/**
 * SP低空履约平台 - 无障碍样式系统
 * 基于 WCAG 2.1 AA 标准
 * 
 * 本文件定义所有无障碍相关样式，包括：
 * - 键盘焦点样式
 * - 屏幕阅读器辅助类
 * - 高对比度模式支持
 * - 减少动画偏好支持
 * - 焦点可见性增强
 * 
 * Requirements: 14.1-14.6
 */

/* ========================================
 * 屏幕阅读器辅助类 - Screen Reader Utilities
 * Requirements: 14.1
 * ======================================== */

/* 仅对屏幕阅读器可见的内容 */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* 聚焦时可见（跳过链接等） */
.sr-only-focusable:focus,
.sr-only-focusable:active {
  position: static;
  width: auto;
  height: auto;
  padding: inherit;
  margin: inherit;
  overflow: visible;
  clip: auto;
  white-space: normal;
}

/* 跳过导航链接 */
.skip-link {
  position: absolute;
  top: -100%;
  left: var(--spacing-4);
  z-index: calc(var(--z-fixed) + 100);
  padding: var(--spacing-3) var(--spacing-4);
  background-color: var(--color-primary);
  color: var(--color-text-inverse);
  font-weight: var(--font-weight-medium);
  text-decoration: none;
  border-radius: var(--radius-sm);
  box-shadow: var(--shadow-4);
  transition: top 200ms var(--easing-standard);
}

.skip-link:focus {
  top: var(--spacing-4);
  outline: 2px solid var(--color-text-inverse);
  outline-offset: 2px;
}

/* ========================================
 * 键盘焦点样式 - Keyboard Focus Styles
 * Requirements: 14.2, 14.3
 * ======================================== */

/* 全局焦点样式重置 */
*:focus {
  outline: none;
}

/* 键盘焦点可见样式（仅键盘导航时显示） */
*:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

/* 按钮焦点样式 */
.btn:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
  box-shadow: 0 0 0 4px var(--color-primary-hover);
}

.btn-primary:focus-visible {
  outline-color: var(--color-text-inverse);
  box-shadow: 0 0 0 4px rgba(26, 115, 232, 0.4);
}

/* 输入框焦点样式 */
.form-input:focus-visible,
.form-select:focus-visible,
.form-textarea:focus-visible {
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px var(--color-primary-hover);
}

/* 复选框和单选框焦点样式 */
.form-checkbox input:focus-visible + .checkbox-box,
.form-radio input:focus-visible + .radio-circle {
  box-shadow: 0 0 0 4px var(--color-primary-hover);
}

/* 开关焦点样式 */
.form-switch input:focus-visible + .switch-track {
  box-shadow: 0 0 0 4px var(--color-primary-hover);
}

/* 链接焦点样式 */
a:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
  border-radius: var(--radius-sm);
}

/* 导航项焦点样式 */
.nav-item:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: -2px;
  background-color: var(--color-primary-hover);
}

/* 卡片焦点样式 */
.card:focus-visible,
.feature-card:focus-visible,
.stat-card:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
  box-shadow: var(--shadow-4);
}

/* 表格行焦点样式 */
.data-table tbody tr:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: -2px;
  background-color: var(--color-primary-hover);
}

/* 芯片焦点样式 */
.chip:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

/* 图标按钮焦点样式 */
.icon-btn:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
  background-color: var(--color-primary-hover);
  border-radius: var(--radius-full);
}

/* 下拉菜单项焦点样式 */
.dropdown-item:focus-visible {
  outline: none;
  background-color: var(--color-primary-hover);
}

/* 标签页焦点样式 */
.tab-item:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: -2px;
}

/* 时间线项焦点样式 */
.timeline-item:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

/* ========================================
 * 高对比度模式支持 - High Contrast Mode
 * Requirements: 14.4
 * ======================================== */

@media (prefers-contrast: high) {
  :root {
    /* 增强文字对比度 */
    --color-text-primary: #000000;
    --color-text-secondary: #333333;
    --color-text-disabled: #666666;
    
    /* 增强边框对比度 */
    --color-border: #000000;
    --color-border-light: #333333;
    
    /* 增强背景对比度 */
    --color-bg-secondary: #F0F0F0;
    --color-bg-tertiary: #E0E0E0;
  }
  
  /* 增强按钮边框 */
  .btn {
    border: 2px solid currentColor;
  }
  
  .btn-primary {
    border-color: var(--color-primary-dark);
  }
  
  /* 增强输入框边框 */
  .form-input,
  .form-select,
  .form-textarea {
    border-width: 2px;
  }
  
