#!/usr/bin/env python
#
# Electrum - lightweight Bitcoin client
# Copyright (C) 2011 thomasv@gitorious
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.


import hashlib, base64, re


def rev_hex(s):
    return s.decode('hex')[::-1].encode('hex')

def int_to_hex(i, length=1):
    s = hex(i)[2:].rstrip('L')
    s = "0"*(2*length - len(s)) + s
    return rev_hex(s)

def var_int(i):
    if i<0xfd:
        return int_to_hex(i)
    elif i<=0xffff:
        return "fd"+int_to_hex(i,2)
    elif i<=0xffffffff:
        return "fe"+int_to_hex(i,4)
    else:
        return "ff"+int_to_hex(i,8)


Hash = lambda x: hashlib.sha256(hashlib.sha256(x).digest()).digest()
hash_encode = lambda x: x[::-1].encode('hex')
hash_decode = lambda x: x.decode('hex')[::-1]


def header_to_string(res):
    pbh = res.get('prev_block_hash')
    if pbh is None: pbh = '0'*64
    s = int_to_hex(res.get('version'),4) \
        + rev_hex(pbh) \
        + rev_hex(res.get('merkle_root')) \
        + int_to_hex(int(res.get('timestamp')),4) \
        + int_to_hex(int(res.get('bits')),4) \
        + int_to_hex(int(res.get('nonce')),4)
    return s

def header_from_string( s):
    hex_to_int = lambda s: eval('0x' + s[::-1].encode('hex'))
    h = {}
    h['version'] = hex_to_int(s[0:4])
    h['prev_block_hash'] = hash_encode(s[4:36])
    h['merkle_root'] = hash_encode(s[36:68])
    h['timestamp'] = hex_to_int(s[68:72])
    h['bits'] = hex_to_int(s[72:76])
    h['nonce'] = hex_to_int(s[76:80])
    return h


############ functions from pywallet ##################### 

addrtype = 0

def hash_160(public_key):
    try:
        md = hashlib.new('ripemd160')
        md.update(hashlib.sha256(public_key).digest())
        return md.digest()
    except:
        import ripemd
        md = ripemd.new(hashlib.sha256(public_key).digest())
        return md.digest()


def public_key_to_bc_address(public_key):
    h160 = hash_160(public_key)
    return hash_160_to_bc_address(h160)

def hash_160_to_bc_address(h160):
    if h160 == 'None': return 'None'
    vh160 = chr(addrtype) + h160
    h = Hash(vh160)
    addr = vh160 + h[0:4]
    return b58encode(addr)

def bc_address_to_hash_160(addr):
    if addr == 'None': return 'None'
    bytes = b58decode(addr, 25)
    return bytes[1:21]


__b58chars = '123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz'
__b58base = len(__b58chars)

def b58encode(v):
    """ encode v, which is a string of bytes, to base58."""

    long_value = 0L
    for (i, c) in enumerate(v[::-1]):
        long_value += (256**i) * ord(c)

    result = ''
    while long_value >= __b58base:
        div, mod = divmod(long_value, __b58base)
        result = __b58chars[mod] + result
        long_value = div
    result = __b58chars[long_value] + result

    # Bitcoin does a little leading-zero-compression:
    # leading 0-bytes in the input become leading-1s
    nPad = 0
    for c in v:
        if c == '\0': nPad += 1
        else: break

    return (__b58chars[0]*nPad) + result

def b58decode(v, length):
    """ decode v into a string of len bytes."""
    long_value = 0L
    for (i, c) in enumerate(v[::-1]):
        long_value += __b58chars.find(c) * (__b58base**i)

    result = ''
    while long_value >= 256:
        div, mod = divmod(long_value, 256)
        result = chr(mod) + result
        long_value = div
    result = chr(long_value) + result

    nPad = 0
    for c in v:
        if c == __b58chars[0]: nPad += 1
        else: break

    result = chr(0)*nPad + result
    if length is not None and len(result) != length:
        return None

    return result


def EncodeBase58Check(vchIn):
    hash = Hash(vchIn)
    return b58encode(vchIn + hash[0:4])

def DecodeBase58Check(psz):
    vchRet = b58decode(psz, None)
    key = vchRet[0:-4]
    csum = vchRet[-4:]
    hash = Hash(key)
    cs32 = hash[0:4]
    if cs32 != csum:
        return None
    else:
        return key

def PrivKeyToSecret(privkey):
    return privkey[9:9+32]

def SecretToASecret(secret):
    vchIn = chr(addrtype+128) + secret
    return EncodeBase58Check(vchIn)

def ASecretToSecret(key):
    vch = DecodeBase58Check(key)
    if vch and vch[0] == chr(addrtype+128):
        return vch[1:]
    else:
        return False

########### end pywallet functions #######################