Initial implementation of procfile

Reviewed-on: #1

Pushy.Silo/Grains/TextItemGrain.cs

@@ -0,0 +1,67 @@
+using Pushy.Domain;
+
+namespace Pushy.Silo.Grains;
+
+public sealed class TextItemGrain : IGrainBase, ITextItem, IRemindable
+{
+    private readonly IPersistentState<TextItem> _state;
+    private readonly ILogger<TextItemGrain> _logger;
+    
+    private IGrainReminder? _reminder;
+
+    public TextItemGrain(
+        IGrainContext grainContext,
+        [PersistentState("text")] IPersistentState<TextItem> state,
+        ILogger<TextItemGrain> logger)
+    {
+        _state = state;
+        _logger = logger;
+        GrainContext = grainContext;
+    }
+
+    public IGrainContext GrainContext { get; }
+    
+    /// <inheritdoc />
+    public async Task OnActivateAsync(CancellationToken cancellationToken)
+    {
+        _reminder = await this.RegisterOrUpdateReminder("clear", TimeSpan.FromDays(10), TimeSpan.FromDays(10));
+    }
+
+    /// <inheritdoc />
+    public async ValueTask<TextSetResult> SetText(string text)
+    {
+        try
+        {
+            if (_state.State.Text is not null)
+                return TextSetResult.Failure;
+
+            _state.State.Text = text;
+            await _state.WriteStateAsync();
+
+            return TextSetResult.Success;
+        }
+        catch (Exception)
+        {
+            return TextSetResult.Failure;
+        }
+    }
+
+    /// <inheritdoc />
+    public ValueTask<string> GetText()
+    {
+        return ValueTask.FromResult(_state.State.Text ?? throw new InvalidOperationException("No text was available"));
+    }
+
+    /// <inheritdoc />
+    public async Task ReceiveReminder(string reminderName, TickStatus status)
+    {
+        if (reminderName == "clear")
+        {
+            _state.State.Text = null;
+            await _state.WriteStateAsync(); 
+            this.DeactivateOnIdle();
+            
+            _logger.LogInformation("Text item have been cleared!");
+        }
+    }
+}