// Copyright (c) 2014-2016 The Bitcoin Core developers
// Copyright (c) 2016-2018 The Zcash developers
// Copyright (c) 2019-2020 The Hush developers
// Distributed under the GPLv3 software license, see the accompanying
// file COPYING or https://www.gnu.org/licenses/gpl-3.0.en.html

#include <key_io.h>

#include <base58.h>
#include <bech32.h>
#include <script/script.h>
#include <utilstrencodings.h>

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

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

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 CPubKey& key) const
    {
        std::vector<unsigned char> data = m_params.Base58Prefix(CChainParams::PUBKEY_ADDRESS);
        CKeyID id = key.GetID();
        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();
}

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

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

    std::string operator()(const libzcash::SaplingPaymentAddress& zaddr) const
    {
        CDataStream ss(SER_NETWORK, PROTOCOL_VERSION);
        ss << zaddr;
        // ConvertBits requires unsigned char, but CDataStream uses char
        std::vector<unsigned char> seraddr(ss.begin(), ss.end());
        std::vector<unsigned char> data;
        // See calculation comment below
        data.reserve((seraddr.size() * 8 + 4) / 5);
        ConvertBits<8, 5, true>([&](unsigned char c) { data.push_back(c); }, seraddr.begin(), seraddr.end());
        return bech32::Encode(m_params.Bech32HRP(CChainParams::SAPLING_PAYMENT_ADDRESS), data);
    }

    std::string operator()(const libzcash::InvalidEncoding& no) const { return {}; }
    std::string operator()(const libzcash::SproutPaymentAddress& zaddr) const { return {}; }
};

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

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

    std::string operator()(const libzcash::SaplingIncomingViewingKey& vk) const
    {
        CDataStream ss(SER_NETWORK, PROTOCOL_VERSION);
        ss << vk;
        std::vector<unsigned char> serkey(ss.begin(), ss.end());
        std::vector<unsigned char> data;
        ConvertBits<8, 5, true>([&](unsigned char c) { data.push_back(c); }, serkey.begin(), serkey.end());
        std::string ret = bech32::Encode(m_params.Bech32HRP(CChainParams::SAPLING_INCOMING_VIEWING_KEY), data);
        memory_cleanse(serkey.data(), serkey.size());
        memory_cleanse(data.data(), data.size());
        return ret;
    }

    std::string operator()(const libzcash::InvalidEncoding& no) const { return {}; }
};

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

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

    std::string operator()(const libzcash::SaplingExtendedSpendingKey& zkey) const
    {
        CDataStream ss(SER_NETWORK, PROTOCOL_VERSION);
        ss << zkey;
        // ConvertBits requires unsigned char, but CDataStream uses char
        std::vector<unsigned char> serkey(ss.begin(), ss.end());
        std::vector<unsigned char> data;
        // See calculation comment below
        data.reserve((serkey.size() * 8 + 4) / 5);
        ConvertBits<8, 5, true>([&](unsigned char c) { data.push_back(c); }, serkey.begin(), serkey.end());
        std::string ret = bech32::Encode(m_params.Bech32HRP(CChainParams::SAPLING_EXTENDED_SPEND_KEY), data);
        memory_cleanse(serkey.data(), serkey.size());
        memory_cleanse(data.data(), data.size());
        return ret;
    }

    std::string operator()(const libzcash::InvalidEncoding& no) const { return {}; }
};

// Sizes of SaplingPaymentAddress and SaplingSpendingKey after
// ConvertBits<8, 5, true>(). The calculations below take the
// regular serialized size in bytes, convert to bits, and then
// perform ceiling division to get the number of 5-bit clusters.
const size_t ConvertedSaplingPaymentAddressSize = ((32 + 11) * 8 + 4) / 5;
const size_t ConvertedSaplingExtendedSpendingKeySize = (ZIP32_XSK_SIZE * 8 + 4) / 5;
const size_t ConvertedSaplingIncomingViewingKeySize = (32 * 8 + 4) / 5;
} // 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;
}

CKey DecodeCustomSecret(const std::string& str, uint8_t secret_key)
{
    CKey key;
    std::vector<unsigned char> data;
    if (DecodeBase58Check(str, data)) {
        const std::vector<unsigned char>& privkey_prefix = std::vector<unsigned char>(1, 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;
}

std::string EncodeCustomSecret(const CKey& key,uint8_t secret_key)
{
    assert(key.IsValid());
    std::vector<unsigned char> data = std::vector<unsigned char>(1,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)
{
    return boost::apply_visitor(PaymentAddressEncoder(Params()), zaddr);
}

libzcash::PaymentAddress DecodePaymentAddress(const std::string& str)
{
    std::vector<unsigned char> data;
    auto bech = bech32::Decode(str);
    if (bech.first == Params().Bech32HRP(CChainParams::SAPLING_PAYMENT_ADDRESS) &&
        bech.second.size() == ConvertedSaplingPaymentAddressSize) {
        // Bech32 decoding
        data.reserve((bech.second.size() * 5) / 8);
        if (ConvertBits<5, 8, false>([&](unsigned char c) { data.push_back(c); }, bech.second.begin(), bech.second.end())) {
            CDataStream ss(data, SER_NETWORK, PROTOCOL_VERSION);
            libzcash::SaplingPaymentAddress ret;
            ss >> ret;
            return ret;
        }
    }
    return libzcash::InvalidEncoding();
}

bool IsValidPaymentAddressString(const std::string& str, uint32_t consensusBranchId) {
    return IsValidPaymentAddress(DecodePaymentAddress(str), consensusBranchId);
}

std::string EncodeViewingKey(const libzcash::ViewingKey& vk)
{
    return boost::apply_visitor(ViewingKeyEncoder(Params()), vk);
}

libzcash::ViewingKey DecodeViewingKey(const std::string& str)
{
    std::vector<unsigned char> data;
    auto bech = bech32::Decode(str);
    if(bech.first == Params().Bech32HRP(CChainParams::SAPLING_INCOMING_VIEWING_KEY) &&
       bech.second.size() == ConvertedSaplingIncomingViewingKeySize) {
        // Bech32 decoding
        data.reserve((bech.second.size() * 5) / 8);
        if (ConvertBits<5, 8, false>([&](unsigned char c) { data.push_back(c); }, bech.second.begin(), bech.second.end())) {
            CDataStream ss(data, SER_NETWORK, PROTOCOL_VERSION);
            libzcash::SaplingIncomingViewingKey ret;
            ss >> ret;
            return ret;
        }
    }
    return libzcash::InvalidEncoding();
}

std::string EncodeSpendingKey(const libzcash::SpendingKey& zkey)
{
    return boost::apply_visitor(SpendingKeyEncoder(Params()), zkey);
}

libzcash::SpendingKey DecodeSpendingKey(const std::string& str)
{
    std::vector<unsigned char> data;
    auto bech = bech32::Decode(str);
    if (bech.first == Params().Bech32HRP(CChainParams::SAPLING_EXTENDED_SPEND_KEY) &&
        bech.second.size() == ConvertedSaplingExtendedSpendingKeySize) {
        // Bech32 decoding
        data.reserve((bech.second.size() * 5) / 8);
        if (ConvertBits<5, 8, false>([&](unsigned char c) { data.push_back(c); }, bech.second.begin(), bech.second.end())) {
            CDataStream ss(data, SER_NETWORK, PROTOCOL_VERSION);
            libzcash::SaplingExtendedSpendingKey ret;
            ss >> ret;
            memory_cleanse(data.data(), data.size());
            return ret;
        }
    }
    memory_cleanse(data.data(), data.size());
    return libzcash::InvalidEncoding();
}