#!/usr/bin/env python3
# hacked from https://github.com/mindmedia/paynow.py and
# https://www.emvco.com/wp-content/uploads/documents/EMVCo-Merchant-Presented-QR-Specification-v1.1.pdf
import sys
import binascii

Fields = {
"00" : "Format_ID",
"01" : "Proxy_type",
"26" : "Merchant_Account_Info",
"2600" : "Domain",
"2601" : "PayNow_ID_type",
"2602" : "PayNow_ID",
"2603" : "Is_editable",
"2604" : "Expiration",
"52" : "Merchant_category",
"53" : "Transaction_currency",
"54" : "Transaction_amount",
"55" : "Transaction_convenience_fee_is_presented",
"56" : "Transaction_convenience_fee_fixed",
"57" : "Transaction_convenience_fee_pct",
"58" : "Country_code",
"59" : "Merchant_name",
"60" : "Merchant_city",
"61" : "Merchant_postal_code",
"62" : "Bill_Info",
"6201" : "Bill_number",
"6202" : "Bill_phone_number",
"6203" : "Bill_store_label",
"6204" : "Bill_loyalty_number",
"6204" : "Bill_reference_number",
"6206" : "Bill_customer_label",
"6206" : "Bill_terminal_label",
"6208" : "Bill_transaction_purpose",
"6210" : "Bill_merchant_tax_id",
"6211" : "Bill_merchant_channel",
"63" : "CRC"
}

def Transaction_currency_fn(num):
    ''' Lookup the currency code -- https://www.iban.com/currency-codes '''
    return {
        "036" : "AUD", "096" : "BND", "124" : "CAD", "156" : "CNY", "344" : "HKD",
        "356" : "INR", "360" : "IDR", "392" : "JPY", "410" : "KRW", "446" : "MOP",
        "458" : "MYR", "554" : "NZD", "608" : "PHP", "682" : "SAR", "702" : "SGD",
        "704" : "VND", "764" : "THB", "784" : "AED", "826" : "GBP", "840" : "USD",
        "901" : "TWD", "978" : "EUR",
    }[num]

def has_subfield(field_id):
    ''' do any Field IDs have `field_id` as a prefix? '''
    return 1 < len( [ k for k in Fields.keys() if k.startswith( field_id ) ])

def get_field(Fs, i):
    ''' get the next field, its value, and offset increment '''
    f = Fs[ i : i+2 ]
    l = int( Fs[ i+2 : i+4 ])
    return f, Fs[ i+4 : i+4+l ], i+4+l

def scan(fields, reply={}, i=0, prefix=''):
    ''' parse the fields into `reply` '''
    while i < len(fields):
        f,v,i = get_field(fields, i)
        f = prefix + f
        reply[f] = v
        if has_subfield(f):
            scan( v, reply, prefix=f )
    return reply


qr = ' '.join(sys.argv[1:])
assert qr[ -4: ] == '{:04X}'.format( binascii.crc_hqx(qr[ 0:-4 ].encode('utf-8'), 0xFFFF))

for fid,fval in scan(qr).items():
    if has_subfield(fid):
        continue
    for fn in [ v for k,v in globals().items() if k == Fields[fid] + '_fn' ]:
        fval = fn(fval)
    print(fid, Fields[fid], fval)