Generate strings from translation files

GenerateStrings.kt

package io.github.fourlastor

import com.squareup.javapoet.AnnotationSpec
import com.squareup.javapoet.FieldSpec
import com.squareup.javapoet.JavaFile
import com.squareup.javapoet.MethodSpec
import com.squareup.javapoet.TypeSpec
import org.gradle.api.DefaultTask
import org.gradle.api.file.DirectoryProperty
import org.gradle.api.tasks.InputDirectory
import org.gradle.api.tasks.OutputDirectory
import org.gradle.api.tasks.TaskAction
import java.util.Properties
import javax.lang.model.element.Modifier


abstract class GenerateStrings : DefaultTask() {

    companion object {
        private val PROBLEMATIC_NAMES = setOf(
            "return",
            "default",
            "hakamo-o",
            "jangmo-o",
            "ho-oh",
            "porygon-z",
            "kommo-o",
            "switch",
            "10_000_000_volt_thunderbolt"
        )
    }

    @get:InputDirectory
    abstract val propertiesDir: DirectoryProperty

    @get:OutputDirectory
    abstract val destination: DirectoryProperty

    init {
        destination.convention(project.layout.buildDirectory.dir("generated/sources/strings"))
    }

    @TaskAction
    fun run() {
        val propertiesDir = propertiesDir.asFile.get()
        val propertiesFiles = propertiesDir.walkTopDown()
            .filter { it.isFile && it.extension == "properties" && !it.name.contains("_", ignoreCase = true) }
        val stringsSpec = TypeSpec.classBuilder("R")
            .addAnnotation(AnnotationSpec.builder(SuppressWarnings::class.java).addMember("value", "\$S", "unused").build())
            .addMethod(MethodSpec.constructorBuilder().addModifiers(Modifier.PRIVATE).build())
            .addModifiers(Modifier.PUBLIC, Modifier.FINAL)
            .apply {
                for (propertiesFile in propertiesFiles) {
                    addType(
                        TypeSpec.classBuilder( propertiesFile.getName().replace(".properties", ""))
                            .addMethod(MethodSpec.constructorBuilder().addModifiers(Modifier.PRIVATE).build())
                            .addModifiers(Modifier.PUBLIC, Modifier.FINAL, Modifier.STATIC)
                            .apply {
                                val properties = Properties().apply { load(propertiesFile.reader()) }
                                for (propertyName in properties.propertyNames()) {
                                    if (propertyName in PROBLEMATIC_NAMES) {
                                        continue
                                    }
                                    addField(FieldSpec.builder(
                                        String::class.java, propertyName.toString(), Modifier.PUBLIC, Modifier.STATIC, Modifier.FINAL
                                    ).initializer("\$S", propertyName.toString())
                                        .build())
                                }
                            }
                            .build()
                    )
                }
            }
            .build()
        val outputFile = destination.asFile.get().resolve("com/pkmngen/game/R.java")
        if (!outputFile.exists()) {
            outputFile.getParentFile().mkdirs()
        }
        outputFile.writer().use {
            JavaFile.builder("io.github.fourlastor", stringsSpec).build()
                .writeTo(it)
        }
    }
}