// Copyright © 2017-2020 Trust Wallet.

//

// This file is part of Trust. The full Trust copyright notice, including

// terms governing use, modification, and redistribution, is contained in the

// file LICENSE at the root of the source code distribution tree.

#pragma once

#include "Data.h"

#include <boost/multiprecision/cpp_int.hpp>

namespace TW {

using int256_t = boost::multiprecision::int256_t;

using uint256_t = boost::multiprecision::uint256_t;

/// Loads a `uint256_t` from a collection of bytes.

/// The rightmost bytes are taken from data

inline uint256_t load(const Data& data) {

using boost::multiprecision::cpp_int;

if (data.empty()) {

return uint256_t(0);

}

uint256_t result;

import_bits(result, data.begin(), data.end());

return result;

}

/// Loads a `uint256_t` from a collection of bytes.

/// The leftmost offset bytes are skipped, and the next 32 bytes are taken. At least 32 (+offset) bytes are needed.

inline uint256_t loadWithOffset(const Data& data, size_t offset) {

using boost::multiprecision::cpp_int;

if (data.empty() || (data.size() < (256/8 + offset))) {

// not enough bytes in data

return uint256_t(0);

}

uint256_t result;

import_bits(result, data.begin() + offset, data.begin() + offset + 256/8);

return result;

}

/// Loads a `uint256_t` from Protobuf bytes (which are wrongly represented as

/// std::string).

inline uint256_t load(const std::string& data) {

using boost::multiprecision::cpp_int;

if (data.empty()) {

return uint256_t(0);

}

uint256_t result;

import_bits(result, reinterpret_cast<const byte*>(data.data()),

reinterpret_cast<const byte*>(data.data() + data.size()));

return result;

}

/// Stores a `uint256_t` as a collection of bytes.

inline Data store(const uint256_t& v) {

using boost::multiprecision::cpp_int;

Data bytes;

bytes.reserve(32);

export_bits(v, std::back_inserter(bytes), 8);

return bytes;

}

// Append a uint256_t value as a big-endian byte array into the provided buffer, and limit

// the array size by digit/8.

inline void encode256BE(Data &data, const uint256_t &value, uint32_t digit) {

Data bytes = store(value);

Data buff(digit / 8);

for (int i = 0; i < (int)bytes.size(); ++i) {

int start = (int)buff.size() - (int)bytes.size() + i;

if (start >= 0) {

buff[start] = bytes[i];

}

}

data.insert(data.end(), buff.begin(), buff.end());

}

} // namespace TW