import java.util.Date

import com.auth0.jwt.algorithms.Algorithm
import com.auth0.jwt.interfaces.DecodedJWT
import com.auth0.jwt.{JWT => Auth0JWT}
import com.typesafe.config.Config

import scala.util.Try

object JWT {

  private def algorithm(implicit settings: JWTSettings): Algorithm = Algorithm.HMAC256(secret)
  private def secret(implicit settings: JWTSettings): String = settings.secret
  private def issuer(implicit settings: JWTSettings): String = settings.issuer
  private def expiresAt(issuedAt: Date)(implicit settings: JWTSettings): Date = new Date(issuedAt.getTime + settings.expiresAfter.toMillis)

  def create(subject: String)(implicit settings: JWTSettings): Try[String] = Try {
    val issuedAt = new Date()
    val token =
      Auth0JWT
        .create()
        .withIssuer(issuer)
        .withSubject(subject)
        .withIssuedAt(issuedAt)
        .withExpiresAt(expiresAt(issuedAt))
        .sign(algorithm)
    token
  }

  def verify(token: String)(implicit settings: JWTSettings): Try[DecodedJWT] = Try {
    val verifier =
      Auth0JWT
        .require(algorithm)
        .withIssuer(issuer)
        .build()
    verifier.verify(token)
  }

}

class JWTSettings(config: Config) {
  import utils.DurationExtensions._
  private val jwtConfig = config.getConfig("jwt")
  val secret = jwtConfig.getString("secret")
  val issuer = jwtConfig.getString("issuer")
  val expiresAfter = jwtConfig.getDuration("expires-after").toScala
}

object JWTSettings {
  def apply(config: Config): JWTSettings = new JWTSettings(config)
}