#!/bin/bash

# 颜色定义
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
BLUE='\033[0;34m'
PURPLE='\033[0;35m'
CYAN='\033[0;36m'
NC='\033[0m'

echo -e "${PURPLE}"
echo "=================================================="
echo "              🌈 智能DNS推荐系统"
echo "=================================================="
echo -e "${NC}"

# 测试并推荐最佳DNS
test_and_recommend() {
    declare -A dns_servers=(
        ["119.29.29.29"]="腾讯DNS"
        ["223.5.5.5"]="阿里DNS" 
        ["114.114.114.114"]="114DNS"
        ["8.8.8.8"]="GoogleDNS"
        ["1.1.1.1"]="Cloudflare"
    )
    
    declare -A results
    
    echo -e "${BLUE}🧪 测试各DNS性能...${NC}"
    
    for dns_ip in "${!dns_servers[@]}"; do
        total_time=0
        success_count=0
        test_domains=("baidu.com" "qq.com" "taobao.com")
        
        for domain in "${test_domains[@]}"; do
            start_time=$(date +%s%N)
            nslookup $domain $dns_ip >/dev/null 2>&1
            if [ $? -eq 0 ]; then
                end_time=$(date +%s%N)
                time_ms=$(( (end_time - start_time) / 1000000 ))
                total_time=$(( total_time + time_ms ))
                success_count=$(( success_count + 1 ))
            fi
        done
        
        if [ $success_count -gt 0 ]; then
            avg_time=$(( total_time / success_count ))
            results[$dns_ip]=$avg_time
            echo -e "  ${dns_servers[$dns_ip]} ($dns_ip): ${avg_time}ms"
        else
            echo -e "  ${RED}${dns_servers[$dns_ip]} ($dns_ip): 测试失败${NC}"
        fi
    done
    
    # 找出最快的DNS
    fastest_ip=""
    fastest_time=999999
    
    for ip in "${!results[@]}"; do
        if [ ${results[$ip]} -lt $fastest_time ]; then
            fastest_time=${results[$ip]}
            fastest_ip=$ip
        fi
    done
    
    echo -e "\n${GREEN}🎯 推荐使用: ${dns_servers[$fastest_ip]} ($fastest_ip)${NC}"
    echo -e "${GREEN}📊 平均解析时间: ${fastest_time}ms${NC}"
    
    # 设置推荐DNS
    echo -e "\n${BLUE}🔧 是否设置为推荐DNS？${NC}"
    read -p "输入 y 确认设置: " confirm
    if [ "$confirm" = "y" ]; then
        echo "nameserver $fastest_ip" > /etc/resolv.conf
        echo "nameserver 223.5.5.5" >> /etc/resolv.conf  # 备用
        echo -e "${GREEN}✅ 已设置为 ${dns_servers[$fastest_ip]}${NC}"
    fi
}

test_and_recommend

echo -e "\n${PURPLE}==================================================${NC}"
echo -e "${CYAN}💡 重要提醒:${NC}"
echo -e "${YELLOW}• DNS只影响域名解析速度${NC}"
echo -e "${YELLOW}• 不影响已经建立连接的网络延迟${NC}"  
echo -e "${YELLOW}• 主要提升: 网页第一次打开速度${NC}"
echo -e "${YELLOW}• 不影响: 视频缓冲、游戏延迟、下载速度${NC}"
echo -e "${PURPLE}==================================================${NC}"