#!/bin/bash
# 用法:
# 启用安全模式: ./00-password.sh enable
# 关闭安全模式: ./00-password.sh disable
# 查看状态: ./00-password.sh status
#
# curl -sS -O https://gitea.tohub.top/Share/vps/raw/branch/main/init/00-password.sh && chmod +x 00-password.sh

set -e  # 遇到错误立即退出

# 颜色输出
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
BLUE='\033[0;34m'
NC='\033[0m' # No Color

# 日志函数
log_info() {
    echo -e "${GREEN}[INFO]${NC} $1"
}

log_warn() {
    echo -e "${YELLOW}[WARN]${NC} $1"
}

log_error() {
    echo -e "${RED}[ERROR]${NC} $1"
}

log_status() {
    echo -e "${BLUE}[STATUS]${NC} $1"
}

# 用户设置
NEW_SSH_PORT="4399"  # 根据需求修改端口
DEFAULT_SSH_PORT="22"
BACKUP_DIR="/root/ssh_backup_$(date +%Y%m%d_%H%M%S)"
PERSISTENT_BACKUP_DIR="/root/ssh_config_backup"

# 检查是否为root用户
if [ "$EUID" -ne 0 ]; then
    log_error "请使用 root 用户运行此脚本"
    exit 1
fi

# 显示使用帮助
show_usage() {
    echo "用法: $0 {enable|disable|status}"
    echo ""
    echo "命令:"
    echo "  enable   - 启用 SSH 安全模式（禁用密码登录，使用密钥认证）"
    echo "  disable  - 关闭 SSH 安全模式（恢复密码登录）"
    echo "  status   - 查看当前 SSH 配置状态"
    echo ""
    echo "示例:"
    echo "  $0 enable    # 启用安全模式"
    echo "  $0 disable   # 关闭安全模式"
    echo "  $0 status    # 查看状态"
    exit 1
}

# 获取当前SSH配置状态
get_ssh_config_value() {
    local key=$1
    local config_file="/etc/ssh/sshd_config"

    # 获取配置值（忽略注释行）
    grep "^${key}" "$config_file" 2>/dev/null | awk '{print $2}' | head -n1
}

# 检查当前状态
check_current_status() {
    local port=$(get_ssh_config_value "Port")
    local password_auth=$(get_ssh_config_value "PasswordAuthentication")
    local pubkey_auth=$(get_ssh_config_value "PubkeyAuthentication")
    local permit_root=$(get_ssh_config_value "PermitRootLogin")

    # 默认值
    port=${port:-22}
    password_auth=${password_auth:-yes}
    pubkey_auth=${pubkey_auth:-yes}
    permit_root=${permit_root:-yes}

    echo "当前 SSH 配置状态:"
    echo "----------------------------------------"
    echo "  SSH 端口: $port"
    echo "  密码认证: $password_auth"
    echo "  公钥认证: $pubkey_auth"
    echo "  Root登录: $permit_root"
    echo "----------------------------------------"

    # 判断是否为安全模式
    if [[ "$password_auth" == "no" ]] && [[ "$pubkey_auth" == "yes" ]]; then
        log_status "当前处于【安全模式】- 密码登录已禁用"
        return 0  # 安全模式
    else
        log_status "当前处于【普通模式】- 密码登录已启用"
        return 1  # 普通模式
    fi
}

# 显示状态
show_status() {
    log_info "正在检查 SSH 配置状态..."
    echo ""
    check_current_status

    # 检查是否有备份
    if [ -d "$PERSISTENT_BACKUP_DIR" ] && [ -f "$PERSISTENT_BACKUP_DIR/sshd_config.original" ]; then
        echo ""
        log_info "找到配置备份: $PERSISTENT_BACKUP_DIR"
    fi
}

# 创建持久化备份
create_persistent_backup() {
    if [ ! -d "$PERSISTENT_BACKUP_DIR" ]; then
        mkdir -p "$PERSISTENT_BACKUP_DIR"
        cp /etc/ssh/sshd_config "$PERSISTENT_BACKUP_DIR/sshd_config.original"
        log_info "已创建原始配置备份: $PERSISTENT_BACKUP_DIR/sshd_config.original"
    else
        log_info "使用现有配置备份: $PERSISTENT_BACKUP_DIR"
    fi
}

