// Copyright (c) 2014 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#include "base58.h"

#include "hash.h"
#include "script/script.h"
#include "uint256.h"

#include "version.h"
#include "streams.h"

#include <boost/variant/apply_visitor.hpp>
#include <boost/variant/static_visitor.hpp>

#include <algorithm>
#include <assert.h>
#include <string.h>


/** All alphanumeric characters except for "0", "I", "O", and "l" */
static const char* pszBase58 = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz";

bool DecodeBase58(const char* psz, std::vector<unsigned char>& vch)
{
    // Skip leading spaces.
    while (*psz && isspace(*psz))
        psz++;
    // Skip and count leading '1's.
    int zeroes = 0;
    while (*psz == '1') {
        zeroes++;
        psz++;
    }
    // Allocate enough space in big-endian base256 representation.
    std::vector<unsigned char> b256(strlen(psz) * 733 / 1000 + 1); // log(58) / log(256), rounded up.
    // Process the characters.
    while (*psz && !isspace(*psz)) {
        // Decode base58 character
        const char* ch = strchr(pszBase58, *psz);
        if (ch == NULL)
            return false;
        // Apply "b256 = b256 * 58 + ch".
        int carry = ch - pszBase58;
        for (std::vector<unsigned char>::reverse_iterator it = b256.rbegin(); it != b256.rend(); it++) {
            carry += 58 * (*it);
            *it = carry % 256;
            carry /= 256;
        }
        assert(carry == 0);
        psz++;
    }
    // Skip trailing spaces.
    while (isspace(*psz))
        psz++;
    if (*psz != 0)
        return false;
    // Skip leading zeroes in b256.
    std::vector<unsigned char>::iterator it = b256.begin();
    while (it != b256.end() && *it == 0)
        it++;
    // Copy result into output vector.
    vch.reserve(zeroes + (b256.end() - it));
    vch.assign(zeroes, 0x00);
    while (it != b256.end())
        vch.push_back(*(it++));
    return true;
}

std::string EncodeBase58(const unsigned char* pbegin, const unsigned char* pend)
{
    // Skip & count leading zeroes.
    int zeroes = 0;
    while (pbegin != pend && *pbegin == 0) {
        pbegin++;
        zeroes++;
    }
    // Allocate enough space in big-endian base58 representation.
    std::vector<unsigned char> b58((pend - pbegin) * 138 / 100 + 1); // log(256) / log(58), rounded up.
    // Process the bytes.
    while (pbegin != pend) {
        int carry = *pbegin;
        // Apply "b58 = b58 * 256 + ch".
        for (std::vector<unsigned char>::reverse_iterator it = b58.rbegin(); it != b58.rend(); it++) {
            carry += 256 * (*it);
            *it = carry % 58;
            carry /= 58;
        }
        assert(carry == 0);
        pbegin++;
    }
    // Skip leading zeroes in base58 result.
    std::vector<unsigned char>::iterator it = b58.begin();
    while (it != b58.end() && *it == 0)
        it++;
    // Translate the result into a string.
    std::string str;
    str.reserve(zeroes + (b58.end() - it));
    str.assign(zeroes, '1');
    while (it != b58.end())
        str += pszBase58[*(it++)];
    return str;
}

std::string EncodeBase58(const std::vector<unsigned char>& vch)
{
    return EncodeBase58(vch.data(), vch.data() + vch.size());
}

bool DecodeBase58(const std::string& str, std::vector<unsigned char>& vchRet)
{
    return DecodeBase58(str.c_str(), vchRet);
}

std::string EncodeBase58Check(const std::vector<unsigned char>& vchIn)
{
    // add 4-byte hash check to the end
    std::vector<unsigned char> vch(vchIn);
    uint256 hash = Hash(vch.begin(), vch.end());
    vch.insert(vch.end(), (unsigned char*)&hash, (unsigned char*)&hash + 4);
    return EncodeBase58(vch);
}

bool DecodeBase58Check(const char* psz, std::vector<unsigned char>& vchRet)
{
    if (!DecodeBase58(psz, vchRet) ||
        (vchRet.size() < 4)) {
        vchRet.clear();
        return false;
    }
    // re-calculate the checksum, insure it matches the included 4-byte checksum
    uint256 hash = Hash(vchRet.begin(), vchRet.end() - 4);
    if (memcmp(&hash, &vchRet.end()[-4], 4) != 0) {
        vchRet.clear();
        return false;
    }
    vchRet.resize(vchRet.size() - 4);
    return true;
}

bool DecodeBase58Check(const std::string& str, std::vector<unsigned char>& vchRet)
{
    return DecodeBase58Check(str.c_str(), vchRet);
}

namespace
{
class DestinationEncoder : public boost::static_visitor<std::string>
{
private:
    const CChainParams& m_params;

public:
    DestinationEncoder(const CChainParams& params) : m_params(params) {}

    std::string operator()(const CKeyID& id) const
    {
        std::vector<unsigned char> data = m_params.Base58Prefix(CChainParams::PUBKEY_ADDRESS);
        data.insert(data.end(), id.begin(), id.end());
        return EncodeBase58Check(data);
    }

    std::string operator()(const CScriptID& id) const
    {
        std::vector<unsigned char> data = m_params.Base58Prefix(CChainParams::SCRIPT_ADDRESS);
        data.insert(data.end(), id.begin(), id.end());
        return EncodeBase58Check(data);
    }

    std::string operator()(const CNoDestination& no) const { return ""; }
};

