class FContentBrush;
class FButton;
class FMenu;
class FMenuState;

struct FIntRect
{
    uint32 X;
    uint32 Y;
    uint32 SizeX;
    uint32 SizeY;
};

class FContentBrush
{
public:
    FTexture2D *Sprite;
    FColor32 OutlineColor;
    FColor32 ColorAndOpacity;

public:
    FContentBrush(const FColor32 &ColorAndOpacity);
    FContentBrush(const FColor32 &ColorAndOpacity, const FColor32 &OutlineColor);
    FContentBrush(const FColor32 &ColorAndOpacity, const FColor32 &OutlineColor, const FTexture2D *InSprite);
    FContentBrush(const FColor32 &ColorAndOpacity, const FTexture2D *InSprite);
};

class FButton
{
public:
    FMenu *OwnerMenu;
    FIntRect Position;

    FContentBrush DisabledBrush;
    FContentBrush EnabledBrush;
    FContentBrush HoveredBrush;
    FContentBrush ClickedBrush;

public:
    virtual void OnInitialize();
    virtual void OnRelease();
    virtual void OnUpdate();
    virtual void OnHover();
    virtual void OnClick();
    virtual void OnRelease();

    virtual void Draw(); // Render Self.
};

class FMenu
{
public:
    FMenuState *OwnerMenuState;
    TArray<FButton *> MenuButtons;

public:
    void AddButton(FButton *InButton)
    {
        MenuButtons.Add(InButton);
        InButton->OwnerMenu = this;
    }

    void RemoveButton(FButton *InButton)
    {
        MenuButtons.Remove(InButton);
        InButton->OwnerMenu = 0;
    }

    void Update()
    {
        for (uint32 Index = 0; Index < MenuButtons.GetCount(); ++Index)
        {
            FButton *Button = MenuButtons[Index];
            Button->OnUpdate();
        }
    }

    void Render()
    {
        for (uint32 Index = 0; Index < MenuButtons.GetCount(); ++Index)
        {
            FButton *Button = MenuButtons[Index];
            Button->Draw();
        }
    }
};

class FMenuState
{
public:
    uint32 CurrentMenuIndex;
    TArray<FMenu *> MenuCache;

public:
    void AddMenu(FMenu *InMenu)
    {
        MenuCache.Add(InMenu);
        InMenu->OwnerMenuState = this;
    }

    void RemoveMenu(FMenu *InMenu)
    {
        MenuCache.Remove(InMenu);
        InMenu->OwnerMenuState = 0;
    }

    void UpdateAndRender()
    {
        FMenu *CurrentMenu = MenuCache[CurrentMenuIndex];
        CurrentMenu->Update();
        CurrentMenu->Render();
    }
};

class FLoginButton : public FButton
{
public:
    virtual void OnRelease() override
    {
        bIsPressed = true;
    }

    virtual void OnUpdate() override
    {
        if (bIsPressed)
        {
            OwnerMenu->OwnerMenuState->CurrentMenuIndex++;
        }
    }

private:
    bool bIsPressed;
};

class FLoginMenu : public FMenu
{
public:
    FLoginMenu()
    {
        FButton *LoginButton;
        FMenu::AddButton(LoginButton);
        FButton *ExitButton;
        FMenu::AddButton(ExitButton);
    }
};

void Main()
{
    FLoginButton *LoginButton;
    // ->SetColor and stuff

    FButton *ExitButton;
    // ->SetColor and stuff

    FButton *AccountNameButton;
    // ->SetColor and stuff

    FButton *AccountPasswordButton;
    // ->SetColor and stuff

    FMenu *MenuA;
    MenuA->AddButton(LoginButton);
    MenuA->AddButton(ExitButton);

    FMenu *MenuB;
    MenuB->AddButton(AccountNameButton);
    MenuB->AddButton(AccountPasswordButton);

    FMenuState *MenuState;
    MenuState->AddMenu(MenuA);
    MenuState->AddMenu(MenuB);

    while (bGameIsRunning)
    {
        MenuState->UpdateAndRender();
    }
}

/* - MenuA
->Login
->Exit
*/

/* - MenuB
->AccountName
->AccountPassword
*/