/**
 * UI Transitions and Loading States
 * 
 * Provides consistent animation and loading patterns across the application.
 * Respects prefers-reduced-motion for accessibility.
 */

/* ============================================
   Base Transition Tokens
   ============================================ */
:root {
    --transition-fast: 100ms;
    --transition-normal: 150ms;
    --transition-slow: 250ms;
    --transition-very-slow: 400ms;
    
    --easing-default: cubic-bezier(0.4, 0, 0.2, 1);
    --easing-in: cubic-bezier(0.4, 0, 1, 1);
    --easing-out: cubic-bezier(0, 0, 0.2, 1);
    --easing-bounce: cubic-bezier(0.34, 1.56, 0.64, 1);
}

/* ============================================
   Fade Transitions
   ============================================ */
.fade-enter {
    opacity: 0;
}

.fade-enter-active {
    opacity: 1;
    transition: opacity var(--transition-normal) var(--easing-out);
}

.fade-exit {
    opacity: 1;
}

.fade-exit-active {
    opacity: 0;
    transition: opacity var(--transition-normal) var(--easing-in);
}

/* ============================================
   Slide Transitions
   ============================================ */
.slide-up-enter {
    opacity: 0;
    transform: translateY(10px);
}

.slide-up-enter-active {
    opacity: 1;
    transform: translateY(0);
    transition: opacity var(--transition-normal) var(--easing-out),
                transform var(--transition-normal) var(--easing-out);
}

.slide-down-enter {
    opacity: 0;
    transform: translateY(-10px);
}

.slide-down-enter-active {
    opacity: 1;
    transform: translateY(0);
    transition: opacity var(--transition-normal) var(--easing-out),
                transform var(--transition-normal) var(--easing-out);
}

/* ============================================
   Scale Transitions
   ============================================ */
.scale-enter {
    opacity: 0;
    transform: scale(0.95);
}

.scale-enter-active {
    opacity: 1;
    transform: scale(1);
    transition: opacity var(--transition-normal) var(--easing-out),
                transform var(--transition-normal) var(--easing-bounce);
}

/* ============================================
   Skeleton Loaders
   ============================================ */
.skeleton {
    position: relative;
    overflow: hidden;
    background: var(--surface-2, #374151);
    border-radius: 4px;
}

.skeleton::after {
    content: '';
    position: absolute;
    inset: 0;
    transform: translateX(-100%);
    background: linear-gradient(
        90deg,
        transparent,
        rgba(255, 255, 255, 0.1),
        transparent
    );
    animation: skeleton-shimmer 1.5s infinite;
}

@keyframes skeleton-shimmer {
    100% {
        transform: translateX(100%);
    }
}

/* Common skeleton shapes */
.skeleton--text {
    height: 1rem;
    width: 100%;
    max-width: 200px;
}

.skeleton--text-short {
    height: 1rem;
    width: 60%;
    max-width: 120px;
}

.skeleton--text-long {
    height: 1rem;
    width: 100%;
    max-width: 300px;
}

.skeleton--title {
    height: 1.5rem;
    width: 100%;
    max-width: 250px;
}

.skeleton--avatar {
    height: 40px;
    width: 40px;
    border-radius: 50%;
}

.skeleton--button {
    height: 36px;
    width: 100px;
    border-radius: 6px;
}

.skeleton--card {
    height: 120px;
    width: 100%;
    border-radius: 8px;
}

.skeleton--chart {
    height: 200px;
    width: 100%;
    border-radius: 8px;
}

/* ============================================
   Loading Spinner
   ============================================ */
.spinner {
    width: 20px;
    height: 20px;
    border: 2px solid transparent;
    border-top-color: currentColor;
    border-radius: 50%;
    animation: spinner-rotate 0.75s linear infinite;
}

.spinner--sm {
    width: 14px;
    height: 14px;
}

.spinner--lg {
    width: 32px;
    height: 32px;
}

.spinner--xl {
    width: 48px;
    height: 48px;
}

@keyframes spinner-rotate {
    100% {
        transform: rotate(360deg);
    }
}

