-- | Initializes a window based on the cell counts and cell sizes, storing the
-- window into the state. The window's context will be bound as the current ogl
-- context, and the viewport will be sized to the window's framebuffer. If we
-- can't create a window the program dies. If we create a window but it's not
-- the size we expect then a warning is printed but we proceed anyway.
initWindow :: Hexes ()
initWindow = do
    (rows,cols) <- getRowColCount
    (cWidth, cHeight) <- getCellWidthHeight
    let fbWidth = cols * cWidth
        fbHeight = rows * cHeight
    mWin <- liftIO $ GLFW.createWindow fbWidth fbHeight "" Nothing Nothing
    window <- liftIO $ case mWin of
        Nothing -> error "FATAL: Could Not Create A Window!" -- FIXME a real exception
        Just window -> return window
    Hexes $ modify (\s -> s {window = window})
    liftIO $ GLFW.makeContextCurrent (Just window)
    (fbx,fby) <- liftIO $ GLFW.getFramebufferSize window
    when ((fbx,fby) /= (fbWidth,fbHeight)) (liftIO $ do
        putStrLn $ "WARNING: Framebuffer obtained was the incorrect size."
        putStrLn $ "WARNING: Requested: " ++ show (fbWidth,fbHeight) ++ ", Actual:" ++ show (fbx,fby))
    glViewport 0 0 (fromIntegral fbx) (fromIntegral fby)
    glClearColor 0.2 0.3 0.3 1.0
    -- TODO: Add a framebuffer size change callback to keep our viewport correct?