@Composable
fun Hello() {
    Text(text = "Hello Compose!")
}

@Composable
fun Hello() {
    var name = "Compose"
    Text(text = "Hello $name!")
    TextField(
        value = name,
        onValueChanged = { name = it }
    )
}

@Composable
fun Hello() {
    var name by mutableStateOf("Compose")
    Text(text = "Hello ${name}!")
    TextField(
        value = name,
        onValueChanged = { name = it }
    )
}

@Composable
fun Hello() {
    val name by remember { mutableStateOf("Compose") }
    Text(text = "Hello ${name}!")
    TextField(
        value = name,
        onValueChanged = { name = it }
    )
}

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            val viewModel: MainViewModel = viewModel()
            MyApp(viewModel.user)
        }
    }
}
@Composable
fun MyApp(user: User) {
    UserWidget(user)
}
@Composable
fun UserWidget(user: User) {
    Text(text = user.name)
}

val ActiveUser = compositionLocalOf<User> { error("No active user found!") }
class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            val viewModel: MainViewModel = viewModel()
            CompositionLocalProvider(ActiveUser provides viewModel.user) {
                MyApp()
            }
        }
    }
}
@Composable
fun MyApp() {
    UserWidget()
}
@Composable
fun UserWidget() {
    val user = ActiveUser.current
    Text(text = user.name)
}

data class Localization(
    val locale: Locale,
    val strings: MutableMap<String, String> = mutableMapOf()
)

internal val defaultLocalization: Localization = Localization(Locale.ENGLISH)
private val supportedLocales: MutableSet<Locale> = mutableSetOf()
private val localizationMap = hashMapOf<Locale, Localization>()
fun registerSupportedLocales(vararg locales: Locale): Set<Locale> {
    locales.filter { it != Locale.ENGLISH }
        .forEach {
            if (supportedLocales.add(it)) {
                registerLocalizationForLocale(it)
            }
        }
    return supportedLocales + Locale.ENGLISH
}
private fun registerLocalizationForLocale(locale: Locale) {
    localizationMap[locale] = Localization(locale)
}

fun Translatable(name: String, defaultValue: String, localeToValue: () -> Map<Locale, String>): Localization.() -> String {
    defaultLocalization.strings[name] = defaultValue
    for ((locale, value) in localeToValue().entries) {
        val localization = localizationMap[locale] ?: throw RuntimeException("There is no locale $locale")
        localization.strings[name] = value
    }
    return fun Localization.(): String {
        return this.strings[name] ?: defaultLocalization.strings[name] ?: throw RuntimeException("There is no string called $name in localization $this")
    }
}
fun NonTranslatable(name: String, defaultValue: String): Localization.() -> String {
    defaultLocalization.strings[name] = defaultValue
    return fun Localization.(): String {
        return defaultLocalization.strings[name] ?: throw RuntimeException("There is no string called $name in localization default")
    }
}

val LocalLocalization = compositionLocalOf { defaultLocalization }

object Vocabulary {
    @Composable
    @get:ReadOnlyComposable
    val localization: Localization get() = LocalLocalization.current
}

@Composable
fun Localization(locale: Locale, content: @Composable () -> Unit) {
    CompositionLocalProvider(
        LocalLocalization provides (localizationMap[locale] ?: defaultLocalization),
        children = content
    )
}

val RUSSIAN = Locale("ru")
val TATAR = Locale("tt")
val supportedLocalesNow = registerSupportedLocales(RUSSIAN, TATAR)

val hello = Translatable("hello", "Hello!") {
    hashMapOf(
        RUSSIAN to "Привет!",
        TATAR to "Исәнме!"
    )
}
val nonTrans = NonTranslatable("format", "%1\$d:%2\$02d")

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            Localization(locale = TATAR /*smth from supportedLocalesNow*/) {
                val localization = Vocabulary.localization
                Text(text = localization.hello())
                Text(text = localization.nonTrans().format(20, 9))
            }
        }
    }
}