package middleware

import (
	"net/http"
	"strings"
	"time"

	"github.com/gin-gonic/gin"
	"github.com/golang-jwt/jwt/v5"
)

const (
	jwtSecret   = "lmvpn-jwt-secret-key-2024"
	tokenExpire = 24 * time.Hour
)

type Claims struct {
	UserID   uint   `json:"user_id"`
	Username string `json:"username"`
	Role     string `json:"role"`
	jwt.RegisteredClaims
}

func GenerateToken(userID uint, username, role string) (string, error) {
	claims := Claims{
		UserID:   userID,
		Username: username,
		Role:     role,
		RegisteredClaims: jwt.RegisteredClaims{
			ExpiresAt: jwt.NewNumericDate(time.Now().Add(tokenExpire)),
			IssuedAt:  jwt.NewNumericDate(time.Now()),
		},
	}

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

func ParseToken(tokenStr string) (*Claims, error) {
	token, err := jwt.ParseWithClaims(tokenStr, &Claims{}, func(token *jwt.Token) (interface{}, error) {
		return []byte(jwtSecret), nil
	})
	if err != nil {
		return nil, err
	}

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

	return nil, jwt.ErrSignatureInvalid
}

func AuthMiddleware() gin.HandlerFunc {
	return func(c *gin.Context) {
		authHeader := c.GetHeader("Authorization")
		if authHeader == "" {
			c.JSON(http.StatusUnauthorized, gin.H{"error": "未提供认证令牌"})
			c.Abort()
			return
		}

		parts := strings.SplitN(authHeader, " ", 2)
		if len(parts) != 2 || parts[0] != "Bearer" {
			c.JSON(http.StatusUnauthorized, gin.H{"error": "认证格式错误"})
			c.Abort()
			return
		}

		claims, err := ParseToken(parts[1])
		if err != nil {
			c.JSON(http.StatusUnauthorized, gin.H{"error": "令牌无效或已过期"})
			c.Abort()
			return
		}

		c.Set("user_id", claims.UserID)
		c.Set("username", claims.Username)
		c.Set("role", claims.Role)
		c.Next()
	}
}