/* ============================================
   Pulse Animation (for indicators)
   ============================================ */
.pulse {
    animation: pulse-animation 2s ease-in-out infinite;
}

@keyframes pulse-animation {
    0%, 100% {
        opacity: 1;
    }
    50% {
        opacity: 0.5;
    }
}

/* ============================================
   Button Loading State
   ============================================ */
.btn--loading {
    position: relative;
    pointer-events: none;
    color: transparent !important;
}

.btn--loading::after {
    content: '';
    position: absolute;
    left: 50%;
    top: 50%;
    width: 16px;
    height: 16px;
    margin: -8px 0 0 -8px;
    border: 2px solid transparent;
    border-top-color: currentColor;
    border-radius: 50%;
    animation: spinner-rotate 0.75s linear infinite;
    color: var(--text-primary, white);
}

/* ============================================
   Progress Bars
   ============================================ */
.progress-bar {
    height: 6px;
    background: var(--surface-2, #374151);
    border-radius: 3px;
    overflow: hidden;
}

.progress-bar__fill {
    height: 100%;
    background: var(--primary-500, #3b82f6);
    border-radius: 3px;
    transition: width var(--transition-slow) var(--easing-out);
}

.progress-bar--success .progress-bar__fill {
    background: var(--success, #10b981);
}

.progress-bar--warning .progress-bar__fill {
    background: var(--warning, #f59e0b);
}

.progress-bar--error .progress-bar__fill {
    background: var(--error, #ef4444);
}

/* Indeterminate progress bar */
.progress-bar--indeterminate .progress-bar__fill {
    width: 30% !important;
    animation: indeterminate-progress 1.5s ease-in-out infinite;
}

@keyframes indeterminate-progress {
    0% {
        transform: translateX(-100%);
    }
    100% {
        transform: translateX(400%);
    }
}

/* ============================================
   Content Loading State
   ============================================ */
.content-loading {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 3rem;
    gap: 1rem;
}

.content-loading__text {
    color: var(--text-secondary, rgba(255,255,255,0.6));
    font-size: 0.875rem;
}

/* ============================================
   Card Loading Animation
   ============================================ */
.card--loading {
    animation: card-pulse 1.5s ease-in-out infinite;
}

@keyframes card-pulse {
    0%, 100% {
        opacity: 1;
    }
    50% {
        opacity: 0.7;
    }
}

/* ============================================
   Stagger Animation for Lists
   ============================================ */
.stagger-item {
    opacity: 0;
    transform: translateY(10px);
    animation: stagger-in var(--transition-normal) var(--easing-out) forwards;
}

.stagger-item:nth-child(1) { animation-delay: 0ms; }
.stagger-item:nth-child(2) { animation-delay: 50ms; }
.stagger-item:nth-child(3) { animation-delay: 100ms; }
.stagger-item:nth-child(4) { animation-delay: 150ms; }
.stagger-item:nth-child(5) { animation-delay: 200ms; }
.stagger-item:nth-child(6) { animation-delay: 250ms; }
.stagger-item:nth-child(7) { animation-delay: 300ms; }
.stagger-item:nth-child(8) { animation-delay: 350ms; }
.stagger-item:nth-child(9) { animation-delay: 400ms; }
.stagger-item:nth-child(10) { animation-delay: 450ms; }

@keyframes stagger-in {
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* ============================================
   Progressive Disclosure Transitions
   ============================================ */

/* Card Expansion with smooth height animation */
.disclosure-container {
    display: grid;
    grid-template-rows: 0fr;
    opacity: 0;
    transition: grid-template-rows var(--transition-slow) var(--easing-out),
                opacity var(--transition-normal) var(--easing-out);
}

.disclosure-container--open {
    grid-template-rows: 1fr;
    opacity: 1;
}

.disclosure-container > * {
    overflow: hidden;
}

/* Alternative: Max-height based disclosure */
.disclosure-content {
    max-height: 0;
    opacity: 0;
    overflow: hidden;
    transition: max-height var(--transition-slow) var(--easing-out),
                opacity var(--transition-normal) var(--easing-out);
}

