i18nliner-kt | I18n made simple - for Kotlin | Internationalization library

class LanguageSupport(private val folder: String = "", private val lang: String) {
    private lateinit var currentLang: Json

    private val languageMutableStateFlow = MutableStateFlow(
        LanguageSupportState.LanguageInit
    )
    val languageStateFlow: StateFlow = languageMutableStateFlow

    init {
        loadJSON()
    }

    fun get(key: String): String {
        val value = currentLang[key]
        check(value != null) {
            throw Exception("key not found to load language definition")
        }
        return if (value is String) {
            value
        } else {
            throw Exception("value of key is not a string")
        }
    }

    fun get(key: String, vararg placeholders: String): String {
        val value = currentLang[key]
        check(value != null) {
            throw Exception("key not found to load language definition")
        }
        return if (value is String) {
            var finalValue: String = value
            for (item in placeholders) {
                finalValue = finalValue.replaceFirst(PLACEHOLDER, item)
            }
            finalValue
        } else {
            throw Exception("value of key is not a string")
        }
    }

    private fun loadJSON() {
        val xobj = XMLHttpRequest()
        xobj.overrideMimeType("application/json")
        xobj.open("GET", "${folder}test_${lang}.json", true)
        xobj.onreadystatechange = {

            if (xobj.readyState.toInt() == 4 && xobj.status.toInt() == 200) {
                // Required use of an anonymous callback
                // as .open() will NOT return a value but simply returns undefined in asynchronous mode
                currentLang = JSON.parse(xobj.responseText)
                languageMutableStateFlow.value = LanguageSupportState.LanguageLoaded
            }
        }
        xobj.send(null)
    }

    companion object {
        const val PLACEHOLDER = "%s"
    }
}

sealed class LanguageSupportState {
    object LanguageLoaded : LanguageSupportState()
    object LanguageError : LanguageSupportState()
    object LanguageInit : LanguageSupportState()
}