/**
 * package utils
 * 作用：IP 归属地查询（基于本地 ip2region.xdb 离线库）
 */
package utils

import (
	"log"
	"strings"
	"sync"

	"github.com/lionsoul2014/ip2region/binding/golang/xdb"
)

var (
	ipSearcher     *xdb.Searcher
	ipSearcherOnce sync.Once
	ipSearcherErr  error
	ipCache        sync.Map
)

/**
 * InitIP2Region
 * 功能：加载 ip2region.xdb，服务启动时调用一次
 */
func InitIP2Region(dbPath string) error {
	ipSearcherOnce.Do(func() {
		ipSearcher, ipSearcherErr = xdb.NewWithFileOnly(xdb.IPv4, dbPath)
		if ipSearcherErr != nil {
			log.Printf("❌ [IP2Region] 加载失败: %v", ipSearcherErr)
			return
		}
		log.Printf("✅ [IP2Region] 已加载: %s", dbPath)
	})
	return ipSearcherErr
}

/**
 * GetIPLocation
 * 功能：查询 IP 归属地，内网/本地返回「本地」
 */
func GetIPLocation(ip string) string {
	if isLocalIP(ip) {
		return "本地"
	}
	if ip == "" {
		return "未知"
	}

	if cached, ok := ipCache.Load(ip); ok {
		return cached.(string)
	}

	if ipSearcher == nil {
		return "未知"
	}

	region, err := ipSearcher.Search(ip)
	if err != nil || region == "" {
		return "未知"
	}

	// 格式: 国家|区域|省份|城市|ISP
	parts := strings.Split(region, "|")
	labels := []string{}
	for _, p := range parts {
		p = strings.TrimSpace(p)
		if p != "" && p != "0" {
			labels = append(labels, p)
		}
	}
	result := "未知"
	if len(labels) > 0 {
		result = strings.Join(labels, " ")
	}
	ipCache.Store(ip, result)
	return result
}

/**
 * isLocalIP
 * 功能：判断是否为本地/内网 IP
 */
func isLocalIP(ip string) bool {
	if ip == "127.0.0.1" || ip == "localhost" || ip == "::1" {
		return true
	}
	if strings.HasPrefix(ip, "192.168.") || strings.HasPrefix(ip, "10.") {
		return true
	}
	if strings.HasPrefix(ip, "172.16.") || strings.HasPrefix(ip, "172.17.") ||
		strings.HasPrefix(ip, "172.18.") || strings.HasPrefix(ip, "172.19.") ||
		strings.HasPrefix(ip, "172.20.") || strings.HasPrefix(ip, "172.21.") ||
		strings.HasPrefix(ip, "172.22.") || strings.HasPrefix(ip, "172.23.") ||
		strings.HasPrefix(ip, "172.24.") || strings.HasPrefix(ip, "172.25.") ||
		strings.HasPrefix(ip, "172.26.") || strings.HasPrefix(ip, "172.27.") ||
		strings.HasPrefix(ip, "172.28.") || strings.HasPrefix(ip, "172.29.") ||
		strings.HasPrefix(ip, "172.30.") || strings.HasPrefix(ip, "172.31.") {
		return true
	}
	return false
}