New: Show previously installed version in Updates UI

Co-Authored-By: Taloth <Taloth@users.noreply.github.com>

src/NzbDrone.Core/Update/History/UpdateHistory.cs

@@ -0,0 +1,12 @@
+using System;
+using NzbDrone.Core.Datastore;
+
+namespace NzbDrone.Core.Update.History
+{
+    public class UpdateHistory : ModelBase
+    {
+        public DateTime Date { get; set; }
+        public Version Version { get; set; }
+        public UpdateHistoryEventType EventType { get; set; }
+    }
+}

src/NzbDrone.Core/Update/History/UpdateHistoryEventType.cs

@@ -0,0 +1,9 @@
+namespace NzbDrone.Core.Update.History
+{
+    public enum UpdateHistoryEventType
+    {
+        Unknown = 0,
+        Initiated = 1,
+        Installed = 2
+    }
+}

src/NzbDrone.Core/Update/History/UpdateHistoryRepository.cs

@@ -0,0 +1,55 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using NzbDrone.Core.Datastore;
+using NzbDrone.Core.Messaging.Events;
+
+namespace NzbDrone.Core.Update.History
+{
+    public interface IUpdateHistoryRepository : IBasicRepository<UpdateHistory>
+    {
+        UpdateHistory LastInstalled();
+        UpdateHistory PreviouslyInstalled();
+        List<UpdateHistory> InstalledSince(DateTime dateTime);
+    }
+
+    public class UpdateHistoryRepository : BasicRepository<UpdateHistory>, IUpdateHistoryRepository
+    {
+        public UpdateHistoryRepository(ILogDatabase logDatabase, IEventAggregator eventAggregator)
+            : base(logDatabase, eventAggregator)
+        {
+        }
+
+        public UpdateHistory LastInstalled()
+        {
+            var history = Query(x => x.EventType == UpdateHistoryEventType.Installed)
+                               .OrderBy(v => v.Date)
+                               .Take(1)
+                               .FirstOrDefault();
+
+            return history;
+        }
+
+        public UpdateHistory PreviouslyInstalled()
+        {
+            var history = Query(x => x.EventType == UpdateHistoryEventType.Installed)
+                               .OrderBy(v => v.Date)
+                               .Skip(1)
+                               .Take(1)
+                               .FirstOrDefault();
+
+            return history;
+        }
+
+        public List<UpdateHistory> InstalledSince(DateTime dateTime)
+        {
+            var history = Query(v => v.EventType == UpdateHistoryEventType.Installed && v.Date >= dateTime)
+                               .OrderBy(v => v.Date)
+                               .ToList();
+
+            return history;
+        }
+    }
+}

src/NzbDrone.Core/Update/History/UpdateHistoryService.cs

@@ -0,0 +1,71 @@
+using System;
+using System.Collections.Generic;
+using NzbDrone.Common.EnvironmentInfo;
+using NzbDrone.Core.Lifecycle;
+using NzbDrone.Core.Messaging.Events;
+using NzbDrone.Core.Update.History.Events;
+
+namespace NzbDrone.Core.Update.History
+{
+    public interface IUpdateHistoryService
+    {
+        Version PreviouslyInstalled();
+        List<UpdateHistory> InstalledSince(DateTime dateTime);
+    }
+
+    public class UpdateHistoryService : IUpdateHistoryService, IHandle<ApplicationStartedEvent>, IHandleAsync<ApplicationStartedEvent>
+    {
+        private readonly IUpdateHistoryRepository _repository;
+        private readonly IEventAggregator _eventAggregator;
+        private Version _prevVersion;
+
+        public UpdateHistoryService(IUpdateHistoryRepository repository, IEventAggregator eventAggregator)
+        {
+            _repository = repository;
+            _eventAggregator = eventAggregator;
+        }
+
+        public Version PreviouslyInstalled()
+        {
+            var history = _repository.PreviouslyInstalled();
+
+            return history?.Version;
+        }
+
+        public List<UpdateHistory> InstalledSince(DateTime dateTime)
+        {
+            return _repository.InstalledSince(dateTime);
+        }
+
+        public void Handle(ApplicationStartedEvent message)
+        {
+            if (BuildInfo.Version.Major == 10)
+            {
+                // Don't save dev versions, they change constantly
+                return;
+            }
+
+            var history = _repository.LastInstalled();
+
+            if (history == null || history.Version != BuildInfo.Version)
+            {
+                _prevVersion = history.Version;
+
+                _repository.Insert(new UpdateHistory
+                {
+                    Date = DateTime.UtcNow,
+                    Version = BuildInfo.Version,
+                    EventType = UpdateHistoryEventType.Installed
+                });
+            }
+        }
+
+        public void HandleAsync(ApplicationStartedEvent message)
+        {
+            if (_prevVersion != null)
+            {
+                _eventAggregator.PublishEvent(new UpdateInstalledEvent(_prevVersion, BuildInfo.Version));
+            }
+        }
+    }
+}