mastodon-ios/Mastodon/Scene/Profile/Timeline/UserTimelineViewModel.swift

168 lines
6.0 KiB
Swift

//
// UserTimelineViewModel.swift
// Mastodon
//
// Created by MainasuK Cirno on 2021-3-29.
//
import os.log
import UIKit
import GameplayKit
import Combine
import CoreData
import CoreDataStack
import MastodonSDK
final class UserTimelineViewModel {
var disposeBag = Set<AnyCancellable>()
// input
let context: AppContext
let domain: CurrentValueSubject<String?, Never>
let userID: CurrentValueSubject<String?, Never>
let queryFilter: CurrentValueSubject<QueryFilter, Never>
let statusFetchedResultsController: StatusFetchedResultsController
var cellFrameCache = NSCache<NSNumber, NSValue>()
let isBlocking = CurrentValueSubject<Bool, Never>(false)
let isBlockedBy = CurrentValueSubject<Bool, Never>(false)
let isSuspended = CurrentValueSubject<Bool, Never>(false)
let userDisplayName = CurrentValueSubject<String?, Never>(nil) // for suspended prompt label
var dataSourceDidUpdate = PassthroughSubject<Void, Never>()
// 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, domain: String?, userID: String?, queryFilter: QueryFilter) {
self.context = context
self.statusFetchedResultsController = StatusFetchedResultsController(
managedObjectContext: context.managedObjectContext,
domain: domain,
additionalTweetPredicate: Status.notDeleted()
)
self.domain = CurrentValueSubject(domain)
self.userID = CurrentValueSubject(userID)
self.queryFilter = CurrentValueSubject(queryFilter)
// super.init()
self.domain
.assign(to: \.value, on: statusFetchedResultsController.domain)
.store(in: &disposeBag)
Publishers.CombineLatest4(
statusFetchedResultsController.objectIDs.removeDuplicates(),
isBlocking,
isBlockedBy,
isSuspended
)
.receive(on: DispatchQueue.main)
.debounce(for: .milliseconds(300), scheduler: DispatchQueue.main)
.sink { [weak self] objectIDs, isBlocking, isBlockedBy, isSuspended 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])
var animatingDifferences = true
defer {
// not animate when empty items fix loader first appear layout issue
diffableDataSource.apply(snapshot, animatingDifferences: animatingDifferences) { [weak self] in
guard let self = self else { return }
self.dataSourceDidUpdate.send()
}
}
let name = self.userDisplayName.value
guard !isBlocking else {
snapshot.appendItems(
[Item.emptyStateHeader(attribute: Item.EmptyStateHeaderAttribute(reason: .blocking(name: name)))],
toSection: .main
)
return
}
guard !isBlockedBy else {
snapshot.appendItems(
[Item.emptyStateHeader(attribute: Item.EmptyStateHeaderAttribute(reason: .blocked(name: name)))],
toSection: .main
)
return
}
guard !isSuspended else {
snapshot.appendItems(
[Item.emptyStateHeader(attribute: Item.EmptyStateHeaderAttribute(reason: .suspended(name: name)))],
toSection: .main
)
return
}
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:
snapshot.appendItems([.emptyBottomLoader], toSection: .main)
animatingDifferences = false
// TODO: handle other states
default:
break
}
}
}
.store(in: &disposeBag)
}
deinit {
os_log("%{public}s[%{public}ld], %{public}s", ((#file as NSString).lastPathComponent), #line, #function)
}
}
extension UserTimelineViewModel {
struct QueryFilter {
let excludeReplies: Bool?
let excludeReblogs: Bool?
let onlyMedia: Bool?
init(
excludeReplies: Bool? = nil,
excludeReblogs: Bool? = nil,
onlyMedia: Bool? = nil
) {
self.excludeReplies = excludeReplies
self.excludeReblogs = excludeReblogs
self.onlyMedia = onlyMedia
}
}
}