package auth

import (
	"time"

	"github.com/golang-jwt/jwt/v5"
)

type JWTService struct {
	secretKey []byte
}

func NewJWTService(config *Config) *JWTService {
	return &JWTService{
		secretKey: []byte(config.SecretKey),
	}
}

func (s *JWTService) GenerateToken(userID string, duration time.Duration) (string, error) {
	claims := jwt.MapClaims{
		"user_id": userID,
		"exp":     time.Now().Add(duration).Unix(),
		"iat":     time.Now().Unix(),
	}

	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	signedToken, err := token.SignedString(s.secretKey)
	if err != nil {
		return "", NewError("generate", err, "failed to sign token")
	}

	return signedToken, nil
}

func (s *JWTService) ValidateToken(tokenString string) (jwt.MapClaims, error) {
	if tokenString == "" {
		return nil, NewError("validate", ErrEmptyToken, "token string is empty")
	}

	token, err := jwt.Parse(tokenString, func(token *jwt.Token) (interface{}, error) {
		if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
			return nil, NewError("validate", ErrInvalidSigningMethod, "unexpected signing method")
		}
		return s.secretKey, nil
	})

	if err != nil {
		return nil, NewError("parse", ErrInvalidToken, err.Error())
	}

	if claims, ok := token.Claims.(jwt.MapClaims); ok && token.Valid {
		return claims, nil
	}

	return nil, NewError("validate", ErrInvalidClaims, "token claims are invalid")
}