#include "dll_loader.hpp"
#include <stdexcept>
#include <filesystem>

#if defined(BASALT_OS_WINDOWS)
#include <windows.h>
#else
#include <unistd.h>
#endif

using ::basalt::shared::char_types::BSStringView;

namespace basalt::presenter::dll_loader {

    static std::filesystem::path get_executable() {
#if defined(BASALT_OS_WINDOWS)
        wchar_t buffer[MAX_PATH];
        DWORD hr = GetModuleFileNameW(NULL, buffer, MAX_PATH);
        if (hr > 0 && hr < MAX_PATH) {
            return std::filesystem::path(buffer);
        } else {
            throw std::runtime_error("Failed to get executable path");
        }
#else
        char buffer[PATH_MAX];
        ssize_t len = readlink("/proc/self/exe", buffer, sizeof(buffer) - 1);
        if (len != -1) {
            buffer[len] = '\0';
            return std::filesystem::path(buffer);
        } else {
            throw std::runtime_error("Failed to get executable path");
        }
#endif
    }

    DllLoader::DllLoader(DllKind kind, const BSStringView& filename) {
        // Build DLL full path
        auto dll_path = get_executable().parent_path();
        dll_path /= BSTEXT("plugin");
        switch (kind) {
            case DllKind::Engine:
                dll_path /= BSTEXT("engine");
                break;
            case DllKind::Deliver:
                dll_path /= BSTEXT("deliver");
                break;
            case DllKind::ObjectLoader:
                dll_path /= BSTEXT("object_loader");
                break;
            case DllKind::AnimeLoader:
                dll_path /= BSTEXT("anime_loader");
                break;
        }
        dll_path /= filename;
#if defined(BASALT_OS_WINDOWS)
        dll_path.replace_extension(BSTEXT(".dll"));
#else
        dll_path.replace_extension(BSTEXT(".so"));
#endif
        // Load DLL
#if defined(BASALT_OS_WINDOWS)
        m_Handle = LoadLibraryW(dll_path.wstring().c_str());
#else
        m_Handle = dlopen(dll_path.string().c_str(), RTLD_LAZY);
#endif
        // Check loaded DLL
        if (!m_Handle) throw std::runtime_error("Can not load given dynamic library.");
    }

    DllLoader::~DllLoader() {
        if (m_Handle) {
#if defined(BASALT_OS_WINDOWS)
            FreeLibrary(m_Handle);
#else
            dlclose(m_Handle);
#endif
        }
    }

    void *DllLoader::get_function_pointer(const char *name) {
        if (!m_Handle) throw std::runtime_error("Can not fetch function pointer on not loaded dynamic library.");
#if defined(BASALT_OS_WINDOWS)
        return (void *) GetProcAddress(m_Handle, name);
#else
        return (void *) dlsym(m_Handle, name);
#endif
    }

} // namespace Basalt::Presenter