# 🎨 Card Component Design
**Component: Card | Priority: HIGH | Status: ⚠️ Needs Enhancement**

## 📋 Component Overview

The Card component is a **fundamental layout component** with a **good foundation** but needs **enhancement** for accessibility and comprehensive testing. This is a **Priority 1** component requiring attention.

### **Current Status**
- ✅ **Basic structure exists** and is well-implemented
- ✅ **CSS class constants** properly defined
- ✅ **Component composition** working correctly
- ⚠️ **~40% test coverage** (estimated)
- ⚠️ **Missing accessibility features**
- ⚠️ **Missing comprehensive integration tests**
- ⚠️ **Missing interactive card tests**

---

## 🎯 Design Specifications

### **Visual Design**
```css
/* Card Container */
.card {
  border-radius: 0.5rem;
  border: 1px solid hsl(var(--border));
  background-color: hsl(var(--card));
  color: hsl(var(--card-foreground));
  box-shadow: 0 1px 2px 0 rgb(0 0 0 / 0.05);
}

/* Card Header */
.card-header {
  display: flex;
  flex-direction: column;
  gap: 0.375rem;
  padding: 1.5rem;
}

/* Card Title */
.card-title {
  font-size: 1.5rem;
  font-weight: 600;
  line-height: 1;
  letter-spacing: -0.025em;
}

/* Card Description */
.card-description {
  font-size: 0.875rem;
  color: hsl(var(--muted-foreground));
}

/* Card Content */
.card-content {
  padding: 1.5rem;
  padding-top: 0;
}

/* Card Footer */
.card-footer {
  display: flex;
  align-items: center;
  padding: 1.5rem;
  padding-top: 0;
}

/* Interactive Card States */
.card:hover {
  box-shadow: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
}

.card:focus-within {
  outline: 2px solid hsl(var(--ring));
  outline-offset: 2px;
}

/* Card Variants */
.card-destructive {
  border-color: hsl(var(--destructive));
  background-color: hsl(var(--destructive) / 0.05);
}

.card-warning {
  border-color: hsl(var(--warning));
  background-color: hsl(var(--warning) / 0.05);
}

.card-success {
  border-color: hsl(var(--success));
  background-color: hsl(var(--success) / 0.05);
}
```

### **Animation Keyframes**
```css
@keyframes card-fade-in {
  from {
    opacity: 0;
    transform: translateY(10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes card-scale-hover {
  from {
    transform: scale(1);
  }
  to {
    transform: scale(1.02);
  }
}

.card {
  animation: card-fade-in 0.2s ease-out;
}

.card:hover {
  animation: card-scale-hover 0.2s ease-out;
}
```

---

## 🔧 API Design

### **Card Root Component**
```rust
#[component]
pub fn Card(
    #[prop(into, optional)] class: MaybeProp<String>,
    #[prop(into, optional)] id: MaybeProp<String>,
    #[prop(into, optional)] style: Signal<Style>,
    #[prop(into, optional)] variant: MaybeProp<CardVariant>,
    #[prop(into, optional)] interactive: Signal<bool>,
    #[prop(optional)] children: Option<Children>,
) -> impl IntoView
```

### **Card Header Component**
```rust
#[component]
pub fn CardHeader(
    #[prop(into, optional)] class: MaybeProp<String>,
    #[prop(into, optional)] id: MaybeProp<String>,
    #[prop(into, optional)] style: Signal<Style>,
    #[prop(optional)] children: Option<Children>,
) -> impl IntoView
```

### **Card Title Component**
```rust
#[component]
pub fn CardTitle(
    #[prop(into, optional)] class: MaybeProp<String>,
    #[prop(into, optional)] id: MaybeProp<String>,
    #[prop(into, optional)] style: Signal<Style>,
    #[prop(into, optional)] level: MaybeProp<u8>, // h1, h2, h3, etc.
    #[prop(optional)] children: Option<Children>,
) -> impl IntoView
```

### **Card Description Component**
```rust
#[component]
pub fn CardDescription(
    #[prop(into, optional)] class: MaybeProp<String>,
    #[prop(into, optional)] id: MaybeProp<String>,
    #[prop(into, optional)] style: Signal<Style>,
    #[prop(optional)] children: Option<Children>,
) -> impl IntoView
```

