/**
 * Button Components - Mindeck Platform
 * Reusable button styles with variants, sizes, and states
 * Requirements: 5.1, 6.1, 6.2, 6.3
 */

/* ============================================
   BASE BUTTON STYLES
   ============================================ */

.btn {
  /* Layout */
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  
  /* Typography */
  font-family: var(--font-family-sans);
  font-weight: var(--font-weight-medium);
  text-decoration: none;
  white-space: nowrap;
  
  /* Borders and spacing */
  border: none;
  border-radius: var(--radius-md);
  cursor: pointer;
  
  /* Transitions for smooth state changes */
  transition: 
    background-color var(--transition-base),
    color var(--transition-base),
    border-color var(--transition-base),
    box-shadow var(--transition-base),
    transform var(--transition-fast);
  
  /* Prevent text selection */
  user-select: none;
  -webkit-user-select: none;
  
  /* Accessibility */
  outline: none;
}

/* Remove default button styles */
.btn::-moz-focus-inner {
  border: 0;
  padding: 0;
}

/* ============================================
   BUTTON VARIANTS
   ============================================ */

/* Primary Button - Main call-to-action */
.btn-primary {
  background-color: var(--interactive-primary);
  color: var(--text-inverse);
  box-shadow: var(--shadow-sm);
}

.btn-primary:hover:not(:disabled) {
  background-color: var(--interactive-primary-hover);
  box-shadow: var(--shadow-md);
  transform: translateY(-1px);
}

.btn-primary:active:not(:disabled) {
  background-color: var(--interactive-primary-active);
  box-shadow: var(--shadow-sm);
  transform: translateY(0);
}

.btn-primary:focus-visible {
  box-shadow: var(--shadow-focus);
}

/* Secondary Button - Secondary actions */
.btn-secondary {
  background-color: transparent;
  color: var(--interactive-primary);
  border: 2px solid var(--interactive-primary);
}

.btn-secondary:hover:not(:disabled) {
  background-color: var(--color-primary-50);
  border-color: var(--interactive-primary-hover);
  color: var(--interactive-primary-hover);
}

.btn-secondary:active:not(:disabled) {
  background-color: var(--color-primary-100);
  border-color: var(--interactive-primary-active);
  color: var(--interactive-primary-active);
}

.btn-secondary:focus-visible {
  box-shadow: var(--shadow-focus);
}

/* Dark mode adjustments for secondary button */
[data-theme="dark"] .btn-secondary:hover:not(:disabled) {
  background-color: rgba(33, 150, 243, 0.1);
}

[data-theme="dark"] .btn-secondary:active:not(:disabled) {
  background-color: rgba(33, 150, 243, 0.2);
}

/* Tertiary Button - Subtle actions */
.btn-tertiary {
  background-color: transparent;
  color: var(--text-secondary);
  border: none;
}

.btn-tertiary:hover:not(:disabled) {
  background-color: var(--bg-tertiary);
  color: var(--text-primary);
}

.btn-tertiary:active:not(:disabled) {
  background-color: var(--border-primary);
  color: var(--text-primary);
}

.btn-tertiary:focus-visible {
  box-shadow: var(--shadow-focus);
}

/* ============================================
   BUTTON SIZES
   ============================================ */

/* Small Button */
.btn-sm {
  padding: var(--space-2) var(--space-4);
  font-size: var(--font-size-sm);
  line-height: var(--line-height-tight);
  min-height: 32px;
}

/* Medium Button (Default) */
.btn-md,
.btn {
  padding: var(--space-3) var(--space-6);
  font-size: var(--font-size-base);
  line-height: var(--line-height-normal);
  min-height: 40px;
}

/* Large Button */
.btn-lg {
  padding: var(--space-4) var(--space-8);
  font-size: var(--font-size-md);
  line-height: var(--line-height-normal);
  min-height: 48px;
}

/* ============================================
   BUTTON STATES
   ============================================ */

/* Disabled State */
.btn:disabled,
.btn.disabled {
  opacity: 0.5;
  cursor: not-allowed;
  pointer-events: none;
}

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

.btn.loading::after {
  content: "";
  position: absolute;
  width: 16px;
  height: 16px;
  top: 50%;
  left: 50%;
  margin-left: -8px;
  margin-top: -8px;
  border: 2px solid currentColor;
  border-radius: 50%;
  border-top-color: transparent;
  animation: btn-spin 0.6s linear infinite;
  color: var(--text-inverse);
}

.btn-secondary.loading::after,
.btn-tertiary.loading::after {
  color: var(--interactive-primary);
}

