/**
 * GCSE Revision Hub - Session Scroll
 *
 * Feature: F-032.5 Today's Session - Horizontal Scroll
 * Version: 1.0
 * Created: 2026-01-20
 *
 * Netflix-style horizontal scrolling task cards with glassmorphism effects,
 * smooth snap scrolling, and dynamic fade indicators.
 *
 * DEPENDENCIES:
 * - css/design-system.css (design tokens)
 * - css/components-v2.css (glassmorphism cards)
 * - css/micro-interactions.css (scroll fade indicators)
 *
 * USAGE:
 * - Include after design-system.css and components-v2.css
 * - Works in both light and dark themes
 * - Respects prefers-reduced-motion
 */

/* ============================================================================
   SESSION SCROLL SECTION
   ============================================================================ */

.session-scroll-section {
  margin-bottom: var(--space-8);
}

/* --------------------------------------------------------------------------
   Section Header
   -------------------------------------------------------------------------- */

.session-scroll-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  margin-bottom: var(--space-5);
  padding: 0;
  gap: var(--space-4);
}

.session-scroll-title {
  font-size: var(--text-2xl);
  font-weight: var(--font-bold);
  color: var(--text-primary);
  margin: 0;
  line-height: 1.1;
}

.session-scroll-title-wrap {
  display: flex;
  flex-direction: column;
  gap: 2px;
  align-items: flex-start;
}

.session-scroll-subtitle {
  margin: 0;
  font-size: var(--text-sm);
  color: var(--text-secondary);
}

.session-scroll-meta {
  font-size: var(--text-xs);
  color: var(--text-muted);
  font-weight: var(--font-semibold);
  letter-spacing: 0.02em;
  margin-top: 0;
}

.session-scroll-badge {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 24px;
  height: 24px;
  padding: 0 var(--space-2);
  background: linear-gradient(135deg, var(--color-primary), #2563eb);
  color: var(--text-inverse);
  font-size: var(--text-xs);
  font-weight: var(--font-bold);
  border-radius: var(--radius-full);
  margin-left: var(--space-2);
}

.session-scroll-xp {
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  gap: 6px;
  min-width: 160px;
}

.session-scroll-xp-meta {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: var(--text-sm);
  font-weight: var(--font-semibold);
  color: var(--text-primary);
}

.session-scroll-xp-icon {
  color: #22c55e;
}

.session-scroll-xp-icon svg {
  width: 16px;
  height: 16px;
}

.session-scroll-xp-bar {
  width: 160px;
  height: 6px;
  background: transparent;
  border: 2px solid color-mix(in srgb, var(--task-color, var(--color-primary)) 35%, var(--border));
  border-radius: var(--radius-full);
  overflow: hidden;
}

.session-scroll-xp-fill {
  display: block;
  height: 100%;
  width: 0%;
  background: linear-gradient(90deg, #22c55e, #16a34a);
  border-radius: var(--radius-full);
  transition: width var(--duration-normal) var(--ease-out);
  box-shadow: 0 0 12px rgba(34, 197, 94, 0.5);
}

.session-scroll-xp-text {
  font-weight: var(--font-bold);
}

/* --------------------------------------------------------------------------
   Horizontal Scroll Container
   -------------------------------------------------------------------------- */

.session-scroll-wrapper {
  position: relative;
  margin: 0;
}

.session-scroll-container {
  display: flex;
  gap: var(--space-4);
  padding: 0 0 var(--space-6) 0;
  overflow-x: auto;
  overflow-y: hidden;
  scroll-behavior: smooth;
  scroll-snap-type: x mandatory;
  -webkit-overflow-scrolling: touch; /* Smooth momentum scroll on iOS */

  /* Hide scrollbar but keep functionality */
  scrollbar-width: none; /* Firefox */
  -ms-overflow-style: none; /* IE/Edge */
}

.session-scroll-container::-webkit-scrollbar {
  display: none; /* Chrome/Safari */
}

/* --------------------------------------------------------------------------
   Scroll Fade Indicators
   -------------------------------------------------------------------------- */

.session-scroll-fade {
  position: absolute;
  top: 0;
  bottom: 0;
  width: 60px;
  pointer-events: none;
  z-index: 2;
  transition: opacity var(--duration-normal) var(--ease-out);
}

.session-scroll-fade--left {
  left: 0;
  background: linear-gradient(to right, var(--bg-primary), transparent);
  opacity: 0; /* Hidden initially */
}