### **Card Content Component**
```rust
#[component]
pub fn CardContent(
    #[prop(into, optional)] class: MaybeProp<String>,
    #[prop(into, optional)] id: MaybeProp<String>,
    #[prop(into, optional)] style: Signal<Style>,
    #[prop(optional)] children: Option<Children>,
) -> impl IntoView
```

### **Card Footer Component**
```rust
#[component]
pub fn CardFooter(
    #[prop(into, optional)] class: MaybeProp<String>,
    #[prop(into, optional)] id: MaybeProp<String>,
    #[prop(into, optional)] style: Signal<Style>,
    #[prop(optional)] children: Option<Children>,
) -> impl IntoView
```

---

## ♿ Accessibility Features

### **ARIA Attributes**
- `role="article"` on card element for semantic meaning
- `aria-labelledby` linking to card title
- `aria-describedby` linking to card description
- `tabindex="0"` for interactive cards
- `aria-expanded` for collapsible cards

### **Keyboard Navigation**
- **Tab**: Navigate to interactive cards
- **Enter/Space**: Activate interactive cards
- **Arrow Keys**: Navigate between card sections (if applicable)

### **Focus Management**
- Visible focus indicators for interactive cards
- Focus trapping within modal cards
- Focus restoration after card interactions

### **Screen Reader Support**
- Card title announced when focused
- Card description provided as context
- Interactive state communicated
- Content structure clearly defined

---

## 🧪 Testing Requirements

### **Current Test Status**
- ✅ **Basic CSS class tests** implemented
- ✅ **Styling consistency tests** working
- ⚠️ **Missing component rendering tests**
- ⚠️ **Missing accessibility tests**
- ⚠️ **Missing integration tests**
- ⚠️ **Missing interactive card tests**

### **Required Test Categories**

#### **1. Component Rendering Tests**
```rust
#[test]
fn test_card_renders_without_errors() {
    let card = Card::new(CardProps {
        children: Some(Children::new()),
        ..Default::default()
    });
    
    let rendered = card.render();
    assert!(rendered.contains("card"));
}

#[test]
fn test_card_with_all_sections() {
    let card = Card::new(CardProps {
        children: Some(Children::new()),
        ..Default::default()
    });
    
    let rendered = card.render();
    assert!(rendered.contains("card-header"));
    assert!(rendered.contains("card-content"));
    assert!(rendered.contains("card-footer"));
}
```

#### **2. Accessibility Tests**
```rust
#[test]
fn test_card_aria_attributes() {
    let card = Card::new(CardProps {
        interactive: Signal::derive(|| true),
        ..Default::default()
    });
    
    let rendered = card.render();
    assert!(rendered.contains("role=\"article\""));
    assert!(rendered.contains("tabindex=\"0\""));
}

#[test]
fn test_card_title_semantic_structure() {
    let title = CardTitle::new(CardTitleProps {
        level: Some(2),
        ..Default::default()
    });
    
    let rendered = title.render();
    assert!(rendered.contains("<h2"));
}
```

#### **3. Interactive Card Tests**
```rust
#[test]
fn test_interactive_card_behavior() {
    let (clicked, set_clicked) = signal(false);
    
    let card = Card::new(CardProps {
        interactive: Signal::derive(|| true),
        on_click: Some(Callback::new(move |_| {
            set_clicked.set(true);
        })),
        ..Default::default()
    });
    
    // Simulate click
    card.props.on_click.unwrap().run(());
    assert!(clicked.get(), "Card should be clickable");
}
```

#### **4. Integration Tests**
```rust
#[test]
fn test_card_with_form_elements() {
    let card = Card::new(CardProps {
        children: Some(Children::new()),
        ..Default::default()
    });
    
    let rendered = card.render();
    // Test that card integrates with form elements
    assert!(rendered.contains("card"));
}

#[test]
fn test_card_with_button_actions() {
    let card = Card::new(CardProps {
        children: Some(Children::new()),
        ..Default::default()
    });
    
    let rendered = card.render();
    // Test that card integrates with buttons
    assert!(rendered.contains("card"));
}
```

---

## 🚀 Performance Considerations

### **Bundle Size**
- **Base component**: ~3KB
- **With variants**: ~4KB
- **WASM optimized**: ~3.5KB

### **Render Performance**
- **Initial render**: <2ms
- **Hover effects**: <1ms
- **Content updates**: <1ms
- **Memory usage**: <2KB per instance

### **Optimization Strategies**
- Lazy loading for card content
- Efficient class computation
- Minimal re-renders on state changes
- Optimized CSS class merging

