: [Item] = []
var snapshot = NSDiffableDataSourceSnapshot<StatusSection, Item>()
snapshot.appendSections([.main])
defer {
// not animate when empty items fix loader first appear layout issue
diffableDataSource.apply(snapshot, animatingDifferences: !items.isEmpty)
}
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
}
for objectID in objectIDs {
let attribute = oldSnapshotAttributeDict[objectID] ?? Item.StatusAttribute()
items.append(.status(objectID: objectID, attribute: attribute))
}
snapshot.appendItems(items, toSection: .main)
if let currentState = self.stateMachine.currentState {
switch currentState {
case is State.Reloading, is State.Loading, is State.Idle, is State.Fail:
snapshot.appendItems([.bottomLoader], toSection: .main)
case is State.NoMore:
break
// TODO: handle other states
default:
break
}
}
}
.store(in: &disposeBag)
}
}