Make progress on favicons.

Evergreen.xcodeproj/project.pbxproj

@@ -13,6 +13,10 @@
 		842E45E51ED8C6B7000A8B52 /* MainWindowSplitView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 842E45E41ED8C6B7000A8B52 /* MainWindowSplitView.swift */; };
 		842E45E71ED8C747000A8B52 /* DB5.plist in Resources */ = {isa = PBXBuildFile; fileRef = 842E45E61ED8C747000A8B52 /* DB5.plist */; };
 		84513F901FAA63950023A1A9 /* FeedListControlsView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 84513F8F1FAA63950023A1A9 /* FeedListControlsView.swift */; };
+		845A29091FC74B8E007B49E3 /* FaviconMetadata.swift in Sources */ = {isa = PBXBuildFile; fileRef = 845A29081FC74B8E007B49E3 /* FaviconMetadata.swift */; };
+		845A29191FC7563E007B49E3 /* FaviconCache.swift in Sources */ = {isa = PBXBuildFile; fileRef = 845A29181FC7563E007B49E3 /* FaviconCache.swift */; };
+		845A291B1FC75AA6007B49E3 /* SeekingFavicon.swift in Sources */ = {isa = PBXBuildFile; fileRef = 845A291A1FC75AA6007B49E3 /* SeekingFavicon.swift */; };
+		845A291D1FC75F49007B49E3 /* ImageDownloader.swift in Sources */ = {isa = PBXBuildFile; fileRef = 845A291C1FC75F49007B49E3 /* ImageDownloader.swift */; };
 		845EE7B11FC2366500854A1F /* StarredFeedDelegate.swift in Sources */ = {isa = PBXBuildFile; fileRef = 845EE7B01FC2366500854A1F /* StarredFeedDelegate.swift */; };
 		845EE7C11FC2488C00854A1F /* SmartFeed.swift in Sources */ = {isa = PBXBuildFile; fileRef = 845EE7C01FC2488C00854A1F /* SmartFeed.swift */; };
 		845F52ED1FB2B9FC00C10BF0 /* FeedPasteboardWriter.swift in Sources */ = {isa = PBXBuildFile; fileRef = 845F52EC1FB2B9FC00C10BF0 /* FeedPasteboardWriter.swift */; };
@@ -403,6 +407,10 @@
 		842E45E41ED8C6B7000A8B52 /* MainWindowSplitView.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = MainWindowSplitView.swift; sourceTree = "<group>"; };
 		842E45E61ED8C747000A8B52 /* DB5.plist */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.plist.xml; name = DB5.plist; path = Evergreen/Resources/DB5.plist; sourceTree = "<group>"; };
 		84513F8F1FAA63950023A1A9 /* FeedListControlsView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = FeedListControlsView.swift; sourceTree = "<group>"; };
+		845A29081FC74B8E007B49E3 /* FaviconMetadata.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = FaviconMetadata.swift; sourceTree = "<group>"; };
+		845A29181FC7563E007B49E3 /* FaviconCache.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = FaviconCache.swift; sourceTree = "<group>"; };
+		845A291A1FC75AA6007B49E3 /* SeekingFavicon.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SeekingFavicon.swift; sourceTree = "<group>"; };
+		845A291C1FC75F49007B49E3 /* ImageDownloader.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ImageDownloader.swift; sourceTree = "<group>"; };
