package middleware

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

	"github.com/gin-gonic/gin"
	"github.com/oschwald/geoip2-golang"
)

func GeoRedirect(mapping map[string]string, defaultHost string) gin.HandlerFunc {
	db, err := geoip2.Open("./GeoLite2-Country/GeoLite2-Country.mmdb")
	if err != nil {
		// 如果打开失败，返回不执行重定向的中间件
		return func(c *gin.Context) { c.Next() }
	}
	return func(c *gin.Context) {
		defer c.Next()
		// 获取真实客户端 IP（考虑代理）
		ipStr := c.Request.Header.Get("X-Forwarded-For")
		if ipStr == "" {
			ipStr = c.ClientIP()
		} else {
			// X-Forwarded-For 可能是逗号分隔的列表，取第一个
			ipStr = strings.TrimSpace(strings.Split(ipStr, ",")[0])
		}
		ip := net.ParseIP(ipStr)
		if ip == nil {
			return
		}
		record, err := db.Country(ip)
		if err != nil {
			return
		}
		iso := record.Country.IsoCode // 如 "US", "CN", "BR"
		target, ok := mapping[iso]
		if !ok {
			target = defaultHost
		}
		// 如果目标域名与当前请求不同，重定向（保留路径/查询）
		if target != "" && !strings.Contains(c.Request.Host, target) {
			location := "https://" + target + c.Request.URL.RequestURI()
			// 302 临时重定向；如需永久改用 http.StatusMovedPermanently
			c.Redirect(http.StatusFound, location)
			c.Abort()
			return
		}
	}
}