# dmm_decoder.py

import json

class DMMDecoder:
    """Base class for DMM screen/binary decoders."""
    def __init__(self, config):
        self.xorkey = self.str2hexarray(config["xorkey"])
        self.icon_regions = config["icon_regions"]["default"]
        self.icon_table = config["icon_table"]

    @staticmethod
    def str2hexarray(string):
        string = string.replace(' ', '').lower()
        return [int(string[i:i+2], 16) for i in range(0, len(string), 2)]

    @staticmethod
    def bytewise_XOR(array, xorkey):
        return [array[x] ^ xorkey[x % len(xorkey)] for x in range(len(array))]

    @staticmethod
    def hex2bin(array):
        return [bin(x)[2:].zfill(8) for x in array]

    @staticmethod
    def flip_bits(array):
        return [b[::-1] for b in array]

    @staticmethod
    def array2str(array):
        return ''.join(array)

    def extract_icon_bits(self, bitstring):
        bits = self.icon_regions
        # Concatenate bit ranges
        return bitstring[bits[0]:bits[1]] + bitstring[bits[2]:bits[3]]

    def decode_icons(self, icon_bits):
        return [self.icon_table[i] for i, b in enumerate(icon_bits) if b == '1' and i < len(self.icon_table)]

    def decode_packet(self, hexstring):
        encoded_array = self.str2hexarray(hexstring)
        # pad xorkey if needed
        xorkey = (self.xorkey * ((len(encoded_array) // len(self.xorkey)) + 1))[:len(encoded_array)]
        xordecoded = self.bytewise_XOR(encoded_array, xorkey)
        binary = self.hex2bin(xordecoded)
        flipped = self.flip_bits(binary)
        bitstring = self.array2str(flipped)
        icon_bits = self.extract_icon_bits(bitstring)
        icons = self.decode_icons(icon_bits)
        return {'icons': icons}

# Example derived decoder for ZT-5B (can be extended for other models)
class ZT5BDecoder(DMMDecoder):
    def __init__(self, config):
        super().__init__(config)
        # add any ZT-5B-specific setup here if needed

# --- Usage Example ---
if __name__ == "__main__":
    # Minimal config example
    config = {
        "xorkey": "41217355a2c1327166aa3bd0e2a833142021aabb",
        "icon_regions": {
            "default": [24, 28, 60, 87]
        },
        "icon_table": [
            "LowBattery","Delta","BT","BUZ","HOLD","ºF","ºC","DIODE",
            "MAX","MIN","%","AC","F","u(F)","m(F)","n(F)","Hz",
            "ohm","K(ohm)","M(ohm)","V","m(V)","DC","A","AUTO",
            "?7","u(A)","m(A)","?8","?9","?10","?11"
        ]
    }

    decoder = ZT5BDecoder(config)
    hexstring = "1b847195453ad9fa668a"
    result = decoder.decode_packet(hexstring)
    print(json.dumps(result, ensure_ascii=False, indent=2))