package auth

import (
	"github.com/gin-gonic/gin"
	"github.com/golang-jwt/jwt/v4"
	"net/http"
	"strings"
	"time"
)

var JWTSecret = []byte("your-secret-key") // 在實際使用時應該從環境變量獲取

type Claims struct {
	Username string `json:"username"`
	jwt.StandardClaims
}

// 生成 JWT token
func GenerateToken(username string) (string, error) {
	claims := Claims{
		username,
		jwt.StandardClaims{
			ExpiresAt: time.Now().Add(24 * time.Hour).Unix(),
			IssuedAt:  time.Now().Unix(),
		},
	}

	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	return token.SignedString(JWTSecret)
}

// JWT 認證中間件
func JWTAuthMiddleware() gin.HandlerFunc {
	return func(c *gin.Context) {
		authHeader := c.GetHeader("Authorization")
		if authHeader == "" {
			c.JSON(http.StatusUnauthorized, gin.H{"error": "Authorization header is required"})
			c.Abort()
			return
		}

		parts := strings.SplitN(authHeader, " ", 2)
		if !(len(parts) == 2 && parts[0] == "Bearer") {
			c.JSON(http.StatusUnauthorized, gin.H{"error": "Invalid authorization format"})
			c.Abort()
			return
		}

		claims := &Claims{}
		token, err := jwt.ParseWithClaims(parts[1], claims, func(token *jwt.Token) (interface{}, error) {
			return JWTSecret, nil
		})

		if err != nil || !token.Valid {
			c.JSON(http.StatusUnauthorized, gin.H{"error": "Invalid or expired token"})
			c.Abort()
			return
		}

		c.Set("username", claims.Username)
		c.Next()
	}
}