/**
 * iNKPPL Design System — .ds-sheet primitive
 * Bottom-sheet modal pattern (drag handle + header + scrollable body + sticky footer).
 *
 * SPEC: docs/specs/.1-impl.md §20 (Founder decision B5, 2026-05-11)
 * Pairs with: inked/assets/js/design-system/ds-sheet.js
 * Initial consumer: Afisha v2.1 mobile calendar + mobile filter rail.
 * retrofit candidate: tattoos-v2 / studios-v2 .filter-panel.
 *
 * Anatomy (§20.2):
 *   .ds-sheet (host, role=dialog, hidden by default)
 *     .ds-sheet__backdrop  (full-screen scrim, click closes)
 *     .ds-sheet__panel     (bottom-anchored card)
 *       .ds-sheet__handle  (drag affordance, swipe-down closes)
 *       .ds-sheet__header  (title + close ✕)
 *       .ds-sheet__body    (scrollable content)
 *       .ds-sheet__footer  (sticky action bar, optional)
 *
 * Tokens-only (no hardcoded values). Dark theme default + light theme override.
 * Respects prefers-reduced-motion (no slide animation).
 */

/* ============================================================================
   Host — fixed full-viewport overlay container
   ============================================================================ */
.ds-sheet {
  position: fixed;
  inset: 0;
  z-index: var(--z-modal);
  display: block;
}
.ds-sheet[hidden] {
  display: none;
}

/* ============================================================================
   Backdrop — full-screen scrim, click closes
   ============================================================================ */
.ds-sheet__backdrop {
  position: absolute;
  inset: 0;
  background: var(--color-overlay-scrim-light);
  opacity: 0;
  animation: ds-sheet-backdrop-in var(--transition-normal) var(--ease-standard) forwards;
  cursor: pointer;
}

@keyframes ds-sheet-backdrop-in {
  from { opacity: 0; }
  to   { opacity: 1; }
}

/* ============================================================================
   Panel — bottom-anchored card
   ============================================================================ */
.ds-sheet__panel {
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  display: flex;
  flex-direction: column;
  max-height: 90vh;
  background: var(--color-bg-elevated);
  border-top-left-radius: var(--radius-lg);
  border-top-right-radius: var(--radius-lg);
  box-shadow: var(--shadow-xl);
  transform: translateY(100%);
  animation: ds-sheet-slide-in var(--transition-normal) var(--ease-standard) forwards;
  /* iOS safe-area for bottom inset */
  padding-bottom: env(safe-area-inset-bottom, 0);
}

@keyframes ds-sheet-slide-in {
  from { transform: translateY(100%); }
  to   { transform: translateY(0); }
}

/* Desktop ≥640px — center the panel with max-width, keep bottom-anchored */
@media (min-width: 640px) {
  .ds-sheet__panel {
    left: 50%;
    right: auto;
    max-width: 560px;
    width: 100%;
    transform: translate(-50%, 100%);
    animation: ds-sheet-slide-in-desktop var(--transition-normal) var(--ease-standard) forwards;
  }
  @keyframes ds-sheet-slide-in-desktop {
    from { transform: translate(-50%, 100%); }
    to   { transform: translate(-50%, 0); }
  }
}

/* ============================================================================
   Drag handle — small hairline pill, indicates swipe affordance
   ============================================================================ */
.ds-sheet__handle {
  display: block;
  width: 40px;
  height: 4px;
  margin: var(--space-2) auto var(--space-1);
  padding: 0;
  border: none;
  border-radius: var(--radius-full);
  background: var(--color-border-hover);
  cursor: grab;
  flex-shrink: 0;
  /* Larger touch target via padding-bottom (hit-area extends downward) */
  position: relative;
}
.ds-sheet__handle::before {
  content: '';
  position: absolute;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
  width: 64px;
  height: 44px; /* 44px touch target */
}
.ds-sheet__handle:active {
  cursor: grabbing;
}

/* ============================================================================
   Header — title + close button + hairline bottom rule
   ============================================================================ */
.ds-sheet__header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
  padding: var(--space-3) var(--space-4) var(--space-3);
  border-bottom: 1px solid var(--color-border);
  flex-shrink: 0;
}
.ds-sheet__title {
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--text-2xs);
  font-weight: var(--font-weight-semibold);
  text-transform: uppercase;
  letter-spacing: var(--letter-spacing-caps);
  color: var(--color-text);
  line-height: 1.4;
}
.ds-sheet__close {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  margin: calc(var(--space-2) * -1) calc(var(--space-2) * -1) calc(var(--space-2) * -1) 0;
  padding: 0;
  border: none;
  background: transparent;
  color: var(--color-text-secondary);
  font-size: var(--text-base);
  line-height: 1;
  cursor: pointer;
  border-radius: var(--radius-md);
  transition: color var(--transition-fast), background-color var(--transition-fast);
}
.ds-sheet__close:hover {
  color: var(--color-text);
  background: var(--color-bg-hover);
}
.ds-sheet__close:focus-visible {
  outline: 2px solid var(--color-brand-accent);
  outline-offset: 2px;
}

/* ============================================================================
   Body — scrollable content area
   ============================================================================ */
.ds-sheet__body {
  flex: 1 1 auto;
  overflow-y: auto;
  overflow-x: hidden;
  padding: var(--space-4);
  /* Smoother iOS scroll */
  -webkit-overflow-scrolling: touch;
  overscroll-behavior: contain;
}

/* ============================================================================
   Footer — sticky action bar (optional)
   ============================================================================ */
.ds-sheet__footer {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: var(--space-2);
  padding: var(--space-3) var(--space-4);
  border-top: 1px solid var(--color-border);
  background: var(--color-bg-elevated);
  flex-shrink: 0;
}
.ds-sheet__footer:empty {
  display: none;
}

/* ============================================================================
   Light theme — uses [data-theme="light"] OR :root.light-theme convention.
   Project's tokens already swap surfaces in dark/light; this section pins a
   couple of overrides that need explicit handling.
   ============================================================================ */
[data-theme="light"] .ds-sheet__panel,
:root.light-theme .ds-sheet__panel {
  background: var(--color-bg-card);
}
[data-theme="light"] .ds-sheet__footer,
:root.light-theme .ds-sheet__footer {
  background: var(--color-bg-card);
}

/* ============================================================================
   Reduced motion — skip slide and fade animations
   ============================================================================ */
@media (prefers-reduced-motion: reduce) {
  .ds-sheet__backdrop {
    animation: none;
    opacity: 1;
  }
  .ds-sheet__panel {
    animation: none;
    transform: translateY(0);
  }
  @media (min-width: 640px) {
    .ds-sheet__panel {
      animation: none;
      transform: translate(-50%, 0);
    }
  }
}