.session-scroll-fade--right {
  right: 0;
  background: linear-gradient(to left, var(--bg-primary), transparent);
  opacity: 1; /* Visible initially (more content to right) */
}

.session-scroll-fade.visible {
  opacity: 1;
}

.session-scroll-fade.hidden {
  opacity: 0;
}

/* --------------------------------------------------------------------------
   Task Cards
   -------------------------------------------------------------------------- */

.session-task-card {
  flex: 0 0 auto;
  width: 280px;
  min-height: 160px;
  scroll-snap-align: start;
  position: relative;
  overflow: hidden;

  /* Glassmorphism effect */
  background: rgba(255, 255, 255, 0.7);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border: 1px solid rgba(255, 255, 255, 0.18);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);

  /* Transitions */
  transition: transform var(--duration-normal) var(--ease-out),
              box-shadow var(--duration-normal) var(--ease-out);

  /* Prevent text selection during scroll */
  user-select: none;
  cursor: pointer;
}

/* Subtle color wash */
.session-task-card::before {
  content: '';
  position: absolute;
  inset: 0;
  background: radial-gradient(120% 120% at 0% 0%,
      color-mix(in srgb, var(--task-color) 18%, transparent) 0%,
      transparent 60%);
  opacity: 0.7;
  pointer-events: none;
  z-index: 0;
}

[data-theme="dark"] .session-task-card::before {
  background: radial-gradient(200% 180% at 0% 0%,
      color-mix(in srgb, var(--task-color) 24%, transparent) 0%,
      transparent 92%);
  opacity: 0.5;
}

/* Light theme glassmorphism - enhanced for visibility */
[data-theme="light"] .session-task-card {
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid rgba(0, 0, 0, 0.06);
  box-shadow: 0 4px 16px rgba(0, 0, 0, 0.04),
              0 8px 32px rgba(0, 0, 0, 0.06);
}

/* Dark theme glassmorphism */
[data-theme="dark"] .session-task-card {
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid rgba(255, 255, 255, 0.1);
}

/* Hover effect (desktop only) */
@media (hover: hover) {
  .session-task-card:hover {
    transform: translateY(-4px) scale(1.01);
    box-shadow: var(--shadow-lg);
  }
}

/* Active/pressed state */
.session-task-card:active {
  transform: translateY(-2px) scale(0.99);
}

/* A3-001: Focus state for keyboard navigation (WCAG AA) */
.session-task-card:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

/* Completed state */
.session-task-card--complete {
  opacity: 0.8;
  cursor: pointer; /* Keep clickable cursor */
}

.session-task-card--complete .session-task-checkmark {
  opacity: 1;
}

/* Strike-through on completed task title */
.session-task-card--complete .session-task-title {
  text-decoration: line-through;
  text-decoration-thickness: 2px;
  text-decoration-color: var(--text-muted);
}

/* --------------------------------------------------------------------------
   Subject Color Accent Bar
   -------------------------------------------------------------------------- */

.session-task-accent {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: var(--task-color, var(--color-primary));
  border-radius: var(--radius-lg) var(--radius-lg) 0 0;
  z-index: 1;
}

/* Subject colors */
.session-task-card[data-subject="physics"] {
  --task-color: #ef4444;
}

.session-task-card[data-subject="chemistry"] {
  --task-color: #f59e0b;
}

.session-task-card[data-subject="biology"] {
  --task-color: #22c55e;
}

.session-task-card[data-subject="maths"] {
  --task-color: #3b82f6;
}

.session-task-card[data-subject="history"] {
  --task-color: #a855f7;
}

.session-task-card[data-subject="computer-science"] {
  --task-color: #06b6d4;
}

/* Task type accent colors */
.session-task-card[data-type="learn"] {
  --task-color: #3b82f6; /* Blue */
}

.session-task-card[data-type="review"] {
  --task-color: #a855f7; /* Purple */
}

.session-task-card[data-type="test"] {
  --task-color: #f59e0b; /* Yellow/Amber */
}

/* Bonus tasks keep their type color but add green glow */
.session-task-card[data-type="bonus"] {
  position: relative;
  animation: bonusGlow 2s ease-in-out infinite;
}

/* Bonus tasks inherit their actual task type colors */
.session-task-card[data-type="bonus"].bonus-learn {
  --task-color: #3b82f6 !important; /* Blue for learn */
}

