// Copyright (c) 2014-2021 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 <key_io.h>

#include <base58.h>

#include <bech32.h>

#include <script/interpreter.h>

#include <script/solver.h>

#include <tinyformat.h>

#include <util/strencodings.h>

#include <algorithm>

#include <assert.h>

#include <string.h>

/// Maximum witness length for Bech32 addresses.

static constexpr std::size_t BECH32_WITNESS_PROG_MAX_LEN = 40;

namespace {

class DestinationEncoder

{

private:

    const CChainParams& m_params;

public:

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

    std::string operator()(const PKHash& 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 ScriptHash& 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 WitnessV0KeyHash& id) const

    {

        std::vector<unsigned char> data = {0};

        data.reserve(33);

        ConvertBits<8, 5, true>([&](unsigned char c) { data.push_back(c); }, id.begin(), id.end());

        return bech32::Encode(bech32::Encoding::BECH32, m_params.Bech32HRP(), data);

    }

    std::string operator()(const WitnessV0ScriptHash& id) const

    {

        std::vector<unsigned char> data = {0};

        data.reserve(53);

        ConvertBits<8, 5, true>([&](unsigned char c) { data.push_back(c); }, id.begin(), id.end());

        return bech32::Encode(bech32::Encoding::BECH32, m_params.Bech32HRP(), data);

    }

    std::string operator()(const WitnessV1Taproot& tap) const

    {

        std::vector<unsigned char> data = {1};

        data.reserve(53);

        ConvertBits<8, 5, true>([&](unsigned char c) { data.push_back(c); }, tap.begin(), tap.end());

        return bech32::Encode(bech32::Encoding::BECH32M, m_params.Bech32HRP(), data);

    }

    std::string operator()(const WitnessUnknown& id) const

    {

        const std::vector<unsigned char>& program = id.GetWitnessProgram();

        if (id.GetWitnessVersion() < 1 || id.GetWitnessVersion() > 16 || program.size() < 2 || program.size() > 40) {

            return {};

        }

        std::vector<unsigned char> data = {(unsigned char)id.GetWitnessVersion()};

        data.reserve(1 + (program.size() * 8 + 4) / 5);

        ConvertBits<8, 5, true>([&](unsigned char c) { data.push_back(c); }, program.begin(), program.end());

        return bech32::Encode(bech32::Encoding::BECH32M, m_params.Bech32HRP(), data);

    }

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

    std::string operator()(const PubKeyDestination& pk) const { return {}; }

};

CTxDestination DecodeDestination(const std::string& str, const CChainParams& params, std::string& error_str, std::vector<int>* error_locations)

{

    std::vector<unsigned char> data;

    uint160 hash;

    error_str = "";

    // Note this will be false if it is a valid Bech32 address for a different network

    bool is_bech32 = (ToLower(str.substr(0, params.Bech32HRP().size())) == params.Bech32HRP());

    if (!is_bech32 && DecodeBase58Check(str, data, 21)) {

        // 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 PKHash(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 ScriptHash(hash);

        }

        // If the prefix of data matches either the script or pubkey prefix, the length must have been wrong

        if ((data.size() >= script_prefix.size() &&

                std::equal(script_prefix.begin(), script_prefix.end(), data.begin())) ||

            (data.size() >= pubkey_prefix.size() &&

                std::equal(pubkey_prefix.begin(), pubkey_prefix.end(), data.begin()))) {

            error_str = "Invalid length for Base58 address (P2PKH or P2SH)";

        } else {

            error_str = "Invalid or unsupported Base58-encoded address.";

        }

        return CNoDestination();

    } else if (!is_bech32) {

        // Try Base58 decoding without the checksum, using a much larger max length

        if (!DecodeBase58(str, data, 100)) {

            error_str = "Invalid or unsupported Segwit (Bech32) or Base58 encoding.";

        } else {

            error_str = "Invalid checksum or length of Base58 address (P2PKH or P2SH)";

        }

        return CNoDestination();

