from jsonschema import validate
import enum

def check_gobotrpc_packge_json(data: dict):
    validate(instance=data, schema={
        "type": "object",
        "properties": {
            "type": {
                "type": "string",
                "enum": ["Req", "Res", "Error"]         
            },
            "rpc": {
                "type": "string",
                "enum": ["Vacum"]
            },
            "data": {"type": "object"}
        },
        "required": ["type", "data", "rpc"]
    })


class GobotRPCNumber(enum.IntEnum):
    VACUM = 0x8

class GobotRPCType(enum.IntEnum):
    REQ   = 0b00
    RES   = 0b01
    ERROR = 0b10

def gen_gobotrpc_header(rpc: GobotRPCNumber, type: GobotRPCType, size: int) -> bytes:
    n = ((rpc.value & 0b1111) << 4)
    n |= ((type.value & 0b11) << 2)
    return int.to_bytes(n, 1, "big") + int.to_bytes(size, 1, "big")

def extract_gobotrpc_header(data: bytes) -> tuple[GobotRPCNumber, GobotRPCType]:
    n = int.from_bytes(data[:1], "big")
    rpc = GobotRPCNumber((n >> 4) & 0b1111)
    type = GobotRPCType((n >> 2) & 0b11)
    sizes = data[1]
    return GobotRPCNumber(rpc), GobotRPCType(type), sizes

def crc16(data: bytes, poly=0x8408):
    '''
    CRC-16-CCITT Algorithm
    '''
    data = bytearray(data)
    crc = 0xFFFF
    for b in data:
        cur_byte = 0xFF & b
        for _ in range(0, 8):
            if (crc & 0x0001) ^ (cur_byte & 0x0001):
                crc = (crc >> 1) ^ poly
            else:
                crc >>= 1
            cur_byte >>= 1
    crc = (~crc & 0xFFFF)
    crc = (crc << 8) | ((crc >> 8) & 0xFF)
    
    return crc & 0xFFFF