Improve history, resume videos, mark watched videos (fixes #42)

Model/HistoryModel.swift

@@ -0,0 +1,73 @@
+import CoreData
+import CoreMedia
+import Foundation
+
+extension PlayerModel {
+    func historyVideo(_ id: String) -> Video? {
+        historyVideos.first { $0.videoID == id }
+    }
+
+    func loadHistoryVideoDetails(_ id: Video.ID) {
+        guard historyVideo(id).isNil else {
+            return
+        }
+
+        accounts.api.video(id).load().onSuccess { [weak self] response in
+            guard let video: Video = response.typedContent() else {
+                return
+            }
+
+            self?.historyVideos.append(video)
+        }
+    }
+
+    func updateWatch(finished: Bool = false) {
+        guard let id = currentVideo?.videoID else {
+            return
+        }
+
+        let time = player.currentTime().seconds
+
+        let watch: Watch!
+        let watchFetchRequest = Watch.fetchRequest()
+        watchFetchRequest.predicate = NSPredicate(format: "videoID = %@", id as String)
+
+        let results = try? context.fetch(watchFetchRequest)
+
+        if results?.isEmpty ?? true {
+            if time < 1 {
+                return
+            }
+            watch = Watch(context: context)
+            watch.videoID = id
+        } else {
+            watch = results?.first
+        }
+
+        if let seconds = playerItemDuration?.seconds {
+            watch.videoDuration = seconds
+        }
+
+        if finished {
+            watch.stoppedAt = watch.videoDuration
+        } else if time.isFinite, time > 0 {
+            watch.stoppedAt = time
+        }
+
+        watch.watchedAt = Date()
+
+        try? context.save()
+    }
+
+    func removeWatch(_ watch: Watch) {
+        context.delete(watch)
+        try? context.save()
+    }
+
+    func removeAllWatches() {
+        let watchesFetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "Watch")
+        let deleteRequest = NSBatchDeleteRequest(fetchRequest: watchesFetchRequest)
+        _ = try? context.execute(deleteRequest)
+        _ = try? context.save()
+    }
+}