.disclosure-content--open {
    max-height: 2000px; /* Large enough for most content */
    opacity: 1;
}

/* Chevron rotation */
.disclosure-trigger__icon {
    transition: transform var(--transition-normal) var(--easing-out);
}

.disclosure-trigger--open .disclosure-trigger__icon,
.disclosure-trigger[aria-expanded="true"] .disclosure-trigger__icon {
    transform: rotate(180deg);
}

/* Section-level disclosure (nested) */
.disclosure-section {
    border: 1px solid var(--border-light, rgba(255,255,255,0.08));
    border-radius: var(--radius-md, 10px);
    margin-bottom: var(--space-3, 12px);
    overflow: hidden;
}

.disclosure-section__header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: var(--space-4, 16px);
    background: var(--bg-tertiary, #3A3A3C);
    cursor: pointer;
    transition: background var(--transition-fast) var(--easing-default);
}

.disclosure-section__header:hover {
    background: var(--bg-elevated, #48484A);
}

.disclosure-section__title {
    font-size: var(--text-sm, 13px);
    font-weight: 600;
    color: var(--text-primary, #F5F5F7);
}

.disclosure-section__summary {
    font-size: var(--text-xs, 11px);
    color: var(--text-tertiary, #6E6E73);
    margin-left: var(--space-2, 8px);
}

.disclosure-section__content {
    display: grid;
    grid-template-rows: 0fr;
    transition: grid-template-rows var(--transition-slow) var(--easing-out);
}

.disclosure-section--open .disclosure-section__content {
    grid-template-rows: 1fr;
}

.disclosure-section__inner {
    overflow: hidden;
}

.disclosure-section__inner > * {
    padding: var(--space-4, 16px);
}

/* Tab-based disclosure */
.tabs-disclosure {
    display: flex;
    gap: var(--space-1, 4px);
    padding: var(--space-3, 12px) 0;
    border-bottom: 1px solid var(--border-light, rgba(255,255,255,0.08));
}

.tabs-disclosure__tab {
    padding: var(--space-2, 8px) var(--space-4, 16px);
    background: transparent;
    border: none;
    border-radius: var(--radius-sm, 6px);
    font-size: var(--text-sm, 13px);
    font-weight: 500;
    color: var(--text-secondary, #A1A1A6);
    cursor: pointer;
    transition: all var(--transition-fast) var(--easing-default);
}

.tabs-disclosure__tab:hover {
    background: var(--bg-tertiary, #3A3A3C);
    color: var(--text-primary, #F5F5F7);
}

.tabs-disclosure__tab--active {
    background: var(--accent, #0071E3);
    color: white;
}

.tabs-disclosure__tab:focus-visible {
    outline: none;
    box-shadow: 0 0 0 2px var(--accent, #0071E3);
}

.tabs-disclosure__panel {
    display: none;
    padding: var(--space-4, 16px) 0;
}

.tabs-disclosure__panel--active {
    display: block;
    animation: fade-in var(--transition-normal) var(--easing-out);
}

@keyframes fade-in {
    from { opacity: 0; }
    to { opacity: 1; }
}

/* ============================================
   Reduced Motion Support
   ============================================ */
@media (prefers-reduced-motion: reduce) {
    .skeleton::after,
    .spinner,
    .pulse,
    .btn--loading::after,
    .progress-bar--indeterminate .progress-bar__fill,
    .card--loading,
    .stagger-item {
        animation: none;
    }
    
    .stagger-item {
        opacity: 1;
        transform: none;
    }
    
    .fade-enter-active,
    .fade-exit-active,
    .slide-up-enter-active,
    .slide-down-enter-active,
    .scale-enter-active,
    .progress-bar__fill,
    .disclosure-container,
    .disclosure-content,
    .disclosure-trigger__icon,
    .disclosure-section__content,
    .tabs-disclosure__tab,
    .tabs-disclosure__panel--active {
        transition: none;
        animation: none;
    }
    
    /* Ensure disclosure content is visible immediately */
    .disclosure-container--open,
    .disclosure-content--open,
    .disclosure-section--open .disclosure-section__content {
        transition: none;
    }
}