/*
 * Shimti Multimedia - slideshow gallery
 *
 * The track is a real horizontally scrolling element with CSS scroll snapping, not a
 * stack of absolutely positioned slides toggled by a class. That choice carries the
 * whole component:
 *
 *   - touch swiping, trackpad swiping and shift-scroll are the browser's own, so no
 *     pointer/drag handling is written here at all. WCAG 2.2 SC 2.5.7 asks that nothing
 *     depend on a dragging movement, and nothing does - the buttons do everything.
 *   - with scripting off the strip still scrolls and every photograph is still reachable,
 *     so the gallery degrades to a scrollable filmstrip rather than to a single frozen
 *     image with four unreachable ones behind it.
 *   - the browser owns the scroll position, so "which slide is showing" is observed
 *     rather than remembered, and the two can never disagree.
 *
 * The controls are hidden until the script marks the gallery ready, because a Pause
 * button with no slideshow behind it is worse than no button.
 */

.gallery {
  margin: 2rem 0 2.5rem;
}

.gallery-track {
  display: flex;
  gap: 0;
  overflow-x: auto;
  scroll-snap-type: x mandatory;
  scroll-behavior: smooth;
  /* The track is the scroll container, so it must not also bounce the sheet behind it. */
  overscroll-behavior-x: contain;
  border-radius: 4px;
  border: 1px solid var(--border-color);
  background: var(--panel-bg);
  margin: 0;
  padding: 0;
  list-style: none;
}

/* The scrollbar is noise under a set of photographs that carry their own position
   indicator; the dots and the counter say where you are. */
.gallery-track {
  scrollbar-width: none;
}

.gallery-track::-webkit-scrollbar {
  display: none;
}

.gallery-slide {
  flex: 0 0 100%;
  scroll-snap-align: center;
  /* Without this a snap target can be scrolled past when the user flicks hard, which
     lands the track between two slides and leaves the dots pointing at neither. */
  scroll-snap-stop: always;
  min-width: 0;
  margin: 0;
}

.gallery-slide img {
  display: block;
  width: 100%;
  height: auto;
  /* Declared in the markup too, but repeated here so the box is reserved even if the
     attributes are ever dropped - a gallery that grows by 400px on load moves the
     paragraph the visitor is reading. */
  aspect-ratio: 1376 / 768;
  object-fit: cover;
}

/* Hidden until the script says the behaviour behind them exists. */
.gallery-controls {
  display: none;
}

.gallery[data-ready] .gallery-controls {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-top: 0.85rem;
}

/*
 * Every control is at least 24x24 CSS pixels of pointer target (WCAG 2.2 SC 2.5.8),
 * including the dots - which are drawn small but padded out to a full target.
 */
.gallery-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 2.25rem;
  height: 2.25rem;
  flex: none;
  padding: 0;
  border: 1px solid var(--border-color);
  border-radius: 4px;
  background: #ffffff;
  color: var(--accent);
  cursor: pointer;
}

.gallery-button:hover {
  background: var(--panel-bg);
}

.gallery-button svg {
  width: 1.1rem;
  height: 1.1rem;
  fill: currentColor;
  pointer-events: none;
}

/* One icon per state, swapped by the button's own pressed state rather than by the
   script rewriting markup - the script sets one attribute and the CSS does the rest. */
.gallery-play .gallery-icon-play {
  display: none;
}

.gallery-play[aria-pressed="false"] .gallery-icon-play {
  display: block;
}

.gallery-play[aria-pressed="false"] .gallery-icon-pause {
  display: none;
}

.gallery-dots {
  display: flex;
  align-items: center;
  gap: 0.15rem;
  margin: 0 auto 0 0.25rem;
  padding: 0;
  list-style: none;
}

.gallery-dot {
  display: block;
  width: 1.5rem;
  height: 1.5rem;
  padding: 0;
  border: 0;
  background: none;
  cursor: pointer;
  /* The visible dot is the pseudo-element; the button around it is the target. */
  position: relative;
}

.gallery-dot::before {
  content: "";
  position: absolute;
  inset: 50% auto auto 50%;
  translate: -50% -50%;
  width: 0.5rem;
  height: 0.5rem;
  border-radius: 50%;
  background: var(--border-color);
}

