172 lines
3.6 KiB
Swift
172 lines
3.6 KiB
Swift
//
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// FaviconDownloader.swift
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// Evergreen
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//
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// Created by Brent Simmons on 11/19/17.
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// Copyright © 2017 Ranchero Software. All rights reserved.
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//
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import AppKit
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import Data
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import RSCore
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import RSWeb
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extension Notification.Name {
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static let FaviconDidBecomeAvailable = Notification.Name("FaviconDidBecomeAvailableNotification") // userInfo keys: homePageURL, faviconURL, image
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}
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final class FaviconDownloader {
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private var cache = ThreadSafeCache<NSImage>() // faviconURL: NSImage
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private var faviconURLCache = ThreadSafeCache<String>() // homePageURL: faviconURL
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private let folder: String
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private var urlsBeingDownloaded = Set<String>()
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private var badURLs = Set<String>() // URLs that didn’t work for some reason; don’t try again
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private let binaryCache: RSBinaryCache
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private var badImages = Set<String>() // keys for images on disk that NSImage can’t handle
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private let queue: DispatchQueue
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public struct UserInfoKey {
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static let homePageURL = "homePageURL"
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static let faviconURL = "faviconURL"
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static let image = "image" // NSImage
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}
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init(folder: String) {
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self.folder = folder
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self.binaryCache = RSBinaryCache(folder: folder)
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self.queue = DispatchQueue(label: "FaviconCache serial queue - \(folder)")
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}
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// MARK: - API
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func favicon(for feed: Feed) -> NSImage? {
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assert(Thread.isMainThread)
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guard let homePageURL = feed.homePageURL else {
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return nil
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}
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if let faviconURL = faviconURL(for: feed) {
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if let cachedFavicon = cache[faviconURL] {
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return cachedFavicon
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}
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// TODO: read from disk and return if present.
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if shouldDownloadFaviconURL(faviconURL) {
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downloadFavicon(faviconURL, homePageURL)
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return nil
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}
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return nil
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}
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// Try to find the faviconURL. It might be in the web page.
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FaviconURLFinder.findFaviconURL(homePageURL) { (faviconURL) in
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if let faviconURL = faviconURL {
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print(faviconURL) // cache it; then download favicon
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}
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else {
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// Try appending /favicon.ico
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// It often works.
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}
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}
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return nil
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}
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}
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private extension FaviconDownloader {
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func shouldDownloadFaviconURL(_ faviconURL: String) -> Bool {
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return !urlsBeingDownloaded.contains(faviconURL) && !badURLs.contains(faviconURL)
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}
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func downloadFavicon(_ faviconURL: String, _ homePageURL: String) {
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guard let url = URL(string: faviconURL) else {
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return
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}
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urlsBeingDownloaded.insert(faviconURL)
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downloadUsingCache(url) { (data, response, error) in
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self.urlsBeingDownloaded.remove(faviconURL)
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if response == nil || !response!.statusIsOK {
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self.badURLs.insert(faviconURL)
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}
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if let data = data {
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self.queue.async {
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let _ = NSImage(data: data)
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}
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}
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}
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}
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func faviconURL(for feed: Feed) -> String? {
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if let faviconURL = feed.faviconURL {
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return faviconURL
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}
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if let homePageURL = feed.homePageURL {
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return faviconURLCache[homePageURL]
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}
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return nil
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}
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func readFaviconFromDisk(_ faviconURL: String, _ callback: @escaping (NSImage?) -> Void) {
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queue.async {
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let image = self.tryToInstantiateNSImageFromDisk(faviconURL)
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DispatchQueue.main.async {
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callback(image)
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}
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}
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}
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func tryToInstantiateNSImageFromDisk(_ faviconURL: String) -> NSImage? {
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// Call on serial queue.
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if badImages.contains(faviconURL) {
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return nil
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}
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let key = keyFor(faviconURL)
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var data: Data?
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do {
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data = try binaryCache.binaryData(forKey: key)
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}
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catch {
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return nil
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}
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if data == nil {
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return nil
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}
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guard let image = NSImage(data: data!) else {
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badImages.insert(faviconURL)
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return nil
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}
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return image
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}
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func keyFor(_ faviconURL: String) -> String {
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return (faviconURL as NSString).rs_md5Hash()
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}
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}
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