lapis-mc/yggdrasil

package com.lapismc.minecraft.yggdrasil

import com.github.kittinunf.result.Result
import com.lapismc.minecraft.yggdrasil.rest.*
import com.lapismc.minecraft.yggdrasil.rest.serialization.AuthenticationResponseDeserializer
import java.util.*

/**
 * Authentication service that connects to a RESTful web application.
 * @param baseUrl URL of the REST application handling authentication.
 */
class WebAuthenticationService(baseUrl: String) : AuthenticationService {
    companion object {
        /**
         * Base URL for the official authentication server.
         */
        private const val OFFICIAL_BASE_URL = "https://authserver.mojang.com"

        /**
         * Official Mojang authentication service.
         */
        fun official() = WebAuthenticationService(OFFICIAL_BASE_URL)
    }

    private val restService: RestService = RestService(baseUrl)

    /**
     * Attempts to authenticate with a user's credentials.
     * @param credentials User credentials for authentication.
     * @param clientToken Token used to uniquely identify the client.
     * @param agent Game to authenticate for.
     * @return Result of the authentication.
     *  Upon success, a [Session] is returned.
     *  If an error occurred, exception information about the problem is returned.
     */
    override fun authenticate(credentials: Credentials, clientToken: UUID, agent: Agent): Result<Session, Exception> {
        val request = AuthenticationRequest(credentials, clientToken, agent)
        val result  = restService.post(request, AuthenticationResponseDeserializer())
        return authResponseToSession(result)
    }

    /**
     * Renews the access token given during authentication.
     * This allows continued use of the token pair.
     * @param session Session acquired during authentication or refresh.
     * @return Result of the refresh.
     *  Upon success, a [Session] is returned.
     *  If an error occurred, exception information about the problem is returned.
     */
    override fun refresh(session: Session): Result<Session, Exception> {
        val request = RefreshRequest(session.tokenPair)
        val result  = restService.post(request, AuthenticationResponseDeserializer())
        return authResponseToSession(result)
    }

    /**
     * Checks whether an access token is still usable.
     * @param session Session acquired during authentication or refresh.
     * @return Result of the validation.
     *  Upon success, a boolean is returned indicating whether the token pair is valid.
     *  If an error occurred, exception information about the problem is returned.
     */
    override fun validate(session: Session): Result<Boolean, Exception> {
        val request = ValidateRequest(session.tokenPair)
        return restService.post(request)
    }

    /**
     * Invalidates all access tokens.
     * Effectively requires all clients using the player's credentials to re-authenticate.
     * @param credentials User credentials.
     * @return Result of the signout.
     *  Upon success, a boolean is returned indicating whether the user was signed out.
     *  If an error occurred, exception information about the problem is returned.
     */
    override fun signout(credentials: Credentials): Result<Boolean, Exception> {
        val request = SignoutRequest(credentials)
        return restService.post(request)
    }

    /**
     * Makes an access token unusable.
     * The user must re-authenticate to use the same client.
     * @param session Session acquired during authentication or refresh.
     * @return Result of the invalidation.
     *  Upon success, a boolean is returned indicating whether the token pair was invalidated.
     *  If an error occurred, exception information about the problem is returned.
     */
    override fun invalidate(session: Session): Result<Boolean, Exception> {
        val request = InvalidateRequest(session.tokenPair)
        return restService.post(request)
    }

    /**
     * Utility method for converting an [AuthenticationResponse] result to a [Session] result.
     * @param result Result of an operation that can return an [AuthenticationResponse].
     * @return Result containing session information from the authentication response or an error.
     */
    private fun authResponseToSession(result: Result<AuthenticationResponse, Exception>): Result<Session, Exception> {
        result.fold(success = {
            val response = result.get()
            return Result.of(Session(response.profiles.selected!!, response.tokenPair))
        }, failure = {
            return Result.error(result.component2()!!)
        })
    }
}