import lib.screenful as screenful

class Update:
    def __init__(self):
        self.model = None
        self.view = None

    def update_model(self, msg):
        # check if completely no action needed
        if msg.no_action():
            return

        # by default, no need to redraw entry
        entry_redraw = False

        # check if we need to signal the data change
        if msg.data_change():
            screenful.changed()
            entry_redraw = True

        # redraw of view can happen even if no data changed
        entry_redraw |= msg.entry_redraw()

        # check if we need to reset the model
        reset = msg.reset()

        if reset:
            self.model.pre_reset()

        # actually run the update_model
        msg.update_model(self.model)
        msg.clear_args()

        # post reset comes now
        if reset:
            self.model.post_reset()

        self.view.view(self.model, entry_redraw)

    def set_model(self, model):
        self.model = model

    def set_view(self, view):
        self.view = view


update = Update()