.session-task-card[data-type="bonus"].bonus-review {
  --task-color: #a855f7 !important; /* Purple for flashcards */
}

.session-task-card[data-type="bonus"].bonus-test {
  --task-color: #f59e0b !important; /* Yellow for quiz */
}

/* Green glow effect for ALL bonus tasks */
@keyframes bonusGlow {
  0%, 100% {
    box-shadow: 
      0 0 20px rgba(34, 197, 94, 0.15),
      0 0 40px rgba(34, 197, 94, 0.1),
      inset 0 0 20px rgba(34, 197, 94, 0.05);
  }
  50% {
    box-shadow: 
      0 0 30px rgba(34, 197, 94, 0.25),
      0 0 60px rgba(34, 197, 94, 0.15),
      inset 0 0 30px rgba(34, 197, 94, 0.08);
  }
}

/* Enhanced reward display for bonus tasks */
.session-task-card[data-type="bonus"] .reward-item--xp {
  color: #22c55e;
  text-shadow: 0 0 12px rgba(34, 197, 94, 0.3);
  animation: xpPulse 2s ease-in-out infinite;
}

@keyframes xpPulse {
  0%, 100% { transform: scale(1); }
  50% { transform: scale(1.05); }
}

/* Bonus badge indicator */
.session-task-card[data-type="bonus"] .session-task-subject {
  position: relative;
}

.session-task-card[data-type="bonus"] .session-task-subject::before {
  content: "BONUS • ";
  color: #22c55e;
  font-weight: 700;
  font-size: 11px;
  letter-spacing: 0.5px;
}

/* --------------------------------------------------------------------------
   Task Card Content
   -------------------------------------------------------------------------- */

.session-task-content {
  padding: var(--space-5);
  display: flex;
  flex-direction: column;
  height: 100%;
  gap: var(--space-3);
  position: relative;
  z-index: 1;
}

/* Task type icon and label */
.session-task-header {
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

.session-task-icon {
  width: 24px;
  height: 24px;
  color: var(--task-color, var(--color-primary));
}

.session-task-type {
  font-size: var(--text-sm);
  font-weight: var(--font-bold);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--task-color, var(--color-primary));
}

/* Subject name removed from layout (Learn • Biology line replaces it) */
.session-task-subject {
  display: none;
}

/* Show subject name on subject cards */
.session-task-card[data-type="subject"] .session-task-subject {
  display: inline-flex;
  align-items: center;
  font-size: var(--text-sm);
  font-weight: var(--font-bold);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--task-color, var(--color-primary));
}

/* Subject card stats row */
.subject-card-stats {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  align-items: stretch;
  gap: var(--space-2);
  margin-top: var(--space-3);
}

.subject-card-stat {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  padding: 8px 6px;
  border-radius: 10px;
  background: rgba(255, 255, 255, 0.35);
  border: none;
  text-align: center;
}

[data-theme="dark"] .subject-card-stat {
  background: rgba(255, 255, 255, 0.06);
}

.subject-card-stat-icon {
  display: inline-flex;
  width: 20px;
  height: 20px;
}

.subject-card-stat-icon svg {
  width: 20px;
  height: 20px;
}

.subject-card-stat-icon .icon {
  width: 20px;
  height: 20px;
  display: block;
}

.subject-card-stat--learn .subject-card-stat-icon {
  color: #2563eb;
}

.subject-card-stat--review .subject-card-stat-icon {
  color: #a855f7;
}

.subject-card-stat--quiz .subject-card-stat-icon {
  color: #eab308;
}

.subject-card-stat-count {
  font-size: var(--text-sm);
  font-weight: var(--font-bold);
  color: var(--text-primary);
}

.subject-card-stat-label {
  font-size: 10px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--text-muted);
}

/* Topic title */
.session-task-title {
  font-size: var(--text-base);
  font-weight: var(--font-regular);
  color: var(--text-primary);
  line-height: 1.35;
  margin-bottom: auto; /* Push footer to bottom */

  /* Truncate long titles */
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

/* SF-15: Reason label — explains why the task was selected */
.session-task-reason {
  font-size: var(--text-xs);
  color: var(--text-muted);
  margin: var(--space-1) 0 auto;
  line-height: var(--leading-normal);
  letter-spacing: 0.02em;
  opacity: 0.8;
  /* Truncate if too long */
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