    }

    data.clear();

    const auto dec = bech32::Decode(str);

    if (dec.encoding == bech32::Encoding::BECH32 || dec.encoding == bech32::Encoding::BECH32M) {

        if (dec.data.empty()) {

            error_str = "Empty Bech32 data section";

            return CNoDestination();

        }

        // Bech32 decoding

        if (dec.hrp != params.Bech32HRP()) {

            error_str = strprintf("Invalid or unsupported prefix for Segwit (Bech32) address (expected %s, got %s).", params.Bech32HRP(), dec.hrp);

            return CNoDestination();

        }

        int version = dec.data[0]; // The first 5 bit symbol is the witness version (0-16)

        if (version == 0 && dec.encoding != bech32::Encoding::BECH32) {

            error_str = "Version 0 witness address must use Bech32 checksum";

            return CNoDestination();

        }

        if (version != 0 && dec.encoding != bech32::Encoding::BECH32M) {

            error_str = "Version 1+ witness address must use Bech32m checksum";

            return CNoDestination();

        }

        // The rest of the symbols are converted witness program bytes.

        data.reserve(((dec.data.size() - 1) * 5) / 8);

        if (ConvertBits<5, 8, false>([&](unsigned char c) { data.push_back(c); }, dec.data.begin() + 1, dec.data.end())) {

            std::string_view byte_str{data.size() == 1 ? "byte" : "bytes"};

            if (version == 0) {

                {

                    WitnessV0KeyHash keyid;

                    if (data.size() == keyid.size()) {

                        std::copy(data.begin(), data.end(), keyid.begin());

                        return keyid;

                    }

                }

                {

                    WitnessV0ScriptHash scriptid;

                    if (data.size() == scriptid.size()) {

                        std::copy(data.begin(), data.end(), scriptid.begin());

                        return scriptid;

                    }

                }

                error_str = strprintf("Invalid Bech32 v0 address program size (%d %s), per BIP141", data.size(), byte_str);

                return CNoDestination();

            }

            if (version == 1 && data.size() == WITNESS_V1_TAPROOT_SIZE) {

                static_assert(WITNESS_V1_TAPROOT_SIZE == WitnessV1Taproot::size());

                WitnessV1Taproot tap;

                std::copy(data.begin(), data.end(), tap.begin());

                return tap;

            }

            if (CScript::IsPayToAnchor(version, data)) {

                return PayToAnchor();

            }

            if (version > 16) {

                error_str = "Invalid Bech32 address witness version";

                return CNoDestination();

            }

            if (data.size() < 2 || data.size() > BECH32_WITNESS_PROG_MAX_LEN) {

                error_str = strprintf("Invalid Bech32 address program size (%d %s)", data.size(), byte_str);

                return CNoDestination();

            }

            return WitnessUnknown{version, data};

        } else {

            error_str = strprintf("Invalid padding in Bech32 data section");

            return CNoDestination();

        }

    }

    // Perform Bech32 error location

    auto res = bech32::LocateErrors(str);

    error_str = res.first;

    if (error_locations) *error_locations = std::move(res.second);

    return CNoDestination();

}

} // namespace

CKey DecodeSecret(const std::string& str)

{

    CKey key;

    std::vector<unsigned char> data;

    if (DecodeBase58Check(str, data, 34)) {

        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);

        }

    }

    if (!data.empty()) {

        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(), UCharCast(key.begin()), UCharCast(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, 78)) {

        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, 78)) {

        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 std::visit(DestinationEncoder(Params()), dest);

}

CTxDestination DecodeDestination(const std::string& str, std::string& error_msg, std::vector<int>* error_locations)

{

    return DecodeDestination(str, Params(), error_msg, error_locations);

}

CTxDestination DecodeDestination(const std::string& str)

{

    std::string error_msg;

    return DecodeDestination(str, error_msg);

}

bool IsValidDestinationString(const std::string& str, const CChainParams& params)

{

    std::string error_msg;

    return IsValidDestination(DecodeDestination(str, params, error_msg, nullptr));

}

bool IsValidDestinationString(const std::string& str)

{

    return IsValidDestinationString(str, Params());

}