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104 lines
3.6 KiB
Swift
104 lines
3.6 KiB
Swift
//
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// StatusFetchedResultsController.swift
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// Mastodon
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//
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// Created by MainasuK Cirno on 2021-3-30.
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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 MastodonSDK
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public final class StatusFetchedResultsController: NSObject {
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var disposeBag = Set<AnyCancellable>()
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let fetchedResultsController: NSFetchedResultsController<Status>
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// input
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@Published public var domain: String? = nil
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@Published public var statusIDs: [Mastodon.Entity.Status.ID] = []
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// output
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let _objectIDs = CurrentValueSubject<[NSManagedObjectID], Never>([])
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@Published public private(set) var records: [ManagedObjectRecord<Status>] = []
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public init(managedObjectContext: NSManagedObjectContext, domain: String?, additionalTweetPredicate: NSPredicate?) {
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self.domain = domain ?? ""
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self.fetchedResultsController = {
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let fetchRequest = Status.sortedFetchRequest
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fetchRequest.predicate = Status.predicate(domain: domain ?? "", ids: [])
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fetchRequest.returnsObjectsAsFaults = false
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fetchRequest.fetchBatchSize = 20
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let controller = NSFetchedResultsController(
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fetchRequest: fetchRequest,
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managedObjectContext: managedObjectContext,
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sectionNameKeyPath: nil,
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cacheName: nil
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)
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return controller
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}()
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super.init()
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// debounce output to prevent UI update issues
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_objectIDs
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.throttle(for: 0.1, scheduler: DispatchQueue.main, latest: true)
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.map { objectIDs in objectIDs.map { ManagedObjectRecord(objectID: $0) } }
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.assign(to: &$records)
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fetchedResultsController.delegate = self
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Publishers.CombineLatest(
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self.$domain.removeDuplicates(),
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self.$statusIDs.removeDuplicates()
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)
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.receive(on: DispatchQueue.main)
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.sink { [weak self] domain, ids in
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guard let self = self else { return }
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var predicates = [Status.predicate(domain: domain ?? "", ids: ids)]
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if let additionalPredicate = additionalTweetPredicate {
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predicates.append(additionalPredicate)
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}
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self.fetchedResultsController.fetchRequest.predicate = NSCompoundPredicate(andPredicateWithSubpredicates: predicates)
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do {
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try self.fetchedResultsController.performFetch()
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} catch {
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assertionFailure(error.localizedDescription)
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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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extension StatusFetchedResultsController {
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public func append(statusIDs: [Mastodon.Entity.Status.ID]) {
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var result = self.statusIDs
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for statusID in statusIDs where !result.contains(statusID) {
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result.append(statusID)
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}
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self.statusIDs = result
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}
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}
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// MARK: - NSFetchedResultsControllerDelegate
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extension StatusFetchedResultsController: NSFetchedResultsControllerDelegate {
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public func controller(_ controller: NSFetchedResultsController<NSFetchRequestResult>, didChangeContentWith snapshot: NSDiffableDataSourceSnapshotReference) {
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let indexes = statusIDs
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let objects = fetchedResultsController.fetchedObjects ?? []
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let items: [NSManagedObjectID] = objects
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.compactMap { object in
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indexes.firstIndex(of: object.id).map { index in (index, object) }
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}
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.sorted { $0.0 < $1.0 }
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.map { $0.1.objectID }
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self._objectIDs.value = items
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}
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}
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