set system language as default language (#386)

desktop/app/src/main/kotlin/com/abdownloadmanager/desktop/pages/settings/SettingsComponent.kt

@@ -318,26 +318,36 @@ fun themeConfig(
 fun languageConfig(
     languageManager: LanguageManager,
     scope: CoroutineScope,
-): EnumConfigurable<LanguageInfo> {
-    val currentLanguageName = languageManager.selectedLanguage
-    val allLanguages = languageManager.languageList
+): EnumConfigurable<LanguageInfo?> {
+    val currentLanguageName = languageManager.selectedLanguageInStorage
+    val allLanguages = languageManager.languageList.value
     return EnumConfigurable(
         title = Res.string.settings_language.asStringSource(),
         description = "".asStringSource(),
         backedBy = createMutableStateFlowFromStateFlow(
-            flow = currentLanguageName.mapStateFlow { l ->
-                allLanguages.value.find {
-                    it.toLocaleString() == l
-                } ?: LanguageManager.DefaultLanguageInfo
+            flow = currentLanguageName.mapStateFlow { language ->
+                language?.let {
+                    allLanguages.find {
+                        it.toLocaleString() == language
+                    }
+                }
             },
             updater = { languageInfo ->
                 languageManager.selectLanguage(languageInfo)
             },
             scope = scope,
         ),
-        possibleValues = allLanguages.value,
+        possibleValues = listOf(null).plus(allLanguages),
         describe = {
-            it.nativeName.asStringSource()
+            val isAuto = it == null
+            val language = it ?: languageManager.systemLanguageOrDefault
+            val languageName = language.nativeName
+            if (isAuto) {
+                // always use english here!
+                "System ($languageName)".asStringSource()
+            } else {
+                languageName.asStringSource()
+            }
         },
     )
 }

desktop/app/src/main/kotlin/com/abdownloadmanager/desktop/storage/AppSettingsStorage.kt

@@ -14,7 +14,7 @@ import java.io.File
 @Serializable
 data class AppSettingsModel(
     val theme: String = "dark",
-    val language: String = "en",
+    val language: String? = null,
     val uiScale: Float? = null,
     val mergeTopBarWithTitleBar: Boolean = false,
     val threadCount: Int = 8,
@@ -95,7 +95,7 @@ data class AppSettingsModel(
         override fun set(source: MapConfig, focus: AppSettingsModel): MapConfig {
             return source.apply {
                 put(Keys.theme, focus.theme)
-                put(Keys.language, focus.language)
+                putNullable(Keys.language, focus.language)
                 putNullable(Keys.uiScale, focus.uiScale)
                 put(Keys.mergeTopBarWithTitleBar, focus.mergeTopBarWithTitleBar)
                 put(Keys.threadCount, focus.threadCount)
@@ -127,6 +127,15 @@ private val uiScaleLens: Lens<AppSettingsModel, Float?>
             s.copy(uiScale = f)
         }
     )
+private val languageLens: Lens<AppSettingsModel, String?>
+    get() = Lens(
+        get = {
+            it.language
+        },
+        set = { s, f ->
+            s.copy(language = f)
+        }
+    )
 
 class AppSettingsStorage(
     settings: DataStore<MapConfig>,
@@ -134,7 +143,7 @@ class AppSettingsStorage(
     ConfigBaseSettingsByMapConfig<AppSettingsModel>(settings, AppSettingsModel.ConfigLens),
     LanguageStorage {
     var theme = from(AppSettingsModel.theme)
-    override val selectedLanguage = from(AppSettingsModel.language)
+    override val selectedLanguage = from(languageLens)
     var uiScale = from(uiScaleLens)
     var mergeTopBarWithTitleBar = from(AppSettingsModel.mergeTopBarWithTitleBar)
     val threadCount = from(AppSettingsModel.threadCount)
@@ -152,4 +161,4 @@ class AppSettingsStorage(
     val browserIntegrationPort = from(AppSettingsModel.browserIntegrationPort)
     val trackDeletedFilesOnDisk = from(AppSettingsModel.trackDeletedFilesOnDisk)
     val useBitsForSpeed = from(AppSettingsModel.useBitsForSpeed)
-}
+}

shared/compose-utils/src/main/kotlin/ir/amirab/util/compose/localizationmanager/LanguageManager.kt

