package net.halfbinary.scavengerhuntapi.config

import io.jsonwebtoken.JwtException
import io.jsonwebtoken.Jwts
import jakarta.annotation.PostConstruct
import org.springframework.beans.factory.annotation.Value
import org.springframework.stereotype.Component
import java.util.*
import javax.crypto.SecretKey
import javax.crypto.spec.SecretKeySpec

@Component
class JwtUtil {
    @Value($$"${jwt.secret}")
    private val jwtSecret: String = ""

    @Value($$"${jwt.expiration}")
    private val jwtExpirationMs = 0

    private var key: SecretKey? = null

    // Initializes the key after the class is instantiated and the jwtSecret is injected,
    // preventing the repeated creation of the key and enhancing performance
    @PostConstruct
    fun init() {
        this.key = SecretKeySpec(jwtSecret.toByteArray(Charsets.UTF_8), "HmacSHA256")
    }

    // Generate JWT token
    fun generateToken(email: String): String {
        return Jwts.builder()
            .subject(email)
            .issuedAt(Date())
            .expiration(Date(System.currentTimeMillis() + jwtExpirationMs))
            .signWith(key)
            .compact()
    }

    // Get username from JWT token
    fun getUsernameFromToken(token: String): String {
        return Jwts.parser()
            .verifyWith(key)
            .build()
            .parseSignedClaims(token)
            .payload
            .subject
    }

    // Validate JWT token
    fun validateJwtToken(token: String?): Boolean {
        try {
            Jwts.parser().verifyWith(key).build().parseSignedClaims(token)
            return true
        } catch (e: SecurityException) {
            println("Invalid JWT signature: " + e.message)
        } catch (e: JwtException) {
            println("Invalid JWT token: " + e.message)
        } catch (e: IllegalArgumentException) {
            println("JWT claims string is empty: " + e.message)
        }
        return false
    }
}