import io
import threading
from typing import Optional, Callable
from dataclasses import dataclass

import paramiko

from config import get_config


@dataclass
class CommandResult:
    """Result of an SSH command execution."""

    stdout: str
    stderr: str
    exit_code: int
    success: bool


class SSHManager:
    """Manages SSH connections to target hosts."""

    def __init__(self):
        self._connections: dict[str, paramiko.SSHClient] = {}
        self._lock = threading.Lock()

    def _get_private_key(self) -> paramiko.PKey:
        """Parse the private key from config."""
        config = get_config()
        key_data = config.ssh_private_key

        # Try different key formats
        key_file = io.StringIO(key_data)

        for key_class in [paramiko.RSAKey, paramiko.Ed25519Key, paramiko.ECDSAKey]:
            try:
                key_file.seek(0)
                return key_class.from_private_key(key_file)
            except Exception:
                continue

        raise ValueError("Unable to parse SSH private key. Supported formats: RSA, Ed25519, ECDSA")

    def connect(self, hostname: str, username: str = "root", port: int = 22) -> bool:
        """Establish SSH connection to a host."""
        connection_key = f"{username}@{hostname}:{port}"

        with self._lock:
            if connection_key in self._connections:
                # Test if connection is still alive
                try:
                    transport = self._connections[connection_key].get_transport()
                    if transport and transport.is_active():
                        return True
                except Exception:
                    pass
                # Remove dead connection
                self._connections.pop(connection_key, None)

            try:
                client = paramiko.SSHClient()
                client.set_missing_host_key_policy(paramiko.AutoAddPolicy())

                private_key = self._get_private_key()
                client.connect(
                    hostname=hostname,
                    port=port,
                    username=username,
                    pkey=private_key,
                    timeout=30,
                    allow_agent=False,
                    look_for_keys=False,
                )
                self._connections[connection_key] = client
                return True
            except Exception as e:
                raise ConnectionError(f"Failed to connect to {connection_key}: {str(e)}")

    def execute(
        self,
        hostname: str,
        command: str,
        username: str = "root",
        port: int = 22,
        timeout: int = 60,
        on_output: Optional[Callable[[str], None]] = None,
    ) -> CommandResult:
        """Execute a command on a remote host."""
        connection_key = f"{username}@{hostname}:{port}"

        with self._lock:
            client = self._connections.get(connection_key)
            if not client:
                raise ConnectionError(f"Not connected to {connection_key}. Call connect() first.")

        try:
            stdin, stdout, stderr = client.exec_command(command, timeout=timeout)

            # Read output
            stdout_data = ""
            stderr_data = ""

            # Stream stdout if callback provided
            if on_output:
                for line in stdout:
                    stdout_data += line
                    on_output(line.rstrip("\n"))
            else:
                stdout_data = stdout.read().decode("utf-8", errors="replace")

            stderr_data = stderr.read().decode("utf-8", errors="replace")
            exit_code = stdout.channel.recv_exit_status()

            return CommandResult(
                stdout=stdout_data,
                stderr=stderr_data,
                exit_code=exit_code,
                success=exit_code == 0,
            )
        except Exception as e:
            return CommandResult(
                stdout="",
                stderr=str(e),
                exit_code=-1,
                success=False,
            )

    def disconnect(self, hostname: str, username: str = "root", port: int = 22) -> None:
        """Close SSH connection to a host."""
        connection_key = f"{username}@{hostname}:{port}"

        with self._lock:
            client = self._connections.pop(connection_key, None)
            if client:
                try:
                    client.close()
                except Exception:
                    pass

    def disconnect_all(self) -> None:
        """Close all SSH connections."""
        with self._lock:
            for client in self._connections.values():
                try:
                    client.close()
                except Exception:
                    pass
            self._connections.clear()

    def is_connected(self, hostname: str, username: str = "root", port: int = 22) -> bool:
        """Check if connected to a host."""
        connection_key = f"{username}@{hostname}:{port}"

        with self._lock:
            client = self._connections.get(connection_key)
            if not client:
                return False
            try:
                transport = client.get_transport()
                return transport is not None and transport.is_active()
            except Exception:
                return False


# Global SSH manager instance
_ssh_manager: Optional[SSHManager] = None


def get_ssh_manager() -> SSHManager:
    """Get the global SSH manager instance."""
    global _ssh_manager
    if _ssh_manager is None:
        _ssh_manager = SSHManager()
    return _ssh_manager