/* Transitions.dev — Error state shake */

/*
  Usage:
    <!-- Apply .t-input-wrap to your wrapper, .t-input to the
         element that should shake (your input field, its
         bordered wrapper — whatever owns the visible border),
         and .t-error-msg to the message you want to reveal.
         Bring your own sizing, padding, border colors, and
         typography. -->
    <div class="t-input-wrap">
      <div class="t-input">
        <input type="text">
      </div>
      <p class="t-error-msg">Please enter a valid email.</p>
    </div>

  Trigger:
    - Add `.is-error` to .t-input-wrap and .t-input. Your
      own border-color rules drive the visible color; this
      stylesheet only owns the tween.
    - Restart the shake by removing `.is-shaking` from
      .t-input, forcing a reflow, then re-adding it.
    - Optional: after --revert-hold ms, drop both
      `.is-error` classes so border + message fade back
      to neutral over --revert-dur.

  Per-segment ease: each keyframe stop carries its own
  animation-timing-function so each leg follows the Figma
  cubic-bezier curve independently.
*/

:root {
  --shake-distance: 6px;
  --shake-overshoot: 4px;
  --shake-dur-a: 80ms;
  --shake-dur-b: 60ms;
  --shake-ease: cubic-bezier(0.22, 1, 0.36, 1);
  --revert-hold: 3000ms;
  --revert-dur: 280ms;
}

/* Border-color tween. Define your input's default / focused
   / error border-color in your own component CSS — this rule
   only owns the interpolation. Use a constant border-width
   across states so the tween never shifts inner content. */
.t-input {
  transition: border-color 150ms ease-out;
  will-change: transform;
}
.t-input:has(:user-invalid) {
  /* Error border auto-reverts on the hold timer, so the
     fade-out uses the slower revert duration (matches the
     message fade). */
  transition: border-color var(--revert-dur, 280ms) ease-out;
}

/* Error message reveal. Visibility is delayed by --revert-dur
   on hide so the message stays painted for the full opacity
   fade-out. Entering .is-error drops the delay to 0 so the
   message becomes visible immediately. */
.t-error-msg {
  opacity: 0;
  visibility: hidden;
  transition:
    opacity    var(--revert-dur, 280ms) ease-out,
    visibility 0s linear var(--revert-dur, 280ms);
}
.t-input-wrap:has(:user-invalid) .t-error-msg {
  opacity: 1;
  visibility: visible;
  transition:
    opacity    var(--revert-dur, 280ms) ease-out,
    visibility 0s linear 0s;
}

/* Multi-segment keyframe with per-stop easing so each leg
   of the shake follows its own cubic-bezier independently.
   %-stops are cumulative durations as a fraction of the
   total (80, 60, 80, 60 = 280ms): 28.57%, 57.14%, 78.57%,
   100%. Recompute if any segment duration changes. */
.t-input:has(:user-invalid) {
  animation: t-input-shake calc(
      var(--shake-dur-a) * 2 + var(--shake-dur-b) * 2
    ) linear;
}
@keyframes t-input-shake {
  0%      { transform: translateX(0);                                 animation-timing-function: var(--shake-ease); }
  28.57%  { transform: translateX(var(--shake-distance));             animation-timing-function: var(--shake-ease); }
  57.14%  { transform: translateX(calc(var(--shake-distance) * -1)); animation-timing-function: var(--shake-ease); }
  78.57%  { transform: translateX(var(--shake-overshoot));            animation-timing-function: var(--shake-ease); }
  100%    { transform: translateX(0); }
}

@media (prefers-reduced-motion: reduce) {
  .t-input { animation: none !important; transform: none !important; }
}