#!/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.

#
# address.py
#
# This file encodes and decodes BASE58 P2PKH and P2SH addresses
#

import unittest

from .script import hash160, hash256, CScript

# Note unlike in bitcoin, this address isn't bech32 since we don't (at this time) support bech32.
ADDRESS_BCRT1_UNSPENDABLE = 'yVg3NBUHNEhgDceqwVUjsZHreC5PBHnUo9'
ADDRESS_BCRT1_UNSPENDABLE_DESCRIPTOR = 'addr(yVg3NBUHNEhgDceqwVUjsZHreC5PBHnUo9)#e5kt0jtk'
ADDRESS_BCRT1_P2SH_OP_TRUE = '8zJctvfrzGZ5s1zQ3kagwyW1DsPYSQ4V2P'


b58chars = '123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz'


def byte_to_base58(b, version):
    result = ''
    b = bytes([version]) + b  # prepend version
    b += hash256(b)[:4]       # append checksum
    value = int.from_bytes(b, 'big')
    while value > 0:
        result = b58chars[value % 58] + result
        value //= 58
    while b[0] == 0:
        result = b58chars[0] + result
        b = b[1:]
    return result


def base58_to_byte(s):
    """Converts a base58-encoded string to its data and version.

    Throws if the base58 checksum is invalid."""
    if not s:
        return b''
    n = 0
    for c in s:
        n *= 58
        assert c in b58chars
        digit = b58chars.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 == b58chars[0]:
            pad += 1
        else:
            break
    res = b'\x00' * pad + res

    if hash256(res[:-4])[:4] != res[-4:]:
        raise ValueError('Invalid Base58Check checksum')

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


def keyhash_to_p2pkh(hash, main=False):
    assert len(hash) == 20
    version = 76 if main else 140
    return byte_to_base58(hash, version)

def scripthash_to_p2sh(hash, main=False):
    assert len(hash) == 20
    version = 16 if main else 19
    return byte_to_base58(hash, version)

def key_to_p2pkh(key, main=False):
    key = check_key(key)
    return keyhash_to_p2pkh(hash160(key), main)

def script_to_p2sh(script, main=False):
    script = check_script(script)
    return scripthash_to_p2sh(hash160(script), main)

def check_key(key):
    if (type(key) is str):
        key = bytes.fromhex(key)  # Assuming this is hex string
    if (type(key) is bytes and (len(key) == 33 or len(key) == 65)):
        return key
    assert False

def check_script(script):
    if (type(script) is str):
        script = bytes.fromhex(script)  # Assuming this is hex string
    if (type(script) is bytes or type(script) is CScript):
        return script
    assert False


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(bytes.fromhex('1f8ea1702a7bd4941bca0941b852c4bbfedb2e05'), 111)
        check_base58(bytes.fromhex('3a0b05f4d7f66c3ba7009f453530296c845cc9cf'), 111)
        check_base58(bytes.fromhex('41c1eaf111802559bad61b60d62b1f897c63928a'), 111)
        check_base58(bytes.fromhex('0041c1eaf111802559bad61b60d62b1f897c63928a'), 111)
        check_base58(bytes.fromhex('000041c1eaf111802559bad61b60d62b1f897c63928a'), 111)
        check_base58(bytes.fromhex('00000041c1eaf111802559bad61b60d62b1f897c63928a'), 111)
        check_base58(bytes.fromhex('1f8ea1702a7bd4941bca0941b852c4bbfedb2e05'), 0)
        check_base58(bytes.fromhex('3a0b05f4d7f66c3ba7009f453530296c845cc9cf'), 0)
        check_base58(bytes.fromhex('41c1eaf111802559bad61b60d62b1f897c63928a'), 0)
        check_base58(bytes.fromhex('0041c1eaf111802559bad61b60d62b1f897c63928a'), 0)
        check_base58(bytes.fromhex('000041c1eaf111802559bad61b60d62b1f897c63928a'), 0)
        check_base58(bytes.fromhex('00000041c1eaf111802559bad61b60d62b1f897c63928a'), 0)
