[Fusion] Added source schema enricher (#8719)

Author: glen-84

src/HotChocolate/Fusion-vnext/src/Fusion.Composition/Extensions/OutputFieldDefinitionExtensions.cs

@@ -1,4 +1,5 @@
 using System.Collections.Immutable;
+using HotChocolate.Fusion.Features;
 using HotChocolate.Types;
 using static HotChocolate.Fusion.WellKnownArgumentNames;
 using static HotChocolate.Fusion.WellKnownDirectiveNames;
@@ -24,4 +25,9 @@ public static ImmutableArray<string> GetSchemaNames(
 
         return [.. schemaNames];
     }
+
+    public static SourceFieldMetadata? GetSourceFieldMetadata(this IOutputFieldDefinition field)
+    {
+        return field.Features.Get<SourceFieldMetadata>();
+    }
 }

src/HotChocolate/Fusion-vnext/src/Fusion.Composition/Features/SourceFieldMetadata.cs

@@ -0,0 +1,8 @@
+namespace HotChocolate.Fusion.Features;
+
+internal sealed class SourceFieldMetadata
+{
+    public bool IsKeyField { get; set; }
+
+    public bool IsShareable { get; set; }
+}

src/HotChocolate/Fusion-vnext/src/Fusion.Composition/SchemaComposer.cs

@@ -51,6 +51,14 @@ public CompositionResult<MutableSchemaDefinition> Compose()
             return preprocessResult;
         }
 
+        // Enrich Source Schemas
+        var enrichmentResult = schemas.Select(schema => new SourceSchemaEnricher(schema).Enrich()).Combine();
+
+        if (enrichmentResult.IsFailure)
+        {
+            return enrichmentResult;
+        }
+
         // Validate Source Schemas
         var validationResult =
             new SourceSchemaValidator(schemas, s_sourceSchemaRules, _log).Validate();

src/HotChocolate/Fusion-vnext/src/Fusion.Composition/SourceSchemaEnricher.cs

@@ -0,0 +1,71 @@
+using HotChocolate.Features;
+using HotChocolate.Fusion.Extensions;
+using HotChocolate.Fusion.Features;
+using HotChocolate.Fusion.Results;
+using HotChocolate.Fusion.SyntaxWalkers;
+using HotChocolate.Language;
+using HotChocolate.Types.Mutable;
+using ArgumentNames = HotChocolate.Fusion.WellKnownArgumentNames;
+using DirectiveNames = HotChocolate.Fusion.WellKnownDirectiveNames;
+
+namespace HotChocolate.Fusion;
+
+internal sealed class SourceSchemaEnricher(MutableSchemaDefinition schema)
+{
+    public CompositionResult Enrich()
+    {
+        foreach (var type in schema.Types)
+        {
+            if (type is MutableComplexTypeDefinition complexType)
+            {
+                // Key fields.
+                foreach (var keyField in GetKeyFields(complexType, schema))
+                {
+                    var sourceFieldMetadata = keyField.Features.GetOrSet<SourceFieldMetadata>();
+                    sourceFieldMetadata.IsKeyField = true;
+                }
+
+                foreach (var field in complexType.Fields)
+                {
+                    EnrichField(field, complexType);
+                }
+            }
+        }
+
+        return CompositionResult.Success();
+    }
+
+    private static void EnrichField(MutableOutputFieldDefinition field, MutableComplexTypeDefinition complexType)
+    {
+        var sourceFieldMetadata = field.Features.GetOrSet<SourceFieldMetadata>();
+
+        // Shareable fields.
+        if (!field.HasExternalDirective()
+            && (
+                sourceFieldMetadata.IsKeyField
+                || field.HasShareableDirective()
+                || (complexType is MutableObjectTypeDefinition objectType && objectType.HasShareableDirective())))
+        {
+            sourceFieldMetadata.IsShareable = true;
+        }
+    }
+
+    private static List<MutableOutputFieldDefinition> GetKeyFields(
+        MutableComplexTypeDefinition complexType,
+        MutableSchemaDefinition schema)
+    {
+        var keyDirectives = complexType.Directives.AsEnumerable().Where(d => d.Name == DirectiveNames.Key);
+        var keyFields = new List<MutableOutputFieldDefinition>();
+
+        foreach (var keyDirective in keyDirectives)
+        {
+            var fieldsArgument = ((StringValueNode)keyDirective.Arguments[ArgumentNames.Fields]).Value;
+            var selectionSet = Utf8GraphQLParser.Syntax.ParseSelectionSet($"{{ {fieldsArgument} }}");
+            var fieldsExtractor = new SelectionSetFieldsExtractor(schema);
+            var fieldGroup = fieldsExtractor.ExtractFields(selectionSet, complexType);
+            keyFields.AddRange(fieldGroup.Select(f => f.Field));
+        }
+
+        return keyFields;
+    }
+}

src/HotChocolate/Fusion-vnext/test/Fusion.Composition.Tests/SourceSchemaEnricherTests.cs

