//! The [`Animation`] trait and supporting types.
//!
//! An animation encapsulates a time-bounded visual effect: it advances via
//! [`update`](Animation::update), renders via [`draw`](Animation::draw), and
//! reports its layer, which [`InputMode`] is active while it runs
//! ([`input_mode_during`](Animation::input_mode_during)), and which mode to
//! enter when it finishes ([`input_mode_after`](Animation::input_mode_after)).
//! Most animations use the default `input_mode_during` ([`InputMode::Ignore`]),
//! but open animations may advertise an interactive mode so the overlay is
//! responsive before the animation completes.

use crate::input::InputMode;
use ratatui::buffer::Buffer;
use ratatui::layout::Rect;
use ratatui::widgets::Widget;

/// Which region of the terminal an animation occupies.
pub enum AnimationLayer {
    /// Renders in the inner board area, replacing the board (e.g. the wipe transition).
    Board,
    /// Renders over the full terminal area on top of the board (e.g. scroll open/close).
    Overlay,
}

/// A time-bounded visual effect managed by [`Ui`](crate::ui::Ui).
pub trait Animation {
    /// Advance the animation by `dt` seconds. Returns `true` when the animation is done.
    fn update(&mut self, dt: f32) -> bool;
    /// Draw the current animation frame into `area` on `buf`.
    fn draw(&self, area: Rect, buf: &mut Buffer);
    /// Which region this animation draws to (board area vs. full overlay).
    fn layer(&self) -> AnimationLayer;
    /// Which [`InputMode`] is active while this animation is running.
    /// Defaults to [`InputMode::Ignore`] (all input discarded).
    fn input_mode_during(&self) -> InputMode {
        InputMode::Ignore
    }
    /// Which [`InputMode`] to enter when the animation finishes.
    fn input_mode_after(&self) -> InputMode;
}

/// Wraps a `&dyn Animation` as a ratatui [`Widget`] so it can be passed to
/// `frame.render_widget`. The animation's [`draw`](Animation::draw) is called
/// with the area provided by the layout.
pub struct AnimWidget<'a>(pub &'a dyn Animation);

impl Widget for AnimWidget<'_> {
    fn render(self, area: Rect, buf: &mut Buffer) {
        self.0.draw(area, buf);
    }
}