audium 2.0.0

A terminal music app
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//! Shared list-navigation keymap. Every scrollable list routes cursor
//! movement through [`list_move`], so the keys behave the same everywhere.

use ratatui::crossterm::event::KeyCode;

/// Rows moved by `PageUp` / `PageDown`.
pub const PAGE: usize = 10;

/// Maps a navigation key to the new cursor index over a list of `len` items,
/// clamped to range. `None` for anything that is not navigation, so callers
/// fall through to their own bindings.
pub fn list_move(code: KeyCode, cursor: usize, len: usize) -> Option<usize> {
    let last = len.saturating_sub(1);
    let target = match code {
        KeyCode::Char('j') | KeyCode::Down => (cursor + 1).min(last),
        KeyCode::Char('k') | KeyCode::Up => cursor.saturating_sub(1),
        KeyCode::Char('g') | KeyCode::Home => 0,
        KeyCode::Char('G') | KeyCode::End => last,
        KeyCode::PageDown => (cursor + PAGE).min(last),
        KeyCode::PageUp => cursor.saturating_sub(PAGE),
        _ => return None,
    };
    Some(target)
}