/* ===================================
   MODERN LOADING & TRANSITION STATES
   =================================== */

/* ===================================
   PAGE LOADING ANIMATIONS
   =================================== */

/* Page Loader Overlay */
.page-loader {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100vh;
  background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-light) 50%, var(--color-accent) 100%);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  z-index: 9999;
  transition: opacity 0.5s ease-out, visibility 0.5s ease-out;
}

.page-loader.hidden {
  opacity: 0;
  visibility: hidden;
}

/* Loading Spinner */
.loading-spinner {
  width: 60px;
  height: 60px;
  border: 4px solid rgba(255, 255, 255, 0.3);
  border-top: 4px solid var(--color-white);
  border-radius: 50%;
  animation: spin 1s linear infinite;
  margin-bottom: var(--space-4);
}

@keyframes spin {
  0% { transform: rotate(0deg); }
  100% { transform: rotate(360deg); }
}

/* Modern Loading Dots */
.loading-dots {
  display: flex;
  gap: var(--space-1);
  margin-bottom: var(--space-4);
}

.loading-dot {
  width: 12px;
  height: 12px;
  background: var(--color-white);
  border-radius: 50%;
  animation: loadingPulse 1.4s ease-in-out infinite both;
}

.loading-dot:nth-child(1) { animation-delay: -0.32s; }
.loading-dot:nth-child(2) { animation-delay: -0.16s; }
.loading-dot:nth-child(3) { animation-delay: 0s; }

@keyframes loadingPulse {
  0%, 80%, 100% {
    transform: scale(0.8);
    opacity: 0.5;
  }
  40% {
    transform: scale(1);
    opacity: 1;
  }
}

/* Loading Text */
.loading-text {
  color: var(--color-white);
  font-family: var(--font-family-primary);
  font-size: var(--font-size-lg);
  font-weight: var(--font-weight-medium);
  text-align: center;
  opacity: 0.9;
}

/* Progress Bar */
.loading-progress {
  width: 200px;
  height: 4px;
  background: rgba(255, 255, 255, 0.3);
  border-radius: var(--radius-full);
  overflow: hidden;
  margin-top: var(--space-4);
}

.loading-progress-bar {
  height: 100%;
  background: linear-gradient(90deg, var(--color-white) 0%, rgba(255, 255, 255, 0.8) 100%);
  border-radius: var(--radius-full);
  width: 0%;
  animation: loadingProgress 2s ease-out forwards;
}

@keyframes loadingProgress {
  0% { width: 0%; }
  50% { width: 70%; }
  100% { width: 100%; }
}

/* ===================================
   SKELETON SCREENS
   =================================== */

/* Skeleton Base */
.skeleton {
  background: linear-gradient(90deg, 
    var(--color-gray-200) 25%, 
    var(--color-gray-100) 50%, 
    var(--color-gray-200) 75%
  );
  background-size: 200% 100%;
  animation: skeletonLoading 1.5s ease-in-out infinite;
  border-radius: var(--radius-base);
}

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

/* Skeleton Text Lines */
.skeleton-text {
  height: 1em;
  margin-bottom: var(--space-2);
}

.skeleton-text.short { width: 60%; }
.skeleton-text.medium { width: 80%; }
.skeleton-text.long { width: 100%; }

/* Skeleton Card */
.skeleton-card {
  padding: var(--space-6);
  border-radius: var(--radius-lg);
  background: var(--color-white);
  box-shadow: var(--shadow-base);
  margin-bottom: var(--space-4);
}

.skeleton-avatar {
  width: 60px;
  height: 60px;
  border-radius: 50%;
  margin-bottom: var(--space-3);
}

.skeleton-title {
  height: 1.5em;
  width: 70%;
  margin-bottom: var(--space-2);
}

.skeleton-paragraph {
  height: 1em;
  margin-bottom: var(--space-1);
}

.skeleton-paragraph:last-child {
  width: 80%;
}

/* ===================================
   SMOOTH PAGE TRANSITIONS
   =================================== */

/* Page Transition Overlay */
.page-transition {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100vh;
  background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-accent) 100%);
  z-index: 9998;
  transform: translateX(-100%);
  transition: transform 0.6s cubic-bezier(0.77, 0, 0.175, 1);
}

.page-transition.active {
  transform: translateX(0);
}

.page-transition.exit {
  transform: translateX(100%);
}

/* Section Transitions */
.section-transition {
  opacity: 0;
  transform: translateY(30px);
  transition: all 0.6s ease-out;
}

.section-transition.visible {
  opacity: 1;
  transform: translateY(0);
}

/* Staggered Section Animations */
.section-transition.delay-1 { transition-delay: 0.1s; }
.section-transition.delay-2 { transition-delay: 0.2s; }
.section-transition.delay-3 { transition-delay: 0.3s; }
.section-transition.delay-4 { transition-delay: 0.4s; }

/* ===================================
   MODERN BUTTON LOADING STATES
   =================================== */

/* Button Loading State */
.btn.loading {
  position: relative;
  color: transparent !important;
  pointer-events: none;
  cursor: not-allowed;
}

.btn.loading::after {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 20px;
  height: 20px;
  border: 2px solid rgba(255, 255, 255, 0.3);
  border-top: 2px solid var(--color-white);
  border-radius: 50%;
  animation: buttonSpin 1s linear infinite;
}

.btn-primary.loading::after {
  border-color: rgba(255, 255, 255, 0.3);
  border-top-color: var(--color-white);
}

.btn-secondary.loading::after {
  border-color: rgba(0, 102, 255, 0.3);
  border-top-color: var(--color-primary);
}

