/**
 * Modern Skeleton Loader System
 * Content-aware skeletons with wave shimmer animation
 * Supports light and dark modes
 */

/* ============================================
   CSS Variables
   ============================================ */
:root {
    --skeleton-base: #e2e8f0;
    --skeleton-highlight: #f8fafc;
    --skeleton-radius-sm: 4px;
    --skeleton-radius-md: 8px;
    --skeleton-radius-lg: 12px;
    --skeleton-radius-full: 9999px;
    --skeleton-animation-duration: 1.8s;
}

[data-theme="dark"] {
    --skeleton-base: #2d3748;
    --skeleton-highlight: #4a5568;
}

/* ============================================
   Base Skeleton Class
   ============================================ */
.skeleton {
    background: linear-gradient(
        90deg,
        var(--skeleton-base) 0%,
        var(--skeleton-base) 40%,
        var(--skeleton-highlight) 50%,
        var(--skeleton-base) 60%,
        var(--skeleton-base) 100%
    );
    background-size: 200% 100%;
    animation: skeleton-wave var(--skeleton-animation-duration) ease-in-out infinite;
    border-radius: var(--skeleton-radius-md);
    position: relative;
    overflow: hidden;
}

@keyframes skeleton-wave {
    0% {
        background-position: 200% 0;
    }
    100% {
        background-position: -200% 0;
    }
}

/* Pulse animation variant */
.skeleton-pulse {
    animation: skeleton-pulse 2s cubic-bezier(0.4, 0, 0.6, 1) infinite;
}

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

/* ============================================
   Text Skeletons
   ============================================ */
.skeleton-text {
    height: 1rem;
    border-radius: var(--skeleton-radius-sm);
}

.skeleton-text-xs {
    height: 0.625rem;
    border-radius: var(--skeleton-radius-sm);
}

.skeleton-text-sm {
    height: 0.75rem;
    border-radius: var(--skeleton-radius-sm);
}

.skeleton-text-md {
    height: 1rem;
    border-radius: var(--skeleton-radius-sm);
}

.skeleton-text-lg {
    height: 1.25rem;
    border-radius: var(--skeleton-radius-sm);
}

.skeleton-text-xl {
    height: 1.5rem;
    border-radius: var(--skeleton-radius-md);
}

.skeleton-text-2xl {
    height: 2rem;
    border-radius: var(--skeleton-radius-md);
}

.skeleton-text-3xl {
    height: 2.5rem;
    border-radius: var(--skeleton-radius-md);
}

/* ============================================
   Avatar & Icon Skeletons
   ============================================ */
.skeleton-avatar {
    border-radius: var(--skeleton-radius-full);
}

.skeleton-avatar-sm {
    width: 32px;
    height: 32px;
    border-radius: var(--skeleton-radius-full);
}

.skeleton-avatar-md {
    width: 40px;
    height: 40px;
    border-radius: var(--skeleton-radius-full);
}

.skeleton-avatar-lg {
    width: 48px;
    height: 48px;
    border-radius: var(--skeleton-radius-full);
}

.skeleton-icon {
    width: 24px;
    height: 24px;
    border-radius: var(--skeleton-radius-sm);
}

.skeleton-icon-lg {
    width: 40px;
    height: 40px;
    border-radius: var(--skeleton-radius-md);
}

/* ============================================
   Metric Card Skeleton
   ============================================ */
.skeleton-metric-card {
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    border-radius: 1rem;
    padding: 1.5rem;
    border: 1px solid rgba(255, 255, 255, 0.2);
    position: relative;
    overflow: hidden;
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.skeleton-metric-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 3px;
    background: linear-gradient(135deg, var(--skeleton-base) 0%, var(--skeleton-highlight) 100%);
}

[data-theme="dark"] .skeleton-metric-card {
    background: rgba(45, 55, 72, 0.95);
    border-color: rgba(255, 255, 255, 0.1);
}

.skeleton-metric-label {
    height: 0.875rem;
    width: 60%;
    border-radius: var(--skeleton-radius-sm);
}

.skeleton-metric-value {
    height: 2.5rem;
    width: 50%;
    border-radius: var(--skeleton-radius-md);
}

.skeleton-metric-trend {
    height: 0.875rem;
    width: 40%;
    border-radius: var(--skeleton-radius-sm);
}

