mijin2/source/mijin/virtual_filesystem/memory.cpp

#include "./memory.hpp"

#include "../io/stream.hpp"

namespace mijin
{
std::vector<FileInfo> MemoryFileSystemAdapter::listFiles(const fs::path& folder)
{
    const detail::MemoryFolder* folderObj = findFolder(folder);
    if (folderObj == nullptr)
    {
        return {};
    }
    std::vector<FileInfo> result;
    result.reserve(folderObj->folders.size() + folderObj->files.size());

    for (const auto& [name, subFolder] : folderObj->folders)
    {
        result.push_back(folderInfo(folder / name, subFolder));
    }

    for (const auto& [name, file] : folderObj->files)
    {
        result.push_back(fileInfo(folder / name, file));
    }

    return result;
}

FileInfo MemoryFileSystemAdapter::getFileInfo(const fs::path& file)
{
#if 0 // shouldn't be necessary
    // empty means root
    if (file.empty())
    {
        return {
            .path = {},
            .size = root_.folders.size() + root_.files.size(),
            .exists = true,
            .isFolder = true
        };
    }
#endif

    const detail::MemoryFolder* folderObj = findFolder(file.parent_path());
    if (folderObj == nullptr)
    {
        return {};
    }
    const std::string filename = file.filename().generic_string();

    if (auto itFolder = folderObj->folders.find(filename); itFolder != folderObj->folders.end())
    {
        return folderInfo(file, itFolder->second);
    }
    if (auto itFile = folderObj->files.find(filename); itFile != folderObj->files.end())
    {
        return fileInfo(file, itFile->second);
    }
    return {};
}

StreamError MemoryFileSystemAdapter::open(const fs::path& path, FileOpenMode mode, std::unique_ptr<Stream>& outStream)
{
    if (mode != FileOpenMode::READ)
    {
        return StreamError::IO_ERROR;
    }

    const detail::MemoryFolder* folderObj = findFolder(path.parent_path());
    if (folderObj == nullptr)
    {
        return StreamError::IO_ERROR;
    }

    auto itFile = folderObj->files.find(path.filename().generic_string());
    if (itFile == folderObj->files.end())
    {
        return StreamError::IO_ERROR;
    }

    std::unique_ptr<MemoryStream> stream = std::make_unique<MemoryStream>();
    stream->openRO(itFile->second.data);
    outStream = std::move(stream);

    return StreamError::SUCCESS;
}

bool MemoryFileSystemAdapter::addFile(const fs::path& path, std::span<const std::uint8_t> data, Overwrite overwrite, CopyData copyData)
{
    detail::MemoryFolder& folder = *findFolder(path.parent_path(), true);
    std::string filename = path.filename().generic_string();

    if (folder.folders.contains(filename))
    {
        return false;
    }

    if (!overwrite && folder.files.contains(filename))
    {
        return false;
    }

    if (copyData)
    {
        data = fileData_.emplace_back(data.begin(), data.end());
    }

    folder.files.emplace(std::move(filename), detail::MemoryFile{.data = data});
    return true;
}

void MemoryFileSystemAdapter::addFolder(const fs::path& path)
{
    (void) findFolder(path, true);
}

detail::MemoryFolder* MemoryFileSystemAdapter::findFolder(const fs::path& path, bool create) MIJIN_NOEXCEPT
{
    detail::MemoryFolder* folder = &root_;
    for (const fs::path& part : path)
    {
        std::string partname = part.generic_string();
        auto it = folder->folders.find(partname);
        if (it == folder->folders.end())
        {
            if (!create)
            {
                return nullptr;
            }
            folder = &folder->folders[std::move(partname)];
        }
        else
        {
            folder = &it->second;
        }
    }
    return folder;
}

FileInfo MemoryFileSystemAdapter::folderInfo(const fs::path& path, const detail::MemoryFolder& folder) const MIJIN_NOEXCEPT
{
    return {
        .path = path,
        .size = folder.folders.size() + folder.files.size(),
        .exists = true,
        .isFolder = true
    };
}

FileInfo MemoryFileSystemAdapter::fileInfo(const fs::path& path, const detail::MemoryFile& file) const MIJIN_NOEXCEPT
{
    return {
        .path = path,
        .size = file.data.size(),
        .exists = true
    };
}
}