/**
 * Button Component
 * 統一されたボタンシステム
 */

/* ========================================
   Base Button Styles
   ======================================== */

.btn {
  /* Layout */
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);

  /* Typography */
  font-family: var(--font-family-primary);
  font-size: var(--font-size-base);
  font-weight: var(--font-weight-medium);
  line-height: var(--line-height-tight);
  text-decoration: none;
  white-space: nowrap;

  /* Spacing & Sizing */
  padding: var(--button-padding-base);
  min-height: var(--size-11); /* 44px for accessibility */

  /* Appearance */
  border: 1px solid transparent;
  border-radius: var(--button-radius-base);
  cursor: pointer;
  user-select: none;

  /* Transitions */
  transition: var(--transition-colors), var(--transition-shadow), var(--transition-transform);

  /* Focus */
  outline: none;
}

.btn:focus-visible {
  box-shadow: var(--button-focus-ring);
  outline: 2px solid transparent;
  outline-offset: 2px;
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  pointer-events: none;
}

/* ========================================
   Button Variants
   ======================================== */

/* Primary Button */
.btn-primary {
  background-color: var(--color-primary-500);
  color: var(--color-neutral-0);
  border-color: var(--color-primary-500);
}

.btn-primary:hover:not(:disabled) {
  background-color: var(--color-primary-600);
  border-color: var(--color-primary-600);
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}

.btn-primary:active:not(:disabled) {
  background-color: var(--color-primary-700);
  border-color: var(--color-primary-700);
  transform: translateY(0);
  box-shadow: var(--shadow-sm);
}

/* Secondary Button */
.btn-secondary {
  background-color: var(--color-secondary-500);
  color: var(--color-neutral-0);
  border-color: var(--color-secondary-500);
}

.btn-secondary:hover:not(:disabled) {
  background-color: var(--color-secondary-600);
  border-color: var(--color-secondary-600);
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}

.btn-secondary:active:not(:disabled) {
  background-color: var(--color-secondary-700);
  border-color: var(--color-secondary-700);
  transform: translateY(0);
  box-shadow: var(--shadow-sm);
}

/* Outline Button */
.btn-outline {
  background-color: transparent;
  color: var(--color-primary-500);
  border-color: var(--color-primary-500);
}

.btn-outline:hover:not(:disabled) {
  background-color: var(--color-primary-50);
  transform: translateY(-1px);
  box-shadow: var(--shadow-sm);
}

.btn-outline:active:not(:disabled) {
  background-color: var(--color-primary-100);
  transform: translateY(0);
}

/* Ghost Button */
.btn-ghost {
  background-color: transparent;
  color: var(--color-neutral-700);
  border-color: transparent;
}

.btn-ghost:hover:not(:disabled) {
  background-color: var(--color-neutral-100);
  transform: translateY(-1px);
}

.btn-ghost:active:not(:disabled) {
  background-color: var(--color-neutral-200);
  transform: translateY(0);
}

/* Link Button */
.btn-link {
  background-color: transparent;
  color: var(--color-primary-500);
  border-color: transparent;
  text-decoration: underline;
  text-underline-offset: 2px;
}

.btn-link:hover:not(:disabled) {
  color: var(--color-primary-600);
  text-decoration-thickness: 2px;
}

.btn-link:active:not(:disabled) {
  color: var(--color-primary-700);
}

/* ========================================
   Button Sizes
   ======================================== */

.btn-sm {
  padding: var(--button-padding-sm);
  font-size: var(--font-size-sm);
  min-height: var(--size-8); /* 32px */
}

.btn-lg {
  padding: var(--button-padding-lg);
  font-size: var(--font-size-lg);
  min-height: var(--size-12); /* 48px */
}

.btn-xl {
  padding: var(--space-4) var(--space-10);
  font-size: var(--font-size-xl);
  min-height: var(--size-14); /* 56px */
}

/* ========================================
   Button States
   ======================================== */

/* Success State */
.btn-success {
  background-color: var(--color-success-500);
  color: var(--color-neutral-0);
  border-color: var(--color-success-500);
}

.btn-success:hover:not(:disabled) {
  background-color: var(--color-success-600);
  border-color: var(--color-success-600);
}

/* Warning State */
.btn-warning {
  background-color: var(--color-warning-500);
  color: var(--color-neutral-0);
  border-color: var(--color-warning-500);
}

.btn-warning:hover:not(:disabled) {
  background-color: var(--color-warning-600);
  border-color: var(--color-warning-600);
}

/* Error/Danger State */
.btn-error,
.btn-danger {
  background-color: var(--color-error-500);
  color: var(--color-neutral-0);
  border-color: var(--color-error-500);
}

.btn-error:hover:not(:disabled),
.btn-danger:hover:not(:disabled) {
  background-color: var(--color-error-600);
  border-color: var(--color-error-600);
}

/* ========================================
   Button Modifiers
   ======================================== */

/* Block Button */
.btn-block {
  width: 100%;
  justify-content: center;
}

/* Icon Only Button */
.btn-icon {
  padding: var(--space-3);
  min-width: var(--size-11);
}

.btn-icon.btn-sm {
  padding: var(--space-2);
  min-width: var(--size-8);
}

.btn-icon.btn-lg {
  padding: var(--space-4);
  min-width: var(--size-12);
}

/* Rounded Button */
.btn-rounded {
  border-radius: var(--radius-full);
}

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

.btn-loading::after {
  content: "";
  position: absolute;
  top: 50%;
  left: 50%;
  width: 1rem;
  height: 1rem;
  margin: -0.5rem 0 0 -0.5rem;
  border: 2px solid;
  border-color: transparent currentColor currentColor transparent;
  border-radius: 50%;
  animation: btn-spin 1s linear infinite;
}

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

/* ========================================
   Button Groups
   ======================================== */

.btn-group {
  display: inline-flex;
  align-items: center;
  vertical-align: middle;
}

.btn-group .btn {
  position: relative;
  flex: 1 1 auto;
}

.btn-group .btn:not(:first-child) {
  margin-left: -1px;
  border-top-left-radius: 0;
  border-bottom-left-radius: 0;
}

.btn-group .btn:not(:last-child) {
  border-top-right-radius: 0;
  border-bottom-right-radius: 0;
}

.btn-group .btn:hover,
.btn-group .btn:focus {
  z-index: 1;
}

/* ========================================
   Responsive Modifications
   ======================================== */

/* Mobile Optimizations */
@media (max-width: 767px) {
  .btn-mobile-block {
    width: 100%;
    justify-content: center;
  }

  .btn-mobile-sm {
    padding: var(--button-padding-sm);
    font-size: var(--font-size-sm);
  }

  /* Ensure minimum touch target size */
  .btn {
    min-height: var(--size-11); /* 44px minimum for touch */
  }
}

/* ========================================
   Dark Mode Support
   ======================================== */

@media (prefers-color-scheme: dark) {
  .btn-ghost {
    color: var(--color-neutral-300);
  }

  .btn-ghost:hover:not(:disabled) {
    background-color: var(--color-neutral-800);
  }

  .btn-ghost:active:not(:disabled) {
    background-color: var(--color-neutral-700);
  }
}

/* ========================================
   Accessibility Enhancements
   ======================================== */

/* High contrast mode support */
@media (prefers-contrast: high) {
  .btn {
    border-width: 2px;
  }

  .btn-outline {
    border-width: 2px;
  }
}

/* Reduced motion support */
@media (prefers-reduced-motion: reduce) {
  .btn {
    transition: none;
  }

  .btn:hover {
    transform: none;
  }

  .btn-loading::after {
    animation: none;
  }
}