@keyframes btn-spin {
  to {
    transform: rotate(360deg);
  }
}

/* ============================================
   BUTTON GROUPS
   ============================================ */

.btn-group {
  display: inline-flex;
  gap: var(--space-2);
}

.btn-group .btn {
  flex: 0 1 auto;
}

/* Attached button group (no gap) */
.btn-group-attached {
  display: inline-flex;
}

.btn-group-attached .btn {
  border-radius: 0;
  margin-left: -1px;
}

.btn-group-attached .btn:first-child {
  border-top-left-radius: var(--radius-md);
  border-bottom-left-radius: var(--radius-md);
  margin-left: 0;
}

.btn-group-attached .btn:last-child {
  border-top-right-radius: var(--radius-md);
  border-bottom-right-radius: var(--radius-md);
}

/* ============================================
   BUTTON WITH ICONS
   ============================================ */

.btn-icon {
  padding: var(--space-3);
  min-width: 40px;
}

.btn-icon.btn-sm {
  padding: var(--space-2);
  min-width: 32px;
}

.btn-icon.btn-lg {
  padding: var(--space-4);
  min-width: 48px;
}

/* Icon within button */
.btn svg,
.btn img {
  width: 1em;
  height: 1em;
  flex-shrink: 0;
}

/* ============================================
   FULL WIDTH BUTTON
   ============================================ */

.btn-block {
  display: flex;
  width: 100%;
}

/* ============================================
   SEMANTIC BUTTON VARIANTS
   ============================================ */

/* Success Button */
.btn-success {
  background-color: var(--color-success-500);
  color: var(--text-inverse);
  box-shadow: var(--shadow-sm);
}

.btn-success:hover:not(:disabled) {
  background-color: var(--color-success-700);
  box-shadow: var(--shadow-md);
  transform: translateY(-1px);
}

.btn-success:active:not(:disabled) {
  box-shadow: var(--shadow-sm);
  transform: translateY(0);
}

.btn-success:focus-visible {
  box-shadow: 0 0 0 3px rgba(76, 175, 80, 0.3);
}

/* Warning Button */
.btn-warning {
  background-color: var(--color-warning-500);
  color: var(--text-inverse);
  box-shadow: var(--shadow-sm);
}

.btn-warning:hover:not(:disabled) {
  background-color: var(--color-warning-700);
  box-shadow: var(--shadow-md);
  transform: translateY(-1px);
}

.btn-warning:active:not(:disabled) {
  box-shadow: var(--shadow-sm);
  transform: translateY(0);
}

.btn-warning:focus-visible {
  box-shadow: 0 0 0 3px rgba(255, 152, 0, 0.3);
}

/* Error/Danger Button */
.btn-error,
.btn-danger {
  background-color: var(--color-error-500);
  color: var(--text-inverse);
  box-shadow: var(--shadow-sm);
}

.btn-error:hover:not(:disabled),
.btn-danger:hover:not(:disabled) {
  background-color: var(--color-error-700);
  box-shadow: var(--shadow-md);
  transform: translateY(-1px);
}

.btn-error:active:not(:disabled),
.btn-danger:active:not(:disabled) {
  box-shadow: var(--shadow-sm);
  transform: translateY(0);
}

.btn-error:focus-visible,
.btn-danger:focus-visible {
  box-shadow: 0 0 0 3px rgba(244, 67, 54, 0.3);
}

/* ============================================
   ACCESSIBILITY ENHANCEMENTS
   ============================================ */

/* High contrast mode support */
@media (prefers-contrast: high) {
  .btn {
    border: 2px solid currentColor;
  }
  
  .btn-primary,
  .btn-success,
  .btn-warning,
  .btn-error,
  .btn-danger {
    border-color: transparent;
  }
}

/* Reduced motion support */
@media (prefers-reduced-motion: reduce) {
  .btn {
    transition: none;
  }
  
  .btn:hover:not(:disabled) {
    transform: none;
  }
  
  .btn.loading::after {
    animation: none;
    border-top-color: currentColor;
    opacity: 0.5;
  }
}

/* Focus visible for keyboard navigation */
.btn:focus-visible {
  outline: 2px solid var(--border-focus);
  outline-offset: 2px;
}

/* ============================================
   RESPONSIVE ADJUSTMENTS
   ============================================ */

@media (max-width: 767px) {
  /* Slightly larger touch targets on mobile */
  .btn {
    min-height: 44px;
  }
  
  .btn-sm {
    min-height: 36px;
  }
  
  .btn-lg {
    min-height: 52px;
  }
}