 		845B14A51FC2299E0013CF92 /* README.md */ = {isa = PBXFileReference; lastKnownFileType = net.daringfireball.markdown; path = README.md; sourceTree = "<group>"; };
 		845EE7B01FC2366500854A1F /* StarredFeedDelegate.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = StarredFeedDelegate.swift; sourceTree = "<group>"; };
 		845EE7C01FC2488C00854A1F /* SmartFeed.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SmartFeed.swift; sourceTree = "<group>"; };
@@ -581,6 +589,10 @@
 			isa = PBXGroup;
 			children = (
 				848F6AE41FC29CFA002D422E /* FaviconDownloader.swift */,
+				845A291C1FC75F49007B49E3 /* ImageDownloader.swift */,
+				845A291A1FC75AA6007B49E3 /* SeekingFavicon.swift */,
+				845A29081FC74B8E007B49E3 /* FaviconMetadata.swift */,
+				845A29181FC7563E007B49E3 /* FaviconCache.swift */,
 				84FF69B01FC3793300DC198E /* FaviconURLFinder.swift */,
 			);
 			name = Favicons;
@@ -1308,6 +1320,7 @@
 				84F2D5371FC22FCC00998D64 /* PseudoFeed.swift in Sources */,
 				845EE7C11FC2488C00854A1F /* SmartFeed.swift in Sources */,
 				84702AA41FA27AC0006B8943 /* MarkReadOrUnreadCommand.swift in Sources */,
+				845A291B1FC75AA6007B49E3 /* SeekingFavicon.swift in Sources */,
 				849A979F1ED9F130007D329B /* SidebarCell.swift in Sources */,
 				849A97651ED9EB96007D329B /* SidebarTreeControllerDelegate.swift in Sources */,
 				849A97671ED9EB96007D329B /* UnreadCountView.swift in Sources */,
@@ -1329,9 +1342,11 @@
 				849A97831ED9EC63007D329B /* StatusBarView.swift in Sources */,
 				84F2D5381FC22FCC00998D64 /* TodayFeedDelegate.swift in Sources */,
 				849A97431ED9EAA9007D329B /* AddFolderWindowController.swift in Sources */,
+				845A29191FC7563E007B49E3 /* FaviconCache.swift in Sources */,
 				849A97921ED9EF65007D329B /* IndeterminateProgressWindowController.swift in Sources */,
 				849A97801ED9EC42007D329B /* DetailViewController.swift in Sources */,
 				849A976E1ED9EBC8007D329B /* TimelineViewController.swift in Sources */,
+				845A291D1FC75F49007B49E3 /* ImageDownloader.swift in Sources */,
 				849A978D1ED9EE4D007D329B /* FeedListWindowController.swift in Sources */,
 				849A97771ED9EC04007D329B /* TimelineCellData.swift in Sources */,
 				84B99C6B1FAE370B00ECDEDB /* FeedListFeed.swift in Sources */,
@@ -1345,6 +1360,7 @@
 				84B99C691FAE36B800ECDEDB /* FeedListFolder.swift in Sources */,
 				84F204DE1FAACB8B0076E152 /* FeedListTimelineViewController.swift in Sources */,
 				849A97A31ED9F180007D329B /* FolderTreeControllerDelegate.swift in Sources */,
+				845A29091FC74B8E007B49E3 /* FaviconMetadata.swift in Sources */,
 				849A97851ED9ECCD007D329B /* PreferencesWindowController.swift in Sources */,
 				849A977A1ED9EC04007D329B /* TimelineTableCellView.swift in Sources */,
 				849A97761ED9EC04007D329B /* TimelineCellAppearance.swift in Sources */,

