156 lines
3.0 KiB
Swift
156 lines
3.0 KiB
Swift
//
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// SingleFaviconDownloader.swift
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// NetNewsWire
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//
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// Created by Brent Simmons on 11/23/17.
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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 RSCore
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import RSWeb
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// The image may be on disk already. If not, download it.
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// Post .DidLoadFavicon notification once it’s in memory.
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extension Notification.Name {
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static let DidLoadFavicon = Notification.Name("DidLoadFaviconNotification")
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}
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final class SingleFaviconDownloader {
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enum DiskStatus {
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case unknown, notOnDisk, onDisk
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}
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let faviconURL: String
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var image: RSImage?
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private var lastDownloadAttemptDate: Date
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private var diskStatus = DiskStatus.unknown
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private var diskCache: BinaryDiskCache
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private let queue: DispatchQueue
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private var diskKey: String {
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return (faviconURL as NSString).rs_md5Hash()
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}
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init(faviconURL: String, diskCache: BinaryDiskCache, queue: DispatchQueue) {
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self.faviconURL = faviconURL
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self.diskCache = diskCache
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self.queue = queue
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self.lastDownloadAttemptDate = Date()
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findFavicon()
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}
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func downloadFaviconIfNeeded() {
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// If we don’t have an image, and lastDownloadAttemptDate is a while ago, try again.
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if let _ = image {
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return
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}
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let retryInterval: TimeInterval = 30 * 60 // 30 minutes
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if Date().timeIntervalSince(lastDownloadAttemptDate) < retryInterval {
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return
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}
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lastDownloadAttemptDate = Date()
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findFavicon()
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}
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}
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private extension SingleFaviconDownloader {
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func findFavicon() {
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readFromDisk { (image) in
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if let image = image {
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self.diskStatus = .onDisk
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self.image = image
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self.postDidLoadFaviconNotification()
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return
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}
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self.diskStatus = .notOnDisk
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self.downloadFavicon { (image) in
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if let image = image {
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self.image = image
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self.postDidLoadFaviconNotification()
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}
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}
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}
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}
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func readFromDisk(_ callback: @escaping (RSImage?) -> Void) {
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guard diskStatus != .notOnDisk else {
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callback(nil)
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return
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}
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queue.async {
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if let data = self.diskCache[self.diskKey], !data.isEmpty {
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RSImage.rs_image(with: data, imageResultBlock: callback)
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return
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}
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DispatchQueue.main.async {
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callback(nil)
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}
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}
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}
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func saveToDisk(_ data: Data) {
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queue.async {
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do {
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try self.diskCache.setData(data, forKey: self.diskKey)
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DispatchQueue.main.async {
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self.diskStatus = .onDisk
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}
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}
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catch {}
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}
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}
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func downloadFavicon(_ callback: @escaping (RSImage?) -> Void) {
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guard let url = URL(string: faviconURL) else {
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callback(nil)
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return
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}
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downloadUsingCache(url) { (data, response, error) in
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if let data = data, !data.isEmpty, let response = response, response.statusIsOK, error == nil {
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self.saveToDisk(data)
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RSImage.rs_image(with: data, imageResultBlock: callback)
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return
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}
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if let error = error {
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appDelegate.logMessage("Error downloading favicon at \(url): \(error)", type: .warning)
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}
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callback(nil)
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}
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}
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func postDidLoadFaviconNotification() {
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assert(Thread.isMainThread)
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NotificationCenter.default.post(name: .DidLoadFavicon, object: self)
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}
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}
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