package auth

import (
	"fmt"
	"time"

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

// JWTService handles JWT token generation and validation
type JWTService struct {
	secret     []byte
	expiration time.Duration
}

// NewJWTService creates a new JWTService
func NewJWTService(secret string, expiration time.Duration) *JWTService {
	return &JWTService{
		secret:     []byte(secret),
		expiration: expiration,
	}
}

// Claims represents JWT claims
type Claims struct {
	UserID string `json:"user_id"`
	Email  string `json:"email"`
	Role   string `json:"role"`
	jwt.RegisteredClaims
}

// GenerateToken generates a JWT token for a user
func (s *JWTService) GenerateToken(userID uuid.UUID, email string) (string, time.Time, error) {
	return s.GenerateTokenWithRole(userID, email, "user")
}

// GenerateTokenWithRole generates a JWT token for a user with a specific role
func (s *JWTService) GenerateTokenWithRole(userID uuid.UUID, email, role string) (string, time.Time, error) {
	expiresAt := time.Now().Add(s.expiration)
	// Default role to "user" if not specified
	if role == "" {
		role = "user"
	}
	claims := &Claims{
		UserID: userID.String(),
		Email:  email,
		Role:   role,
		RegisteredClaims: jwt.RegisteredClaims{
			ExpiresAt: jwt.NewNumericDate(expiresAt),
			IssuedAt:  jwt.NewNumericDate(time.Now()),
			NotBefore: jwt.NewNumericDate(time.Now()),
		},
	}

	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	tokenString, err := token.SignedString(s.secret)
	if err != nil {
		return "", time.Time{}, fmt.Errorf("failed to sign token: %w", err)
	}

	return tokenString, expiresAt, nil
}

// ValidateToken validates a JWT token and returns the claims
func (s *JWTService) ValidateToken(tokenString string) (*Claims, error) {
	token, err := jwt.ParseWithClaims(tokenString, &Claims{}, func(token *jwt.Token) (any, error) {
		if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
			return nil, fmt.Errorf("unexpected signing method: %v", token.Header["alg"])
		}
		return s.secret, nil
	})

	if err != nil {
		return nil, fmt.Errorf("failed to parse token: %w", err)
	}

	claims, ok := token.Claims.(*Claims)
	if !ok || !token.Valid {
		return nil, fmt.Errorf("invalid token")
	}

	return claims, nil
}