"""Shell interface — run commands, backed by a Transport."""

from __future__ import annotations

from dataclasses import dataclass

from cua_sandbox.transport.base import Transport


@dataclass
class CommandResult:
    stdout: str
    stderr: str
    returncode: int

    @property
    def success(self) -> bool:
        return self.returncode == 0


class Shell:
    """Shell command execution."""

    def __init__(self, transport: Transport):
        self._t = transport

    async def run(
        self,
        command: str,
        timeout: int = 30,
        background: bool = False,
    ) -> CommandResult:
        """Run a shell command and return the result.

        When ``background=True``, returns immediately with ``stdout=str(pid)``
        and ``returncode=0``; poll for completion via a sentinel file or by
        inspecting the process list.
        """
        if background:
            session = await self._t.pty_create(command=command)
            pid = session.get("pid") if isinstance(session, dict) else None
            return CommandResult(stdout=str(pid or ""), stderr="", returncode=0)

        result = await self._t.send("run_command", command=command, timeout=timeout)
        if isinstance(result, dict):
            rc = result.get("returncode", result.get("return_code", -1))
            return CommandResult(
                stdout=result.get("stdout", ""),
                stderr=result.get("stderr", ""),
                returncode=rc if rc is not None else 0,
            )
        # LocalTransport returns cua_auto.shell.CommandResult directly
        return CommandResult(
            stdout=getattr(result, "stdout", ""),
            stderr=getattr(result, "stderr", ""),
            returncode=getattr(result, "returncode", -1),
        )