Neo invocation script parser

scriptparser.py

from neocore.Cryptography.Crypto import Crypto
from neocore.UInt160 import UInt160
from neo.VM.OpCode import *
import binascii
import json
import sys
import io

tokens = {}
with open('tokens.json') as t:
    tokens = json.load(t)

def bytesToAddress(bytes):
    return Crypto.ToAddress(UInt160(data=bytes))

def contractName(scripthash):
    scripthash = "0x{}".format(scripthash)
    for token in tokens['results']:
        if token['token']['script_hash'] == scripthash:
            return token['token']['name']
    return "Unknown contract"

if len(sys.argv) != 2:
    print(f"Usage: {sys.argv[0]} [script hex]")
    sys.exit(-1)

script = ""
try:
    script = binascii.unhexlify(sys.argv[1])
except:
    print("Malformed script (should be even number of hex digits)")
    sys.exit(-1)

f = io.BufferedReader(io.BytesIO(script))
print(f"Parsing {sys.argv[1]}")
while True:
    opcode = f.read(1)
    if not opcode: break
    sarg = ""
    if opcode == APPCALL:
        sc = bytearray(f.read(20))
        sc.reverse()
        hexhash = binascii.hexlify(sc).decode()
        sarg = "{} ({})".format(hexhash, contractName(hexhash))
    elif opcode > b'\x00' and opcode < b'\x4c':
        sc = bytearray(f.read(ord(opcode)))
        if (opcode == PUSHBYTES20):
            sarg = bytesToAddress(sc)
        elif f.peek(1)[0] == ord(APPCALL):
            sarg = sc.decode()
        else:
            sarg = binascii.hexlify(sc).decode()
    print(f"{ToName(opcode)} {sarg}")

print("")