#!/bin/bash

# 查找随机空闲端口
# 用途：
#   在指定端口范围内，随机选择一个当前未被监听（TCP/UDP）的端口
# 参数：
#   $1: 起始端口（默认 10001）
#   $2: 结束端口（默认 65535）
#   $3: 最大随机尝试次数（默认 100）
find_free_port() {
  local start="${1:-10001}"
  local max="${2:-65535}"
  local attempts="${3:-100}"

  # ------------------------------------------------------------
  # 收集当前正在监听的端口（TCP + UDP）
  # 优先使用 ss，其次 netstat
  # ------------------------------------------------------------
  local used_ports raw
  if command -v ss >/dev/null 2>&1; then
    # ss 输出示例：
    # LISTEN 0 128 0.0.0.0:22
    raw=$(ss -lntu 2>/dev/null || true)
    used_ports=$(printf "%s\n" "$raw" \
      | awk '{print $5}' \
      | sed -E 's/.*[:]//g')
  elif command -v netstat >/dev/null 2>&1; then
    # netstat 输出示例：
    # tcp 0 0 0.0.0.0:22
    raw=$(netstat -lntu 2>/dev/null || true)
    used_ports=$(printf "%s\n" "$raw" \
      | awk '{print $4}' \
      | sed -E 's/.*[:]//g')
  else
    echo "Error: ss or netstat is required to check listening ports." >&2
    return 2
  fi

  # ------------------------------------------------------------
  # 将已占用端口存入关联数组，便于 O(1) 判断
  # 需要 bash 4+
  # ------------------------------------------------------------
  declare -A used_map
  local p
  for p in $used_ports; do
    # 过滤非数字字段（如 *、:::）
    if [[ $p =~ ^[0-9]+$ ]]; then
      used_map["$p"]=1
    fi
  done

  # ------------------------------------------------------------
  # 随机尝试若干次
  # 每次随机生成一个端口，只要未被监听就立即返回
  # ------------------------------------------------------------
  local port i
  for ((i=0; i<attempts; i++)); do
    # 在 [start, max] 范围内生成随机端口
    port=$(( RANDOM % (max - start + 1) + start ))

    # 如果端口不在已监听表中，则认为可用
    if [[ -z "${used_map[$port]}" ]]; then
      echo "$port"
      return 0
    fi
  done

  # ------------------------------------------------------------
  # 多次随机尝试后仍未找到可用端口
  # 通常意味着端口范围过小或已被大量占用
  # ------------------------------------------------------------
  echo "Error: no free port found after $attempts random attempts." >&2
  return 1
}

# ==========================================
# 函数名: manage_port
# 参数1: allow 或 deny (操作类型)
# 参数2: 端口号
# --- 使用示例 ---
# 开启端口 8888
# manage_port allow 8888

# 关闭端口 8888
# manage_port deny 8888
# ==========================================
manage_port() {
    local ACTION=$1
    local PORT=$2

    if [[ -z "$PORT" ]]; then
        echo "错误: 未提供端口号"
        return 1
    fi

    # 统一转换为小写，增强鲁棒性
    ACTION=$(echo "$ACTION" | tr '[:upper:]' '[:lower:]')

    echo "--- 正在对端口 $PORT 执行 $ACTION 操作 ---"

    # 1. 防火墙 (Firewall) 逻辑处理
    if command -v firewall-cmd >/dev/null 2>&1 && systemctl is-active --quiet firewalld; then
        # CentOS/RHEL/Fedora (firewalld)
        if [ "$ACTION" == "allow" ]; then
            sudo firewall-cmd --zone=public --add-port=${PORT}/tcp --permanent
            sudo firewall-cmd --zone=public --add-port=${PORT}/udp --permanent
        elif [ "$ACTION" == "deny" ]; then
            sudo firewall-cmd --zone=public --remove-port=${PORT}/tcp --permanent
            sudo firewall-cmd --zone=public --remove-port=${PORT}/udp --permanent
        fi
        sudo firewall-cmd --reload
        echo "[OK] firewalld 规则已更新 ($ACTION)"

    elif command -v ufw >/dev/null 2>&1 && systemctl is-active --quiet ufw; then
        # Ubuntu/Debian (ufw)
        if [ "$ACTION" == "allow" ]; then
            sudo ufw allow ${PORT}/tcp
            sudo ufw allow ${PORT}/udp
        elif [ "$ACTION" == "deny" ]; then
            sudo ufw delete allow ${PORT}/tcp
            sudo ufw delete allow ${PORT}/udp
        fi
        echo "[OK] ufw 规则已更新 ($ACTION)"

    else
        # 兜底方案 (iptables)
        # allow 使用 -I (Insert) 插入到规则首行，deny 使用 -D (Delete)
        local FLAG=$([ "$ACTION" == "allow" ] && echo "-I" || echo "-D")
        sudo iptables $FLAG INPUT -p tcp --dport ${PORT} -j ACCEPT 2>/dev/null
        sudo iptables $FLAG INPUT -p udp --dport ${PORT} -j ACCEPT 2>/dev/null
        echo "[OK] iptables 规则已执行 ($ACTION)"
    fi

    # 2. SELinux 逻辑处理
    if command -v getenforce >/dev/null 2>&1; then
        local SELINUX_STATUS=$(getenforce)
        if [ "$SELINUX_STATUS" == "Enforcing" ]; then
            if command -v semanage >/dev/null 2>&1; then
                if [ "$ACTION" == "allow" ]; then
                    # 尝试添加，若存在则尝试修改
                    sudo semanage port -a -t http_port_t -p tcp ${PORT} 2>/dev/null || \
                    sudo semanage port -m -t http_port_t -p tcp ${PORT}
                elif [ "$ACTION" == "deny" ]; then
                    sudo semanage port -d -t http_port_t -p tcp ${PORT} 2>/dev/null
                fi
                echo "[OK] SELinux 端口权限已更新 ($ACTION)"
            else
                # 如果没装 semanage，在 allow 时开启全局布尔值，deny 时通常保持不变以防影响其他业务
                if [ "$ACTION" == "allow" ]; then
                    echo "[!] 警告: 未找到 semanage，尝试开启全局网络连接开关..."
                    sudo setsebool -P httpd_can_network_connect 1
                fi
            fi
        fi
    fi
}

update_port(){
  local script_dir="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"  # 脚本文件夹绝对路径

  local config_dir="$script_dir/../config"
  
  local port=$(find_free_port)
  modify_json_file "$config_dir/config.json" ".inbounds[0].listen_port" "$port"
  manage_port allow "$port"
  echo "设置端口成功"
}