Add ChartJS MCP server for BlazorExpress chart integration

.gitignore

@@ -396,3 +396,4 @@ FodyWeavers.xsd
 
 # JetBrains Rider
 *.sln.iml
+/output

BlazorExpress.ChartJS.Demo.RCL/Pages/Demos/BarChart/BarChartDocumentation.razor

@@ -12,7 +12,7 @@
 
 <DocsLink Href="@DemoRouteConstants.Docs_BarChart" />
 
 <Prerequisites PageUrl="@pageUrl" />
 
 <Section Class="p-0" Size="HeadingSize.H4" Name="How it works" PageUrl="@pageUrl" Link="how-it-works">
     <Block>
@@ -32,6 +32,13 @@
     <Demo Type="typeof(BarChart_Demo_01_Examples)" Tabs="true" />
 </Section>
 
+<Section Class="p-0" Size="HeadingSize.H4" Name="Click event" PageUrl="@pageUrl" Link="click-event">
+    <Block>
+        Set the <code>OnClick</code> callback to react when a chart data item is selected. The callback receives <code>ChartClickEventArgs</code> with the dataset index and label, data-item index and label, and raw value.
+        The basic Bar Chart demo displays the selected item below the chart.
+    </Block>
+</Section>
+
 <Section Class="p-0" Size="HeadingSize.H4" Name="Combo bar/line" PageUrl="@pageUrl" Link="combo-bar-line">
     <Block>
         The <strong>Combo bar/line</strong> demo mixes <code>BarChartDataset</code> and <code>LineChartDataset</code> in the same <code>BarChart</code>.

BlazorExpress.ChartJS.Demo.RCL/Pages/Demos/BarChart/BarChart_Demo_01_Examples.razor

@@ -1,4 +1,11 @@
-<BarChart @ref="barChart" Width="600" />
+<BarChart @ref="barChart" Width="600" OnClick="HandleClickAsync" />
+
+@if (selectedChartItem is not null)
+{
+    <p class="mt-3 mb-0">
+        Selected: @selectedChartItem.DatasetLabel (dataset @selectedChartItem.DatasetIndex), @selectedChartItem.Label (index @selectedChartItem.Index), value @selectedChartItem.Value
+    </p>
+}
 
 <div class="mt-5">
     <Button Color="ButtonColor.Primary" Size="ButtonSize.Small" @onclick="RandomizeAsync"> Randomize </Button>
@@ -12,6 +19,7 @@
     private BarChart barChart = default!;
     private BarChartOptions barChartOptions = default!;
     private ChartData chartData = default!;
+    private ChartClickEventArgs? selectedChartItem;
 
     private int datasetsCount = 0;
     private int labelsCount = 0;
@@ -33,6 +41,12 @@
         await base.OnAfterRenderAsync(firstRender);
     }
 
+    private Task HandleClickAsync(ChartClickEventArgs eventArgs)
+    {
+        selectedChartItem = eventArgs;
+        return Task.CompletedTask;
+    }
+
     private async Task RandomizeAsync()
     {
         if (chartData is null || chartData.Datasets is null || !chartData.Datasets.Any()) return;

BlazorExpress.ChartJS.MCP.Tests/BlazorExpress.ChartJS.MCP.Tests.csproj

@@ -0,0 +1,24 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <IsPackable>false</IsPackable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.AspNetCore.TestHost" Version="10.0.0" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.11.1" />
+    <PackageReference Include="xunit" Version="2.9.2" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="2.8.2">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+    </PackageReference>
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\BlazorExpress.ChartJS.MCP\BlazorExpress.ChartJS.MCP.csproj" />
+  </ItemGroup>
+
+</Project>

BlazorExpress.ChartJS.MCP.Tests/ChartCatalogTests.cs

@@ -0,0 +1,69 @@
+namespace BlazorExpress.ChartJS.MCP.Tests;
+
+public class ChartCatalogTests
+{
+    [Fact]
+    public void All_Returns_Current_Public_Chart_Types()
+    {
+        var names = ChartCatalog.All.Select(x => x.Name).ToArray();
+
+        Assert.Equal(["Bar", "Bubble", "Doughnut", "Line", "Pie", "PolarArea", "Radar", "Scatter"], names);
+    }
+
+    [Theory]
+    [InlineData("Bar", "BarChart", "BarChartOptions", "BarChartDataset")]
+    [InlineData("polar-area", "PolarAreaChart", "PolarAreaChartOptions", "PolarAreaChartDataset")]
+    public void GetSchema_Returns_Metadata_For_Chart_Type(string chartType, string component, string options, string dataset)
+    {
+        var schema = ChartCatalog.GetSchema(chartType);
+
+        Assert.Equal(component, schema.Component);
+        Assert.Equal(options, schema.OptionsType);
+        Assert.Equal(dataset, schema.DatasetType);
+        Assert.NotEmpty(schema.CommonInputs);
+        Assert.NotEmpty(schema.Examples);
+    }
+
+    [Fact]
+    public void Radar_Is_Not_Datalabel_Safe()
+    {
+        var schema = ChartCatalog.GetSchema("Radar");
+
+        Assert.False(schema.SupportsDatalabels);
+    }
+
+    [Theory]
+    [InlineData("Bubble")]
+    [InlineData("Radar")]
+    public void Charts_Without_Plugins_Report_No_Title_Or_Legend_Support(string chartType)
+    {
+        var schema = ChartCatalog.GetSchema(chartType);
+
+        Assert.False(schema.SupportsPluginOptions);
+        Assert.False(schema.SupportsTitleOptions);
+        Assert.False(schema.SupportsLegendOptions);
+    }
+
+    [Theory]
+    [InlineData("Bar")]
+    [InlineData("Scatter")]
+    public void Charts_With_Plugins_Report_Title_And_Legend_Support(string chartType)
+    {
+        var schema = ChartCatalog.GetSchema(chartType);
+
+        Assert.True(schema.SupportsPluginOptions);
+        Assert.True(schema.SupportsTitleOptions);
+        Assert.True(schema.SupportsLegendOptions);
+    }
+
+    [Theory]
+    [InlineData("Bar", "numericDatasetsJson")]
+    [InlineData("Scatter", "pointDatasetsJson")]
+    [InlineData("Bubble", "pointDatasetsJson")]
+    public void GetSchema_Includes_Dataset_Examples(string chartType, string exampleKey)
+    {
+        var schema = ChartCatalog.GetSchema(chartType);
+
+        Assert.True(schema.Examples.ContainsKey(exampleKey));
+    }
+}