# 1. 检查公钥是否存在
check_ssh_keys() {
    log_info "检查 SSH 公钥..."

    if [ ! -f ~/.ssh/authorized_keys ] || [ ! -s ~/.ssh/authorized_keys ]; then
        log_error "未找到 SSH 公钥文件或文件为空！"
        log_error "路径: ~/.ssh/authorized_keys"
        echo ""
        log_warn "如果继续，您将无法通过 SSH 登录服务器！"
        read -p "是否要继续？(输入 YES 继续): " confirm
        if [ "$confirm" != "YES" ]; then
            log_info "操作已取消"
            exit 0
        fi
    else
        log_info "找到 SSH 公钥，密钥数量: $(grep -c "^ssh-" ~/.ssh/authorized_keys || echo 0)"
        echo "密钥内容预览:"
        head -n 2 ~/.ssh/authorized_keys
    fi
}

# 2. 检查端口是否被占用
check_port() {
    local port=$1
    log_info "检查端口 $port 是否可用..."

    if ss -tlnp 2>/dev/null | grep -q ":$port " || netstat -tlnp 2>/dev/null | grep -q ":$port "; then
        # 检查是否是SSH服务占用
        if ss -tlnp 2>/dev/null | grep ":$port " | grep -q "sshd" || netstat -tlnp 2>/dev/null | grep ":$port " | grep -q "sshd"; then
            log_info "端口 $port 已被 SSH 服务占用（正常）"
        else
            log_error "端口 $port 已被其他服务占用！"
            ss -tlnp 2>/dev/null | grep ":$port " || netstat -tlnp 2>/dev/null | grep ":$port "
            exit 1
        fi
    else
        log_info "端口 $port 可用"
    fi
}

# 3. 修改SSH配置
modify_ssh_config() {
    local mode=$1  # enable 或 disable
    log_info "开始配置 SSH..."

    # 创建临时备份目录
    mkdir -p "$BACKUP_DIR"

    # 备份原始配置
    cp /etc/ssh/sshd_config "$BACKUP_DIR/sshd_config.bak"
    log_info "已备份 SSH 配置到: $BACKUP_DIR/sshd_config.bak"

    # 创建新配置
    cp /etc/ssh/sshd_config /etc/ssh/sshd_config.tmp

    if [ "$mode" == "enable" ]; then
        log_info "配置安全模式..."

        # 1. 禁止 root 密码登录，但允许密钥登录
        if grep -q "^PermitRootLogin" /etc/ssh/sshd_config.tmp; then
            sed -i 's/^PermitRootLogin.*/PermitRootLogin prohibit-password/' /etc/ssh/sshd_config.tmp
        else
            sed -i 's/^#PermitRootLogin.*/PermitRootLogin prohibit-password/' /etc/ssh/sshd_config.tmp
        fi

        # 2. 禁用密码认证
        if grep -q "^PasswordAuthentication" /etc/ssh/sshd_config.tmp; then
            sed -i 's/^PasswordAuthentication.*/PasswordAuthentication no/' /etc/ssh/sshd_config.tmp
        else
            sed -i 's/^#PasswordAuthentication.*/PasswordAuthentication no/' /etc/ssh/sshd_config.tmp
        fi

        # 3. 启用公钥认证
        if grep -q "^PubkeyAuthentication" /etc/ssh/sshd_config.tmp; then
            sed -i 's/^PubkeyAuthentication.*/PubkeyAuthentication yes/' /etc/ssh/sshd_config.tmp
        else
            sed -i 's/^#PubkeyAuthentication.*/PubkeyAuthentication yes/' /etc/ssh/sshd_config.tmp
        fi

        # 4. 修改端口
        if grep -q "^Port " /etc/ssh/sshd_config.tmp; then
            sed -i "s/^Port [0-9]\+/Port $NEW_SSH_PORT/" /etc/ssh/sshd_config.tmp
        else
            sed -i "s/^#Port 22/Port $NEW_SSH_PORT/" /etc/ssh/sshd_config.tmp
        fi

        # 5. 额外的安全加固
        # 禁用空密码
        if grep -q "^PermitEmptyPasswords" /etc/ssh/sshd_config.tmp; then
            sed -i 's/^PermitEmptyPasswords.*/PermitEmptyPasswords no/' /etc/ssh/sshd_config.tmp
        else
            sed -i 's/^#PermitEmptyPasswords.*/PermitEmptyPasswords no/' /etc/ssh/sshd_config.tmp
        fi

        # 禁用质询响应认证
        if grep -q "^ChallengeResponseAuthentication" /etc/ssh/sshd_config.tmp; then
            sed -i 's/^ChallengeResponseAuthentication.*/ChallengeResponseAuthentication no/' /etc/ssh/sshd_config.tmp
        fi

    elif [ "$mode" == "disable" ]; then
        log_info "配置普通模式（允许密码登录）..."

