/* ============================================
   Button 组件 - Button Component
   ============================================ */

/* ========== 基础按钮样式 ========== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-2);
  height: var(--height-btn);
  padding: 0 var(--spacing-4);
  font-size: var(--font-base);
  font-weight: var(--font-weight-medium);
  line-height: 1;
  border: none;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all var(--transition-fast);
  white-space: nowrap;
  user-select: none;
  -webkit-user-select: none;
  text-decoration: none;
  font-family: inherit;
}

.btn:not(:disabled):hover {
  transform: translateY(-1px);
}

.btn:not(:disabled):active {
  transform: scale(0.98);
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  transform: none !important;
}

/* ========== 主按钮 - Primary ========== */
.btn-primary {
  background: linear-gradient(135deg, var(--color-primary), var(--color-primary-dark));
  color: white;
  box-shadow: var(--shadow-sm);
}

.btn-primary:not(:disabled):hover {
  background: linear-gradient(135deg, var(--color-primary-dark), var(--color-primary-dark));
  box-shadow: var(--shadow-md);
}

/* ========== 次要按钮 - Secondary ========== */
.btn-secondary {
  background: transparent;
  color: var(--color-text-primary);
  border: 1px solid var(--color-border);
}

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

/* ========== 危险按钮 - Danger ========== */
.btn-danger {
  background: linear-gradient(135deg, var(--color-danger), var(--color-danger-dark));
  color: white;
  box-shadow: var(--shadow-sm);
}

.btn-danger:not(:disabled):hover {
  background: linear-gradient(135deg, var(--color-danger-dark), var(--color-danger-dark));
  box-shadow: var(--shadow-md);
}

/* ========== 成功按钮 - Success ========== */
.btn-success {
  background: linear-gradient(135deg, var(--color-success), var(--color-success-dark));
  color: white;
  box-shadow: var(--shadow-sm);
}

.btn-success:not(:disabled):hover {
  background: linear-gradient(135deg, var(--color-success-dark), var(--color-success-dark));
  box-shadow: var(--shadow-md);
}

/* ========== 警告按钮 - Warning ========== */
.btn-warning {
  background: linear-gradient(135deg, var(--color-warning), var(--color-warning-dark));
  color: white;
  box-shadow: var(--shadow-sm);
}

.btn-warning:not(:disabled):hover {
  background: linear-gradient(135deg, var(--color-warning-dark), var(--color-warning-dark));
  box-shadow: var(--shadow-md);
}

/* ========== 幽灵按钮 - Ghost ========== */
.btn-ghost {
  background: transparent;
  color: var(--color-text-secondary);
}

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

/* ========== 图标按钮 - Icon Button ========== */
.btn-icon {
  width: var(--height-btn);
  padding: 0;
}

.btn-icon-sm {
  width: var(--height-btn-sm);
  height: var(--height-btn-sm);
  padding: 0;
}

/* ========== 尺寸变体 - Sizes ========== */
.btn-sm {
  height: var(--height-btn-sm);
  padding: 0 var(--spacing-3);
  font-size: var(--font-sm);
}

.btn-lg {
  height: var(--height-btn-lg);
  padding: 0 var(--spacing-6);
  font-size: var(--font-lg);
}

/* ========== 块级按钮 - Block ========== */
.btn-block {
  width: 100%;
}

/* ========== 按钮组 - Button Group ========== */
.btn-group {
  display: inline-flex;
}

.btn-group .btn {
  border-radius: 0;
}

.btn-group .btn:first-child {
  border-radius: var(--radius-md) 0 0 var(--radius-md);
}

.btn-group .btn:last-child {
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
}

.btn-group .btn:not(:last-child) {
  border-right: 1px solid var(--color-border-light);
}

/* ========== 文字按钮 - Text Button ========== */
.btn-text {
  background: transparent;
  color: var(--color-primary);
  padding: 0 var(--spacing-2);
  height: auto;
}

.btn-text:not(:disabled):hover {
  color: var(--color-primary-dark);
  background: var(--color-primary-alpha-10);
}

/* ========== 加载状态 - Loading ========== */
.btn-loading {
  position: relative;
  color: transparent !important;
  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 transparent;
  border-top-color: currentColor;
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
  color: white;
}

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

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