Security.kt

package com.example.auth

import io.ktor.application.*
import io.ktor.auth.*
import io.ktor.client.*
import io.ktor.client.engine.apache.*
import io.ktor.http.*
import io.ktor.locations.*
import io.ktor.request.*
import io.ktor.response.*
import io.ktor.routing.*


val loginProviders = listOf(
    OAuthServerSettings.OAuth2ServerSettings(
        name = "vk",
        authorizeUrl = "https://oauth.vk.com/authorize",
        accessTokenUrl = "https://oauth.vk.com/access_token",
        clientId = "айди",
        clientSecret = "секрет",
        defaultScopes = listOf("email"),
        authorizeUrlInterceptor = { print(this) }
    )
).associateBy {it.name}

@Location("/login/{type?}") class login(val type: String = "", val redirectUri: String = "/")

fun Application.configureSecurity(){
    install(Authentication){
        oauth("vk") {
            client = HttpClient(Apache)
            providerLookup = { loginProviders[application.locations.resolve<login>(login::class, this).type]}
            urlProvider = { url(login(it.name, this.request.uri))}
        }
    }
    routing {
        authenticate("vk") {
            location<login>(){
                param("error") {
                    handle {
                        call.response.status(HttpStatusCode.ExpectationFailed)
                        call.respond("fail")
                    }
                }

                handle {
                    val principal = call.authentication.principal<OAuthAccessTokenResponse.OAuth2>()
                    if (principal != null) {
                        call.response.status(HttpStatusCode.OK)
                        call.respond(principal.extraParameters.entries())
                    } else {
                        call.respondRedirect(application.locations.href(login("vk")))
                    }
                }
            }
            get("/locked"){
                val principal = call.authentication.principal<OAuthAccessTokenResponse.OAuth2>()//ожидаю, что здесь не должно быть нулла
                call.respondText {
                    "Oh hi mark!"
                }
            }
        }
    }
}