        # 如果有原始备份，直接恢复
        if [ -f "$PERSISTENT_BACKUP_DIR/sshd_config.original" ]; then
            log_info "从原始备份恢复配置..."
            cp "$PERSISTENT_BACKUP_DIR/sshd_config.original" /etc/ssh/sshd_config.tmp
        else
            # 手动修改为允许密码登录
            log_info "手动修改配置..."

            # 1. 允许 root 密码登录
            if grep -q "^PermitRootLogin" /etc/ssh/sshd_config.tmp; then
                sed -i 's/^PermitRootLogin.*/PermitRootLogin yes/' /etc/ssh/sshd_config.tmp
            else
                sed -i 's/^#PermitRootLogin.*/PermitRootLogin yes/' /etc/ssh/sshd_config.tmp
            fi

            # 2. 启用密码认证
            if grep -q "^PasswordAuthentication" /etc/ssh/sshd_config.tmp; then
                sed -i 's/^PasswordAuthentication.*/PasswordAuthentication yes/' /etc/ssh/sshd_config.tmp
            else
                sed -i 's/^#PasswordAuthentication.*/PasswordAuthentication yes/' /etc/ssh/sshd_config.tmp
            fi

            # 3. 启用公钥认证（保持）
            if grep -q "^PubkeyAuthentication" /etc/ssh/sshd_config.tmp; then
                sed -i 's/^PubkeyAuthentication.*/PubkeyAuthentication yes/' /etc/ssh/sshd_config.tmp
            else
                sed -i 's/^#PubkeyAuthentication.*/PubkeyAuthentication yes/' /etc/ssh/sshd_config.tmp
            fi

            # 4. 恢复默认端口
            if grep -q "^Port " /etc/ssh/sshd_config.tmp; then
                sed -i "s/^Port [0-9]\+/Port $DEFAULT_SSH_PORT/" /etc/ssh/sshd_config.tmp
            fi
        fi
    fi

    # 验证配置文件语法
    log_info "验证 SSH 配置文件语法..."
    if sshd -t -f /etc/ssh/sshd_config.tmp; then
        log_info "SSH 配置文件语法正确"
        mv /etc/ssh/sshd_config.tmp /etc/ssh/sshd_config
    else
        log_error "SSH 配置文件语法错误！"
        rm /etc/ssh/sshd_config.tmp
        exit 1
    fi
}

# 4. 重启 SSH 服务（兼容多种系统）
restart_ssh() {
    log_info "重启 SSH 服务..."

    # 保持当前连接
    log_warn "注意: SSH 服务将重启，但当前连接会保持"

    if command -v systemctl &> /dev/null; then
        systemctl restart sshd || systemctl restart ssh
        log_info "SSH 服务已通过 systemctl 重启"
    elif command -v service &> /dev/null; then
        service sshd restart || service ssh restart
        log_info "SSH 服务已通过 service 重启"
    else
        /etc/init.d/sshd restart || /etc/init.d/ssh restart
        log_info "SSH 服务已通过 init.d 重启"
    fi
}

# 5. 配置防火墙（启用模式）
configure_firewall_enable() {
    log_info "配置防火墙..."

    # 检查系统并安装 UFW
    if ! command -v ufw &> /dev/null; then
        log_info "安装 UFW 防火墙..."
        apt-get update -y && apt-get install -y ufw
    fi

    # 备份当前防火墙规则
    mkdir -p "$BACKUP_DIR"
    ufw status numbered > "$BACKUP_DIR/ufw_rules.bak" 2>/dev/null || true

    # 配置防火墙规则
    log_info "设置防火墙规则..."

    # 先允许新端口，避免锁死
    ufw allow $NEW_SSH_PORT/tcp comment "SSH"

    # 询问是否允许其他常用端口
    read -p "是否允许 HTTP (80) 和 HTTPS (443) 端口? (y/n): " allow_web
    if [[ $allow_web =~ ^[Yy]$ ]]; then
        ufw allow 80/tcp comment "HTTP"
        ufw allow 443/tcp comment "HTTPS"
        log_info "已允许 HTTP 和 HTTPS 端口"
    fi

    # 启用防火墙
    ufw --force enable

    log_info "防火墙状态:"
    ufw status verbose
}

# 6. 配置防火墙（禁用模式）
configure_firewall_disable() {
    log_info "恢复防火墙配置..."

    if ! command -v ufw &> /dev/null; then
        log_info "未安装 UFW，跳过防火墙配置"
        return
    fi