/* ============================================
   Card Skeleton
   ============================================ */
.skeleton-card {
    background: white;
    border-radius: var(--skeleton-radius-lg);
    padding: 1.5rem;
    border: 1px solid #e2e8f0;
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

[data-theme="dark"] .skeleton-card {
    background: #252525;
    border-color: #404040;
}

.skeleton-card-header {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.skeleton-card-content {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.skeleton-card-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: 0.5rem;
    border-top: 1px solid #e2e8f0;
}

[data-theme="dark"] .skeleton-card-footer {
    border-top-color: #404040;
}

/* ============================================
   Chart Skeleton
   ============================================ */
.skeleton-chart {
    background: white;
    border-radius: var(--skeleton-radius-lg);
    padding: 1.5rem;
    border: 1px solid #e2e8f0;
    position: relative;
    min-height: 250px;
}

[data-theme="dark"] .skeleton-chart {
    background: #252525;
    border-color: #404040;
}

.skeleton-chart-title {
    height: 1.5rem;
    width: 180px;
    margin-bottom: 1rem;
    border-radius: var(--skeleton-radius-sm);
}

.skeleton-chart-area {
    height: 200px;
    border-radius: var(--skeleton-radius-md);
    position: relative;
    overflow: hidden;
}

/* Simulated chart bars */
.skeleton-chart-bars {
    display: flex;
    align-items: flex-end;
    justify-content: space-around;
    height: 100%;
    padding: 1rem;
    gap: 0.5rem;
}

.skeleton-chart-bar {
    flex: 1;
    border-radius: var(--skeleton-radius-sm) var(--skeleton-radius-sm) 0 0;
    min-width: 20px;
    max-width: 40px;
}

/* ============================================
   Table Skeleton
   ============================================ */
.skeleton-table {
    width: 100%;
    border-collapse: collapse;
}

.skeleton-table-header {
    display: flex;
    gap: 1rem;
    padding: 1rem;
    background: #f8fafc;
    border-radius: var(--skeleton-radius-md) var(--skeleton-radius-md) 0 0;
}

[data-theme="dark"] .skeleton-table-header {
    background: #2d3748;
}

.skeleton-table-row {
    display: flex;
    gap: 1rem;
    padding: 1rem;
    border-bottom: 1px solid #e2e8f0;
    align-items: center;
}

[data-theme="dark"] .skeleton-table-row {
    border-bottom-color: #404040;
}

.skeleton-table-cell {
    flex: 1;
    height: 1rem;
    border-radius: var(--skeleton-radius-sm);
}

/* ============================================
   Sidebar Skeleton
   ============================================ */
.skeleton-sidebar-item {
    padding: 1.15rem;
    margin: 0.5rem;
    background: #f8fafc;
    border: 2px solid #e2e8f0;
    border-radius: 0.875rem;
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

[data-theme="dark"] .skeleton-sidebar-item {
    background: #252525;
    border-color: #404040;
}

.skeleton-sidebar-date {
    height: 0.75rem;
    width: 35%;
    border-radius: var(--skeleton-radius-sm);
}

.skeleton-sidebar-score {
    height: 1.5rem;
    width: 45%;
    border-radius: var(--skeleton-radius-md);
}

.skeleton-sidebar-stats {
    display: flex;
    gap: 1rem;
    padding-top: 0.5rem;
    border-top: 1px solid #e2e8f0;
}

[data-theme="dark"] .skeleton-sidebar-stats {
    border-top-color: #404040;
}

.skeleton-sidebar-stat {
    height: 0.75rem;
    width: 60px;
    border-radius: var(--skeleton-radius-sm);
}

/* ============================================
   Stat Card Skeleton
   ============================================ */
.skeleton-stat-card {
    background: white;
    border-radius: var(--skeleton-radius-lg);
    padding: 1.5rem;
    text-align: center;
    border: 2px solid #e2e8f0;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.75rem;
}

[data-theme="dark"] .skeleton-stat-card {
    background: #252525;
    border-color: #404040;
}

.skeleton-stat-label {
    height: 0.75rem;
    width: 70%;
    border-radius: var(--skeleton-radius-sm);
}

.skeleton-stat-value {
    height: 2rem;
    width: 50%;
    border-radius: var(--skeleton-radius-md);
}

.skeleton-stat-subtitle {
    height: 0.625rem;
    width: 60%;
    border-radius: var(--skeleton-radius-sm);
}

