import asyncio
import time
from typing import Optional
import paramiko
from app.core.device.manager import device_manager
from app.schemas.ssh import SSHExecRequest, SSHExecResponse, SSHConnectionInfo
from app.utils.log import get_logger

logger = get_logger(__name__)

class SSHService:
    """SSH服务类 - 实现SSH协议相关操作"""
    
    def __init__(self):
        self.connections = {}  # 存储SSH连接
    
    async def _get_connection(self, device_id: str) -> paramiko.SSHClient:
        """获取SSH连接"""
        if device_id in self.connections:
            return self.connections[device_id]
        
        # 从设备管理器获取连接信息
        device = await device_manager.get_device(device_id)
        if not device:
            raise ValueError(f"设备 {device_id} 不存在")
        
        connection_info = device.connection_info
        
        # 创建SSH连接
        ssh_client = paramiko.SSHClient()
        ssh_client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
        
        try:
            # 连接参数
            host = connection_info.get('host')
            port = connection_info.get('port', 22)
            username = connection_info.get('username')
            password = connection_info.get('password')
            key_file = connection_info.get('key_file')
            timeout = connection_info.get('timeout', 30)
            
            # 建立连接
            if key_file:
                ssh_client.connect(
                    hostname=host,
                    port=port,
                    username=username,
                    key_filename=key_file,
                    timeout=timeout
                )
            else:
                ssh_client.connect(
                    hostname=host,
                    port=port,
                    username=username,
                    password=password,
                    timeout=timeout
                )
            
            # 存储连接
            self.connections[device_id] = ssh_client
            logger.info(f"SSH连接建立成功: {device_id} -> {host}:{port}")
            
            return ssh_client
            
        except Exception as e:
            logger.error(f"SSH连接失败: {device_id}, 错误: {e}")
            raise ValueError(f"SSH连接失败: {str(e)}")
    
    async def exec_command(self, device_id: str, command: str, timeout: int = 30, 
                          working_directory: Optional[str] = None) -> SSHExecResponse:
        """执行SSH命令"""
        start_time = time.time()
        
        try:
            ssh_client = await self._get_connection(device_id)
            
            # 如果指定工作目录，先切换到该目录
            if working_directory:
                command = f"cd {working_directory} && {command}"
            
            # 执行命令
            stdin, stdout, stderr = ssh_client.exec_command(command, timeout=timeout)
            
            # 获取输出
            stdout_data = stdout.read().decode('utf-8', errors='ignore')
            stderr_data = stderr.read().decode('utf-8', errors='ignore')
            exit_code = stdout.channel.recv_exit_status()
            
            execution_time = time.time() - start_time
            
            success = exit_code == 0
            
            logger.info(f"SSH命令执行完成: {device_id} -> {command}, 退出码: {exit_code}")
            
            return SSHExecResponse(
                success=success,
                stdout=stdout_data,
                stderr=stderr_data,
                exit_code=exit_code,
                execution_time=execution_time
            )
            
        except Exception as e:
            execution_time = time.time() - start_time
            logger.error(f"SSH命令执行失败: {device_id} -> {command}, 错误: {e}")
            
            return SSHExecResponse(
                success=False,
                stdout="",
                stderr=str(e),
                exit_code=-1,
                execution_time=execution_time
            )
    
    async def upload_file(self, device_id: str, local_path: str, remote_path: str) -> dict:
        """上传文件"""
        try:
            ssh_client = await self._get_connection(device_id)
            sftp = ssh_client.open_sftp()
            
            # 上传文件
            sftp.put(local_path, remote_path)
            sftp.close()
            
            logger.info(f"SSH文件上传成功: {device_id} -> {local_path} -> {remote_path}")
            return {
                "success": True,
                "message": "文件上传成功",
                "local_path": local_path,
                "remote_path": remote_path
            }
            
        except Exception as e:
            logger.error(f"SSH文件上传失败: {device_id}, 错误: {e}")
            return {
                "success": False,
                "message": f"文件上传失败: {str(e)}"
            }
    
    async def download_file(self, device_id: str, remote_path: str, local_path: str) -> dict:
        """下载文件"""
        try:
            ssh_client = await self._get_connection(device_id)
            sftp = ssh_client.open_sftp()
            
            # 下载文件
            sftp.get(remote_path, local_path)
            sftp.close()
            
            logger.info(f"SSH文件下载成功: {device_id} -> {remote_path} -> {local_path}")
            return {
                "success": True,
                "message": "文件下载成功",
                "remote_path": remote_path,
                "local_path": local_path
            }
            
        except Exception as e:
            logger.error(f"SSH文件下载失败: {device_id}, 错误: {e}")
            return {
                "success": False,
                "message": f"文件下载失败: {str(e)}"
            }
    
    async def close_connection(self, device_id: str) -> bool:
        """关闭SSH连接"""
        try:
            if device_id in self.connections:
                ssh_client = self.connections[device_id]
                ssh_client.close()
                del self.connections[device_id]
                logger.info(f"SSH连接已关闭: {device_id}")
                return True
            return False
        except Exception as e:
            logger.error(f"关闭SSH连接失败: {device_id}, 错误: {e}")
            return False
    
    async def test_connection(self, device_id: str) -> bool:
        """测试SSH连接"""
        try:
            ssh_client = await self._get_connection(device_id)
            # 执行简单命令测试连接
            stdin, stdout, stderr = ssh_client.exec_command("echo 'test'", timeout=5)
            result = stdout.read().decode('utf-8').strip()
            return result == "test"
        except Exception as e:
            logger.error(f"SSH连接测试失败: {device_id}, 错误: {e}")
            return False