  /* 增强焦点样式 */
  *:focus-visible {
    outline-width: 3px;
  }
  
  /* 增强链接下划线 */
  a {
    text-decoration: underline;
  }
  
  /* 增强状态徽章边框 */
  .status-badge {
    border: 1px solid currentColor;
  }
  
  /* 增强卡片边框 */
  .card {
    border: 1px solid var(--color-border);
  }
}

/* Windows 高对比度模式 */
@media (forced-colors: active) {
  .btn {
    border: 2px solid ButtonText;
  }
  
  .btn-primary {
    background-color: Highlight;
    color: HighlightText;
    border-color: Highlight;
  }
  
  .btn-primary:hover {
    background-color: HighlightText;
    color: Highlight;
  }
  
  .form-input,
  .form-select,
  .form-textarea {
    border: 2px solid ButtonText;
  }
  
  .form-input:focus,
  .form-select:focus,
  .form-textarea:focus {
    border-color: Highlight;
  }
  
  *:focus-visible {
    outline: 3px solid Highlight;
  }
  
  .nav-item.active {
    border-left: 3px solid Highlight;
  }
  
  .status-badge {
    border: 1px solid currentColor;
  }
}

/* ========================================
 * 减少动画偏好支持 - Reduced Motion
 * Requirements: 14.5
 * ======================================== */

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
  
  /* 禁用骨架屏动画 */
  .skeleton-animated::after {
    animation: none;
  }
  
  /* 禁用加载动画 */
  .loading-spinner-element {
    animation: none;
    border-top-color: var(--color-primary);
    border-right-color: var(--color-primary);
  }
  
  .loading-dot {
    animation: none;
    opacity: 1;
    transform: scale(1);
  }
  
  .loading-bar-element::after {
    animation: none;
    width: 100%;
    transform: none;
  }
  
  /* 禁用涟漪效果 */
  .ripple {
    animation: none;
    display: none;
  }
  
  /* 禁用图表动画 */
  .chart-animated .chart-bar {
    animation: none;
    height: var(--bar-percent, 0%);
  }
  
  .chart-animated .chart-line-path {
    animation: none;
    stroke-dasharray: none;
    stroke-dashoffset: 0;
  }
  
  .chart-animated .chart-line-area {
    animation: none;
    opacity: 1;
  }
  
  .chart-animated .chart-line-dot {
    animation: none;
    opacity: 1;
  }
  
  /* 禁用进度条动画 */
  .progress-indeterminate .progress-bar {
    animation: none;
    width: 100%;
    transform: none;
  }
}

/* ========================================
 * 表单无障碍增强 - Form Accessibility
 * Requirements: 14.6
 * ======================================== */

/* 必填字段标记 */
.form-field.required .form-label::after {
  content: ' *';
  color: var(--color-error);
}

/* 错误状态增强 */
.form-field.has-error .form-input,
.form-field.has-error .form-select,
.form-field.has-error .form-textarea {
  border-color: var(--color-error);
  background-color: rgba(234, 67, 53, 0.02);
}

.form-field.has-error .form-input:focus,
.form-field.has-error .form-select:focus,
.form-field.has-error .form-textarea:focus {
  box-shadow: 0 0 0 3px rgba(234, 67, 53, 0.2);
}

/* 错误消息样式 */
.form-error {
  display: flex;
  align-items: center;
  gap: var(--spacing-1);
  margin-top: var(--spacing-1);
  padding-left: var(--spacing-4);
  font-size: var(--font-size-sm);
  color: var(--color-error);
}

.form-error::before {
  content: '[!]';
  font-weight: var(--font-weight-bold);
}

/* 成功状态增强 */
.form-field.has-success .form-input,
.form-field.has-success .form-select,
.form-field.has-success .form-textarea {
  border-color: var(--color-success);
  background-color: rgba(52, 168, 83, 0.02);
}

/* 禁用状态增强 */
.form-field.disabled {
  opacity: 0.6;
  cursor: not-allowed;
}

.form-field.disabled .form-label {
  color: var(--color-text-disabled);
}

/* 表单组标题 */
fieldset {
  border: none;
  padding: 0;
  margin: 0 0 var(--spacing-6);
}

legend {
  font-size: var(--font-size-md);
  font-weight: var(--font-weight-medium);
  color: var(--color-text-primary);
  margin-bottom: var(--spacing-4);
  padding: 0;
}

