NetNewsWire/Evergreen/Favicons/FaviconDownloader.swift

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//
// FaviconDownloader.swift
// Evergreen
//
// Created by Brent Simmons on 11/19/17.
// Copyright © 2017 Ranchero Software. All rights reserved.
//
import AppKit
import Data
import RSCore
extension Notification.Name {
static let FaviconDidBecomeAvailable = Notification.Name("FaviconDidBecomeAvailableNotification") // userInfo key: FaviconDownloader.UserInfoKey.faviconURL
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}
final class FaviconDownloader {
private let folder: String
private let diskCache: BinaryDiskCache
private var singleFaviconDownloaderCache = [String: SingleFaviconDownloader]() // faviconURL: SingleFaviconDownloader
private var homePageToFaviconURLCache = [String: String]() //homePageURL: faviconURL
private var homePageURLsWithNoFaviconURL = Set<String>()
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private let queue: DispatchQueue
struct UserInfoKey {
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static let faviconURL = "faviconURL"
}
init(folder: String) {
self.folder = folder
self.diskCache = BinaryDiskCache(folder: folder)
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self.queue = DispatchQueue(label: "FaviconDownloader serial queue - \(folder)")
NotificationCenter.default.addObserver(self, selector: #selector(didLoadFavicon(_:)), name: .DidLoadFavicon, object: nil)
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}
// MARK: - API
func favicon(for feed: Feed) -> NSImage? {
assert(Thread.isMainThread)
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if let faviconURL = feed.faviconURL {
return favicon(with: faviconURL)
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}
var homePageURL = feed.homePageURL
if homePageURL == nil {
// Base homePageURL off feedURL if needed. Wont always be accurate, but is good enough.
if let feedURL = URL(string: feed.url), let scheme = feedURL.scheme, let host = feedURL.host {
homePageURL = scheme + "://" + host + "/"
}
}
if let homePageURL = homePageURL {
return favicon(withHomePageURL: homePageURL)
}
return nil
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}
func favicon(with faviconURL: String) -> NSImage? {
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let downloader = faviconDownloader(withURL: faviconURL)
return downloader.image
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}
func favicon(withHomePageURL homePageURL: String) -> NSImage? {
let url = normalizedHomePageURL(homePageURL)
if homePageURLsWithNoFaviconURL.contains(url) {
return nil
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}
if let faviconURL = homePageToFaviconURLCache[url] {
return favicon(with: faviconURL)
}
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findFaviconURL(with: url) { (faviconURL) in
if let faviconURL = faviconURL {
self.homePageToFaviconURLCache[url] = faviconURL
let _ = self.favicon(with: faviconURL)
}
else {
self.homePageURLsWithNoFaviconURL.insert(url)
}
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}
return nil
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}
// MARK: - Notifications
@objc func didLoadFavicon(_ note: Notification) {
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guard let singleFaviconDownloader = note.object as? SingleFaviconDownloader else {
return
}
guard let _ = singleFaviconDownloader.image else {
return
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}
postFaviconDidBecomeAvailableNotification(singleFaviconDownloader.faviconURL)
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}
}
private extension FaviconDownloader {
static let localeForLowercasing = Locale(identifier: "en_US")
func findFaviconURL(with homePageURL: String, _ completion: @escaping (String?) -> Void) {
guard let url = URL(string: homePageURL) else {
completion(nil)
return
}
FaviconURLFinder.findFaviconURL(homePageURL) { (faviconURL) in
if let faviconURL = faviconURL {
completion(faviconURL)
return
}
guard let scheme = url.scheme, let host = url.host else {
completion(nil)
return
}
let defaultFaviconURL = "\(scheme)://\(host)/favicon.ico".lowercased(with: FaviconDownloader.localeForLowercasing)
completion(defaultFaviconURL)
}
}
func normalizedHomePageURL(_ url: String) -> String {
// Many times the homePageURL is missing a trailing /.
// We add one when needed.
guard !url.hasSuffix("/") else {
return url
}
let lowercasedURL = url.lowercased(with: FaviconDownloader.localeForLowercasing)
guard lowercasedURL.hasPrefix("http://") || lowercasedURL.hasPrefix("https://") else {
return url
}
guard url.components(separatedBy: "/").count < 4 else {
return url
}
return url + "/"
}
func faviconDownloader(withURL faviconURL: String) -> SingleFaviconDownloader {
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if let downloader = singleFaviconDownloaderCache[faviconURL] {
downloader.downloadFaviconIfNeeded()
return downloader
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}
let downloader = SingleFaviconDownloader(faviconURL: faviconURL, diskCache: diskCache, queue: queue)
singleFaviconDownloaderCache[faviconURL] = downloader
return downloader
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}
func postFaviconDidBecomeAvailableNotification(_ faviconURL: String) {
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let userInfo: [AnyHashable: Any] = [UserInfoKey.faviconURL: faviconURL]
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NotificationCenter.default.post(name: .FaviconDidBecomeAvailable, object: self, userInfo: userInfo)
}
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}