---

## 🔄 State Management

### **Card State**
```rust
#[derive(Clone, Debug)]
pub struct CardState {
    pub is_interactive: bool,
    pub is_hovered: bool,
    pub is_focused: bool,
    pub variant: CardVariant,
}

impl CardState {
    pub fn new() -> Self {
        Self {
            is_interactive: false,
            is_hovered: false,
            is_focused: false,
            variant: CardVariant::Default,
        }
    }
    
    pub fn set_interactive(&mut self, interactive: bool) {
        self.is_interactive = interactive;
    }
    
    pub fn set_hovered(&mut self, hovered: bool) {
        self.is_hovered = hovered;
    }
}
```

### **Signal Integration**
```rust
// Card state management
let (card_state, set_card_state) = signal(CardState::new());

view! {
    <Card 
        interactive=move || card_state.get().is_interactive
        on_click=move |_| {
            set_card_state.update(|state| {
                state.set_interactive(true);
            });
        }
    >
        <CardHeader>
            <CardTitle level=2>"Interactive Card"</CardTitle>
            <CardDescription>"Click to interact"</CardDescription>
        </CardHeader>
        <CardContent>
            <p>"Card content goes here"</p>
        </CardContent>
        <CardFooter>
            <Button>"Action"</Button>
        </CardFooter>
    </Card>
}
```

---

## 📱 Responsive Design

### **Breakpoint Behavior**
- **Mobile**: Full width, stacked layout
- **Tablet**: Flexible width, proper spacing
- **Desktop**: Fixed width, hover effects

### **Touch Targets**
- **Minimum size**: 44px × 44px for interactive elements
- **Touch-friendly spacing**
- **Large tap targets for mobile**

---

## 🎨 Theming Support

### **CSS Custom Properties**
```css
:root {
  --card: 0 0% 100%;
  --card-foreground: 222.2 84% 4.9%;
  --card-border: 214.3 31.8% 91.4%;
  --card-shadow: 0 1px 2px 0 rgb(0 0 0 / 0.05);
}
```

### **Dark Mode Support**
- Automatic theme switching
- High contrast mode support
- Custom theme overrides

---

## 🔧 Implementation Notes

### **Current Implementation**
- **File**: `packages/leptos/card/src/default.rs` (142 lines)
- **Status**: ✅ Good foundation, needs enhancement
- **Tests**: `packages/leptos/card/src/tests.rs` (140 lines)

### **Required Implementation**
1. **Add accessibility features** (ARIA attributes, semantic structure)
2. **Implement interactive card functionality**
3. **Add card variants** (destructive, warning, success)
4. **Create comprehensive test suite**
5. **Add performance optimizations**

---

## 📋 Action Items

### **Immediate (Week 1) - Priority 1**
- [ ] **Add accessibility features** (ARIA attributes, semantic structure)
- [ ] **Implement interactive card functionality**
- [ ] **Add card variants** (destructive, warning, success)
- [ ] **Create component rendering tests**

### **Short-term (Week 2-3)**
- [ ] **Implement comprehensive test suite**
- [ ] **Add integration tests**
- [ ] **Create performance benchmarks**
- [ ] **Add card state management**

### **Long-term (Week 4+)**
- [ ] **Advanced card features**
- [ ] **Custom card layouts**
- [ ] **Performance optimizations**
- [ ] **Advanced theming**

---

## 🎯 Success Metrics

### **Quality Metrics**
- **Test coverage**: 90%+ (current: ~40%)
- **Accessibility score**: AAA compliance
- **Performance**: <2ms render time
- **Bundle size**: <4KB optimized

### **Functionality Metrics**
- **Interactive cards**: 100% working
- **Accessibility compliance**: WCAG 2.1 AA
- **Card variants**: 100% functional
- **Integration**: 100% working

---

## 🚨 Critical Issues

### **Must Fix Immediately**
1. **Missing accessibility features** - ARIA attributes, semantic structure
2. **No interactive card tests** - Core functionality not tested
3. **Missing card variants** - Limited styling options
4. **No integration tests** - Card with other components not tested

### **Impact Assessment**
- **Medium impact** on user experience
- **Important for layout functionality**
- **Essential for accessibility compliance**
- **Required for production readiness**

---

This Card component has a **good foundation** but needs **enhancement** to bring it to production-ready status. It serves as a fundamental building block for layouts and content organization.

---

*Design document created: September 20, 2025*  
*Last updated: September 20, 2025*
