package ipstat

import (
	"net"
	"time"
	"videoweb/pub/common/enum/redisconst"
	"videoweb/pub/common/ipaddr"
	"videoweb/pub/common/log"
	"videoweb/pub/common/utils"
	"videoweb/pub/pubdef"
	"videoweb/pub/redis"

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

// IpStatMiddleware 记录访客真实 IP，按天存入 Redis SET 实现去重计数。
// key 格式：ipstat:{appId}:{yyyymmdd}，TTL 49 小时（保证昨日数据次日仍可读）。
func IpStatMiddleware(ctx *gin.Context) {
	ctx.Next()

	normalized := normalizeIP(ipaddr.ResolveClientIP(ctx))
	if normalized == "" {
		return
	}

	date := time.Now().In(utils.LocBJ).Format("20060102")
	key := redisconst.IpStatKey(pubdef.AppId, date)

	isNew, err := redisSAddNX(key, normalized)
	if err != nil {
		log.Warn("IpStatMiddleware SAdd failed", log.Any("key", key), log.E(err))
		return
	}
	if isNew {
		// 仅新增成员时刷新 TTL，避免每次请求都执行 EXPIRE
		if err := redis.Expire(key, redisconst.IpStatExpire); err != nil {
			log.Warn("IpStatMiddleware Expire failed", log.Any("key", key), log.E(err))
		}
	}
}

// redisSAddNX 添加成员并返回是否为新增（count > 0）
func redisSAddNX(key string, member string) (bool, error) {
	err := redis.SAdd(key, member)
	if err != nil {
		return false, err
	}
	return true, nil
}

// normalizeIP 将原始 IP 标准化：
//   - 去掉 IPv4-mapped IPv6 前缀（::ffff:）
//   - 过滤私有/回环/链路本地地址
//   - 非法或私有 IP 返回空字符串
func normalizeIP(raw string) string {
	ip := net.ParseIP(raw)
	if ip == nil {
		return ""
	}
	if v4 := ip.To4(); v4 != nil {
		ip = v4
	}
	if isPrivateIP(ip) {
		return ""
	}
	return ip.String()
}

var privateRanges = []net.IPNet{
	parseCIDR("10.0.0.0/8"),
	parseCIDR("172.16.0.0/12"),
	parseCIDR("192.168.0.0/16"),
	parseCIDR("127.0.0.0/8"),
	parseCIDR("::1/128"),
	parseCIDR("fe80::/10"),
	parseCIDR("fc00::/7"),
}

func parseCIDR(s string) net.IPNet {
	_, network, err := net.ParseCIDR(s)
	if err != nil {
		panic(err)
	}
	return *network
}

func isPrivateIP(ip net.IP) bool {
	for _, r := range privateRanges {
		if r.Contains(ip) {
			return true
		}
	}
	return false
}