forked from zelo72/mastodon-ios
102 lines
3.9 KiB
Swift
102 lines
3.9 KiB
Swift
//
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// FavoriteViewModel.swift
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// Mastodon
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//
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// Created by MainasuK Cirno on 2021-4-6.
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//
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import UIKit
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import Combine
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import CoreData
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import CoreDataStack
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import GameplayKit
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final class FavoriteViewModel {
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var disposeBag = Set<AnyCancellable>()
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// input
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let context: AppContext
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let activeMastodonAuthenticationBox: CurrentValueSubject<MastodonAuthenticationBox?, Never>
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let statusFetchedResultsController: StatusFetchedResultsController
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let cellFrameCache = NSCache<NSNumber, NSValue>()
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// output
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var diffableDataSource: UITableViewDiffableDataSource<StatusSection, Item>?
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private(set) lazy var stateMachine: GKStateMachine = {
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let stateMachine = GKStateMachine(states: [
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State.Initial(viewModel: self),
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State.Reloading(viewModel: self),
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State.Fail(viewModel: self),
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State.Idle(viewModel: self),
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State.Loading(viewModel: self),
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State.NoMore(viewModel: self),
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])
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stateMachine.enter(State.Initial.self)
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return stateMachine
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}()
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init(context: AppContext) {
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self.context = context
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self.activeMastodonAuthenticationBox = CurrentValueSubject(context.authenticationService.activeMastodonAuthenticationBox.value)
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self.statusFetchedResultsController = StatusFetchedResultsController(
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managedObjectContext: context.managedObjectContext,
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domain: nil,
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additionalTweetPredicate: Status.notDeleted()
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)
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context.authenticationService.activeMastodonAuthenticationBox
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.assign(to: \.value, on: activeMastodonAuthenticationBox)
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.store(in: &disposeBag)
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activeMastodonAuthenticationBox
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.map { $0?.domain }
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.assign(to: \.value, on: statusFetchedResultsController.domain)
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.store(in: &disposeBag)
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statusFetchedResultsController.objectIDs
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.receive(on: DispatchQueue.main)
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.sink { [weak self] objectIDs in
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guard let self = self else { return }
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guard let diffableDataSource = self.diffableDataSource else { return }
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var items: [Item] = []
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var snapshot = NSDiffableDataSourceSnapshot<StatusSection, Item>()
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snapshot.appendSections([.main])
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defer {
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// not animate when empty items fix loader first appear layout issue
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diffableDataSource.apply(snapshot, animatingDifferences: !items.isEmpty)
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}
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var oldSnapshotAttributeDict: [NSManagedObjectID : Item.StatusAttribute] = [:]
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let oldSnapshot = diffableDataSource.snapshot()
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for item in oldSnapshot.itemIdentifiers {
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guard case let .status(objectID, attribute) = item else { continue }
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oldSnapshotAttributeDict[objectID] = attribute
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}
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for objectID in objectIDs {
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let attribute = oldSnapshotAttributeDict[objectID] ?? Item.StatusAttribute()
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items.append(.status(objectID: objectID, attribute: attribute))
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}
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snapshot.appendItems(items, toSection: .main)
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if let currentState = self.stateMachine.currentState {
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switch currentState {
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case is State.Reloading, is State.Loading, is State.Idle, is State.Fail:
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snapshot.appendItems([.bottomLoader], toSection: .main)
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case is State.NoMore:
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break
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// TODO: handle other states
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default:
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break
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}
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}
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}
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.store(in: &disposeBag)
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}
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}
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