@@ -0,0 +1,79 @@
+using HotChocolate.Fusion.Extensions;
+using HotChocolate.Fusion.Logging;
+using HotChocolate.Types.Mutable;
+
+namespace HotChocolate.Fusion;
+
+public sealed class SourceSchemaEnricherTests
+{
+    [Fact]
+    public void Enrich_SourceSchema_SetsIsKeyFieldAndIsShareableMetadata()
+    {
+        // arrange
+        var sourceSchemaText =
+            new SourceSchemaText(
+                "A",
+                """
+                type Product
+                    @key(fields: "id, category { id }")
+                    @key(fields: "sku")
+                    @key(fields: "alreadyShareable")
+                    @key(fields: "externalField") {
+                    id: ID!
+                    category: Category!
+                    sku: String!
+                    alreadyShareable: String! @shareable
+                    externalField: String! @external
+                    nonKeyField: String
+                }
+
+                interface Category {
+                    id: ID!
+                }
+
+                type BookCategory implements Category @shareable {
+                    id: ID!
+                    count: Int!
+                }
+                """);
+        var sourceSchemaParser = new SourceSchemaParser([sourceSchemaText], new CompositionLog());
+        var schema = sourceSchemaParser.Parse().Value.Single();
+        var enricher = new SourceSchemaEnricher(schema);
+
+        // act
+        enricher.Enrich();
+
+        var productType = (MutableObjectTypeDefinition)schema.Types["Product"];
+        var productIdFieldMetadata = productType.Fields["id"].GetSourceFieldMetadata();
+        var productCategoryFieldMetadata = productType.Fields["category"].GetSourceFieldMetadata();
+        var productSkuFieldMetadata = productType.Fields["sku"].GetSourceFieldMetadata();
+        var productAlreadyShareableFieldMetadata = productType.Fields["alreadyShareable"].GetSourceFieldMetadata();
+        var productExternalFieldMetadata = productType.Fields["externalField"].GetSourceFieldMetadata();
+        var productNonKeyFieldMetadata = productType.Fields["nonKeyField"].GetSourceFieldMetadata();
+        var categoryType = (MutableInterfaceTypeDefinition)schema.Types["Category"];
+        var categoryIdFieldMetadata = categoryType.Fields["id"].GetSourceFieldMetadata();
+        var bookCategoryType = (MutableObjectTypeDefinition)schema.Types["BookCategory"];
+        var bookCategoryIdFieldMetadata = bookCategoryType.Fields["id"].GetSourceFieldMetadata();
+        var bookCategoryCountFieldMetadata = bookCategoryType.Fields["count"].GetSourceFieldMetadata();
+
+        // assert
+        Assert.True(productIdFieldMetadata?.IsKeyField);
+        Assert.True(productIdFieldMetadata?.IsShareable);
+        Assert.True(productCategoryFieldMetadata?.IsKeyField);
+        Assert.True(productCategoryFieldMetadata?.IsShareable);
+        Assert.True(productSkuFieldMetadata?.IsKeyField);
+        Assert.True(productSkuFieldMetadata?.IsShareable);
+        Assert.True(productAlreadyShareableFieldMetadata?.IsKeyField);
+        Assert.True(productAlreadyShareableFieldMetadata?.IsShareable);
+        Assert.True(productExternalFieldMetadata?.IsKeyField);
+        Assert.False(productExternalFieldMetadata?.IsShareable);
+        Assert.False(productNonKeyFieldMetadata?.IsKeyField);
+        Assert.False(productNonKeyFieldMetadata?.IsShareable);
+        Assert.True(categoryIdFieldMetadata?.IsKeyField);
+        Assert.True(categoryIdFieldMetadata?.IsShareable);
+        Assert.False(bookCategoryIdFieldMetadata?.IsKeyField);
+        Assert.True(bookCategoryIdFieldMetadata?.IsShareable);
+        Assert.False(bookCategoryCountFieldMetadata?.IsKeyField);
+        Assert.True(bookCategoryCountFieldMetadata?.IsShareable);
+    }
+}