Dactyloidae iOS initial commit

mobile/ios/Client/Frontend/Home/PanelDataObservers.swift

@@ -0,0 +1,97 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+import Foundation
+import Deferred
+import Shared
+
+public let ActivityStreamTopSiteCacheSize: Int32 = 16
+
+private let log = Logger.browserLogger
+
+protocol DataObserver {
+    var profile: Profile { get }
+    weak var delegate: DataObserverDelegate? { get set }
+
+    func refreshIfNeeded(forceHighlights highlights: Bool, forceTopSites topSites: Bool)
+}
+
+protocol DataObserverDelegate: class {
+    func didInvalidateDataSources(refresh forced: Bool, highlightsRefreshed: Bool, topSitesRefreshed: Bool)
+    func willInvalidateDataSources(forceHighlights highlights: Bool, forceTopSites topSites: Bool)
+}
+
+// Make these delegate methods optional by providing default implementations
+extension DataObserverDelegate {
+    func didInvalidateDataSources(refresh forced: Bool, highlightsRefreshed: Bool, topSitesRefreshed: Bool) {}
+    func willInvalidateDataSources(forceHighlights highlights: Bool, forceTopSites topSites: Bool) {}
+}
+
+open class PanelDataObservers {
+    var activityStream: DataObserver
+
+    init(profile: Profile) {
+        self.activityStream = ActivityStreamDataObserver(profile: profile)
+    }
+}
+
+class ActivityStreamDataObserver: DataObserver {
+    let profile: Profile
+    weak var delegate: DataObserverDelegate?
+    private var invalidationTime = OneMinuteInMilliseconds * 15
+
+    fileprivate let events = [NotificationFirefoxAccountChanged, NotificationProfileDidFinishSyncing, NotificationPrivateDataClearedHistory]
+
+    init(profile: Profile) {
+        self.profile = profile
+        self.profile.history.setTopSitesCacheSize(ActivityStreamTopSiteCacheSize)
+        events.forEach { NotificationCenter.default.addObserver(self, selector: #selector(self.notificationReceived(_:)), name: $0, object: nil) }
+    }
+
+    /*
+     refreshIfNeeded will refresh the underlying caches for both TopSites and Highlights.
+     By default this will only refresh the highlights if the last fetch is older than 15 mins
+     By default this will only refresh topSites if KeyTopSitesCacheIsValid is false
+     */
+    func refreshIfNeeded(forceHighlights highlights: Bool, forceTopSites topSites: Bool) {
+        guard !profile.isShutdown else {
+            return
+        }
+
+        // Highlights are cached for 15 mins
+        let userEnabledHighlights = profile.prefs.boolForKey(PrefsKeys.ASRecentHighlightsVisible) ?? true
+        let lastInvalidationTime = profile.prefs.unsignedLongForKey(PrefsKeys.ASLastInvalidation) ?? 0
+        let shouldInvalidateHighlights = (highlights || (Date.now() - lastInvalidationTime > invalidationTime)) && userEnabledHighlights
+        
+        // KeyTopSitesCacheIsValid is false when we want to invalidate. Thats why this logic is so backwards
+        let shouldInvalidateTopSites = topSites || !(profile.prefs.boolForKey(PrefsKeys.KeyTopSitesCacheIsValid) ?? false)
+        if !shouldInvalidateTopSites && !shouldInvalidateHighlights {
+            // There is nothing to refresh. Bye
+            return
+        }
+
+        self.delegate?.willInvalidateDataSources(forceHighlights: highlights, forceTopSites: topSites)
+        self.profile.recommendations.repopulate(invalidateTopSites: shouldInvalidateTopSites, invalidateHighlights: shouldInvalidateHighlights).uponQueue(DispatchQueue.main) { _ in
+            if shouldInvalidateTopSites {
+                self.profile.prefs.setBool(true, forKey: PrefsKeys.KeyTopSitesCacheIsValid)
+            }
+            
+            if shouldInvalidateHighlights {
+                let newInvalidationTime = shouldInvalidateHighlights ? Date.now() : lastInvalidationTime
+                self.profile.prefs.setLong(newInvalidationTime, forKey: PrefsKeys.ASLastInvalidation)
+            }
+            
+            self.delegate?.didInvalidateDataSources(refresh: highlights || topSites, highlightsRefreshed: shouldInvalidateHighlights, topSitesRefreshed: shouldInvalidateTopSites)
+        }
+    }
+
+    @objc func notificationReceived(_ notification: Notification) {
+        switch notification.name {
+        case NotificationProfileDidFinishSyncing, NotificationFirefoxAccountChanged, NotificationPrivateDataClearedHistory:
+             refreshIfNeeded(forceHighlights: true, forceTopSites: true)
+        default:
+            log.warning("Received unexpected notification \(notification.name)")
+        }
+    }
+}