Create generic JSON migration helper

app/src/main/java/me/magnum/melonds/di/MigrationModule.kt

@@ -14,13 +14,17 @@ import me.magnum.melonds.domain.repositories.RomsRepository
 import me.magnum.melonds.domain.repositories.SettingsRepository
 import me.magnum.melonds.impl.RomIconProvider
 import me.magnum.melonds.migrations.*
-import me.magnum.melonds.migrations.helper.LayoutMigrationHelper
-import me.magnum.melonds.migrations.helper.RomMigrationHelper
+import me.magnum.melonds.migrations.helper.GenericJsonArrayMigrationHelper
 
 @Module
 @InstallIn(SingletonComponent::class)
 object MigrationModule {
 
+    @Provides
+    fun provideJsonArrayMigrationHelper(@ApplicationContext context: Context, gson: Gson): GenericJsonArrayMigrationHelper {
+        return GenericJsonArrayMigrationHelper(context, gson)
+    }
+
     @Provides
     fun provideMigration(
         @ApplicationContext context: Context,
@@ -30,7 +34,8 @@ object MigrationModule {
         settingsRepository: SettingsRepository,
         directoryAccessValidator: DirectoryAccessValidator,
         uriHandler: UriHandler,
-        gson: Gson
+        gson: Gson,
+        genericJsonArrayMigrationHelper: GenericJsonArrayMigrationHelper,
     ): Migrator {
 
         return Migrator(context, sharedPreferences).apply {
@@ -40,8 +45,8 @@ object MigrationModule {
             registerMigration(Migration16to17(romsRepository))
             registerMigration(Migration20to21(settingsRepository, romsRepository, directoryAccessValidator))
             registerMigration(Migration21to22(context, gson, uriHandler))
-            registerMigration(Migration24to25(RomMigrationHelper(context, gson), context))
-            registerMigration(Migration25to26(LayoutMigrationHelper(context, gson)))
+            registerMigration(Migration24to25(genericJsonArrayMigrationHelper, context))
+            registerMigration(Migration25to26(genericJsonArrayMigrationHelper))
         }
     }
 }

app/src/main/java/me/magnum/melonds/migrations/Migration24to25.kt

@@ -1,22 +1,26 @@
 package me.magnum.melonds.migrations
 
 import android.content.Context
-import me.magnum.melonds.migrations.helper.RomMigrationHelper
+import me.magnum.melonds.migrations.helper.GenericJsonArrayMigrationHelper
 import me.magnum.melonds.migrations.legacy.Rom22
-import me.magnum.melonds.migrations.legacy.RomDto25
 import me.magnum.melonds.migrations.legacy.RomConfigDto25
+import me.magnum.melonds.migrations.legacy.RomDto25
 import me.magnum.melonds.utils.RomProcessor
 
 class Migration24to25(
-    private val romMigrationHelper: RomMigrationHelper,
+    private val romMigrationHelper: GenericJsonArrayMigrationHelper,
     private val context: Context,
 ) : Migration {
 
+    companion object {
+        private const val ROM_DATA_FILE = "rom_data.json"
+    }
+
     override val from = 24
     override val to = 25
 
     override fun migrate() {
-        romMigrationHelper.migrateRoms(Rom22::class.java) { rom ->
+        romMigrationHelper.migrateJsonArrayData<Rom22, RomDto25>(ROM_DATA_FILE) { rom ->
             runCatching {
                 context.contentResolver.openInputStream(rom.uri)?.use {
                     RomProcessor.getRomMetadata(it.buffered())

app/src/main/java/me/magnum/melonds/migrations/Migration25to26.kt

@@ -4,19 +4,23 @@ import me.magnum.melonds.impl.dtos.layout.LayoutConfigurationDto
 import me.magnum.melonds.impl.dtos.layout.PositionedLayoutComponentDto
 import me.magnum.melonds.impl.dtos.layout.RectDto
 import me.magnum.melonds.impl.dtos.layout.UILayoutDto
-import me.magnum.melonds.migrations.helper.LayoutMigrationHelper
+import me.magnum.melonds.migrations.helper.GenericJsonArrayMigrationHelper
 import me.magnum.melonds.migrations.legacy.layout.LayoutConfiguration25
 import me.magnum.melonds.migrations.legacy.layout.UILayout25
 
 class Migration25to26(
-    private val layoutMigrationHelper: LayoutMigrationHelper,
+    private val layoutMigrationHelper: GenericJsonArrayMigrationHelper,
 ) : Migration {
 
+    companion object {
+        private const val LAYOUTS_DATA_FILE = "layouts.json"
+    }
+
     override val from = 25
     override val to = 26
 
     override fun migrate() {
-        layoutMigrationHelper.migrateLayouts(LayoutConfiguration25::class.java) {
+        layoutMigrationHelper.migrateJsonArrayData<LayoutConfiguration25, LayoutConfigurationDto>(LAYOUTS_DATA_FILE) {
             try {
                 LayoutConfigurationDto(
                     it.id,

app/src/main/java/me/magnum/melonds/migrations/helper/GenericJsonArrayMigrationHelper.kt

@@ -0,0 +1,48 @@
+package me.magnum.melonds.migrations.helper
+
+import android.content.Context
+import com.google.gson.Gson
+import com.google.gson.reflect.TypeToken
+import java.io.File
+import java.io.FileReader
+import java.io.OutputStreamWriter
+
+class GenericJsonArrayMigrationHelper(
+    private val context: Context,
+    private val gson: Gson,
+) {
+
+    inline fun <reified T, U> migrateJsonArrayData(jsonFile: String, noinline dataMapper: (T) -> U?) {
+        migrateJsonArrayData(jsonFile, T::class.java, dataMapper)
+    }
+
+    fun <T, U> migrateJsonArrayData(jsonFile: String, fromClass: Class<T>, dataMapper: (T) -> U?) {
+        val originalData = getOriginalData(jsonFile, fromClass)
+        val newData = originalData.mapNotNull { data ->
+            dataMapper(data)
+        }
+
+        saveNewData(jsonFile, newData)
+    }
+
+    private fun <T> getOriginalData(jsonFile: String, fromClass: Class<T>): List<T> {
+        val dataFile = File(context.filesDir, jsonFile)
+        if (!dataFile.isFile) {
+            return emptyList()
+        }
+
+        val dataListType = TypeToken.getParameterized(List::class.java, fromClass).type
+        return runCatching {
+            gson.fromJson<List<T>>(FileReader(dataFile), dataListType)
+        }.getOrElse { emptyList() }
+    }
+
+    private fun <U> saveNewData(jsonFile: String, data: List<U>) {
+        val dataFile = File(context.filesDir, jsonFile)
+
+        OutputStreamWriter(dataFile.outputStream()).use {
+            val json = gson.toJson(data)
+            it.write(json)
+        }
+    }
+}