#!/usr/bin/env python3
# Copyright (c) 2016-2020 The Bitcoin Core developers
# Distributed under the MIT software license, see the accompanying
# file COPYING or http://www.opensource.org/licenses/mit-license.php.
"""Encode BASE58."""

import unittest

from .messages import hash256
from .util import hex_str_to_bytes, assert_equal

chars = '123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz'

def byte_to_base58(b, version):
    result = ''
    str = b.hex()
    str = chr(version).encode('latin-1').hex() + str
    checksum = hash256(hex_str_to_bytes(str)).hex()
    str += checksum[:8]
    value = int('0x'+str,0)
    while value > 0:
        result = chars[value % 58] + result
        value //= 58
    while (str[:2] == '00'):
        result = chars[0] + result
        str = str[2:]
    return result

def base58_to_byte(s, verify_checksum=True):
    if not s:
        return b''
    n = 0
    for c in s:
        n *= 58
        assert c in chars
        digit = chars.index(c)
        n += digit
    h = '%x' % n
    if len(h) % 2:
        h = '0' + h
    res = n.to_bytes((n.bit_length() + 7) // 8, 'big')
    pad = 0
    for c in s:
        if c == chars[0]:
            pad += 1
        else:
            break
    res = b'\x00' * pad + res
    if verify_checksum:
        assert_equal(hash256(res[:-4])[:4], res[-4:])

    return res[1:-4], int(res[0])

class TestFrameworkScript(unittest.TestCase):
    def test_base58encodedecode(self):
        def check_base58(data, version):
            self.assertEqual(base58_to_byte(byte_to_base58(data, version)), (data, version))

        check_base58(b'\x1f\x8e\xa1p*{\xd4\x94\x1b\xca\tA\xb8R\xc4\xbb\xfe\xdb.\x05', 111)
        check_base58(b':\x0b\x05\xf4\xd7\xf6l;\xa7\x00\x9fE50)l\x84\\\xc9\xcf', 111)
        check_base58(b'A\xc1\xea\xf1\x11\x80%Y\xba\xd6\x1b`\xd6+\x1f\x89|c\x92\x8a', 111)
        check_base58(b'\0A\xc1\xea\xf1\x11\x80%Y\xba\xd6\x1b`\xd6+\x1f\x89|c\x92\x8a', 111)
        check_base58(b'\0\0A\xc1\xea\xf1\x11\x80%Y\xba\xd6\x1b`\xd6+\x1f\x89|c\x92\x8a', 111)
        check_base58(b'\0\0\0A\xc1\xea\xf1\x11\x80%Y\xba\xd6\x1b`\xd6+\x1f\x89|c\x92\x8a', 111)
        check_base58(b'\x1f\x8e\xa1p*{\xd4\x94\x1b\xca\tA\xb8R\xc4\xbb\xfe\xdb.\x05', 0)
        check_base58(b':\x0b\x05\xf4\xd7\xf6l;\xa7\x00\x9fE50)l\x84\\\xc9\xcf', 0)
        check_base58(b'A\xc1\xea\xf1\x11\x80%Y\xba\xd6\x1b`\xd6+\x1f\x89|c\x92\x8a', 0)
        check_base58(b'\0A\xc1\xea\xf1\x11\x80%Y\xba\xd6\x1b`\xd6+\x1f\x89|c\x92\x8a', 0)
        check_base58(b'\0\0A\xc1\xea\xf1\x11\x80%Y\xba\xd6\x1b`\xd6+\x1f\x89|c\x92\x8a', 0)
        check_base58(b'\0\0\0A\xc1\xea\xf1\x11\x80%Y\xba\xd6\x1b`\xd6+\x1f\x89|c\x92\x8a', 0)