CTxDestination DecodeDestination(const std::string& str, const CChainParams& params)
{
    std::vector<unsigned char> data;
    uint160 hash;
    if (DecodeBase58Check(str, data)) {
        // base58-encoded Bitcoin addresses.
        // Public-key-hash-addresses have version 0 (or 111 testnet).
        // The data vector contains RIPEMD160(SHA256(pubkey)), where pubkey is the serialized public key.
        const std::vector<unsigned char>& pubkey_prefix = params.Base58Prefix(CChainParams::PUBKEY_ADDRESS);
        if (data.size() == hash.size() + pubkey_prefix.size() && std::equal(pubkey_prefix.begin(), pubkey_prefix.end(), data.begin())) {
            std::copy(data.begin() + pubkey_prefix.size(), data.end(), hash.begin());
            return CKeyID(hash);
        }
        // Script-hash-addresses have version 5 (or 196 testnet).
        // The data vector contains RIPEMD160(SHA256(cscript)), where cscript is the serialized redemption script.
        const std::vector<unsigned char>& script_prefix = params.Base58Prefix(CChainParams::SCRIPT_ADDRESS);
        if (data.size() == hash.size() + script_prefix.size() && std::equal(script_prefix.begin(), script_prefix.end(), data.begin())) {
            std::copy(data.begin() + script_prefix.size(), data.end(), hash.begin());
            return CScriptID(hash);
        }
    }
    return CNoDestination();
}
} // namespace

CKey DecodeSecret(const std::string& str)
{
    CKey key;
    std::vector<unsigned char> data;
    if (DecodeBase58Check(str, data)) {
        const std::vector<unsigned char>& privkey_prefix = Params().Base58Prefix(CChainParams::SECRET_KEY);
        if ((data.size() == 32 + privkey_prefix.size() || (data.size() == 33 + privkey_prefix.size() && data.back() == 1)) &&
            std::equal(privkey_prefix.begin(), privkey_prefix.end(), data.begin())) {
            bool compressed = data.size() == 33 + privkey_prefix.size();
            key.Set(data.begin() + privkey_prefix.size(), data.begin() + privkey_prefix.size() + 32, compressed);
        }
    }
    memory_cleanse(data.data(), data.size());
    return key;
}

std::string EncodeSecret(const CKey& key)
{
    assert(key.IsValid());
    std::vector<unsigned char> data = Params().Base58Prefix(CChainParams::SECRET_KEY);
    data.insert(data.end(), key.begin(), key.end());
    if (key.IsCompressed()) {
        data.push_back(1);
    }
    std::string ret = EncodeBase58Check(data);
    memory_cleanse(data.data(), data.size());
    return ret;
}

CExtPubKey DecodeExtPubKey(const std::string& str)
{
    CExtPubKey key;
    std::vector<unsigned char> data;
    if (DecodeBase58Check(str, data)) {
        const std::vector<unsigned char>& prefix = Params().Base58Prefix(CChainParams::EXT_PUBLIC_KEY);
        if (data.size() == BIP32_EXTKEY_SIZE + prefix.size() && std::equal(prefix.begin(), prefix.end(), data.begin())) {
            key.Decode(data.data() + prefix.size());
        }
    }
    return key;
}

std::string EncodeExtPubKey(const CExtPubKey& key)
{
    std::vector<unsigned char> data = Params().Base58Prefix(CChainParams::EXT_PUBLIC_KEY);
    size_t size = data.size();
    data.resize(size + BIP32_EXTKEY_SIZE);
    key.Encode(data.data() + size);
    std::string ret = EncodeBase58Check(data);
    return ret;
}

CExtKey DecodeExtKey(const std::string& str)
{
    CExtKey key;
    std::vector<unsigned char> data;
    if (DecodeBase58Check(str, data)) {
        const std::vector<unsigned char>& prefix = Params().Base58Prefix(CChainParams::EXT_SECRET_KEY);
        if (data.size() == BIP32_EXTKEY_SIZE + prefix.size() && std::equal(prefix.begin(), prefix.end(), data.begin())) {
            key.Decode(data.data() + prefix.size());
        }
    }
    return key;
}

std::string EncodeExtKey(const CExtKey& key)
{
    std::vector<unsigned char> data = Params().Base58Prefix(CChainParams::EXT_SECRET_KEY);
    size_t size = data.size();
    data.resize(size + BIP32_EXTKEY_SIZE);
    key.Encode(data.data() + size);
    std::string ret = EncodeBase58Check(data);
    memory_cleanse(data.data(), data.size());
    return ret;
}

std::string EncodeDestination(const CTxDestination& dest)
{
    return boost::apply_visitor(DestinationEncoder(Params()), dest);
}