@keyframes buttonSpin {
  0% { transform: translate(-50%, -50%) rotate(0deg); }
  100% { transform: translate(-50%, -50%) rotate(360deg); }
}

/* Button Success State */
.btn.success {
  background-color: #10B981 !important;
  border-color: #10B981 !important;
  position: relative;
}

.btn.success::after {
  content: '✓';
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  color: var(--color-white);
  font-size: var(--font-size-lg);
  font-weight: var(--font-weight-bold);
}

.btn.success span {
  opacity: 0;
}

/* Button Error State */
.btn.error {
  background-color: #EF4444 !important;
  border-color: #EF4444 !important;
  animation: shake 0.5s ease-in-out;
}

@keyframes shake {
  0%, 100% { transform: translateX(0); }
  25% { transform: translateX(-5px); }
  75% { transform: translateX(5px); }
}

/* Download Button Loading */
.btn-download.loading {
  background: linear-gradient(135deg, var(--color-gray-400) 0%, var(--color-gray-500) 100%);
}

.btn-download.loading .fa-download {
  animation: downloadPulse 1s ease-in-out infinite;
}

@keyframes downloadPulse {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-3px); }
}

/* ===================================
   ERROR STATES & FALLBACKS
   =================================== */

/* Error Container */
.error-state {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: var(--space-8);
  text-align: center;
  background: var(--color-surface);
  border-radius: var(--radius-lg);
  border: 2px dashed var(--color-gray-300);
  margin: var(--space-4) 0;
}

.error-icon {
  width: 80px;
  height: 80px;
  background: linear-gradient(135deg, #EF4444 0%, #DC2626 100%);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: var(--space-4);
  animation: errorPulse 2s ease-in-out infinite;
}

.error-icon i {
  font-size: var(--font-size-2xl);
  color: var(--color-white);
}

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

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

.error-message {
  font-size: var(--font-size-base);
  color: var(--color-text-secondary);
  margin-bottom: var(--space-4);
  max-width: 400px;
}

.error-actions {
  display: flex;
  gap: var(--space-3);
  flex-wrap: wrap;
  justify-content: center;
}

/* Retry Button */
.btn-retry {
  background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-light) 100%);
  color: var(--color-white);
  border: none;
  padding: var(--space-2) var(--space-4);
  border-radius: var(--radius-base);
  font-weight: var(--font-weight-medium);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.btn-retry:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

/* Network Error State */
.network-error {
  background: linear-gradient(135deg, rgba(239, 68, 68, 0.1) 0%, rgba(220, 38, 38, 0.1) 100%);
  border-color: rgba(239, 68, 68, 0.3);
}

/* Loading Failed State */
.loading-failed {
  background: linear-gradient(135deg, rgba(245, 158, 11, 0.1) 0%, rgba(217, 119, 6, 0.1) 100%);
  border-color: rgba(245, 158, 11, 0.3);
}

.loading-failed .error-icon {
  background: linear-gradient(135deg, #F59E0B 0%, #D97706 100%);
}

/* ===================================
   CONTENT LOADING STATES
   =================================== */

/* Image Loading Placeholder */
.image-placeholder {
  background: var(--color-gray-200);
  border-radius: var(--radius-base);
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  overflow: hidden;
}

.image-placeholder::before {
  content: '';
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, 
    transparent 0%, 
    rgba(255, 255, 255, 0.4) 50%, 
    transparent 100%
  );
  animation: shimmer 1.5s ease-in-out infinite;
}

@keyframes shimmer {
  0% { left: -100%; }
  100% { left: 100%; }
}

.image-placeholder-icon {
  font-size: var(--font-size-2xl);
  color: var(--color-gray-400);
}

/* Form Loading States */
.form-loading {
  position: relative;
  pointer-events: none;
}

.form-loading::after {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(255, 255, 255, 0.8);
  backdrop-filter: blur(2px);
  -webkit-backdrop-filter: blur(2px);
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  justify-content: center;
}

/* ===================================
   RESPONSIVE LOADING STATES
   =================================== */

@media (max-width: 768px) {
  .page-loader {
    padding: var(--space-4);
  }
  
  .loading-spinner {
    width: 50px;
    height: 50px;
  }
  
  .loading-progress {
    width: 150px;
  }
  
  .error-state {
    padding: var(--space-6);
  }
  
  .error-icon {
    width: 60px;
    height: 60px;
  }
  
  .error-actions {
    flex-direction: column;
    width: 100%;
  }
  
  .btn-retry {
    width: 100%;
  }
}

@media (max-width: 480px) {
  .loading-text {
    font-size: var(--font-size-base);
  }
  
  .error-title {
    font-size: var(--font-size-lg);
  }
  
  .error-message {
    font-size: var(--font-size-sm);
  }
}

/* ===================================
   ACCESSIBILITY CONSIDERATIONS
   =================================== */

/* Respect reduced motion preferences */
@media (prefers-reduced-motion: reduce) {
  .loading-spinner,
  .loading-dot,
  .loading-progress-bar,
  .skeleton,
  .page-transition,
  .section-transition,
  .btn.loading::after,
  .error-icon,
  .image-placeholder::before {
    animation: none !important;
  }
  
  .page-transition {
    transition: none !important;
  }
  
  .section-transition {
    transition: opacity 0.3s ease-out !important;
    transform: none !important;
  }
}

/* High contrast mode support */
@media (prefers-contrast: high) {
  .skeleton {
    background: var(--color-gray-400);
  }
  
  .error-state {
    border-color: var(--color-gray-600);
    background: var(--color-white);
  }
  
  .image-placeholder {
    background: var(--color-gray-300);
    border: 2px solid var(--color-gray-600);
  }
}