import subprocess
import threading
import importlib


def _get_multiplexer_functions():
    """Lazy import multiplexer functions to avoid circular imports."""
    multiplexer = importlib.import_module("pr.multiplexer")
    return {
        "create_multiplexer": multiplexer.create_multiplexer,
        "get_multiplexer": multiplexer.get_multiplexer,
        "close_multiplexer": multiplexer.close_multiplexer,
        "get_all_multiplexer_states": multiplexer.get_all_multiplexer_states,
    }


def start_interactive_session(command, session_name=None, process_type="generic", cwd=None):
    """
    Start an interactive session in a dedicated multiplexer.

    Args:
        command: The command to run (list or string)
        session_name: Optional name for the session
        process_type: Type of process (ssh, vim, apt, etc.)
        cwd: Current working directory for the command

    Returns:
        session_name: The name of the created session
    """
    funcs = _get_multiplexer_functions()
    name, mux = funcs["create_multiplexer"](session_name)
    mux.update_metadata("process_type", process_type)

    # Start the process
    if isinstance(command, str):
        command = command.split()

    try:
        process = subprocess.Popen(
            command,
            stdin=subprocess.PIPE,
            stdout=subprocess.PIPE,
            stderr=subprocess.PIPE,
            text=True,
            bufsize=1,
            cwd=cwd,
        )

        mux.process = process
        mux.update_metadata("pid", process.pid)

        # Set process type and handler
        from pr.tools.process_handlers import detect_process_type

        detected_type = detect_process_type(command)
        mux.set_process_type(detected_type)

        # Start output readers
        stdout_thread = threading.Thread(
            target=_read_output, args=(process.stdout, mux.write_stdout, detected_type), daemon=True
        )
        stderr_thread = threading.Thread(
            target=_read_output, args=(process.stderr, mux.write_stderr, detected_type), daemon=True
        )

        stdout_thread.start()
        stderr_thread.start()

        mux.stdout_thread = stdout_thread
        mux.stderr_thread = stderr_thread

        return name
    except Exception as e:
        funcs["close_multiplexer"](name)
        raise e


def _read_output(stream, write_func, process_type):
    """Read from a stream and write to multiplexer buffer."""
    if process_type in ["vim", "ssh"]:
        try:
            while True:
                char = stream.read(1)
                if not char:
                    break
                write_func(char)
        except Exception as e:
            print(f"Error reading output: {e}")
    else:
        try:
            for line in iter(stream.readline, ""):
                if line:
                    write_func(line.rstrip("\n"))
        except Exception as e:
            print(f"Error reading output: {e}")


def send_input_to_session(session_name, input_data):
    """
    Send input to an interactive session.

    Args:
        session_name: Name of the session
        input_data: Input string to send
    """
    funcs = _get_multiplexer_functions()
    mux = funcs["get_multiplexer"](session_name)
    if not mux:
        raise ValueError(f"Session {session_name} not found")

    if not hasattr(mux, "process") or mux.process.poll() is not None:
        raise ValueError(f"Session {session_name} is not active")

    try:
        mux.process.stdin.write(input_data + "\n")
        mux.process.stdin.flush()
    except Exception as e:
        raise RuntimeError(f"Failed to send input to session {session_name}: {e}")


def read_session_output(session_name, lines=None):
    funcs = _get_multiplexer_functions()
    """
    Read output from a session.

    Args:
        session_name: Name of the session
        lines: Number of recent lines to return (None for all)

    Returns:
        dict: {'stdout': str, 'stderr': str}
    """
    mux = funcs["get_multiplexer"](session_name)
    if not mux:
        raise ValueError(f"Session {session_name} not found")

    output = mux.get_all_output()
    if lines is not None:
        # Return last N lines
        stdout_lines = output["stdout"].split("\n")[-lines:] if output["stdout"] else []
        stderr_lines = output["stderr"].split("\n")[-lines:] if output["stderr"] else []
        output = {"stdout": "\n".join(stdout_lines), "stderr": "\n".join(stderr_lines)}
    return output


def list_active_sessions():
    """
    List all active interactive sessions.

    Returns:
        dict: Session states
    """
    funcs = _get_multiplexer_functions()
    return funcs["get_all_multiplexer_states"]()


def get_session_status(session_name):
    """
    Get detailed status of a session.

    Args:
        session_name: Name of the session

    Returns:
        dict: Session metadata and status
    """
    funcs = _get_multiplexer_functions()
    mux = funcs["get_multiplexer"](session_name)
    if not mux:
        return None

    status = mux.get_metadata()
    status["is_active"] = hasattr(mux, "process") and mux.process.poll() is None
    if status["is_active"]:
        status["pid"] = mux.process.pid
    status["output_summary"] = {
        "stdout_lines": len(mux.stdout_buffer),
        "stderr_lines": len(mux.stderr_buffer),
    }
    return status


def close_interactive_session(session_name):
    """
    Close an interactive session.
    """
    try:
        funcs = _get_multiplexer_functions()
        mux = funcs["get_multiplexer"](session_name)
        if mux:
            mux.process.kill()
        funcs["close_multiplexer"](session_name)
        return {"status": "success"}
    except Exception as e:
        return {"status": "error", "error": str(e)}