149 lines
3.3 KiB
Swift
149 lines
3.3 KiB
Swift
//
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// FeedIconDownloader.swift
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// NetNewsWire
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//
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// Created by Brent Simmons on 11/26/17.
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// Copyright © 2017 Ranchero Software. All rights reserved.
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//
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import Foundation
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import Articles
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import Account
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import RSCore
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import RSWeb
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import RSParser
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extension Notification.Name {
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static let FeedIconDidBecomeAvailable = Notification.Name("FeedIconDidBecomeAvailableNotification") // UserInfoKey.feed
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}
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public final class FeedIconDownloader {
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private let imageDownloader: ImageDownloader
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private var homePageToIconURLCache = [String: String]()
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private var homePagesWithNoIconURL = Set<String>()
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private var urlsInProgress = Set<String>()
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private var cache = [Feed: RSImage]()
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init(imageDownloader: ImageDownloader) {
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self.imageDownloader = imageDownloader
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}
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func resetCache() {
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cache = [Feed: RSImage]()
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}
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func icon(for feed: Feed) -> RSImage? {
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if let cachedImage = cache[feed] {
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return cachedImage
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}
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func checkHomePageURL() {
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guard let homePageURL = feed.homePageURL else {
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return
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}
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icon(forHomePageURL: homePageURL) { (image) in
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if let image = image {
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self.postFeedIconDidBecomeAvailableNotification(feed)
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self.cache[feed] = image
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}
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}
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}
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if let iconURL = feed.iconURL {
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icon(forURL: iconURL) { (image) in
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if let image = image {
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self.postFeedIconDidBecomeAvailableNotification(feed)
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self.cache[feed] = image
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}
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else {
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checkHomePageURL()
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}
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}
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}
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else {
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checkHomePageURL()
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}
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return nil
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}
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}
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private extension FeedIconDownloader {
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func icon(forHomePageURL homePageURL: String, _ imageResultBlock: @escaping (RSImage?) -> Void) {
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if homePagesWithNoIconURL.contains(homePageURL) {
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imageResultBlock(nil)
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return
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}
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if let iconURL = cachedIconURL(for: homePageURL) {
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icon(forURL: iconURL, imageResultBlock)
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return
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}
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findIconURLForHomePageURL(homePageURL)
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}
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func icon(forURL url: String, _ imageResultBlock: @escaping (RSImage?) -> Void) {
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guard let imageData = imageDownloader.image(for: url) else {
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imageResultBlock(nil)
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return
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}
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RSImage.scaledForAvatar(imageData, imageResultBlock: imageResultBlock)
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}
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func postFeedIconDidBecomeAvailableNotification(_ feed: Feed) {
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DispatchQueue.main.async {
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let userInfo: [AnyHashable: Any] = [UserInfoKey.feed: feed]
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NotificationCenter.default.post(name: .FeedIconDidBecomeAvailable, object: self, userInfo: userInfo)
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}
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}
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func cachedIconURL(for homePageURL: String) -> String? {
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return homePageToIconURLCache[homePageURL]
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}
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func cacheIconURL(for homePageURL: String, _ iconURL: String) {
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homePagesWithNoIconURL.remove(homePageURL)
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homePageToIconURLCache[homePageURL] = iconURL
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}
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func findIconURLForHomePageURL(_ homePageURL: String) {
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guard !urlsInProgress.contains(homePageURL) else {
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return
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}
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urlsInProgress.insert(homePageURL)
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HTMLMetadataDownloader.downloadMetadata(for: homePageURL) { (metadata) in
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self.urlsInProgress.remove(homePageURL)
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guard let metadata = metadata else {
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return
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}
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self.pullIconURL(from: metadata, homePageURL: homePageURL)
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}
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}
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func pullIconURL(from metadata: RSHTMLMetadata, homePageURL: String) {
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if let url = metadata.bestWebsiteIconURL() {
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cacheIconURL(for: homePageURL, url)
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icon(forURL: url) { (image) in
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}
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return
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}
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homePagesWithNoIconURL.insert(homePageURL)
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}
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}
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