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// Initializes the boot graphics system
void screen_init()
{
    EFI_GUID gopguid = EFI_GRAPHICS_OUTPUT_PROTOCOL_GUID;
    UINTN bufsize = 0;
    EFI_HANDLE* handles = NULL;
    // Obtain the size of the GOP handle list
    EFI_STATUS status = gBS->LocateHandle(ByProtocol, &gopguid, NULL, &bufsize, handles);
    // Status must equal EFI_BUFFER_TOO_SMALL
    if(status != EFI_BUFFER_TOO_SMALL)
        efi_panicearly(L"unable to locate GOP handle list\r\n");
    // Allocate the buffer
    handles = (EFI_HANDLE*)efi_alloc(bufsize);
    if(!handles)
        efi_panicearly(L"unable to allocate GOP handle list\r\n");
    // Read in the handle list
    status = gBS->LocateHandle(ByProtocol, &gopguid, NULL, &bufsize, handles);
    if(EFI_ERROR(status))
        efi_panicearly(L"unable to locate GOP handles list\r\n");
    // Loop through every handle, attempting to open up GOP and EDID until we succeed
    UINTN numhandles = bufsize / sizeof(EFI_HANDLE);
    EFI_EDID_ACTIVE_PROTOCOL* edid = NULL;
    for(int i = 0; i < numhandles; ++i)
    {
        // Obtain the current handle
        EFI_HANDLE handle = handles[i];
        // Attempt to open up the GOP on it. At the moment, we only use the first display
        status = gBS->HandleProtocol(handle, &gopguid, (VOID**)&gop);
        // Check if it worked
        if(EFI_ERROR(status))
        {
            // No display is supported
            if(i + 1 == numhandles)
                break;
            else
                continue;
        }
        // Open up EDID now
        EFI_GUID edidguid = EFI_EDID_ACTIVE_PROTOCOL_GUID;
        status = gBS->HandleProtocol(handle, &edidguid, (VOID**)&edid);
        if(EFI_ERROR(status))
        {
            if(i + 1 == numhandles)
                efi_panicearly(L"could not find EDID\r\n");
        }
    }
}

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void EfiBoot::InitDisplays()
{
    UINTN size = 0;
    std::vector<EFI_HANDLE> handles;
    EFI_STATUS status;

    while ((status = g_efiBootServices->LocateHandle(ByProtocol, &g_efiGraphicsOutputProtocolGuid, nullptr, &size, handles.data())) == EFI_BUFFER_TOO_SMALL)
    {
        handles.resize(size / sizeof(EFI_HANDLE));
    }

    if (EFI_ERROR(status))
    {
        // Likely EFI_NOT_FOUND, but any error should be handled as "no display available"
        return;
    }

    for (auto handle: handles)
    {
        EFI_DEVICE_PATH_PROTOCOL* dpp = nullptr;
        g_efiBootServices->HandleProtocol(handle, &g_efiDevicePathProtocolGuid, (void**)&dpp);
        // If dpp is NULL, this is the "Console Splitter" driver. It is used to draw on all
        // screens at the same time and doesn't represent a real hardware device.
        if (!dpp) continue;

        EFI_GRAPHICS_OUTPUT_PROTOCOL* gop = nullptr;
        g_efiBootServices->HandleProtocol(handle, &g_efiGraphicsOutputProtocolGuid, (void**)&gop);
        // gop is not expected to be null, but let's play safe.
        if (!gop) continue;

        EFI_EDID_ACTIVE_PROTOCOL* edid = nullptr;
        if (EFI_ERROR(g_efiBootServices->HandleProtocol(handle, &g_efiEdidActiveProtocolGuid, (void**)&edid)) || !edid)
        {
            g_efiBootServices->HandleProtocol(handle, &g_efiEdidDiscoveredProtocolGuid, (void**)&edid);
        }
 
        // edid can be null, don't rely on it to exist

        m_displays.push_back(std::move(EfiDisplay(gop, edid)));
    }
}