chore: rework mutagen controller, add polling (#65)

- Use locks during operations for daemon process consistency
- Use a state model for UI rendering
- Use events to signal state changes
- Fix some tooltip problems that arise from polling

Author: deansheather

Diff for: App/App.xaml.cs

@@ -120,7 +120,7 @@ protected override void OnLaunched(LaunchActivatedEventArgs args)
         // Initialize file sync.
         var syncSessionCts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
         var syncSessionController = _services.GetRequiredService<ISyncSessionController>();
-        _ = syncSessionController.Initialize(syncSessionCts.Token).ContinueWith(t =>
+        _ = syncSessionController.RefreshState(syncSessionCts.Token).ContinueWith(t =>
         {
             // TODO: log
 #if DEBUG

Diff for: App/Models/RpcModel.cs

@@ -1,5 +1,4 @@
 using System.Collections.Generic;
-using System.Linq;
 using Coder.Desktop.Vpn.Proto;
 
 namespace Coder.Desktop.App.Models;
@@ -26,18 +25,18 @@ public class RpcModel
 
     public VpnLifecycle VpnLifecycle { get; set; } = VpnLifecycle.Unknown;
 
-    public List<Workspace> Workspaces { get; set; } = [];
+    public IReadOnlyList<Workspace> Workspaces { get; set; } = [];
 
-    public List<Agent> Agents { get; set; } = [];
+    public IReadOnlyList<Agent> Agents { get; set; } = [];
 
     public RpcModel Clone()
     {
         return new RpcModel
         {
             RpcLifecycle = RpcLifecycle,
             VpnLifecycle = VpnLifecycle,
-            Workspaces = Workspaces.ToList(),
-            Agents = Agents.ToList(),
+            Workspaces = Workspaces,
+            Agents = Agents,
         };
     }
 }

Diff for: App/Models/SyncSessionControllerStateModel.cs

@@ -0,0 +1,43 @@
+using System.Collections.Generic;
+
+namespace Coder.Desktop.App.Models;
+
+public enum SyncSessionControllerLifecycle
+{
+    // Uninitialized means that the daemon has not been started yet. This can
+    // be resolved by calling RefreshState (or any other RPC method
+    // successfully).
+    Uninitialized,
+
+    // Stopped means that the daemon is not running. This could be because:
+    // - It was never started (pre-Initialize)
+    // - It was stopped due to no sync sessions (post-Initialize, post-operation)
+    // - The last start attempt failed (DaemonError will be set)
+    // - The last daemon process crashed (DaemonError will be set)
+    Stopped,
+
+    // Running is the normal state where the daemon is running and managing
+    // sync sessions. This is only set after a successful start (including
+    // being able to connect to the daemon).
+    Running,
+}
+
+public class SyncSessionControllerStateModel
+{
+    public SyncSessionControllerLifecycle Lifecycle { get; init; } = SyncSessionControllerLifecycle.Stopped;
+
+    /// <summary>
+    ///     May be set when Lifecycle is Stopped to signify that the daemon failed
+    ///     to start or unexpectedly crashed.
+    /// </summary>
+    public string? DaemonError { get; init; }
+
+    public required string DaemonLogFilePath { get; init; }
+
+    /// <summary>
+    ///     This contains the last known state of all sync sessions. Sync sessions
+    ///     are periodically refreshed if the daemon is running. This list is
+    ///     sorted by creation time.
+    /// </summary>
+    public IReadOnlyList<SyncSessionModel> SyncSessions { get; init; } = [];
+}

Diff for: App/Models/SyncSessionModel.cs

@@ -51,6 +51,7 @@ public string Description(string linePrefix = "")
 public class SyncSessionModel
 {
     public readonly string Identifier;
+    public readonly DateTime CreatedAt;
 
     public readonly string AlphaName;
     public readonly string AlphaPath;
@@ -99,6 +100,7 @@ public string SizeDetails
     public SyncSessionModel(State state)
     {
         Identifier = state.Session.Identifier;
+        CreatedAt = state.Session.CreationTime.ToDateTime();
 
         (AlphaName, AlphaPath) = NameAndPathFromUrl(state.Session.Alpha);
         (BetaName, BetaPath) = NameAndPathFromUrl(state.Session.Beta);