/* Task footer (status + progress) */
.session-task-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-top: auto;
  padding-top: var(--space-3);
}

.session-task-footer--rewards {
  padding-top: var(--space-2);
  justify-content: flex-end;
}

.session-task-rewards {
  display: flex;
  align-items: center;
  gap: var(--space-4);
}

.reward-item {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: var(--text-sm);
  font-weight: var(--font-semibold);
  color: var(--text-secondary);
}

.reward-item svg {
  width: 24px;
  height: 24px;
  animation: rewardPulse 2.6s ease-in-out infinite;
}

.reward-item--xp {
  color: #22c55e;
  text-shadow: 0 0 10px rgba(34, 197, 94, 0.45);
}

.reward-item--mastery {
  color: var(--task-color, var(--color-primary));
  text-shadow: 0 0 10px color-mix(in srgb, var(--task-color, var(--color-primary)) 55%, transparent);
}

.reward-value {
  font-weight: var(--font-bold);
}

@keyframes rewardPulse {
  0%, 100% {
    transform: scale(1);
    opacity: 0.95;
  }
  50% {
    transform: scale(1.08);
    opacity: 1;
  }
}

/* Mastery badge in subject cards uses header icons */
.session-task-footer .mastery-badge,
.session-task-footer .mastery-badge-component,
.subject-card-mastery {
  padding: 0;
  background: transparent;
  border: none;
  color: var(--text-secondary);
}

/* Subject card mastery badge pinned top-right — larger shield */
.subject-card-mastery {
  position: absolute;
  top: var(--space-3);
  right: var(--space-3);
}

.subject-card-mastery .mastery-badge-icon svg {
  width: 36px !important;
  height: 36px !important;
}

/* --------------------------------------------------------------------------
   Status Badge
   -------------------------------------------------------------------------- */

.session-task-status {
  display: inline-flex;
  align-items: center;
  gap: var(--space-1);
  padding: var(--space-1) var(--space-3);
  font-size: var(--text-xs);
  font-weight: var(--font-semibold);
  border-radius: var(--radius-full);
  transition: all var(--duration-fast) var(--ease-out);
}

/* Pending status */
.session-task-status--pending {
  background: rgba(59, 130, 246, 0.1);
  color: #3b82f6;
}

[data-theme="dark"] .session-task-status--pending {
  background: rgba(59, 130, 246, 0.15);
  color: #60a5fa;
}

/* In Progress status */
.session-task-status--in-progress {
  background: rgba(245, 158, 11, 0.1);
  color: #f59e0b;
}

[data-theme="dark"] .session-task-status--in-progress {
  background: rgba(245, 158, 11, 0.15);
  color: #fbbf24;
}

/* Complete status */
.session-task-status--complete {
  background: rgba(34, 197, 94, 0.1);
  color: #22c55e;
}

[data-theme="dark"] .session-task-status--complete {
  background: rgba(34, 197, 94, 0.15);
  color: #4ade80;
}

/* --------------------------------------------------------------------------
   Progress Indicator
   -------------------------------------------------------------------------- */

.session-task-progress {
  flex: 1;
  max-width: 60px;
  height: 4px;
  background: var(--bg-tertiary);
  border-radius: var(--radius-full);
  overflow: hidden;
}

.session-task-progress-bar {
  height: 100%;
  background: var(--task-color, var(--color-primary));
  border-radius: var(--radius-full);
  transition: width var(--duration-slow) var(--ease-out);
}

/* --------------------------------------------------------------------------
   Completion Checkmark
   -------------------------------------------------------------------------- */

.session-task-checkmark {
  position: absolute;
  top: var(--space-4);
  right: var(--space-4);
  width: 28px;
  height: 28px;
  background: var(--color-success);
  border-radius: var(--radius-full);
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  transition: opacity var(--duration-normal) var(--ease-out);
}

.session-task-checkmark svg {
  width: 16px;
  height: 16px;
  color: white;
  stroke-width: 3;
}

/* --------------------------------------------------------------------------
   Empty State
   -------------------------------------------------------------------------- */

.session-scroll-empty {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 200px;
  padding: var(--space-8) var(--space-4);
  text-align: center;

  /* Glassmorphism */
  background: rgba(255, 255, 255, 0.7);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border: 1px solid rgba(255, 255, 255, 0.18);
  border-radius: var(--radius-lg);
  margin: 0 var(--space-4);
}