/* ========================================
 * 交互元素无障碍增强 - Interactive Elements
 * Requirements: 14.1, 14.2
 * ======================================== */

/* 确保所有交互元素有足够的点击区域（最小 44x44px） */
.btn,
.icon-btn,
.nav-item,
.dropdown-item,
.chip.clickable {
  min-height: 44px;
  min-width: 44px;
}

.btn-sm {
  min-height: 36px;
  min-width: 36px;
}

/* 图标按钮点击区域扩展 */
.icon-btn {
  position: relative;
}

.icon-btn::before {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  width: 44px;
  height: 44px;
  border-radius: var(--radius-full);
}

/* 链接可访问性增强 */
a:not(.btn):not(.nav-item):not(.feature-card) {
  text-decoration: underline;
  text-underline-offset: 2px;
}

a:not(.btn):not(.nav-item):not(.feature-card):hover {
  text-decoration-thickness: 2px;
}

/* ========================================
 * 颜色对比度增强 - Color Contrast
 * Requirements: 14.4
 * ======================================== */

/* 确保文字颜色对比度符合 WCAG AA 标准 (4.5:1) */
.text-on-primary {
  color: var(--color-text-inverse);
}

.text-on-success {
  color: var(--color-text-inverse);
}

.text-on-error {
  color: var(--color-text-inverse);
}

.text-on-warning {
  color: var(--color-text-primary);
}

/* 状态指示器增强（不仅依赖颜色） */
.status-indicator {
  display: inline-flex;
  align-items: center;
  gap: var(--spacing-1);
}

.status-indicator::before {
  content: '';
  width: 8px;
  height: 8px;
  border-radius: var(--radius-full);
  flex-shrink: 0;
}

.status-indicator.online::before {
  background-color: var(--color-success);
}

.status-indicator.offline::before {
  background-color: var(--color-text-disabled);
}

.status-indicator.error::before {
  background-color: var(--color-error);
}

.status-indicator.warning::before {
  background-color: var(--color-warning);
}

/* 为状态添加文字标签（不仅依赖颜色） */
.status-badge::before {
  content: '';
  width: 6px;
  height: 6px;
  border-radius: var(--radius-full);
  background-color: currentColor;
  flex-shrink: 0;
}

/* ========================================
 * 实时区域 - Live Regions
 * Requirements: 14.1
 * ======================================== */

/* 实时通知区域 */
[aria-live="polite"],
[aria-live="assertive"] {
  position: relative;
}

/* 状态消息容器 */
.status-message {
  padding: var(--spacing-3) var(--spacing-4);
  border-radius: var(--radius-sm);
  font-size: var(--font-size-base);
}

.status-message-success {
  background-color: rgba(52, 168, 83, 0.1);
  color: var(--color-success-dark);
  border-left: 3px solid var(--color-success);
}

.status-message-error {
  background-color: rgba(234, 67, 53, 0.1);
  color: var(--color-error-dark);
  border-left: 3px solid var(--color-error);
}

.status-message-warning {
  background-color: rgba(251, 188, 4, 0.1);
  color: var(--color-warning-dark);
  border-left: 3px solid var(--color-warning);
}

.status-message-info {
  background-color: rgba(66, 133, 244, 0.1);
  color: var(--color-info-dark);
  border-left: 3px solid var(--color-info);
}

/* ========================================
 * 打印样式 - Print Styles
 * ======================================== */

@media print {
  /* 隐藏非必要元素 */
  .top-nav,
  .side-nav,
  .sidebar-overlay,
  .skip-link,
  .btn,
  .snackbar-container,
  .dialog-overlay {
    display: none !important;
  }
  
  /* 调整主内容区域 */
  .main-content {
    margin: 0 !important;
    padding: 0 !important;
  }
  
  /* 确保链接显示 URL */
  a[href]::after {
    content: ' (' attr(href) ')';
    font-size: var(--font-size-sm);
    color: var(--color-text-secondary);
  }
  
  a[href^="#"]::after,
  a[href^="javascript:"]::after {
    content: '';
  }
  
  /* 避免分页问题 */
  .card,
  .stat-card,
  .feature-card,
  table {
    break-inside: avoid;
  }
  
  /* 确保背景色打印 */
  .status-badge,
  .chip,
  .badge {
    -webkit-print-color-adjust: exact;
    print-color-adjust: exact;
  }
}