from serial import Serial
from serial import SerialException
from serial import EIGHTBITS
from serial import PARITY_NONE
from serial import STOPBITS_ONE
from serial.tools import list_ports

class SerialPort:
    """
    A utility class for managing a RS232 serial connection using the pyserial library.
 
    """

    def __init__(self, com_port: str, baud_rate: int, report: bool = True):
        self.serial_port = Serial()
        self.com_port = com_port
        self.baud_rate = baud_rate
        # user feedback settings
        self.report = report
        self.print = self.report_to_console
 
    @staticmethod
    def scan_ports() -> list[str]:
        """Returns a sorted list of COM ports."""
        com_ports = [port.device for port in list_ports.comports()]
        com_ports.sort(key=lambda value: int(value[3:]))
        return com_ports
 
    def connect_to_serial(self, rx_size: int = 12800, tx_size: int = 12800, read_timeout: int = 1, write_timeout: int = 1) -> None:
        """Connect to the serial port."""
        # serial port settings
        self.serial_port.port = self.com_port
        self.serial_port.baudrate = self.baud_rate
        self.serial_port.parity = PARITY_NONE
        self.serial_port.bytesize = EIGHTBITS
        self.serial_port.stopbits = STOPBITS_ONE
        self.serial_port.xonoff = False
        self.serial_port.rtscts = False
        self.serial_port.dsrdtr = False
        self.serial_port.write_timeout = write_timeout
        self.serial_port.timeout = read_timeout

        # set the size of the rx and tx buffers before calling open
        self.serial_port.set_buffer_size(rx_size, tx_size)

        # try to open the serial port
        try:
            self.serial_port.open()
        except SerialException:
            self.print(f"SerialException: can't connect to {self.com_port} at {self.baud_rate}!")

        if self.is_open():
            # clear the rx and tx buffers
            self.serial_port.reset_input_buffer()
            self.serial_port.reset_output_buffer()
            # report connection status to user
            self.print("Connected to the serial port.")
            self.print(f"Serial port = {self.com_port} :: Baud rate = {self.baud_rate}")
 
    def disconnect_from_serial(self) -> None:
        """Disconnect from the serial port if it's open."""
        if self.is_open():
            self.serial_port.close()
            self.print("Disconnected from the serial port.")
 
    def is_open(self) -> bool:
        """Returns True if the serial port exists and is open."""
        # short circuits if serial port is None
        return self.serial_port and self.serial_port.is_open
    
    def report_to_console(self, message: str) -> None:
        """Print message to the output device, usually the console."""
        # useful if we want to output data to something other than the console (ui element etc)
        if self.report:
            print(message)
 
    def send_command(self, cmd: bytes) -> None:
        """Send a serial command to the device."""
        # always reset the buffers before a new command is sent
        self.serial_port.reset_input_buffer()
        self.serial_port.reset_output_buffer()
        # send the serial command to the controller
        command = bytes(f"{cmd}\r", encoding="ascii")
        self.serial_port.write(command)
        self.print(f"Send: {command.decode(encoding='ascii')}")
 
    def read_response(self) -> str:
        """Read a line from the serial response."""
        response = self.serial_port.readline()
        response = response.decode(encoding="ascii")
        self.print(f"Recv: {response.strip()}")
        return response # in case we want to read the response