// 中间件：Gin 的中间件是 func(*gin.Context)，通过 c.Next() 控制执行链
// 执行顺序：请求进入 → 中间件1(c.Next前) → 中间件2(c.Next前) → Handler → 中间件2(c.Next后) → 中间件1(c.Next后) → 响应
package middleware

import (
	"net/http"

	"github.com/gin-gonic/gin"
)

// CORS 跨域中间件，允许 H5 调试时跨域访问
func CORS() gin.HandlerFunc {
	return func(c *gin.Context) {
		c.Header("Access-Control-Allow-Origin", "*")
		c.Header("Access-Control-Allow-Headers", "Content-Type, Authorization, X-Requested-With")
		c.Header("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, OPTIONS")
		c.Header("Access-Control-Expose-Headers", "Content-Length, Content-Type")

		if c.Request.Method == "OPTIONS" {
			c.AbortWithStatus(http.StatusNoContent)
			return
		}
		c.Next()
	}
}