BlazorExpress.ChartJS.MCP.Tests/ChartClickEventArgsTests.cs

@@ -0,0 +1,87 @@
+using BlazorExpress.ChartJS;
+using Microsoft.AspNetCore.Components;
+using System.Text.Json;
+
+namespace BlazorExpress.ChartJS.MCP.Tests;
+
+public class ChartClickEventArgsTests
+{
+    [Fact]
+    public async Task HandleClickAsync_Invokes_Configured_Callback_With_Selected_Item_Metadata()
+    {
+        var component = new TestChartComponent();
+        ChartClickEventArgs? receivedEventArgs = null;
+        component.ConfigureOnClick(EventCallback.Factory.Create<ChartClickEventArgs>(new object(), eventArgs => receivedEventArgs = eventArgs));
+
+        using var document = JsonDocument.Parse("""{"value":42}""");
+        var eventArgs = new ChartClickEventArgs
+        {
+            DatasetIndex = 1,
+            DatasetLabel = "Revenue",
+            Index = 2,
+            Label = "March",
+            Value = document.RootElement.Clone()
+        };
+
+        await component.HandleClickAsync(eventArgs);
+
+        Assert.NotNull(receivedEventArgs);
+        Assert.Equal(1, receivedEventArgs.DatasetIndex);
+        Assert.Equal("Revenue", receivedEventArgs.DatasetLabel);
+        Assert.Equal(2, receivedEventArgs.Index);
+        Assert.Equal("March", receivedEventArgs.Label);
+        Assert.Equal(42, receivedEventArgs.Value?.GetProperty("value").GetInt32());
+    }
+
+    [Fact]
+    public async Task HandleClickAsync_Without_Callback_Completes_Without_Throwing()
+    {
+        var component = new TestChartComponent();
+
+        var exception = await Record.ExceptionAsync(() => component.HandleClickAsync(new ChartClickEventArgs
+        {
+            DatasetIndex = 0,
+            Index = 0,
+            Value = null
+        }));
+
+        Assert.Null(exception);
+    }
+
+    [Fact]
+    public void JavaScript_Click_Bridge_Maps_Selected_Item_And_Protects_No_Item_Path()
+    {
+        var source = File.ReadAllText(GetRepositoryFile("BlazorExpress.ChartJS", "wwwroot", "blazorexpress.chartjs.js"));
+
+        Assert.Equal(9, source.Split("initialize: (elementId, type, data, options, plugins, dotNetObjectReference)").Length - 1);
+        Assert.Contains("chart.getElementsAtEventForMode(event, 'nearest', { intersect: true }, true)", source);
+        Assert.Contains("if (!activeElements || activeElements.length === 0) return;", source);
+        Assert.Contains("dotNetObjectReference.invokeMethodAsync('HandleClickAsync'", source);
+        Assert.Contains("datasetIndex: activeElement.datasetIndex", source);
+        Assert.Contains("datasetLabel: dataset?.label ?? null", source);
+        Assert.Contains("index: activeElement.index", source);
+        Assert.Contains("label: chart.data.labels?.[activeElement.index] ?? null", source);
+        Assert.Contains("value: dataset?.data?.[activeElement.index] ?? null", source);
+        Assert.DoesNotContain("options.onClick", source);
+    }
+
+    private static string GetRepositoryFile(params string[] pathSegments)
+    {
+        var directory = new DirectoryInfo(AppContext.BaseDirectory);
+
+        while (directory is not null)
+        {
+            if (File.Exists(Path.Combine(directory.FullName, "BlazorExpress.ChartJS.sln")))
+                return Path.Combine([directory.FullName, .. pathSegments]);
+
+            directory = directory.Parent;
+        }
+
+        throw new DirectoryNotFoundException("The ChartJS repository root could not be located.");
+    }
+
+    private sealed class TestChartComponent : ChartComponentBase
+    {
+        public void ConfigureOnClick(EventCallback<ChartClickEventArgs> onClick) => OnClick = onClick;
+    }
+}