#pragma once

#if !defined(MIJIN_UTIL_OS_HPP_INCLUDED)
#define MIJIN_UTIL_OS_HPP_INCLUDED 1

#include <csignal>
#include <string>
#include <string_view>
#include <utility>
#include "../detect.hpp"
#include "../types/result.hpp"

namespace mijin
{

//
// public defines
//

//
// public constants
//

#if MIJIN_TARGET_OS == MIJIN_OS_LINUX
inline const std::string_view LIBRARY_EXT = "so";
#elif MIJIN_TARGET_OS == MIJIN_OS_WINDOWS
inline const std::string_view LIBRARY_EXT = "dll";
#else
[[deprecated("OS not supported.")]]
inline const int LIBRARY_EXT = 0;
#endif

//
// public types
//

struct LibraryHandle
{
    void* data = nullptr;

    constexpr operator bool() const noexcept { return data != nullptr; }
    constexpr bool operator!() const noexcept { return data == nullptr; }
};

class SharedLibrary
{
private:
    LibraryHandle mHandle;
public:
    SharedLibrary() noexcept = default;
    SharedLibrary(const SharedLibrary&) = delete;
    SharedLibrary(SharedLibrary&& other) noexcept : mHandle(std::exchange(other.mHandle, {})) {}
    inline ~SharedLibrary() noexcept;

    SharedLibrary& operator=(const SharedLibrary&) = delete;
    SharedLibrary& operator=(SharedLibrary&& other) noexcept
    {
        mHandle = std::exchange(other.mHandle, {});
        return *this;
    }

    constexpr operator bool() const noexcept { return static_cast<bool>(mHandle); }
    constexpr bool operator!() const noexcept { return !mHandle; }

    [[nodiscard]] inline Result<bool> open(std::string_view libraryFile) noexcept;
    inline bool close() noexcept;
    [[nodiscard]] inline void* loadSymbol(const char* symbolName) noexcept;
};

//
// public functions
//

[[nodiscard]] Result<LibraryHandle> openSharedLibrary(std::string_view libraryFile) noexcept;
bool closeSharedLibrary(const LibraryHandle library) noexcept;
[[nodiscard]] void* loadSymbolFromLibrary(const LibraryHandle library, const char* symbolName) noexcept;
void setCurrentThreadName(const char* threadName) noexcept;

[[nodiscard]] std::string makeLibraryFilename(std::string_view libraryName) noexcept;

SharedLibrary::~SharedLibrary() noexcept
{
    close();
}

Result<bool> SharedLibrary::open(std::string_view libraryFile) noexcept
{
    close();
    Result<LibraryHandle> openResult = openSharedLibrary(libraryFile);
    if (openResult.isSuccess())
    {
        mHandle = openResult.getValue();
        return true;
    }
    return ResultError(openResult.getError());
}

bool SharedLibrary::close() noexcept
{
    if (mHandle)
    {
        return closeSharedLibrary(std::exchange(mHandle, {}));
    }
    return false;
}

void* SharedLibrary::loadSymbol(const char* symbolName) noexcept
{
    return loadSymbolFromLibrary(mHandle, symbolName);
}
} // namespace mijin

#endif // !defined(MIJIN_UTIL_OS_HPP_INCLUDED)