import sys, os
import select
from typing import Callable

import serial
import re
from threading import Thread, Lock

class DeviceInterface:
    """
    Helper class for interfacing the device running flexPTP.
    """

    def reader_routine(self) -> None:
        """
        Thread routine for receiving all incoming communication from
        the device.
        """

        while not self.device.closed:
            try:
                data = self.device.readline() # read serial port line-by-line

                if type(data) is bytes:
                    # remove colorization escape sequences
                    data = re.sub(r"\x1b\[[0-9;]*m", "", data.decode())
                    
                    if len(data) > 0: # write (remaining) data to the pipe
                        os.write(self.__outpipe_rw_fd[1], data.encode())
                        
                        if self.__out_cb is not None: # invoke callback if provided
                            self.__out_cb(data)

            except:
                break # handle closing the device
                    

    def __init__(self, url: str, options: dict = {}) -> None:
        """
        Initialize the interface.

        :param str url: url of the device (tty, socket etc.)
        :param dict options: collection of several options (baudrate, bytesize, parity, stopbits etc.)
        :rtype: None
        """

        self.device = serial.serial_for_url(url, timeout=None) # open remote device

        # set serial port options if applicable
        if "baudrate" in options:
            self.device.baudrate = options["baudrate"]
        if "bytesize" in options:
            self.device.bytesize = options["bytesize"]
        if "parity" in options:
            self.device.parity = options["parity"]
        if "stopbits" in options:
            self.device.stopbits = options["stopbits"]

        # ----

        self.__out_cb: Callable | None = None

        r, w = os.pipe()
        self.__outpipe_rw_fd = [ r, w ]
        self.__outpipe_rw = [ os.fdopen(r, "rb"), os.fdopen(w, "wb") ]

        self.__reader_thread = Thread(target=self.reader_routine)
        self.__reader_thread.start()

    def close(self) -> None:
        """
        Close the device interface.

        :rtype: None
        """

        self.device.close()
        self.__reader_thread.join()
        self.__outpipe_rw[0].close()
        self.__outpipe_rw[1].close()

    def readline(self) -> bytes:
        """
        Read a line from the device.

        :return: bytes read
        :rtype: bytes
        """

        return self.__outpipe_rw[0].readline().encode()


    def write(self, data: bytes) -> None:
        """
        Write data onto the device

        :param bytes data: data to transfer
        """

        self.device.write(data)
        

    def execute_command(self, cmd: str, expect_results: bool = True, separate_results: bool = False) -> str | dict[str, str] | None:
        """
        Execute command on the device

        :param str cmd: command to launch
        :param bool expect_results: is there any return values expected and awaited?
        :param bool separate_results: if True a key-value separation attempted on the results
        :return: results (if requested)
        :rtype: str | None
        """

        pure_final_cmd = cmd.strip("\r\n")
        final_cmd = (pure_final_cmd + "\r\n").encode() # sanitize commands
        #self.skip(len(final_cmd)) # flush echo
        self.write(final_cmd) # send command

        # wait for the echo to arrive
        line = ""
        while line != pure_final_cmd:
            line = self.__outpipe_rw[0].readline().decode().strip()
        
        if expect_results: # store results if required
            timeout = False
            results = ""

            poller = select.poll()
            poller.register(self.__outpipe_rw_fd[0], select.POLLIN)

            while not timeout: # store continuous chunks
                res = poller.poll(100)

                if len(res) > 0 and res[0][1] == select.POLLIN:
                    data = self.__outpipe_rw[0].read(1)
                    if len(data) > 0:
                        results += data.decode()
                    else:
                        timeout = True
                else:
                    timeout = True
            
            if separate_results: # separation requested
                records = re.findall("^[ ]*([^:]+)[ ]*:[ ]*(.+)[ ]*$", results.strip(), flags=re.MULTILINE)
                results = dict[str, str]()
                for rec in records:
                    results[rec[0]] = rec[1].strip()
                return results
            else:
                return results
        else:
            return None
        
    def register_out_callback(self, cb: Callable) -> None:
        """
        Register callback for receiving all printed messages from the
        device.

        :param Callable cb: callback invoked at each reception
        :rtype: None
        """

        self.__out_cb = cb