Added PowerPoint templates to the Slide Assistant (#1055)

Co-authored-by: Thorsten Sommer <SommerEngineering@users.noreply.github.com>

app/MindWork AI Studio/Assistants/SlideBuilder/SlideAssistant.razor.Progress.cs

@@ -0,0 +1,60 @@
+using AIStudio.Chat;
+using AIStudio.Tools.AssistantSessions;
+using AIStudio.Tools.PowerPoint;
+
+namespace AIStudio.Assistants.SlideBuilder;
+
+/// <summary>
+/// The part of the Slide Assistant which tells, below the progress bar, what the LLM is doing while
+/// it plans.
+/// </summary>
+/// <remarks>
+/// The answer is JSON, which the assistant does not show. Without these texts, the user would watch
+/// a bar for minutes without knowing whether anything happens: the LLM first thinks about the
+/// structure, which streams nothing at all, then writes the slides one by one, and may fit them to
+/// the layouts in a second round.
+/// </remarks>
+public partial class SlideAssistant
+{
+    private PlanningStep planningStep;
+    private static readonly AssistantSessionStateKey<PlanningStep> PLANNING_STEP_STATE_KEY = new(nameof(planningStep));
+
+    private ContentText? countedAnswer;
+    private StreamedSlideCounter slideCounter = new();
+
+    protected override string ProgressText => this.planningStep switch
+    {
+        PlanningStep.PLANNING when this.SlidesSoFar() is var slides and > 0 => string.Format(T("The LLM is writing slide {0}..."), slides),
+        PlanningStep.PLANNING => T("The LLM is planning the structure of the presentation..."),
+        PlanningStep.REPAIRING => T("The LLM is fitting the slides to the layouts..."),
+
+        _ => string.Empty,
+    };
+
+    /// <summary>
+    /// Counts the slides which the answer streaming in has started so far.
+    /// </summary>
+    private int SlidesSoFar()
+    {
+        if (this.ResultingContentBlock?.Content is not ContentText answer)
+            return 0;
+
+        if (!ReferenceEquals(answer, this.countedAnswer))
+        {
+            this.countedAnswer = answer;
+            this.slideCounter = new();
+        }
+
+        return this.slideCounter.Count(answer.Text);
+    }
+
+    /// <summary>
+    /// What the LLM is asked to do right now.
+    /// </summary>
+    private enum PlanningStep
+    {
+        NONE,
+        PLANNING,
+        REPAIRING,
+    }
+}