Implement “Save as” in save dialog wxpython

I have a saving routine that should prompt the user in the following way:

If the currently selected file name exists, prompt for overwrite
If the currently selected file name is empty (i.e. ""), set up a dialog to ask user to insert file name
If the currently selected file name does not exist, save it!

My code is currently like below, but I feel like there should be a better way of doing this. As it is now the user is prompted with a dialog with choices "Yes, No, Cancel", but I would want it to be "Yes, Save as, Cancel". I really could not find any way to change the "No" button to a "Save as" button that opens a dialog where the user can insert the wanted file name. Any suggestions of improving this?

def saveProject(window):

if os.path.exists(window.getGlobalSettings().getCurrentFileName()): #File exists from before   
    dlg = wx.MessageDialog(window,
                "Overwrite existing project file " + window.getGlobalSettings().getCurrentFileName() + "?",
                "Overwrite existing project file",
                wx.SAVE|wx.CANCEL|wx.ICON_QUESTION)

    result = dlg.ShowModal()
    dlg.Destroy()

    if result == wx.ID_YES:
        save(window,currentFileName)
        return True
    elif result == wx.ID_SAVEAS:
        #TODO: do shit here
        return False
    elif result == wx.ID_NO:
        return False
    elif result == wx.ID_CANCEL:
        return False

elif window.getGlobalSettings().getCurrentFileName == "":
    #TODO: do shit here
    return False

else:
    save(window,window.getGlobalSettings().getCurrentFileName())
    return True

UPDATE

The code was successfully changed to:

def saveProject(window):

dlg = wx.FileDialog(window, "Save project as...", os.getcwd(), "", "*.kfxproject", \
                    wx.SAVE|wx.OVERWRITE_PROMPT)
result = dlg.ShowModal()
inFile = dlg.GetPath()
dlg.Destroy()

if result == wx.ID_OK:          #Save button was pressed
    save(window,inFile)
    return True
elif result == wx.ID_CANCEL:    #Either the cancel button was pressed or the window was closed
    return False

You're using the wrong dialog type. Use FileDialog instead:

It already includes the "prompt for a confirmation if a file will be overwritten" feature with wx.FD_OVERWRITE_PROMPT
That's what everyone else uses so users will expect this kind of dialog and be confused when they get something else

I couldn't find a way to replace "Save" with "Save as" in the dialog (it just has wx.FD_SAVE) but most people won't notice that.