.gallery-dot[aria-current="true"]::before {
  background: var(--accent);
  width: 0.65rem;
  height: 0.65rem;
}

.gallery-count {
  font-size: 0.85rem;
  font-variant-numeric: tabular-nums;
  color: var(--muted-color);
  flex: none;
}

/*
 * Reduce-motion.
 *
 * The site-wide rule at the end of section.css flattens animations and transitions, but
 * smooth scrolling is neither, so it has to be turned off by name. The script separately
 * declines to start the slideshow at all under the same preference - the two together
 * mean nothing in this component moves unless the visitor asks it to.
 */
@media (prefers-reduced-motion: reduce) {
  .gallery-track {
    scroll-behavior: auto;
  }
}

/*
 * Stacked transitions: fade and flip.
 *
 * Both take the slides out of the row and pile them in one place, so the track stops
 * being a scroller. Scroll snapping is switched off with them - leaving it on would let a
 * trackpad drag the stack sideways underneath the animation.
 */
[data-transition="fade"] .gallery-track,
[data-transition="flip"] .gallery-track {
  display: block;
  position: relative;
  overflow: hidden;
  scroll-snap-type: none;
}

[data-transition="fade"] .gallery-slide,
[data-transition="flip"] .gallery-slide {
  position: absolute;
  inset: 0;
  width: 100%;
}

/* --- fade ------------------------------------------------------------------------- */

[data-transition="fade"] .gallery-slide {
  opacity: 0;
  transition: opacity 520ms ease;
  pointer-events: none;
  z-index: 0;
}

[data-transition="fade"] .gallery-slide.is-current {
  opacity: 1;
  pointer-events: auto;
  z-index: 2;
}

/* The outgoing frame stays lit underneath for the length of the crossfade, so the two
   pictures dissolve into one another rather than both dimming through the paper. */
[data-transition="fade"] .gallery-slide.is-leaving {
  opacity: 0;
  z-index: 1;
}

/* --- flip ------------------------------------------------------------------------- */

/*
 * A page turn. The track is given depth and each slide is a leaf hinged on its left edge,
 * so the outgoing frame swings away from the spine like a comic being read.
 *
 * backface-visibility hides the reverse of the leaf mid-turn; without it the image shows
 * through mirrored, which reads as a glitch rather than as paper.
 */
[data-transition="flip"] .gallery-track {
  perspective: 1600px;
}

[data-transition="flip"] .gallery-slide {
  transform-origin: left center;
  transform: rotateY(-105deg);
  backface-visibility: hidden;
  opacity: 0;
  transition: transform 620ms cubic-bezier(0.4, 0.05, 0.2, 1), opacity 200ms ease 120ms;
  pointer-events: none;
  z-index: 0;
}

[data-transition="flip"] .gallery-slide.is-current {
  transform: rotateY(0deg);
  opacity: 1;
  pointer-events: auto;
  z-index: 2;
}

[data-transition="flip"] .gallery-slide.is-leaving {
  transform: rotateY(-105deg);
  opacity: 1;
  z-index: 3;
  transition: transform 620ms cubic-bezier(0.4, 0.05, 0.2, 1), opacity 200ms ease 420ms;
}

/* Going backwards, the leaf comes back from the same side it left by. */
[data-transition="flip"] .gallery-slide.is-reverse.is-current {
  transform: rotateY(0deg);
}

/* A spine, so the hinge has something to turn on. */
[data-transition="flip"] .gallery-track::after {
  content: "";
  position: absolute;
  inset: 0 auto 0 0;
  width: 3px;
  background: linear-gradient(to right, rgba(16, 21, 28, 0.35), rgba(16, 21, 28, 0));
  z-index: 4;
  pointer-events: none;
}

/*
 * Under reduce-motion both become a plain cut. The site-wide rule already collapses the
 * durations; these turn off the transform as well, so nothing swings at 0.01ms either.
 */
@media (prefers-reduced-motion: reduce) {
  [data-transition="flip"] .gallery-slide {
    transform: none;
  }

  [data-transition="flip"] .gallery-slide:not(.is-current) {
    opacity: 0;
  }
}