ApiVersionCondition.kt

data class ApiVersionCondition(private val apiVersion: ApiVersionValue) : RequestCondition<ApiVersionCondition> {
    override fun combine(other: ApiVersionCondition) = ApiVersionCondition(other.apiVersion)

    override fun getMatchingCondition(request: HttpServletRequest): ApiVersionCondition? {
        val requestApiVersion =
            request.getHeader(ACCEPT_VERSION_HEADER)
                ?.let { ApiVersionValue.valueOf("V${it.replace('.', '_')}") }
                ?: ApiVersionValue.V1_0_0

        if (requestApiVersion >= apiVersion) {
            return this
        }

        return null
    }

    override fun compareTo(other: ApiVersionCondition, request: HttpServletRequest): Int = other.apiVersion.compareTo(apiVersion)

    companion object {
        const val ACCEPT_VERSION_HEADER = "accept-version"
    }
}