import socket
import threading
import atexit
import re

IP = "0.0.0.0"
PORT = 5025

# Bind server socket when this module is included
_serverSocket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
_serverSocket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
_serverSocket.bind((IP, PORT))
_serverSocket.listen(1)

# Close it when the program exits
def _cleanUp():
    _serverSocket.close()
atexit.register(_cleanUp)

class MockSDS1000XEDevice:
    def __init__(self):
        self._stopFlag = False
        self._clientSocket = None
        self._mainThread = threading.Thread(target=self._mainLoop)
        self._mainThread.start()

        # Mock measured values
        self._channels = [{"AMPL" : None} for i in range(0, 4)]

    def _mainLoop(self) -> None:
        self._clientSocket, _ = _serverSocket.accept()
        self._clientSocket.settimeout(0.1)

        try:
            while not self._stopFlag:
                try:
                    request = self._clientSocket.recv(4096).decode()
                    response = self._handleRequest(request)
                    if response is not None:
                        self._clientSocket.send(response.encode())
                except TimeoutError as e:
                    pass
        finally:
            self._clientSocket.close()
    
    def _handleRequest(self, request: str) -> str:
        m = re.search(r"C(?P<channel>\d):(?P<opcode>\w+)\?\s(?P<arg>\w+)", request)
        if not m:
            return None
        
        channelIndex = int(m.group("channel")) - 1
        opcode = m.group("opcode")

        if opcode == "PAVA":
            arg = m.group("arg")
            value = self._channels[channelIndex].get(arg)
            unit = "Hz" if arg == "FREQ" else "V"
            
            if value is None:
                return None
            else:
                response = f"C{m.group('channel')}:PAVA {arg},{value:.6E}{unit}"
                return response

    def stop(self) -> None:
        self._stopFlag = True
        self._mainThread.join()

    def setAmplitude(self, channel: int, value: float) -> None:
        self._channels[channel - 1]["AMPL"] = value

    def setPeakToPeak(self, channel: int, value: float) -> None:
        self._channels[channel - 1]["PKPK"] = value

    def setRMS(self, channel: int, value: float) -> None:
        self._channels[channel - 1]["RMS"] = value

    def setFrequency(self, channel: int, value: float) -> None:
        self._channels[channel - 1]["FREQ"] = value