advent_of_code_2021/day16/part1.py

import argparse
import functools
from typing import List
import binascii
from dataclasses import dataclass
from enum import Enum
from typing import Protocol


def hexToPaddedBin(hex: str):
    return "".join([bin(int(char, 16))[2:].zfill(4) for char in hex])


class DataBuffer:
    def __init__(self, data_str, already_binary=False):
        if already_binary:
            self.data = data_str
        else:
            self.data = hexToPaddedBin(data_str)

    def readInt(self, num_bits) -> int:
        ret_val = int(self.data[0:num_bits], 2)
        self.data = self.data[num_bits:]
        return ret_val

    def readRaw(self, num_bits) -> str:
        ret_val = self.data[0:num_bits]
        self.data = self.data[num_bits:]
        return ret_val

    def hasData(self, bits=0) -> bool:
        return len(self.data) >= bits

    def peek(self) -> str:
        return self.data[0]

    def pop(self) -> str:
        ret_val = self.data[0]
        self.data = self.data[1:]
        return ret_val

    def __str__(self) -> str:
        return self.data


def readIntoNewBuffer(buffer: DataBuffer, num_bits: int) -> DataBuffer:
    payload = buffer.readRaw(num_bits)
    return DataBuffer(payload, True)


MIN_PACKET_SIZE = 6 + 5


class PacketType(Enum):
    LITERAL = 4
    OPERATOR = 0


@dataclass
class ProtoPacket:
    version: int
    type: PacketType


class Packet(Protocol):
    proto: ProtoPacket

    def sumVersions(self) -> int:
        raise NotImplemented

    def __repr__(self):
        return self.__str__()


class LiteralPacket(Packet):
    def __init__(self, proto: ProtoPacket, value: int):
        self.proto = proto
        self.value = value

    def sumVersions(self):
        return self.proto.version

    def __str__(self):
        return f"{self.proto.type} v{self.proto.version} = {self.value}"


class OperatorPacket(Packet):
    def __init__(self, proto: ProtoPacket, children: List[Packet]):
        self.proto = proto
        self.children = children

    def sumVersions(self) -> int:
        return sum([child.sumVersions() for child in self.children] + [self.proto.version])

    def __str__(self):
        return f"{self.proto.type} v{self.proto.version} # {len(self.children)} [{', '.join([str(child) for child in self.children])}]"


def parseLiteral(proto: ProtoPacket, buffer: DataBuffer) -> Packet:
    sub_buffer = ""
    while buffer.readRaw(1) != "0":
        sub_buffer += buffer.readRaw(4)
    sub_buffer += buffer.readRaw(4)

    value = int(sub_buffer, 2)
    return LiteralPacket(proto, value)


def parseRawOperator(proto: ProtoPacket, buffer: DataBuffer) -> Packet:
    # pull children for our operator out of the buffer
    children = parseBuffer(buffer)
    return OperatorPacket(proto, children)


def parseNestedOperator(proto: ProtoPacket, buffer: DataBuffer, numPackets: int) -> Packet:
    children = parseNPacketsFromBuffer(buffer, numPackets)
    return OperatorPacket(proto, children)


def parsePacket(protoPacket: ProtoPacket, buffer: DataBuffer) -> Packet:
    if protoPacket.type == PacketType.LITERAL:
        return parseLiteral(protoPacket, buffer)
    else:
        if buffer.readRaw(1) == "0":
            return parseRawOperator(protoPacket, readIntoNewBuffer(buffer, buffer.readInt(15)))
        else:
            return parseNestedOperator(protoPacket, buffer, buffer.readInt(11))


def _readProto(buffer: DataBuffer) -> ProtoPacket:
    new_ver = buffer.readInt(3)
    new_type = PacketType.LITERAL if buffer.readInt(3) == 4 else PacketType.OPERATOR
    return ProtoPacket(new_ver, new_type)


def parseNPacketsFromBuffer(buffer: DataBuffer, numPackets: int) -> List[Packet]:
    packets = []
    for _ in range(0, numPackets):
        proto = _readProto(buffer)
        packets.append(parsePacket(proto, buffer))
    return packets


def parseBuffer(buffer: DataBuffer) -> List[Packet]:
    packets: List[Packet] = []
    while buffer.hasData(MIN_PACKET_SIZE):
        proto = _readProto(buffer)
        packets.append(parsePacket(proto, buffer))
    return packets


def main(buffer: DataBuffer):
    packets = parseBuffer(buffer)
    print(packets)
    print(sum([packet.sumVersions() for packet in packets]))


if __name__ == "__main__":
    parser = argparse.ArgumentParser()
    parser.add_argument("ifile", type=argparse.FileType('r'))
    args = parser.parse_args()

    superpacket = args.ifile.readline().strip()
    # convert hex to bin, then trim the leading python binary sig
    main(DataBuffer(superpacket))