fix: Fix Android build issues where dependent libraries can't link RNWC (#252)

* first version of fix

* mvoe to fix-prefab

Author: hannojg

android/build.gradle

@@ -51,6 +51,7 @@ def reactNativeArchitectures() {
 }
 
 apply plugin: "com.android.library"
+apply from: "./gradle/fix-prefab.gradle"
 
 if (isNewArchitectureEnabled()) {
     apply plugin: "com.facebook.react"

android/gradle/fix-prefab.gradle

@@ -0,0 +1,51 @@
+tasks.configureEach { task ->
+  // Make sure that we generate our prefab publication file only after having built the native library
+  // so that not a header publication file, but a full configuration publication will be generated, which
+  // will include the .so file
+
+  def prefabConfigurePattern = ~/^prefab(.+)ConfigurePackage$/
+  def matcher = task.name =~ prefabConfigurePattern
+  if (matcher.matches()) {
+    def variantName = matcher[0][1]
+    task.outputs.upToDateWhen { false }
+    task.dependsOn("externalNativeBuild${variantName}")
+  }
+}
+
+afterEvaluate {
+  def abis = reactNativeArchitectures()
+  rootProject.allprojects.each { proj ->
+    if (proj === rootProject) return
+
+    def dependsOnThisLib = proj.configurations.findAll { it.canBeResolved }.any { config ->
+      config.dependencies.any { dep ->
+        dep.group == project.group && dep.name == project.name
+      }
+    }
+    if (!dependsOnThisLib && proj != project) return
+
+    if (!proj.plugins.hasPlugin('com.android.application') && !proj.plugins.hasPlugin('com.android.library')) {
+      return
+    }
+
+    def variants = proj.android.hasProperty('applicationVariants') ? proj.android.applicationVariants : proj.android.libraryVariants
+    // Touch the prefab_config.json files to ensure that in ExternalNativeJsonGenerator.kt we will re-trigger the prefab CLI to
+    // generate a libnameConfig.cmake file that will contain our native library (.so).
+    // See this condition: https://cs.android.com/android-studio/platform/tools/base/+/mirror-goog-studio-main:build-system/gradle-core/src/main/java/com/android/build/gradle/tasks/ExternalNativeJsonGenerator.kt;l=207-219?q=createPrefabBuildSystemGlue
+    variants.all { variant ->
+      def variantName = variant.name
+      abis.each { abi ->
+        def searchDir = new File(proj.projectDir, ".cxx/${variantName}")
+        if (!searchDir.exists()) return
+        def matches = []
+        searchDir.eachDir { randomDir ->
+          def prefabFile = new File(randomDir, "${abi}/prefab_config.json")
+          if (prefabFile.exists()) matches << prefabFile
+        }
+        matches.each { prefabConfig ->
+          prefabConfig.setLastModified(System.currentTimeMillis())
+        }
+      }
+    }
+  }
+}