Re-copy the prefab headers when a header changes

PreparePrefabHeadersTask declared only the directory paths it copies
from, so Gradle found it up to date after a header under them changed
and the prefab package every app and library compiles against kept the
old header. The headers it copies are now its input files, read through
the same file trees the copy uses, and each library's folder is rebuilt
from scratch so a removed header leaves no copy behind.

Author: YevheniiKotyrlo

packages/gradle-plugin/react-native-gradle-plugin/src/main/kotlin/com/facebook/react/tasks/internal/PreparePrefabHeadersTask.kt

@@ -12,10 +12,14 @@ import java.io.File
 import javax.inject.Inject
 import org.gradle.api.DefaultTask
 import org.gradle.api.file.DirectoryProperty
+import org.gradle.api.file.FileCollection
 import org.gradle.api.file.FileSystemOperations
+import org.gradle.api.file.FileTree
 import org.gradle.api.file.RegularFile
+import org.gradle.api.model.ObjectFactory
 import org.gradle.api.provider.ListProperty
 import org.gradle.api.tasks.Input
+import org.gradle.api.tasks.InputFiles
 import org.gradle.api.tasks.OutputDirectory
 import org.gradle.api.tasks.TaskAction
 
@@ -35,44 +39,64 @@ abstract class PreparePrefabHeadersTask : DefaultTask() {
 
   @get:OutputDirectory abstract val outputDir: DirectoryProperty
 
+  @get:InputFiles
+  val headers: FileCollection
+    get() =
+        objects
+            .fileCollection()
+            .from(
+                input.map { entries ->
+                  entries.flatMap { (_, pathToPrefixCouples) ->
+                    pathToPrefixCouples.map { (headerPath, _) -> headersUnder(headerPath) }
+                  }
+                }
+            )
+
   @get:Inject abstract val fs: FileSystemOperations
 
+  @get:Inject abstract val objects: ObjectFactory
+
   @TaskAction
   fun taskAction() {
     input.get().forEach { (libraryName, pathToPrefixCouples) ->
       val outputFolder: RegularFile = outputDir.file(libraryName).get()
+      fs.delete { deleteSpec -> deleteSpec.delete(outputFolder) }
       pathToPrefixCouples.forEach { (headerPath, headerPrefix) ->
         fs.copy { copySpec ->
-          copySpec.from(headerPath)
-          copySpec.include("**/*.h")
-          copySpec.exclude("**/*.cpp")
-          copySpec.exclude("**/*.txt")
-          // We don't want to copy all the boost headers as they are 250Mb+
-          copySpec.include("boost/config.hpp")
-          copySpec.include("boost/config/**/*.hpp")
-          copySpec.include("boost/core/*.hpp")
-          copySpec.include("boost/detail/workaround.hpp")
-          copySpec.include("boost/operators.hpp")
-          copySpec.include("boost/preprocessor/**/*.hpp")
-          // Headers needed for exposing rrc_text and rrc_textinput
-          copySpec.include("boost/container_hash/**/*.hpp")
-          copySpec.include("boost/detail/**/*.hpp")
-          copySpec.include("boost/intrusive/**/*.hpp")
-          copySpec.include("boost/iterator/**/*.hpp")
-          copySpec.include("boost/move/**/*.hpp")
-          copySpec.include("boost/mpl/**/*.hpp")
-          copySpec.include("boost/mp11/**/*.hpp")
-          copySpec.include("boost/describe/**/*.hpp")
-          copySpec.include("boost/type_traits/**/*.hpp")
-          copySpec.include("boost/utility/**/*.hpp")
-          copySpec.include("boost/assert.hpp")
-          copySpec.include("boost/static_assert.hpp")
-          copySpec.include("boost/cstdint.hpp")
-          copySpec.include("boost/utility.hpp")
-          copySpec.include("boost/version.hpp")
+          copySpec.from(headersUnder(headerPath))
           copySpec.into(File(outputFolder.asFile, headerPrefix))
         }
       }
     }
   }
+
+  private fun headersUnder(headerPath: String): FileTree =
+      objects.fileTree().from(headerPath).matching { patterns ->
+        patterns.include("**/*.h")
+        patterns.exclude("**/*.cpp")
+        patterns.exclude("**/*.txt")
+        // We don't want to copy all the boost headers as they are 250Mb+
+        patterns.include("boost/config.hpp")
+        patterns.include("boost/config/**/*.hpp")
+        patterns.include("boost/core/*.hpp")
+        patterns.include("boost/detail/workaround.hpp")
+        patterns.include("boost/operators.hpp")
+        patterns.include("boost/preprocessor/**/*.hpp")
+        // Headers needed for exposing rrc_text and rrc_textinput
+        patterns.include("boost/container_hash/**/*.hpp")
+        patterns.include("boost/detail/**/*.hpp")
+        patterns.include("boost/intrusive/**/*.hpp")
+        patterns.include("boost/iterator/**/*.hpp")
+        patterns.include("boost/move/**/*.hpp")
+        patterns.include("boost/mpl/**/*.hpp")
+        patterns.include("boost/mp11/**/*.hpp")
+        patterns.include("boost/describe/**/*.hpp")
+        patterns.include("boost/type_traits/**/*.hpp")
+        patterns.include("boost/utility/**/*.hpp")
+        patterns.include("boost/assert.hpp")
+        patterns.include("boost/static_assert.hpp")
+        patterns.include("boost/cstdint.hpp")
+        patterns.include("boost/utility.hpp")
+        patterns.include("boost/version.hpp")
+      }
 }