package com.weEat.services

import play.api.Configuration
import codes.reactive.scalatime._
import com.github.t3hnar.bcrypt._
import com.weEat.models.{User,Authorization}
import java.time.Instant
import javax.inject.{Inject,Singleton}
import scala.concurrent.{ExecutionContext,Future}
import scala.util.Success
import scalaoauth2.provider._
import org.mongodb.scala.model.Filters._
import org.mongodb.scala.bson.DefaultBsonTransformers
import org.mongodb.scala.bson.conversions.Bson
import scala.language.implicitConversions

@Singleton
class OAuth2Service @Inject()(db: MongoDBService, config: Configuration)
    extends AuthorizationHandler[User]
    with ProtectedResourceHandler[Authorization]
    with DefaultBsonTransformers {

  implicit val ec: ExecutionContext = ExecutionContext.global

  import db.withCollection

  override def createAccessToken(auth: AuthInfo[User]) = {
    val newAuth = Authorization(auth.user)
    withCollection(Authorization) { (auths) =>
      auths.insertOne(newAuth).head().map((_) => newAuth.toToken())
    }.flatten
  }

  val devMode = config.getOptional[Boolean](s"oauth.dev").getOrElse(false)

  override def validateClient(
    cred: Option[ClientCredential],
    requ: AuthorizationRequest
  ): Future[Boolean] = {
    cred.fold[Future[Boolean]](Future.failed(new UnauthorizedClient("username required"))) { (cc) =>
      requ.grantType match {
        case OAuthGrantType.PASSWORD =>
          cc.clientSecret.fold[Future[Boolean]](Future.failed(new UnauthorizedClient("password required"))) { (sec) =>
            validateUsernamePassword(cc.clientId, sec).map(_.isDefined)
          }
        case OAuthGrantType.REFRESH_TOKEN => validateUsernameRefresh(
          cc.clientId,
          Authorization.decodeToken(RefreshTokenRequest(requ).refreshToken)
        )
        case OAuthGrantType.AUTHORIZATION_CODE => Future.failed(new UnsupportedGrantType())
        case OAuthGrantType.CLIENT_CREDENTIALS => Future.failed(new UnsupportedGrantType())
        case OAuthGrantType.IMPLICIT => Future.failed(new UnsupportedGrantType())
      }
    }
  }

  def validateUsernamePassword(
    username: String,
    pass: String
  ): Future[Option[User]] = withCollection(User) { (users) =>
    users.find(withDevModeCond(equal("email", username)))
      .first()
      .toFutureOption()
      // TODO: Replace bcrypt with something that doesn't use String objects.
      .filter {
        case Some(user) => pass.isBcryptedSafeBounded(user.password) == Success(true)
        case None => false
      }
      
  }.flatten

  private def withDevModeCond(bson: Bson) =
    if (devMode) bson else and(bson, not(equal("devOnly", true)))

  private def validateUsernameRefresh(username: String, refresh: Array[Byte]) = 
  withCollection(Authorization) { (auths) =>
    auths.find(and(
      equal("email", username),
      equal("refreshToken", refresh)
    )).first().toFutureOption().map { _.nonEmpty }
  }.flatten

  override def findUser(
    cred: Option[ClientCredential],
    requ: AuthorizationRequest
  ): Future[Option[User]] = withCollection(User) { (users) =>
    cred.fold[Future[Option[User]]](Future.failed(new UnsupportedGrantType("client_id required"))) { (cc) =>
      users.find(withDevModeCond(equal("email", cc.clientId))).first().toFutureOption()
    }
  }.flatten
  
  /* 2020-07-25: Never re-issue the same authorization token. Always generate a
   * new one.
   */
  override def getStoredAccessToken(auth: AuthInfo[User]) = {
    Future.successful(None)
  }

  override def findAccessToken(token: String): Future[Option[AccessToken]] = 
    withCollection(Authorization) { (auths) =>
      auths.find(
        freshAccessToken(Authorization.decodeToken(token))
      ).first().toFutureOption()
        .map(_.map(_.toToken()))
    }.flatten    

  override def findAuthInfoByAccessToken(token: AccessToken) =
    withCollection(Authorization) { (auths) =>
      auths.find(freshAccessToken(Authorization.decodeToken(token.token)))
        .first()
        .toFutureOption()
        .map(_.map(auth => AuthInfo(auth, Some(auth.email), None, None)))
    }.flatten

  private def freshAccessToken(token: Array[Byte]) = and(
    gt("created", Instant.now() - Authorization.accessFreshTime),
    equal("accessToken", token)
  )

  implicit def optFut2FutOpt[A](
    x: Option[Future[A]]
  )(implicit ec: ExecutionContext): Future[Option[A]] = x.fold[Future[Option[A]]](Future.successful(None)) {
    _.map(Some(_))
  }

  override def findAuthInfoByRefreshToken(token: String) =
    withCollection(Authorization) { (auths) =>
      auths.find(freshRefreshToken(Authorization.decodeToken(token)))
        .first()
        .toFutureOption()
    }.flatten
      .map(authOpt => withCollection(User) { (users) =>
        optFut2FutOpt(authOpt.map({ (auth) => users.find(
          withDevModeCond(equal("_id", auth.userId))
        ).first()
          .toFuture()
          .map({ (user) => AuthInfo(user, Some(user.email), None, None)})
        }))
      }.flatten).flatten
  
  private def freshRefreshToken(token: Array[Byte]) = and(
    gt("created", Instant.now() - Authorization.refreshFreshTime),
    equal("refreshToken", token)
  )

  override def refreshAccessToken(
    auth: AuthInfo[User],
    refreshToken: String
  ): Future[AccessToken] = {
    val newAuth = Authorization(auth.user)
    withCollection(Authorization) { (auths) =>
      auths.replaceOne(
        and(
          equal("userId", auth.user._id),
          equal("refreshToken", Authorization.decodeToken(refreshToken)),
          gt("created", Instant.now() - Authorization.refreshFreshTime),
        ),
        newAuth
      ).head().map( (_) => newAuth.toToken())
    }.flatten
  }

  def revokeAccessToken(
    auth: AuthInfo[Authorization],
    user: String,
    refresh: String
  ): Future[Unit] = 
    if (user != auth.user.email)
      Future.failed(
        new InvalidClient("Invalid client or client is not authorized")
      )
    else withCollection(Authorization) { (auths) =>
      auths.deleteOne(and(
        equal("userId", auth.user.userId),
        equal("refreshToken", Authorization.decodeToken(refresh))
      )).head().map { (_) => {} }
    }.flatten

  override def deleteAuthCode(token: String): Future[Unit] =
    Future.failed(new UnsupportedGrantType("Code grant authorizations are not supported."))

  override def findAuthInfoByCode(
    code: String
  ): Future[Option[AuthInfo[User]]] =
    Future.failed(new UnsupportedGrantType("Code grant authorizations are not supported."))
}