Navigator index multi-language render JSON support

Adds support for the navigator index to process render JSON that
contains variant overrides by applying patches for the languages in
which the page is available.

rdar://83398083

Author: franklinsch

Sources/SwiftDocC/Indexing/Navigator/NavigatorIndex.swift

@@ -707,6 +707,22 @@ extension NavigatorIndex {
                 multiCuratedUnvisited.remove(normalizedIdentifier)
             }
 
+            // Check if the render node has a variant for Objective-C
+            let objCVariantTrait = renderNode.variantOverrides?.values.flatMap({ $0.traits }).first { trait in
+                switch trait {
+                case .interfaceLanguage(let language):
+                    return InterfaceLanguage.from(string: language) == .objc
+                }
+            }
+            
+            // In case we have a variant for Objective-C, apply the variant and re-index the render node.
+            if let variantToApply = objCVariantTrait {
+                let encodedRenderNode = try renderNode.encodeToJSON()
+                let transformedData = try RenderNodeVariantOverridesApplier().applyVariantOverrides(in: encodedRenderNode, for: [variantToApply])
+                let variantRenderNode = try RenderNode.decode(fromJSON: transformedData)
+                try index(renderNode: variantRenderNode)
+            }
+            
             // Bump the nodes counter.
             counter += 1
         }

Tests/SwiftDocCTests/Indexing/NavigatorIndexTests.swift

@@ -406,6 +406,38 @@ Root
         assertEqualDumps(results.first ?? "", try testTree(named: "testNavigatorIndexGeneration"))
     }
 
+    func testNavigatorIndexGenerationVariantsPayload() throws {
+        let jsonFile = Bundle.module.url(forResource: "Variant-render-node", withExtension: "json", subdirectory: "Test Resources")!
+        let jsonData = try Data(contentsOf: jsonFile)
+        
+        let targetURL = URL(fileURLWithPath: NSTemporaryDirectory()).appendingPathComponent(UUID().uuidString)
+        let builder = NavigatorIndex.Builder(outputURL: targetURL, bundleIdentifier: testBundleIndetifier, sortRootChildrenByName: true, groupByLanguage: true)
+        builder.setup()
+        
+        let renderNode = try XCTUnwrap(RenderJSONDecoder.makeDecoder().decode(RenderNode.self, from: jsonData))
+        try builder.index(renderNode: renderNode)
+        
+        builder.finalize()
+        
+        let navigatorIndex = builder.navigatorIndex!
+        
+        assertUniqueIDs(node: navigatorIndex.navigatorTree.root)
+        assertEqualDumps(navigatorIndex.navigatorTree.root.dumpTree(), """
+        [Root]
+        ┣╸Objective-C
+        ┃ ┗╸My Article in Objective-C
+        ┃   ┣╸Task Group 1
+        ┃   ┣╸Task Group 2
+        ┃   ┗╸Task Group 3
+        ┗╸Swift
+          ┗╸My Article
+            ┣╸Task Group 1
+            ┣╸Task Group 2
+            ┗╸Task Group 3
+        """)
+        try FileManager.default.removeItem(at: targetURL)
+    }
+    
     func testNavigatorIndexUsingPageTitleGeneration() throws {
         let (bundle, context) = try testBundleAndContext(named: "TestBundle")
         let renderContext = RenderContext(documentationContext: context, bundle: bundle)

Tests/SwiftDocCTests/Test Resources/Variant-render-node.json

@@ -0,0 +1,134 @@
+{
+  "abstract": [],
+  "documentVersion": 0,
+  "identifier": {
+    "interfaceLanguage": "swift",
+    "url": "doc://org.swift.docc/documentation/mykit/my-article"
+  },
+  "kind": "article",
+  "metadata": {
+    "modules": [
+      {
+        "name": "mykit"
+      }
+    ],
+    "role": "article",
+    "roleHeading": "Article",
+    "title": "My Article"
+  },
+  "primaryContentSections": [],
+  "references": {
+    "doc://org.swift.docc/documentation/mykit": {
+      "identifier": "doc://org.swift.docc/documentation/mykit",
+      "kind": "symbol",
+      "role": "collection",
+      "title": "mykit",
+      "type": "topic",
+      "url": "/documentation/mykit"
+    },
+    "doc://org.swift.docc/documentation/mykit/my-article": {
+      "abstract": [],
+      "identifier": "doc://org.swift.docc/documentation/mykit/my-article",
+      "kind": "article",
+      "role": "article",
+      "title": "My Article",
+      "type": "topic",
+      "url": "/documentation/mykit/my-article"
+    },
+    "doc://org.swift.docc/documentation/mykit/myclass": {
+      "abstract": [],
+      "fragments": [
+        {
+          "kind": "text",
+          "text": "class "
+        },
+        {
+          "kind": "identifier",
+          "text": "myclass"
+        }
+      ],
+      "identifier": "doc://org.swift.docc/documentation/mykit/myclass",
+      "kind": "symbol",
+      "role": "symbol",
+      "title": "myclass",
+      "type": "topic",
+      "url": "/documentation/mykit/myclass"
+    }
+  },
+  "schemaVersion": {
+    "major": 0,
+    "minor": 1,
+    "patch": 0
+  },
+  "sections": [],
+  "seeAlsoSections": [],
+  "topicSections": [
+    {
+      "anchor": "2959524",
+      "identifiers": [
+        "doc://org.swift.docc/documentation/mykit/myclass"
+      ],
+      "kind": "taskGroup",
+      "title": "Task Group 1"
+    },
+    {
+      "anchor": "2958803",
+      "identifiers": [
+        "doc://org.swift.docc/documentation/mykit/myclass"
+      ],
+      "kind": "taskGroup",
+      "title": "Task Group 2"
+    },
+    {
+      "anchor": "3016821",
+      "identifiers": [
+        "doc://org.swift.docc/documentation/mykit/myclass"
+      ],
+      "kind": "taskGroup",
+      "title": "Task Group 3"
+    }
+  ],
+  "variants": [
+    {
+      "paths": [
+        "documentation/mykit/my-article"
+      ],
+      "traits": [
+        {
+          "interfaceLanguage": "objc"
+        }
+      ]
+    },
+    {
+      "paths": [
+        "documentation/mykit/my-article"
+      ],
+      "traits": [
+        {
+          "interfaceLanguage": "swift"
+        }
+      ]
+    }
+  ],
+  "variantOverrides": [
+    {
+      "patch": [
+        {
+          "op": "replace",
+          "path": "/metadata/title",
+          "value": "My Article in Objective-C"
+        },
+        {
+          "op": "replace",
+          "path": "/identifier/interfaceLanguage",
+          "value": "objc"
+        }
+      ],
+      "traits": [
+        {
+          "interfaceLanguage": "objc"
+        }
+      ]
+    }
+  ]
+}