package middleware

import (
	"backend/config"
	"strings"
	"time"

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

// CORSMiddleware CORS 中间件，使用显式白名单避免携带凭据时放行任意来源。 // Logan.Li
func CORSMiddleware(cfg *config.Config) gin.HandlerFunc {
	origins := filterHTTPOrigins(cfg.CORSOrigins)
	if len(origins) == 0 {
		origins = []string{
			"http://localhost:5181",
			"http://127.0.0.1:5181",
			"http://localhost:3000",
			"http://127.0.0.1:3000",
		}
	}

	return cors.New(cors.Config{
		AllowOrigins:     origins,
		AllowMethods:     []string{"GET", "POST", "PUT", "DELETE", "PATCH", "OPTIONS"},
		AllowHeaders:     []string{"Origin", "Content-Type", "Authorization", "X-Requested-With"},
		ExposeHeaders:    []string{"Content-Length", "Content-Type"},
		AllowCredentials: true,
		MaxAge:           12 * time.Hour,
	})
}

// filterHTTPOrigins keeps only origins gin-contrib/cors accepts (http/https or *). // Logan.Li
func filterHTTPOrigins(origins []string) []string {
	out := make([]string, 0, len(origins))
	for _, origin := range origins {
		o := strings.TrimSpace(origin)
		if o == "" {
			continue
		}
		if o == "*" || strings.HasPrefix(o, "http://") || strings.HasPrefix(o, "https://") {
			out = append(out, o)
		}
	}
	return out
}