from asciimatics.exceptions import NextScene
from asciimatics.widgets import Frame, Layout, Divider, Button, Label


class CeoFrame(Frame):
    def __init__(
        self,
        screen,
        height,
        width,
        model,
        name,  # key in model.viewdata
        on_load=None,
        title=None,
        save_data=False,  # whether to save widget state for resizing
    ):
        super().__init__(
            screen,
            height,
            width,
            name=name,
            can_scroll=False,
            title=title,
            on_load=self._ceoframe_on_load,
        )
        self._save_data = save_data
        self._extra_on_load = on_load
        self._model = model
        self._name = name
        self._loaded = False

    def _ceoframe_on_load(self):
        # We usually don't want _on_load() to be called multiple times
        # e.g. when switching back to a scene, or after calling reset()
        if self._loaded:
            return
        self._loaded = True
        if self._model.title is not None:
            self.title = self._model.title
            self._model.title = None
        if self._save_data:
            # restore the saved input fields' values
            self.data = self._model.viewdata[self._name]
        if self._extra_on_load is not None:
            self._extra_on_load()

    def _on_unload(self):
        if not self._save_data:
            return
        # save the input fields' values so that they don't disappear when
        # the window gets resized
        self.save()
        self._model.viewdata[self._name] = self.data

    def add_buttons(
        self, back_btn=False, back_btn_text='Back',
        next_scene=None, next_btn_text='Next', on_next=None,
        on_next_excl=None,
    ):
        """
        Add a new layout at the bottom of the frame with buttons.
        If back_btn is True, a Back button is added.
        If next_scene is set to the name of the next scene, or on_next_excl
        is set, a Next button will be added.
        If on_next is set to a function, it will be called when the Next
        button is pressed, and the screen will switch to the next scene.
        If on_next_excl is set to a function, it will be called when the Next
        button is pressed, and the scene will not be switched.
        If both on_next and on_next_excl are set, on_next will be ignored.
        """
        layout = Layout([100])
        self.add_layout(layout)
        layout.add_widget(Divider())

        def _back():
            raise NextScene(self._model.scene_stack.pop())

        def _next():
            if on_next_excl is not None:
                on_next_excl()
                return
            if on_next is not None:
                on_next()
            self.go_to_next_scene(next_scene)

        layout = Layout([1, 1])
        self.add_layout(layout)
        if back_btn:
            layout.add_widget(Button(back_btn_text, _back), 0)
        if next_scene is not None or on_next_excl is not None:
            layout.add_widget(Button(next_btn_text, _next), 1)

    def go_to_next_scene(self, next_scene: str):
        self._model.scene_stack.append(self._name)
        raise NextScene(next_scene)

    def add_flash_message_layout(self):
        layout = Layout([100])
        self.add_layout(layout)
        self._status_label = Label('')
        layout.add_widget(self._status_label)
        
    def flash_message(self, msg: str, force_update: bool = False):
        self._status_label.text = msg
        if force_update:
            self._model.screen.force_update()
            self._model.screen.draw_next_frame()

    def clear_flash_message(self):
        self.flash_message('')