NetNewsWire/Evergreen/Images/FeedIconDownloader.swift
2018-01-04 21:20:09 -08:00

126 lines
2.8 KiB
Swift

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