    # 允许默认SSH端口
    ufw allow $DEFAULT_SSH_PORT/tcp comment "SSH"
    log_info "已允许默认 SSH 端口 $DEFAULT_SSH_PORT"

    # 询问是否删除自定义端口规则
    read -p "是否删除自定义 SSH 端口 $NEW_SSH_PORT 的防火墙规则? (y/n): " remove_port
    if [[ $remove_port =~ ^[Yy]$ ]]; then
        ufw delete allow $NEW_SSH_PORT/tcp 2>/dev/null || true
        log_info "已删除端口 $NEW_SSH_PORT 的防火墙规则"
    fi

    ufw status verbose
}

# 启用安全模式
enable_security() {
    log_info "=== 启用 SSH 安全模式 ==="
    echo ""

    # 检查当前状态
    if check_current_status > /dev/null 2>&1; then
        log_warn "SSH 已经处于安全模式"
        read -p "是否要重新配置? (y/n): " reconfig
        if [[ ! $reconfig =~ ^[Yy]$ ]]; then
            log_info "操作已取消"
            exit 0
        fi
    fi

    # 显示当前配置
    log_info "当前 SSH 配置:"
    echo "  - 当前端口: $(get_ssh_config_value "Port" || echo "22 (默认)")"
    echo "  - 将修改为: $NEW_SSH_PORT"
    echo ""

    # 确认执行
    read -p "是否继续执行? (y/n): " confirm
    if [[ ! $confirm =~ ^[Yy]$ ]]; then
        log_info "操作已取消"
        exit 0
    fi

    # 创建持久化备份
    create_persistent_backup

    # 执行配置
    check_ssh_keys
    check_port "$NEW_SSH_PORT"
    modify_ssh_config "enable"
    restart_ssh
    configure_firewall_enable

    # 显示完成信息
    echo ""
    echo "========================================"
    log_info "SSH 安全模式已启用！"
    echo "========================================"
    echo ""
    echo "修改后的配置:"
    echo "  - SSH 端口: $NEW_SSH_PORT"
    echo "  - 密码登录: 已禁用"
    echo "  - 密钥登录: 已启用"
    echo "  - Root 密码登录: 已禁用"
    echo ""
    echo "备份信息:"
    echo "  - 临时备份: $BACKUP_DIR"
    echo "  - 永久备份: $PERSISTENT_BACKUP_DIR"
    echo ""
    echo "重要提示:"
    echo "  1. 请勿关闭当前 SSH 连接"
    echo "  2. 在新终端测试登录: ssh -p $NEW_SSH_PORT root@your_server_ip"
    echo "  3. 确认新连接成功后再关闭此窗口"
    echo "  4. 如需恢复，运行: $0 disable"
    echo ""
    echo "========================================"
}

# 关闭安全模式
disable_security() {
    log_info "=== 关闭 SSH 安全模式 ==="
    echo ""

    # 检查当前状态
    if ! check_current_status > /dev/null 2>&1; then
        log_warn "SSH 已经处于普通模式"
        read -p "是否要重新配置? (y/n): " reconfig
        if [[ ! $reconfig =~ ^[Yy]$ ]]; then
            log_info "操作已取消"
            exit 0
        fi
    fi

    # 警告
    log_warn "警告: 此操作将允许密码登录，安全性会降低！"
    read -p "确认要关闭安全模式吗? (输入 YES 继续): " confirm
    if [ "$confirm" != "YES" ]; then
        log_info "操作已取消"
        exit 0
    fi

    # 执行配置
    check_port "$DEFAULT_SSH_PORT"
    modify_ssh_config "disable"
    restart_ssh
    configure_firewall_disable

    # 显示完成信息
    echo ""
    echo "========================================"
    log_info "SSH 安全模式已关闭！"
    echo "========================================"
    echo ""
    echo "修改后的配置:"
    echo "  - SSH 端口: $DEFAULT_SSH_PORT"
    echo "  - 密码登录: 已启用"
    echo "  - 密钥登录: 已启用"
    echo ""
    echo "重要提示:"
    echo "  1. 请勿关闭当前 SSH 连接"
    echo "  2. 在新终端测试登录: ssh -p $DEFAULT_SSH_PORT root@your_server_ip"
    echo "  3. 确认新连接成功后再关闭此窗口"
    echo "  4. 如需重新启用安全模式，运行: $0 enable"
    echo ""
    echo "========================================"
}

# 主流程
main() {
    local action=${1:-}

    case "$action" in
        enable)
            enable_security
            ;;
        disable)
            disable_security
            ;;
        status)
            show_status
            ;;
        *)
            show_usage
            ;;
    esac
}

# 执行主函数
main "$@"