@use '../config' as *;

// A highlight that sweeps across the text, for "Thinking…" or "Generating…" labels
.text-shimmer {
  // scss-docs-start text-shimmer-css-vars
  --text-shimmer-duration: #{$text-shimmer-duration};
  --text-shimmer-opacity: #{$text-shimmer-opacity};
  --text-shimmer-width: #{$text-shimmer-width};
  --text-shimmer-fade-duration: #{$text-shimmer-fade-duration};
  --text-shimmer-fade-easing: #{$text-shimmer-fade-easing};
  --text-shimmer-loader-size: #{$text-shimmer-loader-size};
  --text-shimmer-loader-border-width: #{$text-shimmer-loader-border-width};
  --text-shimmer-loader-margin: #{$text-shimmer-loader-margin};
  --text-shimmer-loader-duration: #{$text-shimmer-loader-duration};
  --text-shimmer-loader-opacity: #{$text-shimmer-loader-opacity};
  // scss-docs-end text-shimmer-css-vars
  display: inline-block;
  // The mask dims the text and lets a band of full opacity move through it, so the text keeps its own color
  mask-image: linear-gradient(90deg, rgba(0, 0, 0, var(--text-shimmer-opacity)) calc(50% - var(--text-shimmer-width) / 2), $black 50%, rgba(0, 0, 0, var(--text-shimmer-opacity)) calc(50% + var(--text-shimmer-width) / 2));
  mask-size: 300% 100%;
  // The label fades in once, then the highlight keeps sweeping
  animation:
    text-shimmer-in var(--text-shimmer-fade-duration) var(--text-shimmer-fade-easing) both,
    text-shimmer var(--text-shimmer-duration) linear infinite;

  @media (prefers-reduced-motion: reduce) {
    mask-image: none;
    animation: none;
  }
}

// A small spinner before the label: the element is a 1em box, ::before draws
// a faint ring in the text color and ::after the bright arc that turns on top
// of it. It sits inside the mask, so it dims and lights up with the text
.text-shimmer-loader {
  position: relative;
  display: inline-block;
  width: 1em;
  height: 1em;
  margin-inline-end: var(--text-shimmer-loader-margin);
  vertical-align: -0.125em;

  // The ring is --text-shimmer-loader-size wide, centered in the 1em box
  &::before,
  &::after {
    position: absolute;
    inset: 0;
    width: var(--text-shimmer-loader-size);
    height: var(--text-shimmer-loader-size);
    margin: auto;
    content: '';
    border: var(--text-shimmer-loader-border-width) solid;
    border-radius: 50%;
  }

  &::before {
    border-color: currentColor;
    opacity: var(--text-shimmer-loader-opacity);
  }

  &::after {
    border-color: currentColor transparent transparent;
    animation: rotate-360 var(--text-shimmer-loader-duration) linear infinite;

    @media (prefers-reduced-motion: reduce) {
      animation-duration: calc(var(--text-shimmer-loader-duration) * 2);
    }
  }
}

@keyframes text-shimmer-in {
  from {
    opacity: 0;
  }

  to {
    opacity: 1;
  }
}

// The highlight travels in the reading direction: --dir flips the start and end in RTL
@keyframes text-shimmer {
  from {
    /* rtl:ignore */
    mask-position: calc(50% + var(--dir) * 50%) 0;
  }

  to {
    /* rtl:ignore */
    mask-position: calc(50% - var(--dir) * 50%) 0;
  }
}