120 lines
4.5 KiB
Swift
120 lines
4.5 KiB
Swift
// Copyright © 2021 Metabolist. All rights reserved.
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import Combine
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import Mastodon
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import UIKit
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import ViewModels
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final class ExploreDataSource: UICollectionViewDiffableDataSource<ExploreViewModel.Section, ExploreViewModel.Item> {
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private let updateQueue =
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DispatchQueue(label: "com.metabolist.metatext.explore-data-source.update-queue")
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private weak var collectionView: UICollectionView?
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private var cancellables = Set<AnyCancellable>()
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init(collectionView: UICollectionView, viewModel: ExploreViewModel) {
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self.collectionView = collectionView
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let tagRegistration = UICollectionView.CellRegistration<TagCollectionViewCell, TagViewModel> {
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$0.viewModel = $2
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}
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let instanceRegistration = UICollectionView.CellRegistration<InstanceCollectionViewCell, InstanceViewModel> {
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$0.viewModel = $2
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}
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let itemRegistration = UICollectionView.CellRegistration
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<SeparatorConfiguredCollectionViewListCell, ExploreViewModel.Item> {
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var configuration = $0.defaultContentConfiguration()
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switch $2 {
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case .profileDirectory:
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configuration.text = NSLocalizedString("explore.profile-directory", comment: "")
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configuration.image = UIImage(systemName: "person.crop.square.fill.and.at.rectangle")
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default:
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break
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}
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$0.contentConfiguration = configuration
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$0.accessories = [.disclosureIndicator()]
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}
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super.init(collectionView: collectionView) {
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switch $2 {
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case let .tag(tag):
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return $0.dequeueConfiguredReusableCell(
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using: tagRegistration,
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for: $1,
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item: viewModel.viewModel(tag: tag))
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case .instance:
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return $0.dequeueConfiguredReusableCell(
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using: instanceRegistration,
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for: $1,
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item: viewModel.instanceViewModel)
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default:
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return $0.dequeueConfiguredReusableCell(using: itemRegistration, for: $1, item: $2)
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}
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}
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let headerRegistration = UICollectionView.SupplementaryRegistration
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<ExploreSectionHeaderView>(elementKind: UICollectionView.elementKindSectionHeader) { [weak self] in
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$0.label.text = self?.snapshot().sectionIdentifiers[$2.section].displayName
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}
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supplementaryViewProvider = {
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$0.dequeueConfiguredReusableSupplementary(using: headerRegistration, for: $2)
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}
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viewModel.$trends.combineLatest(viewModel.$instanceViewModel)
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.sink { [weak self] in self?.update(tags: $0, instanceViewModel: $1) }
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.store(in: &cancellables)
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}
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override func apply(_ snapshot: NSDiffableDataSourceSnapshot<ExploreViewModel.Section, ExploreViewModel.Item>,
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animatingDifferences: Bool = true,
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completion: (() -> Void)? = nil) {
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updateQueue.async {
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super.apply(snapshot, animatingDifferences: animatingDifferences, completion: completion)
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}
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}
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}
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private extension ExploreDataSource {
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func update(tags: [Tag], instanceViewModel: InstanceViewModel?) {
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var newsnapshot = NSDiffableDataSourceSnapshot<ExploreViewModel.Section, ExploreViewModel.Item>()
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if !tags.isEmpty {
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newsnapshot.appendSections([.trending])
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newsnapshot.appendItems(tags.map(ExploreViewModel.Item.tag), toSection: .trending)
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}
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if let instanceViewModel = instanceViewModel {
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newsnapshot.appendSections([.instance])
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newsnapshot.appendItems([.instance], toSection: .instance)
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if instanceViewModel.instance.canShowProfileDirectory {
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newsnapshot.appendItems([.profileDirectory], toSection: .instance)
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}
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}
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let wasEmpty = self.snapshot().itemIdentifiers.isEmpty
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let contentOffset = collectionView?.contentOffset
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apply(newsnapshot, animatingDifferences: false) {
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if let contentOffset = contentOffset, !wasEmpty {
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self.collectionView?.contentOffset = contentOffset
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}
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}
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}
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}
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private extension ExploreViewModel.Section {
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var displayName: String {
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switch self {
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case .trending:
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return NSLocalizedString("explore.trending", comment: "")
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case .instance:
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return NSLocalizedString("explore.instance", comment: "")
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}
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}
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}
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