CTxDestination DecodeDestination(const std::string& str)
{
    return DecodeDestination(str, Params());
}

bool IsValidDestinationString(const std::string& str, const CChainParams& params)
{
    return IsValidDestination(DecodeDestination(str, params));
}

bool IsValidDestinationString(const std::string& str)
{
    return IsValidDestinationString(str, Params());
}

std::string EncodePaymentAddress(const libzcash::PaymentAddress& zaddr)
{
    CDataStream ss(SER_NETWORK, PROTOCOL_VERSION);
    ss << zaddr;
    std::vector<unsigned char> data = Params().Base58Prefix(CChainParams::ZCPAYMENT_ADDRRESS);
    data.insert(data.end(), ss.begin(), ss.end());
    return EncodeBase58Check(data);
}

boost::optional<libzcash::PaymentAddress> DecodePaymentAddress(const std::string& str)
{
    std::vector<unsigned char> data;
    if (DecodeBase58Check(str, data)) {
        const std::vector<unsigned char>& zaddr_prefix = Params().Base58Prefix(CChainParams::ZCPAYMENT_ADDRRESS);
        if ((data.size() == libzcash::SerializedPaymentAddressSize + zaddr_prefix.size()) &&
            std::equal(zaddr_prefix.begin(), zaddr_prefix.end(), data.begin())) {
            CSerializeData serialized(data.begin() + zaddr_prefix.size(), data.end());
            CDataStream ss(serialized, SER_NETWORK, PROTOCOL_VERSION);
            libzcash::PaymentAddress ret;
            ss >> ret;
            return ret;
        }
    }
    return boost::none;
}

std::string EncodeViewingKey(const libzcash::ViewingKey& vk)
{
    CDataStream ss(SER_NETWORK, PROTOCOL_VERSION);
    ss << vk;
    std::vector<unsigned char> data = Params().Base58Prefix(CChainParams::ZCVIEWING_KEY);
    data.insert(data.end(), ss.begin(), ss.end());
    std::string ret = EncodeBase58Check(data);
    memory_cleanse(data.data(), data.size());
    return ret;
}

boost::optional<libzcash::ViewingKey> DecodeViewingKey(const std::string& str)
{
    std::vector<unsigned char> data;
    if (DecodeBase58Check(str, data)) {
        const std::vector<unsigned char>& vk_prefix = Params().Base58Prefix(CChainParams::ZCVIEWING_KEY);
        if ((data.size() == libzcash::SerializedViewingKeySize + vk_prefix.size()) &&
            std::equal(vk_prefix.begin(), vk_prefix.end(), data.begin())) {
            CSerializeData serialized(data.begin() + vk_prefix.size(), data.end());
            CDataStream ss(serialized, SER_NETWORK, PROTOCOL_VERSION);
            libzcash::ViewingKey ret;
            ss >> ret;
            memory_cleanse(serialized.data(), serialized.size());
            memory_cleanse(data.data(), data.size());
            return ret;
        }
    }
    memory_cleanse(data.data(), data.size());
    return boost::none;
}

std::string EncodeSpendingKey(const libzcash::SpendingKey& zkey)
{
    CDataStream ss(SER_NETWORK, PROTOCOL_VERSION);
    ss << zkey;
    std::vector<unsigned char> data = Params().Base58Prefix(CChainParams::ZCSPENDING_KEY);
    data.insert(data.end(), ss.begin(), ss.end());
    std::string ret = EncodeBase58Check(data);
    memory_cleanse(data.data(), data.size());
    return ret;
}

boost::optional<libzcash::SpendingKey> DecodeSpendingKey(const std::string& str)
{
    std::vector<unsigned char> data;
    if (DecodeBase58Check(str, data)) {
        const std::vector<unsigned char>& zkey_prefix = Params().Base58Prefix(CChainParams::ZCSPENDING_KEY);
        if ((data.size() == libzcash::SerializedSpendingKeySize + zkey_prefix.size()) &&
            std::equal(zkey_prefix.begin(), zkey_prefix.end(), data.begin())) {
            CSerializeData serialized(data.begin() + zkey_prefix.size(), data.end());
            CDataStream ss(serialized, SER_NETWORK, PROTOCOL_VERSION);
            libzcash::SpendingKey ret;
            ss >> ret;
            memory_cleanse(serialized.data(), serialized.size());
            memory_cleanse(data.data(), data.size());
            return ret;
        }
    }
    memory_cleanse(data.data(), data.size());
    return boost::none;
}