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// SPDX-FileCopyrightText: 2026 Progmasoft <support@progmasoft.com>
// SPDX-License-Identifier: MPL-2.0 WITH AdditionRef-Progmasoft-Exception-2.0
#include <cstdlib>
#include <fmt/format.h>
#include <fstream>
#include <system_error>
#include <utility>
#include "Progmasoft/Tazelish/VersionFiles.hpp"
namespace Progmasoft::Tazelish
{
namespace
{
namespace fs = std::filesystem;
// A version file is short; anything longer names no version.
constexpr std::size_t kLongestContent = 64;
FileError
Fail(const fs::path &file, std::string message)
{
return FileError{ file, std::move(message) };
}
// The text of a file without the line break and blanks around the
// version.
std::string_view
Trim(std::string_view text)
{
constexpr std::string_view kBlanks = " \t\r\n";
constexpr std::string_view kByteOrderMark = "\xEF\xBB\xBF";
if (text.substr(0, kByteOrderMark.size()) == kByteOrderMark)
{
text.remove_prefix(kByteOrderMark.size());
}
const std::size_t first = text.find_first_not_of(kBlanks);
if (first == std::string_view::npos)
{
return {};
}
const std::size_t last = text.find_last_not_of(kBlanks);
return text.substr(first, last - first + 1);
}
} // namespace
std::optional<fs::path>
HomeDirectory()
{
#ifdef _WIN32
constexpr const char *kVariable = "USERPROFILE";
#else
constexpr const char *kVariable = "HOME";
#endif
// The environment is read once, before any thread starts.
const char *value
= std::getenv(kVariable); // NOLINT(concurrency-mt-unsafe)
if (value == nullptr || *value == '\0')
{
return std::nullopt;
}
return fs::path(value);
}
fs::path
StateDirectory(const fs::path &home)
{
return home / fs::path(kStateDirectoryName);
}
fs::path
ConfigFile(const fs::path &home)
{
return StateDirectory(home) / fs::path(kConfigFileName);
}
std::variant<NoSelection, Version, FileError>
ReadVersionFile(const fs::path &file)
{
std::error_code error;
const fs::file_status status = fs::status(file, error);
if (status.type() == fs::file_type::not_found)
{
return NoSelection{};
}
if (error)
{
return Fail(file, error.message());
}
if (status.type() != fs::file_type::regular)
{
return Fail(file, "is not a regular file");
}
std::ifstream stream(file, std::ios::binary);
if (!stream)
{
return Fail(file, "cannot be read");
}
std::string content;
content.resize(kLongestContent + 1);
stream.read(content.data(),
static_cast<std::streamsize>(content.size()));
content.resize(static_cast<std::size_t>(stream.gcount()));
if (stream.bad())
{
return Fail(file, "cannot be read");
}
const std::string_view text = Trim(content);
if (content.size() > kLongestContent)
{
return Fail(file, "holds more than a version");
}
if (auto version = ParseVersion(text))
{
return *version;
}
return Fail(file,
fmt::format("holds '{}', which is not a version", text));
}
std::variant<NoSelection, Selection, FileError>
SelectVersion(const fs::path &directory,
const std::optional<fs::path> &home)
{
for (fs::path folder = directory;; folder = folder.parent_path())
{
const fs::path file = folder / fs::path(kProjectFileName);
auto read = ReadVersionFile(file);
if (auto *failure = std::get_if<FileError>(&read))
{
return std::move(*failure);
}
if (auto *version = std::get_if<Version>(&read))
{
return Selection{ *version, file, VersionSource::kProject };
}
if (folder == folder.parent_path())
{
break;
}
}
if (!home)
{
return NoSelection{};
}
const fs::path file = ConfigFile(*home);
auto read = ReadVersionFile(file);
if (auto *failure = std::get_if<FileError>(&read))
{
return std::move(*failure);
}
if (auto *version = std::get_if<Version>(&read))
{
return Selection{ *version, file, VersionSource::kUser };
}
return NoSelection{};
}
std::optional<FileError>
WriteVersionFile(const fs::path &file, const Version &version, bool force)
{
std::error_code error;
const bool exists = fs::exists(fs::symlink_status(file, error));
if (error && error != std::errc::no_such_file_or_directory)
{
return Fail(file, error.message());
}
if (exists && !force)
{
return Fail(file, "already exists; --force writes over it");
}
if (file.has_parent_path())
{
fs::create_directories(file.parent_path(), error);
if (error)
{
return Fail(file.parent_path(), error.message());
}
}
std::ofstream stream(file, std::ios::binary | std::ios::trunc);
const std::string content = FormatVersion(version) + "\n";
stream.write(content.data(),
static_cast<std::streamsize>(content.size()));
stream.close();
if (!stream)
{
return Fail(file, "cannot be written");
}
return std::nullopt;
}
} // namespace Progmasoft::Tazelish
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