import argparse
import time
import serial.tools.list_ports
from pymodbus.client import ModbusSerialClient
from src.config import MODBUS_CONFIG, MAX_RECONNECTION_ATTEMPTS, INITIAL_BACKOFF_TIME

def get_default_com_port() -> str:
    """
    Get the first available COM port.
    
    Returns:
        str: The name of the first available COM port.
    """
    ports = list(serial.tools.list_ports.comports())
    return ports[0].device

def parse_commandline_args() -> argparse.Namespace:
    """
    Parse command line arguments.
    
    Returns:
        argparse.Namespace: Parsed command line arguments.
    """
    parser = argparse.ArgumentParser(description='DN23E08 Python Modbus Example')
    parser.add_argument('--com_port', type=str, default=get_default_com_port(),
                        help='COM port for the Modbus connection')
    parser.add_argument('--slave_id', type=int, default=1,
                        help='Slave ID for the Modbus device')
    parser.add_argument('--cycle_time', type=float, default=0.05,
                        help='Cycle time in seconds for the main loop')
    return parser.parse_args()

def connect_modbus_client(args: argparse.Namespace) -> ModbusSerialClient:
    """
    Connect to the Modbus client with exponential backoff.
    
    Args:
        args (argparse.Namespace): Parsed command line arguments.
    
    Returns:
        ModbusSerialClient: Connected Modbus client.
    
    Raises:
        ConnectionError: If unable to connect after maximum attempts.
    """
    client = ModbusSerialClient(
        port=args.com_port,
        **MODBUS_CONFIG
    )
    
    for attempt in range(MAX_RECONNECTION_ATTEMPTS):
        if client.connect():
            time.sleep(3)
            return client
        
        backoff_time = INITIAL_BACKOFF_TIME * (2 ** attempt)
        print(f"Connection attempt {attempt + 1} failed. Retrying in {backoff_time} seconds...")
        time.sleep(backoff_time)
    
    raise ConnectionError("Failed to connect to Modbus client after maximum attempts")