package middleware

import (
	"net/http"
	"strings"

	"github.com/gin-gonic/gin"
	"github.com/golang-jwt/jwt/v4"
)

func BearerAuth(jwtSecret []byte) gin.HandlerFunc {
	return func(c *gin.Context) {
		authHeader := c.GetHeader("Authorization")
		if authHeader == "" {
			c.JSON(http.StatusUnauthorized, gin.H{"error": "missing authorization header"})
			c.Abort()
			return
		}

		// 检查 Bearer 前缀
		parts := strings.Split(authHeader, " ")
		if len(parts) != 2 || parts[0] != "Bearer" {
			c.JSON(http.StatusUnauthorized, gin.H{"error": "invalid authorization header"})
			c.Abort()
			return
		}

		tokenString := parts[1]

		// 解析和验证令牌
		token, err := jwt.Parse(tokenString, func(token *jwt.Token) (interface{}, error) {
			// 验证签名算法
			if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
				return nil, jwt.ErrSignatureInvalid
			}
			return jwtSecret, nil
		})

		if err != nil {
			c.JSON(http.StatusUnauthorized, gin.H{"error": "invalid token"})
			c.Abort()
			return
		}

		if !token.Valid {
			c.JSON(http.StatusUnauthorized, gin.H{"error": "invalid token"})
			c.Abort()
			return
		}

		// 将令牌中的声明存储在上下文中
		if claims, ok := token.Claims.(jwt.MapClaims); ok {
			c.Set("user_id", uint(claims["sub"].(float64)))
			c.Set("scope", claims["scope"].(string))
		}

		c.Next()
	}
}