@@ -4,6 +4,7 @@ import androidx.compose.runtime.Immutable
 import ir.amirab.util.compose.contants.FILE_PROTOCOL
 import ir.amirab.util.compose.contants.RESOURCE_PROTOCOL
 import ir.amirab.util.flow.mapStateFlow
+import ir.amirab.util.flow.mapTwoWayStateFlow
 import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.asStateFlow
 import okio.FileSystem
@@ -11,14 +12,24 @@ import okio.Path.Companion.toPath
 import okio.buffer
 import java.io.InputStream
 import java.net.URI
-import java.util.Properties
+import java.util.*
 
 class LanguageManager(
     private val storage: LanguageStorage,
 ) {
     private val _languageList: MutableStateFlow<List<LanguageInfo>> = MutableStateFlow(emptyList())
     val languageList = _languageList.asStateFlow()
-    val selectedLanguage = storage.selectedLanguage
+    val systemLanguageOrDefault: LanguageInfo by lazy {
+        getSystemLanguageIfWeCanUse()
+    }
+    val selectedLanguageInStorage = storage.selectedLanguage
+    val selectedLanguage = storage.selectedLanguage.mapStateFlow {
+        it ?: systemLanguageOrDefault.toLocaleString()
+    }
+
+    //    val selectedLanguageInfo = selectedLanguage.mapStateFlow {
+//        bestLanguageInfo(it)
+//    }
     val isRtl = selectedLanguage.mapStateFlow { selectedLanguage ->
         rtlLanguages.any { selectedLanguage.startsWith(it) }
     }
@@ -28,11 +39,11 @@ class LanguageManager(
         instance = this
     }
 
-    fun selectLanguage(languageInfo: LanguageInfo) {
+    fun selectLanguage(languageInfo: LanguageInfo?) {
 //        ensure that language info is in the list!
 //        val languageInfo = languageList.value.find { it == languageInfo }
 //        selectedLanguage.value = (languageInfo ?: DefaultLanguageInfo).toLocaleString()
-        selectedLanguage.value = languageInfo.toLocaleString()
+        selectedLanguageInStorage.value = languageInfo?.toLocaleString()
     }
 
     fun getMessage(key: String): String {
@@ -42,7 +53,7 @@ class LanguageManager(
     }
 
     private fun getRequestedLanguage(): String {
-        return selectedLanguage.value
+        return selectedLanguage.value ?: systemLanguageOrDefault.toLocaleString()
     }
 
     @Volatile
@@ -74,6 +85,10 @@ class LanguageManager(
         }
     }
 
+    /**
+     * Find the best language info for the given locale.
+     * the returned language is guaranteed to be available. (at least [DefaultLanguageInfo])
+     */
     private fun bestLanguageInfo(locale: String): LanguageInfo {
         return languageList.value.find {
             it.toLocaleString() == locale
@@ -122,6 +137,11 @@ class LanguageManager(
             }
     }
 
+    private fun getSystemLanguageIfWeCanUse(): LanguageInfo {
+        val systemLocale = getSystemLocale().toString()
+        return bestLanguageInfo(systemLocale)
+    }
+
     companion object {
         lateinit var instance: LanguageManager
         private const val LOCALES_PATH = "/com/abdownloadmanager/resources/locales"
@@ -130,10 +150,8 @@ class LanguageManager(
                 languageCode = "en",
                 countryCode = "US",
             )
-            LanguageInfo(
-                locale = locale,
-                nativeName = "English",
-                path = URI("$RESOURCE_PROTOCOL:$LOCALES_PATH/${locale}.properties")
+            locale.toLanguageInfo(
+                path = "$RESOURCE_PROTOCOL:$LOCALES_PATH/${locale}.properties",
             )
         }
 
@@ -204,3 +222,11 @@ data class LanguageInfo(
         return locale.toString()
     }
 }
+
+private fun getSystemLocale(): MyLocale {
+    val javaSystemLocale = Locale.getDefault(Locale.Category.DISPLAY)
+    return MyLocale(
+        languageCode = javaSystemLocale.language,
+        countryCode = javaSystemLocale.country,
+    )
+}

shared/compose-utils/src/main/kotlin/ir/amirab/util/compose/localizationmanager/LanguageStorage.kt

@@ -3,5 +3,6 @@ package ir.amirab.util.compose.localizationmanager
 import kotlinx.coroutines.flow.MutableStateFlow
 
 interface LanguageStorage {
-    val selectedLanguage: MutableStateFlow<String>
-}
+    // null means auto
+    val selectedLanguage: MutableStateFlow<String?>
+}