import os
import pty
import termios
import threading
import re

class MockJDS6600Device():
    class ChannelState:
        def __init__(self):
            self.on = False
            self.frequency = None
            self.amplitude = None
            self.function = None

    def __init__(self):
        self._master, self._slave = pty.openpty()
        self._masterFile = os.fdopen(self._master, mode="r+b", closefd=False, buffering=0)

        self._portName = os.ttyname(self._slave)
        self._channels = [MockJDS6600Device.ChannelState() for i in [1, 2]]

        self._injectedFailureCounter = 0
        
        self._mainThread = threading.Thread(target=self._mainLoop)
        self._mainThread.start()

    def _mainLoop(self) -> None:
        while True:
            try:
                request = self._masterFile.readline().decode().strip()
                response = self._handleRequest(request)
                
                if response is not None:
                    self._masterFile.write(response.encode())
            except OSError as e:
                break

    def _handleRequest(self, request: str) -> str:
        pattern = r":(?P<opcode>[wrab])(?P<function>\d+)=(?P<args>.*)\."
        m = re.search(pattern, request)
        
        if not m:
            return None

        opcode = m.group("opcode")
        function = int(m.group("function"))
        args = m.group("args").split(",")

        # channel on/off
        if function == 20:
            if opcode == "w":
                self._channels[0].on = args[0] == "1"
                self._channels[1].on = args[1] == "1"
                return ":ok\r\n"
            elif opcode == "r":
                return f":r20={int(self._channels[0].on)},{int(self._channels[1].on)}.\r\n"

        # channel frequency
        elif function == 23 or function == 24:
            ch = function - 23
            if opcode == "w":
                # Actual device takes a second argument for scaling, here we ignore it and always use 0 (Hz)
                frequency = float(args[0]) / 100.0

                if self._injectedFailureCounter > 0:
                    self._channels[ch].frequency = 0.0
                    self._injectedFailureCounter -= 1
                else:
                    self._channels[ch].frequency = frequency
                return ":ok\r\n"
            elif opcode == "r":
                frequency = self._channels[ch].frequency
                return f":r{function}={int(frequency)},0.\r\n"

        # channel amplitude
        elif function == 25 or function == 26:
            if opcode == "w":
                ch = function - 25
                amplitude = float(args[0]) / 1000.0
                self._channels[ch].amplitude = amplitude
                return ":ok\r\n"

        # channel function shape
        elif function == 21 or function == 22:
            if opcode == "w":
                ch = function - 21
                shape = int(args[0])
                self._channels[ch].function = shape
                return ":ok\r\n"

        # Unknown request format, no response
        return None

    def stop(self) -> None:
        self._masterFile.close()
        os.close(self._master)
        os.close(self._slave)
        self._mainThread.join()

    def checkPortConfiguration(self) -> None:
        iflag, oflag, cflag, lflag, ispeed, ospeed, cc = termios.tcgetattr(self._slave)

        # JDS6600 configuration taken from manual
        assert ispeed == termios.B115200
        assert ospeed == termios.B115200
        assert (cflag & termios.CSIZE) == termios.CS8
        assert (cflag & termios.CSTOPB) == 0
        assert (cflag & (termios.PARENB | termios.PARODD)) == 0

    def getPortName(self) -> str:
        return self._portName

    def isOn(self, ch: int) -> bool:
        return self._channels[ch - 1].on

    def getFrequency(self, ch: int) -> float:
        return self._channels[ch - 1].frequency

    def getAmplitude(self, ch: int) -> float:
        return self._channels[ch - 1].amplitude

    def getFunction(self, ch: int) -> int:
        return self._channels[ch - 1].function

    def injectFailures(self, count: int) -> None:
        self._injectedFailureCounter += count