/*
 * Split buttons: shapes that depend on a button's place beside its other half. Button groups and
 * `<x-group>` draw theirs from resources/css/components/button-group.css.
 *
 * Unlayered on purpose, until the split button leaves Tailwind too.
 *
 * Split button (`<x-split-button>`): two halves on their own corner scale — SplitButton*Tokens
 * gives the inner corner 4/4/4/8/12px at rest and *grows* it to 8/12/12/20/20px under the finger,
 * the opposite of a connected group. The trailing half turns round and its chevron turns over
 * while its menu is open, on M3's standard scheme rather than the expressive springs (the site:
 * "the trailing button uses the standard motion scheme, not expressive, when rotating"), and the
 * chevron sits a little towards the leading half so the pair reads as one control
 * (`--split-nudge`: 1/1/2/3/6px). `--split-icon` is the trailing icon's own size,
 * 22/22/26/38/50px, which the icon-button table does not know about.
 *
 * "Full" here is half the size's height (`--group-full`), never `--md-sys-shape-corner-full`'s
 * 9999px: when a box's radii add up to more than its side, CSS scales every radius by the same
 * factor, and a 9999px corner beside an 8px one drew the inner corners square.
 */

[data-button-group] {
    --group-full: 1.25rem;
    --group-outer: var(--group-full);
}

[data-button-group][data-size='xs'] { --group-full: 1rem; }
[data-button-group][data-size='md'] { --group-full: 1.75rem; }
[data-button-group][data-size='lg'] { --group-full: 3rem; }
[data-button-group][data-size='xl'] { --group-full: 4.25rem; }

[data-button-group='split'] { --split-inner: var(--md-sys-shape-corner-xs); --split-inner-pressed: var(--md-sys-shape-corner-md); --split-icon: 22px; --split-nudge: 1px; }
[data-button-group='split'][data-size='xs'] { --split-inner-pressed: var(--md-sys-shape-corner-sm); }
[data-button-group='split'][data-size='md'] { --split-icon: 26px; --split-nudge: 2px; }
[data-button-group='split'][data-size='lg'] { --split-inner: var(--md-sys-shape-corner-sm); --split-inner-pressed: var(--md-sys-shape-corner-lg-increased); --split-icon: 38px; --split-nudge: 3px; }
[data-button-group='split'][data-size='xl'] { --split-inner: var(--md-sys-shape-corner-md); --split-inner-pressed: var(--md-sys-shape-corner-lg-increased); --split-icon: 50px; --split-nudge: 6px; }

/* The halves take their inner corner from `--group-corner`, so pressing changes one variable and
   the rounded outer corners stay put. */
[data-split] {
    --group-corner: var(--split-inner);

    border-start-start-radius: var(--group-corner);
    border-end-start-radius: var(--group-corner);
    border-start-end-radius: var(--group-corner);
    border-end-end-radius: var(--group-corner);
}

[data-split]:active {
    --group-corner: var(--split-inner-pressed);
}

[data-split='trailing'][aria-expanded='true'] {
    --group-corner: var(--group-full);
}

[data-split='leading'] {
    border-start-start-radius: var(--group-outer);
    border-end-start-radius: var(--group-outer);
}

[data-split='trailing'] {
    border-start-end-radius: var(--group-outer);
    border-end-end-radius: var(--group-outer);
}

/*
 * The trailing chevron: its own size, and `--split-nudge` off centre towards the leading half —
 * equal and opposite margins move it by exactly that much inside a centred flex row, in whichever
 * direction the writing mode runs.
 */
[data-split='trailing'] svg {
    width: var(--split-icon);
    height: var(--split-icon);
    margin-inline-start: calc(-1 * var(--split-nudge));
    margin-inline-end: var(--split-nudge);
    transition: rotate var(--md-sys-motion-duration-short) var(--md-sys-motion-easing-standard);
}

[data-split='trailing'][aria-expanded='true'] svg {
    rotate: 180deg;
}