Evergreen/Favicons/FaviconCache.swift

@@ -0,0 +1,29 @@
+//
+//  FaviconCache.swift
+//  Evergreen
+//
+//  Created by Brent Simmons on 11/23/17.
+//  Copyright © 2017 Ranchero Software. All rights reserved.
+//
+
+import Foundation
+
+final class FaviconCache {
+
+	static var cache = [String: Favicon]()
+
+	class func cachedFavicon(_ homePageURL: String) -> Favicon? {
+		
+		return cache[homePageURL]
+	}
+
+	class func cacheFavicon(_ homePageURL: String, _ favicon: Favicon) {
+
+		cache[homePageURL] = favicon
+	}
+
+	class func removeFavicon(_ homePageURL: String) {
+
+		cache[homePageURL] = nil
+	}
+}

Evergreen/Favicons/FaviconDownloader.swift

@@ -18,6 +18,7 @@ extension Notification.Name {
 
 final class FaviconDownloader {
 
+	private var seekingFaviconCache: [String: SeekingFavicon]() // homePageURL: SeekingFavicon
 	private var cache = ThreadSafeCache<NSImage>() // faviconURL: NSImage
 	private var faviconURLCache = ThreadSafeCache<String>() // homePageURL: faviconURL
 	private let folder: String
@@ -37,7 +38,7 @@ final class FaviconDownloader {
 
 		self.folder = folder
 		self.binaryCache = RSBinaryCache(folder: folder)
-		self.queue = DispatchQueue(label: "FaviconCache serial queue - \(folder)")
+		self.queue = DispatchQueue(label: "FaviconDownloader serial queue - \(folder)")
 	}
 
 	// MARK: - API
@@ -45,26 +46,42 @@ final class FaviconDownloader {
 	func favicon(for feed: Feed) -> NSImage? {
 
 		assert(Thread.isMainThread)
-
 		guard let homePageURL = feed.homePageURL else {
 			return nil
 		}
 
+		if let favicon = cachedInMemoryFavicon(for: feed) {
+			return favicon
+		}
+
+		findFavicon(for: feed)
+	}
+
+	func findFavicon(for feed: Feed) {
+
+		if let faviconMetadata = cachedFaviconMetadata
 		if let faviconURL = faviconURL(for: feed) {
 
-			if let cachedFavicon = cache[faviconURL] {
+			// It might be on disk.
-				return cachedFavicon
+
+			readFaviconFromDisk(faviconURL) { (image) in
+
+				if let image = image {
+					self.cache[faviconURL] = image
+					self.postFaviconDidBecomeAvailableNotification(homePageURL: homePageURL, faviconURL: faviconURL, image: image)
+					return
 				}
 
-			// TODO: read from disk and return if present.
+				// Download it (probably).
 
-			if shouldDownloadFaviconURL(faviconURL) {
+				if !self.shouldDownloadFaviconURL(faviconURL) {
-				downloadFavicon(faviconURL, homePageURL)
+					return
-				return nil
 				}
 				
-			return nil
+
 			}
+		}
+
 
 		// Try to find the faviconURL. It might be in the web page.
 		FaviconURLFinder.findFaviconURL(homePageURL) { (faviconURL) in
@@ -84,6 +101,14 @@ final class FaviconDownloader {
 
 private extension FaviconDownloader {
 
+	func cachedInMemoryFavicon(for feed: Feed) -> NSImage? {
+
+		guard let faviconURL = faviconURL(for: feed), let cachedFavicon = cache[faviconURL]  else {
+			return nil
+		}
+		return cachedFavicon
+	}
+
 	func shouldDownloadFaviconURL(_ faviconURL: String) -> Bool {
 
 		return !urlsBeingDownloaded.contains(faviconURL) && !badURLs.contains(faviconURL)
@@ -168,4 +193,10 @@ private extension FaviconDownloader {
 
 		return (faviconURL as NSString).rs_md5Hash()
 	}
+
+	func postFaviconDidBecomeAvailableNotification(homePageURL: String, faviconURL: String, image: NSImage) {
+
+		let userInfo: [AnyHashable: Any] = [UserInfoKey.homePageURL: homePageURL, UserInfoKey.faviconURL: faviconURL, UserInfoKey.image: image]
+		NotificationCenter.default.post(name: .FaviconDidBecomeAvailable, object: self, userInfo: userInfo)
+	}
 }

Evergreen/Favicons/FaviconMetadata.swift

@@ -0,0 +1,26 @@
+//
+//  Favicon.swift
+//  Evergreen
+//
+//  Created by Brent Simmons on 11/23/17.
+//  Copyright © 2017 Ranchero Software. All rights reserved.
+//
+
+import AppKit
+
+final class FaviconMetadata {
+
+	enum DiskStatus {
+		case unknown, notOnDisk, onDisk
+	}
+
+	let faviconURL: String
+	var lastDownloadAttemptDate: Date?
+	var diskStatus = DiskStatus.unknown
+	var image: NSImage?
+
+	init?(faviconURL: String) {
+
+		self.faviconURL = faviconURL
+	}
+}

