package be.simplenotes.domain.security

import be.simplenotes.config.JwtConfig
import com.auth0.jwt.JWT
import com.auth0.jwt.JWTVerifier
import com.auth0.jwt.algorithms.Algorithm
import com.auth0.jwt.exceptions.JWTVerificationException
import java.util.*
import java.util.concurrent.TimeUnit
import javax.inject.Singleton

@Singleton
class SimpleJwt<T>(jwtConfig: JwtConfig, private val mapper: JwtMapper<T>) {
    private val validityInMs = TimeUnit.MILLISECONDS.convert(jwtConfig.validity, jwtConfig.timeUnit)
    private val algorithm = Algorithm.HMAC256(jwtConfig.secret)
    private val verifier: JWTVerifier = JWT.require(algorithm).build()

    fun sign(value: T): String = JWT.create()
        .apply { mapper.build(this, value) }
        .withExpiresAt(getExpiration())
        .sign(algorithm)

    fun extract(token: String): T? = try {
        val decodedJWT = verifier.verify(token)
        mapper.extract(decodedJWT)
    } catch (e: JWTVerificationException) {
        null
    } catch (e: IllegalArgumentException) {
        null
    }

    private fun getExpiration() = Date(System.currentTimeMillis() + validityInMs)
}