resolverFactory

@BConfiguration
object MyCustomLocalizationResolverProvider {
    // The parameter resolver, which will be created once per parameter
    class MyCustomLocalizationResolver(
        private val localizationService: LocalizationService,
        private val guildSettingsService: GuildSettingsService,
        private val bundleName: String,
        private val prefix: String?
    ) : ClassParameterResolver<MyCustomLocalizationResolver, MyCustomLocalization>(MyCustomLocalization::class),
        ICustomResolver<MyCustomLocalizationResolver, MyCustomLocalization> {

        // Called when a command is used
        override suspend fun resolveSuspend(executable: Executable, event: Event): MyCustomLocalization {
            return if (event is Interaction) {
                val guild = event.guild
                    ?: throw IllegalStateException("Cannot get localization outside of guilds")
                // The root localization file not existing isn't an issue on production
                val localization = localizationService.getInstance(bundleName, guildSettingsService.getGuildLocale(guild.idLong))
                    ?: throw IllegalArgumentException("No root bundle exists for '$bundleName'")

                // Return resolved object
                MyCustomLocalization(localization, prefix)
            } else {
                throw UnsupportedOperationException("Unsupported event: ${event.javaClass.simpleNestedName}")
            }
        }
    }

    // Service factory returning a resolver factory
    // The returned factory is used on each command/handler parameter of type "MyCustomLocalization",
    // which is the same type as what MyCustomLocalizationResolver returns
    @ResolverFactory
    fun myCustomLocalizationResolverProvider(localizationService: LocalizationService, guildSettingsService: GuildSettingsService) = resolverFactory { parameter ->
        // Find @LocalizationBundle on the parameter
        val bundle = parameter.parameter.findAnnotation<LocalizationBundle>()
            ?: throw IllegalArgumentException("Parameter ${parameter.parameter} must be annotated with LocalizationBundle")

        // Return our resolver for that parameter
        MyCustomLocalizationResolver(localizationService, guildSettingsService, bundle.value, bundle.prefix.nullIfBlank())
    }
}