Evergreen/Favicons/ImageDownloader.swift

@@ -0,0 +1,57 @@
+//
+//  FaviconImageDownloader.swift
+//  Evergreen
+//
+//  Created by Brent Simmons on 11/23/17.
+//  Copyright © 2017 Ranchero Software. All rights reserved.
+//
+
+import AppKit
+import RSWeb
+import RSCore
+
+// Downloads using cache. Enforces a minimum time interval between attempts.
+
+final class ImageDownloader {
+
+	private var urlsBeingDownloaded = Set<String>()
+	private var lastAttemptDates = [String: Date]()
+	private let minimumAttemptInterval: TimeInterval = 5 * 60
+	
+	func downloadImage(_ url: String, _ callback: @escaping (NSImage?) -> Void) {
+
+		guard shouldDownloadImage(url) else {
+			callback(nil)
+			return
+		}
+
+		urlsBeingDownloaded.insert(url)
+		lastAttemptDates[url] = Date()
+
+		downloadUsingCache(url) { (data, response, error) in
+
+			urlsBeingDownloaded.remove(url)
+
+			if let data = data, let response = response, response.statusIsOK, error == nil {
+				NSImage.rs_image(with: data, imageResultBlock: callback)
+				return
+			}
+			callback(nil)
+		}
+	}
+}
+
+private extension ImageDownload {
+
+	func shouldDownloadImage(_ url: String) -> Bool {
+
+		if urlsBeingDownloaded.contains(url) {
+			return false
+		}
+		if let lastAttemptDate = lastAttemptDates[url], Date().timeIntervalSince(lastAttemptDate) < minimumAttemptInterval {
+			return false
+		}
+
+		return true
+	}
+}

Evergreen/Favicons/SeekingFavicon.swift

@@ -0,0 +1,66 @@
+//
+//  SeekingFavicon.swift
+//  Evergreen
+//
+//  Created by Brent Simmons on 11/23/17.
+//  Copyright © 2017 Ranchero Software. All rights reserved.
+//
+
+import Foundation
+
+extension Notification.Name {
+
+	static let SeekingFaviconDidFindFaviconURL = Notification.Name("SeekingFaviconDidFindFaviconURLNotification")
+	static let SeekingFaviconDidNotFindFaviconURL = Notification.Name("SeekingFaviconDidNotFindFaviconURLNotification")
+}
+
+final class SeekingFavicon {
+
+	// At first, when looking for a favicon, we only know the homePageURL.
+	// The faviconURL may be specified by metadata in the home page,
+	// or it might be at /favicon.ico,
+	// or it might not exist (or be unfindable, which is the same thing).
+
+	let homePageURL: String
+	let defaultFaviconURL: String // /favicon.ico
+	var didAttemptToLookAtHomePageMetadata = false
+	var foundFaviconURL: String?
+
+	var shouldUseDefaultFaviconURL: Bool {
+
+		return didAttemptToLookAtHomePageMetadata && foundFaviconURL == nil
+	}
+
+	private static let localeForLowercasing = Locale(identifier: "en_US")
+
+	init?(homePageURL: String) {
+
+		guard let url = URL(string: homePageURL), let scheme = url.scheme, let host = url.host else {
+			return nil
+		}
+
+		self.homePageURL = homePageURL
+		self.defaultFaviconURL = "\(scheme)://\(host)/favicon.ico".lowercased(with: SeekingFavicon.localeForLowercasing)
+
+		findFaviconURL()
+	}
+}
+
+private extension SeekingFavicon {
+
+	func findFaviconURL() {
+
+		FaviconURLFinder.findFaviconURL(homePageURL) { (faviconURL) in
+
+			self.didAttemptToLookAtHomePageMetadata = true
+			self.foundFaviconURL = faviconURL
+
+			if let _ = faviconURL {
+				NotificationCenter.default.post(name: .SeekingFaviconDidFindFaviconURL, object: self)
+			}
+			else {
+				NotificationCenter.default.post(name: .SeekingFaviconDidNotFindFaviconURL, object: self)
+			}
+		}
+	}
+}