auth.go

package main

import (
	"net/http"
	"time"
	"github.com/gin-gonic/gin"
	"github.com/golang-jwt/jwt/v5"
	"golang.org/x/crypto/bcrypt"
)

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

func HashPassword(pwd string) (string, error) {
	bytes, err := bcrypt.GenerateFromPassword([]byte(pwd), 12)
	return string(bytes), err
}

func CheckPassword(hash, pwd string) bool {
	return bcrypt.CompareHashAndPassword([]byte(hash), []byte(pwd)) == nil
}

func GenerateToken(userID string) (string, error) {
	claims := Claims{
		UserID: userID,
		RegisteredClaims: jwt.RegisteredClaims{
			ExpiresAt: jwt.NewNumericDate(time.Now().Add(7 * 24 * time.Hour)),
			IssuedAt:  jwt.NewNumericDate(time.Now()),
		},
	}
	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	return token.SignedString(jwtSecret)
}

func SetTokenCookie(c *gin.Context, token string) {
	c.SetSameSite(http.SameSiteLaxMode)
	c.SetCookie("token", token, 3600*24*7, "/", "", false, true) // HttpOnly
}

func ClearTokenCookie(c *gin.Context) {
	c.SetCookie("token", "", -1, "/", "", false, true)
}

func AuthMiddleware() gin.HandlerFunc {
	return func(c *gin.Context) {
		tokenStr, err := c.Cookie("token")
		if err != nil {
			c.AbortWithStatusJSON(401, gin.H{"error": "Unauthorized"}); return
		}
		claims := &Claims{}
		token, err := jwt.ParseWithClaims(tokenStr, claims, func(t *jwt.Token) (interface{}, error) { return jwtSecret, nil })
		if err != nil || !token.Valid {
			c.AbortWithStatusJSON(401, gin.H{"error": "Invalid token"}); return
		}
		c.Set("userID", claims.UserID)
		c.Next()
	}
}

// Optional Auth (for public quiz view)
func OptionalAuth() gin.HandlerFunc {
	return func(c *gin.Context) {
		tokenStr, _ := c.Cookie("token")
		if tokenStr != "" {
			claims := &Claims{}
			if token, _ := jwt.ParseWithClaims(tokenStr, claims, func(t *jwt.Token) (interface{}, error) { return jwtSecret, nil }); token.Valid {
				c.Set("userID", claims.UserID)
			}
		}
		c.Next()
	}
}