139 lines
3.7 KiB
Swift
139 lines
3.7 KiB
Swift
//
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// TimelineModel.swift
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// NetNewsWire
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//
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// Created by Maurice Parker on 6/30/20.
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// Copyright © 2020 Ranchero Software. All rights reserved.
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//
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import Foundation
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import RSCore
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import Account
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import Articles
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protocol TimelineModelDelegate: class {
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func timelineRequestedWebFeedSelection(_: TimelineModel, webFeed: WebFeed)
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}
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class TimelineModel: ObservableObject {
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weak var delegate: TimelineModelDelegate?
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@Published var timelineItems = [TimelineItem]()
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private var feeds = [Feed]()
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private var fetchSerialNumber = 0
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private let fetchRequestQueue = FetchRequestQueue()
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private var exceptionArticleFetcher: ArticleFetcher?
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private var isReadFiltered = false
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private var articles = [Article]()
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private var sortDirection = AppDefaults.shared.timelineSortDirection {
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didSet {
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if sortDirection != oldValue {
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sortParametersDidChange()
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}
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}
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}
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private var groupByFeed = AppDefaults.shared.timelineGroupByFeed {
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didSet {
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if groupByFeed != oldValue {
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sortParametersDidChange()
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}
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}
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}
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init() {
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}
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// MARK: API
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func rebuildTimelineItems(_ feed: Feed) {
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feeds = [feed]
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fetchAndReplaceArticlesAsync()
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}
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// TODO: Replace this with ScrollViewReader if we have to keep it
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func loadMoreTimelineItemsIfNecessary(_ timelineItem: TimelineItem) {
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let thresholdIndex = timelineItems.index(timelineItems.endIndex, offsetBy: -10)
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if timelineItems.firstIndex(where: { $0.id == timelineItem.id }) == thresholdIndex {
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nextBatch()
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}
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}
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}
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// MARK: Private
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private extension TimelineModel {
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func sortParametersDidChange() {
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performBlockAndRestoreSelection {
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let unsortedArticles = Set(articles)
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replaceArticles(with: unsortedArticles)
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}
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}
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func performBlockAndRestoreSelection(_ block: (() -> Void)) {
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// let savedSelection = selectedArticleIDs()
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block()
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// restoreSelection(savedSelection)
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}
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// MARK: Article Fetching
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func fetchAndReplaceArticlesAsync() {
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cancelPendingAsyncFetches()
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var fetchers = feeds as [ArticleFetcher]
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if let fetcher = exceptionArticleFetcher {
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fetchers.append(fetcher)
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exceptionArticleFetcher = nil
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}
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fetchUnsortedArticlesAsync(for: fetchers) { [weak self] (articles) in
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self?.replaceArticles(with: articles)
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}
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}
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func cancelPendingAsyncFetches() {
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fetchSerialNumber += 1
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fetchRequestQueue.cancelAllRequests()
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}
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func fetchUnsortedArticlesAsync(for representedObjects: [Any], completion: @escaping ArticleSetBlock) {
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// The callback will *not* be called if the fetch is no longer relevant — that is,
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// if it’s been superseded by a newer fetch, or the timeline was emptied, etc., it won’t get called.
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precondition(Thread.isMainThread)
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cancelPendingAsyncFetches()
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let fetchOperation = FetchRequestOperation(id: fetchSerialNumber, readFilter: isReadFiltered ?? true, representedObjects: representedObjects) { [weak self] (articles, operation) in
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precondition(Thread.isMainThread)
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guard !operation.isCanceled, let strongSelf = self, operation.id == strongSelf.fetchSerialNumber else {
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return
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}
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completion(articles)
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}
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fetchRequestQueue.add(fetchOperation)
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}
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func replaceArticles(with unsortedArticles: Set<Article>) {
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articles = Array(unsortedArticles).sortedByDate(sortDirection ? .orderedDescending : .orderedAscending, groupByFeed: groupByFeed)
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timelineItems = [TimelineItem]()
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nextBatch()
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// TODO: Update unread counts and other item done in didSet on AppKit
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}
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func nextBatch() {
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let rangeEndIndex = timelineItems.endIndex + 50 > articles.endIndex ? articles.endIndex : timelineItems.endIndex + 50
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let range = timelineItems.endIndex..<rangeEndIndex
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for i in range {
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timelineItems.append(TimelineItem(article: articles[i]))
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}
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}
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// MARK: - Notifications
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}
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