class CustomAction(GenericAction):
    """
    The CustomAction exception is raised when the user presses a key
    that is mapped to the "custom" action.

    Args:
        action: action
        selected_item: selected item, if any
        ch: pressed key
        line: user input

    Attributes:
        action: action
        selected_item: selected item, if any
        ch: pressed key
        line: user input
    """

    def __init__(self, action: str, ch: Optional[str], selected_item: Any = None, line: Optional[str] = None):
        super().__init__(action, ch, selected_item, line)

class Finder(ActionsHandler):
    def __init__(
        self,
        candidates: Union[Callable[[], Sequence[Any]], Iterator[Any], Sequence[Any]],
        fullscreen: bool = True,
        height: Optional[int] = None,
        format_fn: Callable[[Any], str] = lambda x: str(x),
        layout: Union[Type[Layout], str] = DEFAULT_LAYOUT,
        info_style: Union[InfoStyle, str] = InfoStyle.DEFAULT,
        pointer_str: str = DEFAULT_POINTER,
        prompt_str: str = DEFAULT_PROMPT,
        header_str: str = DEFAULT_HEADER,
        keys_binding: Optional[KeysBinding] = None,
        matcher: Union[Matcher, Type[Matcher], str] = DEFAULT_MATCHER,
        lazy: bool = False,
        output_stream: TextIO = sys.stderr,
    ):
        """
        Initializate Finder object

        Args:
            candidates: Candidates
            fullscreen: Full screen mode
            height: Finder window height
            format_fn: Items format function
            layout: Finder layout
            info_style: Determines the display style of finder info
            pointer_str: Pointer to the current line
            prompt_str: Input prompt
            header_str: Header
            keys_binding: Custom keys binding
            matcher: Matcher
            lazy: Lazy mode, starts the finder only if the candidates are more than one
            output_stream: Output stream
        """
        super().__init__(keys_binding=keys_binding)
        self.config = Config(fullscreen, height, format_fn, info_style, pointer_str, prompt_str, header_str, lazy, output_stream)
        self.candidates = Candidates(candidates=candidates, format_fn=format_fn, matcher=matcher)
        self.layout: Layout = get_layout(layout=layout, config=self.config, candidates=self.candidates)

    def setup(self, input: Optional[str] = None) -> None:
        """
        Setup Finder execution

        Args:
            input: initial search string
        """
        self.line_editor = LineEditor(line=input or "", keys_handler=self.keys_handler)
        # Load the candidate list
        self.refresh_candidates()
        # Filter the items, calculate the screen offset
        self.apply_filter()
        # If lazy mode is enabled, starts the finder only if the candidates are more than one
        if self.config.lazy and self.candidates.matching_candidates_len <= 1:
            raise AcceptAction(action="lazy-accept", ch=None, selected_item=self.prepare_result(), line=self.line_editor.line)
        # Calculate the required height and setup the screen
        self.layout.screen_setup(self.line_editor)

    def show(self, input: Optional[str] = None) -> Any:
        """
        Open pzp and return the selected element

        Args:
            input: initial search string

        Raises:
            AcceptAction: Raises when the user presses a key that is mapped to the "accept" action.
            AbortAction: Raises when the user presses a key that is mapped to the "abort" action.
            CustomAction: Raises when the user presses a key that is mapped to the "custom" action.
        """
        try:
            self.setup(input=input)
            while True:
                self.process_key()
                self.apply_filter()
                self.update_screen()
        finally:
            self.layout.cleanup()

    def refresh_candidates(self) -> None:
        "Load/reload the candidate list"
        self.candidates.refresh_candidates()
        self.selected: int = 0

    def process_key(self, ch: Optional[str] = None) -> None:
        "Process the pressed key"
        key_event = self.keys_handler.get_key_event(ch)
        try:
            self.line_editor.process_key_event(key_event)
        except MissingHander:
            try:
                self.process_key_event(key_event)
            except MissingHander:
                raise CustomAction(action=key_event.action, ch=key_event.ch, selected_item=self.prepare_result(), line=self.line_editor.line)  # type: ignore

    def apply_filter(self) -> None:
        "Filter the items"
        self.candidates.apply_filter(pattern=str(self.line_editor))
        self.selected = max(min(self.selected, self.candidates.matching_candidates_len - 1), 0)

    def update_screen(self) -> None:
        "Update the screen - erase the old items, print the filtered items and the prompt"
        self.layout.update_screen(selected=self.selected)

    def prepare_result(self) -> Any:
        "Output the selected item, if any"
        try:
            return self.candidates.matching_candidates[self.selected]
        except IndexError:
            return None

    @Action("accept", keys=["enter"])
    def accept(self, key_event: KeyEvent) -> None:
        "Confirm"
        raise AcceptAction(action="accept", ch=key_event.ch, selected_item=self.prepare_result(), line=self.line_editor.line)

    @Action("abort", keys=["ctrl-c", "ctrl-g", "ctrl-q", "esc"])
    def abort(self, key_event: KeyEvent) -> None:
        "Cancel"
        raise AbortAction(action="abort", ch=key_event.ch, line=self.line_editor.line)

    @Action("down", keys=["ctrl-j", "ctrl-n", "down"])
    def down(self) -> None:
        "Move one line down"
        self.selected = self.layout.move_selection(self.selected, lines=-1)

    @Action("up", keys=["ctrl-k", "ctrl-p", "up"])
    def up(self) -> None:
        "Move one line up"
        self.selected = self.layout.move_selection(self.selected, lines=+1)

    @Action("page-down", keys=["page-down", "pgdn"])
    def page_down(self) -> None:
        "Move one page down"
        self.selected = self.layout.move_selection(self.selected, pages=-1)

    @Action("page-up", keys=["page-up", "pgup"])
    def page_up(self) -> None:
        "Move one page up"
        self.selected = self.layout.move_selection(self.selected, pages=+1)

    @Action("ignore", keys=["null", "insert"])
    def ignore(self) -> None:
        "Do nothing"
        pass

class GenericAction(PZPException):
    """
    Generic Action Event

    Args:
        action: action
        ch: pressed key
        selected_item: selected item, if any
        line: user input

    Attributes:
        action: action
        ch: pressed key
        selected_item: selected item, if any
        line: user input
    """

    def __init__(self, action: str, ch: Optional[str], selected_item: Any = None, line: Optional[str] = None):
        super().__init__(action)
        self.action = action
        self.ch = ch
        self.selected_item = selected_item
        self.line = line