Extract languages provider into Gradle plugin

Author: valldrac

app/build.gradle.kts

@@ -8,6 +8,7 @@ plugins {
   id("kotlin-parcelize")
   id("com.squareup.wire")
   id("molly")
+  id("signal-locales")
 }
 
 val canonicalVersionCode = 1641
@@ -18,9 +19,7 @@ val mollyRevision = 1
 
 // MOLLY: Use default debug keystore generated by Android Studio at $HOME/.android/debug.keystore
 
-val languagesProvider = providers.of(LanguageListValueSource::class.java) {
-  parameters.resDir.set(layout.projectDirectory.dir("src/main/res"))
-}
+val languagesProvider = supportedLocales.fromResDir(layout.projectDirectory.dir("src/main/res"))
 
 val languagesForBuildConfigProvider = languagesProvider.map { languages ->
   languages.joinToString(separator = ", ") { language -> "\"$language\"" }

build-logic/plugins/src/main/java/signal-locales.gradle.kts

@@ -0,0 +1,72 @@
+import org.gradle.api.Project
+import org.gradle.api.file.DirectoryProperty
+import org.gradle.api.file.RegularFileProperty
+import org.gradle.api.provider.Provider
+import org.gradle.api.provider.ValueSource
+import org.gradle.api.provider.ValueSourceParameters
+import org.gradle.api.tasks.InputDirectory
+import org.gradle.api.tasks.InputFile
+import org.gradle.api.tasks.Optional
+import org.gradle.api.tasks.PathSensitive
+import org.gradle.api.tasks.PathSensitivity
+import java.io.File
+import java.util.Properties
+import kotlin.apply
+
+abstract class SupportedLocalesExtension(private val project: Project) {
+  fun fromResDir(resDir: Directory): Provider<List<String>> {
+    return project.providers.of(LanguageListValueSource::class.java) {
+      parameters.resDir.set(resDir)
+    }
+  }
+}
+
+project.extensions.create("supportedLocales", SupportedLocalesExtension::class.java, project)
+
+abstract class LanguageListValueSource : ValueSource<List<String>, LanguageListValueSource.Params> {
+  interface Params : ValueSourceParameters {
+    @get:InputDirectory
+    @get:PathSensitive(PathSensitivity.RELATIVE)
+    val resDir: DirectoryProperty
+  }
+
+  override fun obtain(): List<String> {
+    // In API 35, language codes for Hebrew and Indonesian now use the ISO 639-1 code ("he" and "id").
+    // However, the value resources still only support the outdated code ("iw" and "in") so we have
+    // to manually indicate that we support these languages.
+    val updatedLanguageCodes = listOf("he", "id")
+
+    val resRoot = parameters.resDir.asFile.get()
+
+    val languages = resRoot
+      .walkTopDown()
+      .filter { it.isFile && it.name == "strings.xml" }
+      .mapNotNull { stringFile -> stringFile.parentFile?.name }
+      .map { valuesFolderName -> valuesFolderName.removePrefix("values-") }
+      .filter { valuesFolderName -> valuesFolderName != "values" }
+      .map { languageCode -> languageCode.replace("-r", "_") }
+      .toList()
+      .distinct()
+      .sorted()
+
+    return languages + updatedLanguageCodes + "en"
+  }
+}
+
+abstract class PropertiesFileValueSource : ValueSource<Properties?, PropertiesFileValueSource.Params> {
+  interface Params : ValueSourceParameters {
+    @get:InputFile
+    @get:Optional
+    @get:PathSensitive(PathSensitivity.RELATIVE)
+    val file: RegularFileProperty
+  }
+
+  override fun obtain(): Properties? {
+    val f: File = parameters.file.asFile.get()
+    if (!f.exists()) return null
+
+    return Properties().apply {
+      f.inputStream().use { load(it) }
+    }
+  }
+}