"""
ServerGuard - 通用工具库

提供命令执行、日志配置、输出解析等通用功能。
"""

import subprocess
import logging
import sys
import os
import re
import json
from typing import List, Dict, Any, Optional, Tuple, Union
from datetime import datetime


class ServerGuardError(Exception):
    """ServerGuard 基础异常类"""
    pass


class CommandExecutionError(ServerGuardError):
    """命令执行异常"""
    pass


class PermissionError(ServerGuardError):
    """权限异常"""
    pass


def execute_command(
    cmd_list: List[str],
    timeout: int = 60,
    check_returncode: bool = True,
    capture_output: bool = True,
    shell: bool = False,
    input_data: Optional[str] = None
) -> Tuple[int, str, str]:
    """
    安全地执行外部命令。

    Args:
        cmd_list: 命令及其参数的列表
        timeout: 命令超时时间（秒）
        check_returncode: 是否在非零返回码时抛出异常
        capture_output: 是否捕获输出
        shell: 是否使用 shell 执行
        input_data: 输入到命令的字符串数据

    Returns:
        Tuple[returncode, stdout, stderr]

    Raises:
        CommandExecutionError: 命令执行失败
        PermissionError: 权限不足
    """
    logger = logging.getLogger(__name__)
    
    # 安全：禁止使用 shell=True 时传递未经验证的命令字符串
    if shell and isinstance(cmd_list, list):
        cmd_str = ' '.join(cmd_list)
        logger.warning(f"Using shell=True with command: {cmd_str}")
    
    try:
        logger.debug(f"Executing command: {' '.join(cmd_list)}")
        
        kwargs = {
            'timeout': timeout,
            'shell': shell,
            'universal_newlines': True  # Python 3.6 compatible version of text=True
        }
        if capture_output:
            kwargs['stdout'] = subprocess.PIPE
            kwargs['stderr'] = subprocess.PIPE
        if input_data:
            kwargs['input'] = input_data
            
        result = subprocess.run(cmd_list, **kwargs)
        
        stdout = result.stdout if result.stdout else ""
        stderr = result.stderr if result.stderr else ""
        
        if check_returncode and result.returncode != 0:
            error_msg = f"Command failed with code {result.returncode}: {' '.join(cmd_list)}\nstderr: {stderr}"
            logger.error(error_msg)
            raise CommandExecutionError(error_msg)
        
        return result.returncode, stdout, stderr
        
    except subprocess.TimeoutExpired:
        error_msg = f"Command timed out after {timeout}s: {' '.join(cmd_list)}"
        logger.error(error_msg)
        raise CommandExecutionError(error_msg)
    except FileNotFoundError:
        error_msg = f"Command not found: {cmd_list[0]}"
        logger.error(error_msg)
        raise CommandExecutionError(error_msg)
    except PermissionError as e:
        error_msg = f"Permission denied executing: {' '.join(cmd_list)}"
        logger.error(error_msg)
        raise PermissionError(error_msg) from e


def check_root_privileges() -> bool:
    """
    检查当前是否以 root 用户运行。

    Returns:
        bool: 是否为 root 用户
    """
    return os.geteuid() == 0


def require_root(func):
    """
    装饰器：要求函数必须以 root 权限运行。
    """
    def wrapper(*args, **kwargs):
        if not check_root_privileges():
            logging.warning(f"Function {func.__name__} requires root privileges")
            return {
                "status": "error",
                "error": "This function requires root privileges. Please run with sudo."
            }
        return func(*args, **kwargs)
    return wrapper


def setup_logging(
    log_file: Optional[str] = None,
    level: int = logging.INFO,
    console_output: bool = True
) -> logging.Logger:
    """
    配置日志系统。

    Args:
        log_file: 日志文件路径，None 则不写入文件
        level: 日志级别
        console_output: 是否输出到控制台

    Returns:
        logging.Logger: 配置好的 logger 实例
    """
    logger = logging.getLogger()
    logger.setLevel(level)
    
    # 清除已有的 handlers
    logger.handlers = []
    
    formatter = logging.Formatter(
        '%(asctime)s - %(name)s - %(levelname)s - %(message)s',
        datefmt='%Y-%m-%d %H:%M:%S'
    )
    
    if console_output:
        console_handler = logging.StreamHandler(sys.stdout)
        console_handler.setFormatter(formatter)
        logger.addHandler(console_handler)
    
    if log_file:
        os.makedirs(os.path.dirname(log_file) or '.', exist_ok=True)
        file_handler = logging.FileHandler(log_file)
        file_handler.setFormatter(formatter)
        logger.addHandler(file_handler)
    
    return logger


def parse_key_value_output(text: str, delimiter: str = ':') -> Dict[str, str]:
    """
    解析 key: value 格式的文本输出。

    Args:
        text: 要解析的文本
        delimiter: 键值分隔符

    Returns:
        Dict[str, str]: 解析后的字典
    """
    result = {}
    for line in text.strip().split('\n'):
        line = line.strip()
        if not line or line.startswith('#'):
            continue
        
        parts = line.split(delimiter, 1)
        if len(parts) == 2:
            key = parts[0].strip()
            value = parts[1].strip()
            result[key] = value
    
    return result


def parse_table_output(text: str, headers: Optional[List[str]] = None) -> List[Dict[str, str]]:
    """
    解析表格格式的文本输出。

