decode_token.py

from shared import OPAYGOShared
from shared_extended import OPAYGOSharedExtended


class OPAYGODecoder(object):
    MAX_TOKEN_JUMP = 64
    MAX_TOKEN_JUMP_COUNTER_SYNC = 100
    MAX_UNUSED_OLDER_TOKENS = 8*2

    @classmethod
    def get_activation_value_count_and_type_from_token(cls, token, starting_code, key, last_count,
                                                       restricted_digit_set=False, used_counts=None):
        if restricted_digit_set:
            token = OPAYGOShared.convert_from_4_digit_token(token)
        valid_older_token = False
        token_base = OPAYGOShared.get_token_base(token) # We get the base of the token
        current_code = OPAYGOShared.put_base_in_token(starting_code, token_base) # We put it into the starting code
        starting_code_base = OPAYGOShared.get_token_base(starting_code) # We get the base of the starting code
        value = cls._decode_base(starting_code_base, token_base)  # If there is a match we get the value from the token
        # We try all combination up until last_count + TOKEN_JUMP, or to the larger jump if syncing counter
        # We could start directly the loop at the last count if we kept the token value for the last count
        if value == OPAYGOShared.COUNTER_SYNC_VALUE:
            max_count_try = last_count + cls.MAX_TOKEN_JUMP_COUNTER_SYNC + 1
        else:
            max_count_try = last_count + cls.MAX_TOKEN_JUMP + 1
        for count in range(0, max_count_try):
            masked_token = OPAYGOShared.put_base_in_token(current_code, token_base)
            if count % 2:
                type = OPAYGOShared.TOKEN_TYPE_SET_TIME
            else:
                type = OPAYGOShared.TOKEN_TYPE_ADD_TIME
            if masked_token == token:
                if cls._count_is_valid(count, last_count, value, type, used_counts):
                    return value, count, type
                else:
                    valid_older_token = True
            current_code = OPAYGOShared.generate_next_token(current_code, key) # If not we go to the next token
        if valid_older_token:
            return -2, None, None
        return None, None, None

    @classmethod
    def _count_is_valid(cls, count, last_count, value, type, used_counts):
        if value == OPAYGOShared.COUNTER_SYNC_VALUE:
            if count > last_count - 30:
                return True
        elif count > last_count:
            return True
        elif cls.MAX_UNUSED_OLDER_TOKENS > 0:
            if count > last_count - cls.MAX_UNUSED_OLDER_TOKENS:
                if count not in used_counts and type == OPAYGOShared.TOKEN_TYPE_ADD_TIME:
                    return True
        return False

    @classmethod
    def update_used_counts(cls, past_used_counts, value, new_count, type):
        highest_count = max(past_used_counts) if past_used_counts else 0
        if new_count > highest_count:
            highest_count = new_count
        bottom_range = highest_count-cls.MAX_UNUSED_OLDER_TOKENS
        used_counts = []
        if type != OPAYGOShared.TOKEN_TYPE_ADD_TIME or value == OPAYGOShared.COUNTER_SYNC_VALUE or value == OPAYGOShared.PAYG_DISABLE_VALUE:
            # If it is not an Add-Time token, we mark all the past tokens as used in the range
            for count in range(bottom_range, highest_count+1):
                used_counts.append(count)
        else:
            # If it is an Add-Time token, we just mark the tokens actually used in the range
            for count in range(bottom_range, highest_count+1):
                if count == new_count or count in past_used_counts:
                    used_counts.append(count)
        return used_counts

    @classmethod
    def _decode_base(cls, starting_code_base, token_base):
        decoded_value = token_base - starting_code_base
        if decoded_value < 0:
            return decoded_value + 1000
        else:
            return decoded_value

    @classmethod
    def get_activation_value_count_from_extended_token(cls, token, starting_code, key, last_count,
                                                       restricted_digit_set=False):
        if restricted_digit_set:
            token = OPAYGOSharedExtended.convert_from_4_digit_token(token)
        token_base = OPAYGOSharedExtended.get_token_base(token) # We get the base of the token
        current_code = OPAYGOSharedExtended.put_base_in_token(starting_code, token_base) # We put it into the starting code
        starting_code_base = OPAYGOSharedExtended.get_token_base(starting_code) # We get the base of the starting code
        value = cls._decode_base_extended(starting_code_base, token_base)  # If there is a match we get the value from the token
        for count in range(0, 30):
            masked_token = OPAYGOSharedExtended.put_base_in_token(current_code, token_base)
            if masked_token == token and count > last_count:
                clean_count = count-1
                return value, clean_count
            current_code = OPAYGOSharedExtended.generate_next_token(current_code, key) # If not we go to the next token
        return None, None, None

    @classmethod
    def _decode_base_extended(cls, starting_code_base, token_base):
        decoded_value = token_base - starting_code_base
        if decoded_value < 0:
            return decoded_value + 1000000
        else:
            return decoded_value