package jwt

import (
	"errors"
	"time"

	"git.kanopo.dev/rhythm/rhythm-backend/internal/config"
	"github.com/golang-jwt/jwt/v5"
)

type Claims struct {
	UserID string `json:"userId"`
	jwt.RegisteredClaims
}

type TokenPair struct {
	AccessToken  string
	RefreshToken string
}

func GenerateTokenPair(userID string, cfg *config.Config) (TokenPair, error) {
	accessToken, err := generateToken(userID, cfg.JWTSecret, cfg.JWTExpiry)
	if err != nil {
		return TokenPair{}, err
	}

	refreshToken, err := generateToken(userID, cfg.JWTSecret, cfg.RefreshExpiry)
	if err != nil {
		return TokenPair{}, err
	}

	return TokenPair{
		AccessToken:  accessToken,
		RefreshToken: refreshToken,
	}, nil
}

func generateToken(userID, secret string, expiry time.Duration) (string, error) {
	claims := &Claims{
		UserID: userID,
		RegisteredClaims: jwt.RegisteredClaims{
			ExpiresAt: jwt.NewNumericDate(time.Now().Add(expiry)),
			IssuedAt:  jwt.NewNumericDate(time.Now()),
		},
	}

	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	return token.SignedString([]byte(secret))
}

func ValidateToken(tokenString, secret string) (*Claims, error) {
	token, err := jwt.ParseWithClaims(tokenString, &Claims{}, func(token *jwt.Token) (interface{}, error) {
		if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
			return nil, errors.New("unexpected signing method")
		}
		return []byte(secret), nil
	})

	if err != nil {
		return nil, err
	}

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

	return nil, errors.New("invalid token")
}