mastodon-ios/Mastodon/Scene/HomeTimeline/HomeTimelineViewModel+LoadL...

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2021-02-07 07:42:50 +01:00
//
// HomeTimelineViewModel+LoadLatestState.swift
// Mastodon
//
// Created by sxiaojian on 2021/2/5.
//
import os.log
import func QuartzCore.CACurrentMediaTime
import Foundation
import CoreData
import CoreDataStack
import GameplayKit
extension HomeTimelineViewModel {
class LoadLatestState: GKState {
weak var viewModel: HomeTimelineViewModel?
init(viewModel: HomeTimelineViewModel) {
self.viewModel = viewModel
}
override func didEnter(from previousState: GKState?) {
os_log("%{public}s[%{public}ld], %{public}s: enter %s, previous: %s", ((#file as NSString).lastPathComponent), #line, #function, self.debugDescription, previousState.debugDescription)
viewModel?.loadLatestStateMachinePublisher.send(self)
}
}
}
extension HomeTimelineViewModel.LoadLatestState {
class Initial: HomeTimelineViewModel.LoadLatestState {
override func isValidNextState(_ stateClass: AnyClass) -> Bool {
return stateClass == Loading.self
}
}
class Loading: HomeTimelineViewModel.LoadLatestState {
override func isValidNextState(_ stateClass: AnyClass) -> Bool {
return stateClass == Fail.self || stateClass == Idle.self
}
override func didEnter(from previousState: GKState?) {
super.didEnter(from: previousState)
guard let viewModel = viewModel, let stateMachine = stateMachine else { return }
guard let activeMastodonAuthenticationBox = viewModel.context.authenticationService.activeMastodonAuthenticationBox.value else {
// sign out when loading will enter here
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stateMachine.enter(Fail.self)
return
}
let predicate = viewModel.fetchedResultsController.fetchRequest.predicate
let parentManagedObjectContext = viewModel.fetchedResultsController.managedObjectContext
let managedObjectContext = NSManagedObjectContext(concurrencyType: .privateQueueConcurrencyType)
managedObjectContext.parent = parentManagedObjectContext
managedObjectContext.perform {
let start = CACurrentMediaTime()
let latestTootIDs: [Toot.ID]
let request = HomeTimelineIndex.sortedFetchRequest
request.returnsObjectsAsFaults = false
request.predicate = predicate
do {
let timelineIndexes = try managedObjectContext.fetch(request)
let endFetch = CACurrentMediaTime()
os_log(.info, log: .debug, "%{public}s[%{public}ld], %{public}s: collect timelineIndexes cost: %.2fs", ((#file as NSString).lastPathComponent), #line, #function, endFetch - start)
latestTootIDs = timelineIndexes
.prefix(APIService.onceRequestTootMaxCount) // avoid performance issue
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.compactMap { timelineIndex in
timelineIndex.value(forKeyPath: #keyPath(HomeTimelineIndex.toot.id)) as? Toot.ID
}
} catch {
stateMachine.enter(Fail.self)
return
}
let end = CACurrentMediaTime()
os_log(.info, log: .debug, "%{public}s[%{public}ld], %{public}s: collect toots id cost: %.2fs", ((#file as NSString).lastPathComponent), #line, #function, end - start)
// TODO: only set large count when using Wi-Fi
viewModel.context.apiService.homeTimeline(domain: activeMastodonAuthenticationBox.domain, authorizationBox: activeMastodonAuthenticationBox)
.receive(on: DispatchQueue.main)
.sink { completion in
switch completion {
case .failure(let error):
// TODO: handle error
viewModel.isFetchingLatestTimeline.value = false
os_log(.info, log: .debug, "%{public}s[%{public}ld], %{public}s: fetch toots failed. %s", ((#file as NSString).lastPathComponent), #line, #function, error.localizedDescription)
case .finished:
// handle isFetchingLatestTimeline in fetch controller delegate
break
}
stateMachine.enter(Idle.self)
} receiveValue: { response in
// stop refresher if no new toots
let toots = response.value
let newToots = toots.filter { !latestTootIDs.contains($0.id) }
os_log("%{public}s[%{public}ld], %{public}s: load %{public}ld new toots", ((#file as NSString).lastPathComponent), #line, #function, newToots.count)
if newToots.isEmpty {
viewModel.isFetchingLatestTimeline.value = false
}
}
.store(in: &viewModel.disposeBag)
}
}
}
class Fail: HomeTimelineViewModel.LoadLatestState {
override func isValidNextState(_ stateClass: AnyClass) -> Bool {
return stateClass == Loading.self || stateClass == Idle.self
}
}
class Idle: HomeTimelineViewModel.LoadLatestState {
override func isValidNextState(_ stateClass: AnyClass) -> Bool {
return stateClass == Loading.self
}
}
}