package middleware

import (
	"net/http"

	"github.com/gin-gonic/gin"

	"gotest/internal/config"
)

// CORS 跨域中间件，根据配置放行指定来源
func CORS(cfg *config.CORSConfig) gin.HandlerFunc {
	allowed := make(map[string]bool)
	wildcard := false
	for _, origin := range cfg.AllowedOrigins {
		if origin == "*" {
			// 配置中包含 * 表示通配，允许任意来源
			wildcard = true
			continue
		}
		allowed[origin] = true
	}

	return func(c *gin.Context) {
		origin := c.GetHeader("Origin")
		switch {
		case wildcard:
			// 通配模式直接放行所有来源
			c.Header("Access-Control-Allow-Origin", "*")
		case origin != "" && allowed[origin]:
			// 命中白名单时回写具体来源，并标注 Vary 以便缓存正确
			c.Header("Access-Control-Allow-Origin", origin)
			c.Header("Vary", "Origin")
		}

		c.Header("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, OPTIONS, PATCH")
		c.Header("Access-Control-Allow-Headers", "Origin, Content-Type, Authorization, X-Requested-With")
		c.Header("Access-Control-Allow-Credentials", "true")
		c.Header("Access-Control-Max-Age", "86400")

		// 处理 OPTIONS 预检请求，直接返回 204
		if c.Request.Method == http.MethodOptions {
			c.AbortWithStatus(http.StatusNoContent)
			return
		}

		c.Next()
	}
}