    Args:
        text: 要解析的文本
        headers: 表头列表，None 则从第一行自动提取

    Returns:
        List[Dict[str, str]]: 解析后的列表
    """
    lines = [line.strip() for line in text.strip().split('\n') if line.strip()]
    if not lines:
        return []
    
    if headers is None:
        # 尝试自动检测表头
        headers = [h.strip() for h in lines[0].split() if h.strip()]
        data_lines = lines[1:]
    else:
        data_lines = lines
    
    result = []
    for line in data_lines:
        values = line.split()
        if len(values) >= len(headers):
            row = {headers[i]: values[i] for i in range(len(headers))}
            result.append(row)
    
    return result


def extract_with_regex(text: str, pattern: str, group: int = 1, default: Any = None) -> Any:
    """
    使用正则表达式从文本中提取内容。

    Args:
        text: 要搜索的文本
        pattern: 正则表达式模式
        group: 捕获组索引
        default: 未匹配时的默认值

    Returns:
        匹配结果或默认值
    """
    match = re.search(pattern, text)
    if match:
        try:
            return match.group(group)
        except IndexError:
            return default
    return default


def safe_int(value: Any, default: int = 0) -> int:
    """
    安全地将值转换为整数。

    Args:
        value: 要转换的值
        default: 转换失败时的默认值

    Returns:
        int: 转换后的整数
    """
    try:
        # 移除常见单位后缀
        if isinstance(value, str):
            value = value.strip().lower()
            value = re.sub(r'[\s,]', '', value)
            # 处理带单位的数值 (如 "32 GB", "2.5GHz")
            value = re.sub(r'[^\d.-]', '', value)
        return int(float(value))
    except (ValueError, TypeError):
        return default


def safe_float(value: Any, default: float = 0.0) -> float:
    """
    安全地将值转换为浮点数。

    Args:
        value: 要转换的值
        default: 转换失败时的默认值

    Returns:
        float: 转换后的浮点数
    """
    try:
        if isinstance(value, str):
            value = value.strip().lower()
            value = re.sub(r'[\s,]', '', value)
            value = re.sub(r'[^\d.-]', '', value)
        return float(value)
    except (ValueError, TypeError):
        return default


def get_timestamp() -> str:
    """
    获取当前时间戳字符串。

    Returns:
        str: 格式化的时间戳
    """
    return datetime.now().strftime('%Y-%m-%d %H:%M:%S')


def get_file_timestamp() -> str:
    """
    获取适合文件名的当前时间戳字符串。

    Returns:
        str: 格式化的文件名时间戳
    """
    return datetime.now().strftime('%Y%m%d_%H%M%S')


def read_file_lines(filepath: str, max_lines: int = 1000) -> List[str]:
    """
    安全地读取文件内容。

    Args:
        filepath: 文件路径
        max_lines: 最大读取行数

    Returns:
        List[str]: 文件行列表
    """
    try:
        with open(filepath, 'r', encoding='utf-8', errors='ignore') as f:
            lines = []
            for i, line in enumerate(f):
                if i >= max_lines:
                    break
                lines.append(line.rstrip('\n'))
            return lines
    except (IOError, OSError) as e:
        logging.getLogger(__name__).warning(f"Failed to read file {filepath}: {e}")
        return []


def check_command_exists(command: str) -> bool:
    """
    检查命令是否存在。

    Args:
        command: 命令名称

    Returns:
        bool: 命令是否存在
    """
    try:
        # Python 3.6 compatible version
        subprocess.run(
            ['which', command],
            stdout=subprocess.DEVNULL,
            stderr=subprocess.DEVNULL,
            check=True
        )
        return True
    except (subprocess.CalledProcessError, FileNotFoundError):
        return False


def format_bytes(size_bytes: int) -> str:
    """
    将字节数格式化为人类可读的字符串。

    Args:
        size_bytes: 字节数

    Returns:
        str: 格式化后的字符串
    """
    if size_bytes == 0:
        return "0 B"
    
    units = ['B', 'KB', 'MB', 'GB', 'TB', 'PB']
    unit_index = 0
    size = float(size_bytes)
    
    while size >= 1024 and unit_index < len(units) - 1:
        size /= 1024
        unit_index += 1
    
    return f"{size:.2f} {units[unit_index]}"


def sanitize_filename(filename: str) -> str:
    """
    清理文件名，移除不安全字符。

    Args:
        filename: 原始文件名

    Returns:
        str: 清理后的文件名
    """
    # 移除或替换不安全字符
    filename = re.sub(r'[<>:"/\\|?*]', '_', filename)
    filename = filename.strip('. ')
    return filename


def merge_dicts(base: Dict[str, Any], update: Dict[str, Any]) -> Dict[str, Any]:
    """
    递归合并两个字典。

    Args:
        base: 基础字典
        update: 更新字典

    Returns:
        Dict[str, Any]: 合并后的字典
    """
    result = base.copy()
    for key, value in update.items():
        if key in result and isinstance(result[key], dict) and isinstance(value, dict):
            result[key] = merge_dicts(result[key], value)
        else:
            result[key] = value
    return result