use std::convert::TryFrom;use std::time::Duration;use std::time::Instant;use rand::Rng as _;use crate::frames::ALL_VARIANTS;use crate::frames::FRAME_TICK_DEFAULT;use crate::tui::FrameRequester;/// Drives ASCII art animations shared across popups and onboarding widgets.pub(crate) struct AsciiAnimation {    request_frame: FrameRequester,    variants: &'static [&'static [&'static str]],    variant_idx: usize,    frame_tick: Duration,    start: Instant,}impl AsciiAnimation {    pub(crate) fn new(request_frame: FrameRequester) -> Self {        Self::with_variants(request_frame, ALL_VARIANTS, /*variant_idx*/ 0)    }    pub(crate) fn with_variants(        request_frame: FrameRequester,        variants: &'static [&'static [&'static str]],        variant_idx: usize,    ) -> Self {        assert!(            !variants.is_empty(),            "AsciiAnimation requires at least one animation variant",        );        let clamped_idx = variant_idx.min(variants.len() - 1);        Self {            request_frame,            variants,            variant_idx: clamped_idx,            frame_tick: FRAME_TICK_DEFAULT,            start: Instant::now(),        }    }    pub(crate) fn schedule_next_frame(&self) {        let tick_ms = self.frame_tick.as_millis();        if tick_ms == 0 {            self.request_frame.schedule_frame();            return;        }        let elapsed_ms = self.start.elapsed().as_millis();        let rem_ms = elapsed_ms % tick_ms;        let delay_ms = if rem_ms == 0 {            tick_ms        } else {            tick_ms - rem_ms        };        if let Ok(delay_ms_u64) = u64::try_from(delay_ms) {            self.request_frame                .schedule_frame_in(Duration::from_millis(delay_ms_u64));        } else {            self.request_frame.schedule_frame();        }    }    pub(crate) fn current_frame(&self) -> &'static str {        let frames = self.frames();        if frames.is_empty() {            return "";        }        let tick_ms = self.frame_tick.as_millis();        if tick_ms == 0 {            return frames[0];        }        let elapsed_ms = self.start.elapsed().as_millis();        let idx = ((elapsed_ms / tick_ms) % frames.len() as u128) as usize;        frames[idx]    }    pub(crate) fn pick_random_variant(&mut self) -> bool {        if self.variants.len() <= 1 {            return false;        }        let mut rng = rand::rng();        let mut next = self.variant_idx;        while next == self.variant_idx {            next = rng.random_range(0..self.variants.len());        }        self.variant_idx = next;        self.request_frame.schedule_frame();        true    }    fn frames(&self) -> &'static [&'static str] {        self.variants[self.variant_idx]    }}#[cfg(test)]mod tests {    use super::*;    #[test]    fn frame_tick_must_be_nonzero() {        assert!(FRAME_TICK_DEFAULT.as_millis() > 0);    }}