package jwt

import (
	"errors"
	"fmt"
	"strconv"
	"time"

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

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

func GenerateAccessToken(userID int, secret string) (string, error) {
	now := time.Now()
	claims := Claims{
		Type: "access",
		RegisteredClaims: jwt.RegisteredClaims{
			Subject:   strconv.Itoa(userID),
			ID:        uuid.New().String(),
			IssuedAt:  jwt.NewNumericDate(now),
			ExpiresAt: jwt.NewNumericDate(now.Add(15 * time.Minute)),
		},
	}

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

func GenerateRefreshToken(userID int, secret string) (string, error) {
	now := time.Now()
	claims := Claims{
		Type: "refresh",
		RegisteredClaims: jwt.RegisteredClaims{
			Subject:   strconv.Itoa(userID),
			ID:        uuid.New().String(),
			IssuedAt:  jwt.NewNumericDate(now),
			ExpiresAt: jwt.NewNumericDate(now.Add(30 * 24 * time.Hour)),
		},
	}

	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, fmt.Errorf("unexpected signing method: %v", token.Header["alg"])
		}
		return []byte(secret), nil
	})

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

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

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

func GetUserIDFromToken(tokenString, secret string) (int, error) {
	claims, err := ValidateToken(tokenString, secret)
	if err != nil {
		return 0, err
	}

	userID, err := strconv.Atoi(claims.Subject)
	if err != nil {
		return 0, fmt.Errorf("invalid user ID in token: %w", err)
	}

	return userID, nil
}