Prepare for App Check

build-android/app/src/main/AndroidManifest.xml

@@ -9,7 +9,7 @@
         android:supportsRtl="true"
         android:theme="@style/AppTheme"
         android:networkSecurityConfig="@xml/network_security_config">
-        <activity android:name="com.google.firebase.codelab.friendlychat.MainActivity"
+        <activity android:name=".MainActivity"
             android:exported="true">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />

build-android/build.gradle.kts

@@ -1,3 +1,8 @@
+import java.nio.file.Files
+import java.nio.file.Paths
+import kotlin.io.path.readText
+import kotlin.io.path.writeText
+
 // Top-level build file where you can add configuration options common to all sub-projects/modules.
 plugins {
     id("com.android.application") version "8.1.0" apply false
@@ -18,4 +23,51 @@ tasks {
     register("clean", Delete::class) {
         delete(rootProject.buildDir)
     }
+
+    register("rename") {
+        val applicationId = project.properties["applicationId"] as String?
+        val DEFAULT_APP_ID = "com.google.firebase.codelab.friendlychat"
+        val DEFAULT_DIRECTORY = appIdToPath(DEFAULT_APP_ID)
+
+        doFirst {
+            // Assert that an applicationId argument was passed
+            if (applicationId == null) {
+                throw IllegalArgumentException(
+                    "Please specify an applicationId when running this command:\n" +
+                            "./gradlew rename -PapplicationId=com.example.id"
+                )
+            }
+        }
+
+        doLast {
+            // Iterate through all files under DEFAULT_DIRECTORY
+            val defaultDirectoryFile = file(DEFAULT_DIRECTORY)
+            val absolutePath = Paths.get(defaultDirectoryFile.absolutePath)
+            Files.walk(absolutePath).forEach { path ->
+                val file = path.toFile()
+                if (file.isFile) {
+                    // Replace the default applicationId with the new one
+                    // For the package declaration and any relevant imports
+                    path.writeText(path.readText()
+                        .replace("(package|import)\\s+${DEFAULT_APP_ID}".toRegex(), "$1 $applicationId"))
+                }
+
+                // Copy file to new directory
+                val newDirectory = file(appIdToPath(applicationId!!))
+                val newFile = file("${newDirectory.absolutePath}/${file.relativeTo(defaultDirectoryFile)}")
+                file.copyTo(target = newFile)
+                // Delete original file
+                file.delete()
+            }
+
+            // Update applicationId and namespace in build.gradle.kts
+            with (file("app/build.gradle.kts").toPath()) {
+                writeText(
+                    readText().replace("(namespace|applicationId)\\s*=\\s*\"${DEFAULT_APP_ID}\"".toRegex(),
+                        "$1 = \"$applicationId\""))
+            }
+        }
+    }
 }
+
+fun appIdToPath(appId: String) = "app/src/main/java/${appId.replace(".", "/")}"