/* ============================================
   Skills Grid Skeleton
   ============================================ */
.skeleton-skill-card {
    background: linear-gradient(135deg, #f8fafc 0%, #e2e8f0 100%);
    border-radius: 0.75rem;
    padding: 1.5rem;
    text-align: center;
    border: 1px solid rgba(255, 255, 255, 0.8);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.5rem;
}

[data-theme="dark"] .skeleton-skill-card {
    background: linear-gradient(135deg, #2d3748 0%, #1a202c 100%);
    border-color: #404040;
}

.skeleton-skill-name {
    height: 1rem;
    width: 80%;
    border-radius: var(--skeleton-radius-sm);
}

.skeleton-skill-score {
    height: 1.75rem;
    width: 40%;
    border-radius: var(--skeleton-radius-md);
}

.skeleton-skill-progress {
    height: 4px;
    width: 100%;
    border-radius: 2px;
    margin: 0.5rem 0;
}

/* ============================================
   Content Section Skeleton
   ============================================ */
.skeleton-section {
    background: white;
    border-radius: 1rem;
    padding: 2rem;
    margin-bottom: 2rem;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    border: 1px solid #e5e7eb;
}

[data-theme="dark"] .skeleton-section {
    background: #252525;
    border-color: #404040;
}

.skeleton-section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 1.5rem;
}

.skeleton-section-title {
    height: 1.5rem;
    width: 200px;
    border-radius: var(--skeleton-radius-md);
}

.skeleton-section-action {
    height: 2.5rem;
    width: 100px;
    border-radius: 0.5rem;
}

/* ============================================
   Button Skeleton
   ============================================ */
.skeleton-button {
    height: 2.5rem;
    border-radius: 0.5rem;
}

.skeleton-button-sm {
    height: 2rem;
    border-radius: 0.375rem;
}

.skeleton-button-lg {
    height: 3rem;
    border-radius: 0.75rem;
}

/* ============================================
   Progress Bar Skeleton
   ============================================ */
.skeleton-progress {
    height: 6px;
    width: 100%;
    border-radius: 3px;
}

.skeleton-progress-lg {
    height: 8px;
    border-radius: 4px;
}

/* ============================================
   Badge Skeleton
   ============================================ */
.skeleton-badge {
    height: 1.5rem;
    width: 4rem;
    border-radius: var(--skeleton-radius-full);
}

.skeleton-badge-lg {
    height: 2rem;
    width: 5rem;
    border-radius: var(--skeleton-radius-full);
}

/* ============================================
   Hero Section Skeleton (Performance Dashboard)
   ============================================ */
.skeleton-hero-metrics {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 1.5rem;
}

@media (max-width: 1024px) {
    .skeleton-hero-metrics {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 640px) {
    .skeleton-hero-metrics {
        grid-template-columns: 1fr;
    }
}

/* ============================================
   Loading Overlay
   ============================================ */
.skeleton-overlay {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: rgba(255, 255, 255, 0.9);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 10;
    border-radius: inherit;
}

[data-theme="dark"] .skeleton-overlay {
    background: rgba(26, 32, 44, 0.9);
}

/* ============================================
   Stagger Animation Helper
   ============================================ */
.skeleton-stagger > *:nth-child(1) { animation-delay: 0ms; }
.skeleton-stagger > *:nth-child(2) { animation-delay: 100ms; }
.skeleton-stagger > *:nth-child(3) { animation-delay: 200ms; }
.skeleton-stagger > *:nth-child(4) { animation-delay: 300ms; }
.skeleton-stagger > *:nth-child(5) { animation-delay: 400ms; }
.skeleton-stagger > *:nth-child(6) { animation-delay: 500ms; }

/* ============================================
   Transition Helpers
   ============================================ */
.skeleton-fade-out {
    animation: skeleton-fade-out 0.3s ease-out forwards;
}

@keyframes skeleton-fade-out {
    from {
        opacity: 1;
        transform: scale(1);
    }
    to {
        opacity: 0;
        transform: scale(0.98);
    }
}

.skeleton-fade-in {
    animation: skeleton-fade-in 0.3s ease-out forwards;
}

@keyframes skeleton-fade-in {
    from {
        opacity: 0;
        transform: scale(0.98);
    }
    to {
        opacity: 1;
        transform: scale(1);
    }
}