[data-theme="dark"] .session-scroll-empty {
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid rgba(255, 255, 255, 0.1);
}

.session-scroll-empty-icon {
  width: 48px;
  height: 48px;
  color: var(--text-muted);
  margin-bottom: var(--space-4);
}

.session-scroll-empty-title {
  font-size: var(--text-xl);
  font-weight: var(--font-semibold);
  color: var(--text-primary);
  margin-bottom: var(--space-2);
}

.session-scroll-empty-text {
  font-size: var(--text-sm);
  color: var(--text-secondary);
  max-width: 400px;
}

/* --------------------------------------------------------------------------
   CTA Button
   -------------------------------------------------------------------------- */

.session-scroll-cta {
  margin: var(--space-6) var(--space-4) 0;
}

.session-scroll-cta-btn {
  width: 100%;
  max-width: 400px;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  padding: var(--space-4) var(--space-6);
  background: linear-gradient(135deg, var(--color-primary), #2563eb);
  color: var(--text-inverse);
  font-size: var(--text-base);
  font-weight: var(--font-semibold);
  border: none;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: transform var(--duration-normal) var(--ease-out),
              box-shadow var(--duration-normal) var(--ease-out);
  box-shadow: var(--shadow-primary);
}

.session-scroll-cta-btn:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
}

.session-scroll-cta-btn:active {
  transform: translateY(0);
}

.session-scroll-cta-btn svg {
  width: 20px;
  height: 20px;
}

/* --------------------------------------------------------------------------
   Responsive Breakpoints
   -------------------------------------------------------------------------- */

/* Mobile: Smaller cards, more visible next card hint */
@media (max-width: 640px) {
  .session-task-card {
    width: 260px;
  }

  .session-scroll-header {
    flex-direction: column;
    align-items: flex-start;
    gap: var(--space-3);
  }

  .session-scroll-xp {
    align-items: flex-start;
    width: 100%;
  }

  .session-scroll-xp-bar {
    width: 100%;
  }

  .session-scroll-header {
    padding: 0;
  }

  .session-scroll-wrapper {
    margin: 0;
  }

  .session-scroll-container {
    padding: 0 0 var(--space-5) 0;
    gap: var(--space-3);
  }

  .session-scroll-cta {
    margin: var(--space-5) var(--space-3) 0;
  }
}

/* Desktop: Larger cards */
@media (min-width: 1024px) {
  .session-task-card {
    width: 320px;
    min-height: 180px;
  }

  .session-scroll-header {
    padding: 0;
  }

  .session-scroll-wrapper {
    margin: 0;
  }

  .session-scroll-container {
    padding: 0 0 var(--space-8) 0;
    gap: var(--space-5);
  }

  .session-scroll-cta {
    margin: var(--space-8) auto 0;
  }
}

/* --------------------------------------------------------------------------
   Reduced Motion
   -------------------------------------------------------------------------- */

@media (prefers-reduced-motion: reduce) {
  .session-scroll-container {
    scroll-behavior: auto;
  }

  .session-task-card {
    transition: none;
  }

  .session-task-progress-bar {
    transition: none;
  }

  .session-scroll-fade {
    transition: none;
  }
}

/* --------------------------------------------------------------------------
   Dark Theme Adjustments
   -------------------------------------------------------------------------- */

[data-theme="dark"] .session-scroll-fade--left {
  background: linear-gradient(to right, var(--bg-primary), transparent);
}

[data-theme="dark"] .session-scroll-fade--right {
  background: linear-gradient(to left, var(--bg-primary), transparent);
}

/* ============================================================================
   ADDITIONAL TASK CARD ELEMENTS
   ============================================================================ */

/* Topic name (for review/test tasks) */
.session-task-topic {
  font-size: var(--text-sm);
  font-weight: var(--font-medium);
  color: var(--text-secondary);
  margin-bottom: var(--space-2);
  /* Truncate long topic names */
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

/* Task description (for bonus tasks) */
.session-task-description {
  font-size: var(--text-sm);
  color: var(--text-muted);
  margin-bottom: auto; /* Push footer to bottom */
  line-height: var(--leading-relaxed);
  /* Truncate long descriptions */
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

/* Adjust title spacing when topic/description is present */
.session-task-card .session-task-title {
  margin-bottom: var(--space-2);
}

/* SF-20: Focus Areas / Gaps Widget — removed (gaps engine retained in MasteryEngine) */