// Copyright (c) 2009-present The Bitcoin Core developers

// Distributed under the MIT software license, see the accompanying

// file COPYING or https://opensource.org/license/mit/.

#include <memusage.h>

#include <span.h>

#include <streams.h>

#include <util/fs_helpers.h>

#include <util/obfuscation.h>

#include <array>

AutoFile::AutoFile(std::FILE* file, const Obfuscation& obfuscation) : m_file{file}, m_obfuscation{obfuscation}

{

    if (!IsNull()) {

        auto pos{std::ftell(m_file)};

        if (pos >= 0) m_position = pos;

    }

}

std::size_t AutoFile::detail_fread(std::span<std::byte> dst)

{

    if (!m_file) throw std::ios_base::failure("AutoFile::read: file handle is nullptr");

    const size_t ret = std::fread(dst.data(), 1, dst.size(), m_file);

    if (m_obfuscation) {

        if (!m_position) throw std::ios_base::failure("AutoFile::read: position unknown");

        m_obfuscation(dst.subspan(0, ret), *m_position);

    }

    if (m_position) *m_position += ret;

    return ret;

}

void AutoFile::seek(int64_t offset, int origin)

{

    if (IsNull()) {

        throw std::ios_base::failure("AutoFile::seek: file handle is nullptr");

    }

    if (std::fseek(m_file, offset, origin) != 0) {

        throw std::ios_base::failure(feof() ? "AutoFile::seek: end of file" : "AutoFile::seek: fseek failed");

    }

    if (origin == SEEK_SET) {

        m_position = offset;

    } else if (origin == SEEK_CUR && m_position.has_value()) {

        *m_position += offset;

    } else {

        int64_t r{std::ftell(m_file)};

        if (r < 0) {

            throw std::ios_base::failure("AutoFile::seek: ftell failed");

        }

        m_position = r;

    }

}

int64_t AutoFile::tell()

{

    if (!m_position.has_value()) throw std::ios_base::failure("AutoFile::tell: position unknown");

    return *m_position;

}

int64_t AutoFile::size()

{

    if (IsNull()) {

        throw std::ios_base::failure("AutoFile::size: file handle is nullptr");

    }

    // Temporarily save the current position

    int64_t current_pos = tell();

    seek(0, SEEK_END);

    int64_t file_size = tell();

    // Restore the original position

    seek(current_pos, SEEK_SET);

    return file_size;

}

void AutoFile::read(std::span<std::byte> dst)

{

    if (detail_fread(dst) != dst.size()) {

        throw std::ios_base::failure(feof() ? "AutoFile::read: end of file" : "AutoFile::read: fread failed");

    }

}

void AutoFile::ignore(size_t nSize)

{

    if (!m_file) throw std::ios_base::failure("AutoFile::ignore: file handle is nullptr");

    unsigned char data[4096];

    while (nSize > 0) {

        size_t nNow = std::min<size_t>(nSize, sizeof(data));

        if (std::fread(data, 1, nNow, m_file) != nNow) {

            throw std::ios_base::failure(feof() ? "AutoFile::ignore: end of file" : "AutoFile::ignore: fread failed");

        }

        nSize -= nNow;

        if (m_position.has_value()) *m_position += nNow;

    }

}

void AutoFile::write(std::span<const std::byte> src)

{

    if (!m_file) throw std::ios_base::failure("AutoFile::write: file handle is nullptr");

    if (!m_obfuscation) {

        if (std::fwrite(src.data(), 1, src.size(), m_file) != src.size()) {

            throw std::ios_base::failure("AutoFile::write: write failed");

        }

        m_was_written = true;

        if (m_position.has_value()) *m_position += src.size();

    } else {

        std::array<std::byte, 4096> buf;

        while (src.size()) {

            auto buf_now{std::span{buf}.first(std::min<size_t>(src.size(), buf.size()))};

            std::copy_n(src.begin(), buf_now.size(), buf_now.begin());

            write_buffer(buf_now);

            src = src.subspan(buf_now.size());

        }

    }

}

void AutoFile::write_buffer(std::span<std::byte> src)

{

    if (!m_file) throw std::ios_base::failure("AutoFile::write_buffer: file handle is nullptr");

    if (m_obfuscation) {

        if (!m_position) throw std::ios_base::failure("AutoFile::write_buffer: obfuscation position unknown");

        m_obfuscation(src, *m_position); // obfuscate in-place

    }

    if (std::fwrite(src.data(), 1, src.size(), m_file) != src.size()) {

        throw std::ios_base::failure("AutoFile::write_buffer: write failed");

    }

    m_was_written = true;

    if (m_position) *m_position += src.size();

}

bool AutoFile::Commit()

{

    return ::FileCommit(m_file);

}

bool AutoFile::Truncate(unsigned size)

{

    m_was_written = true;

    return ::TruncateFile(m_file, size);

}

size_t DataStream::GetMemoryUsage() const noexcept

{

    return sizeof(*this) + memusage::DynamicUsage(vch);

}