# Component Organization Guide

Guide for splitting large components and modals into manageable files.

## When to Split Components

Split a component when:
- File exceeds 200 lines
- Component has multiple distinct sections (tabs, steps, panels)
- Logic becomes hard to follow
- Multiple developers work on different parts

## Modal Organization Pattern

### Structure for Large Modals

```
src/routes/(app)/feature/
├── +page.svelte              # Main page
├── FeatureModal.svelte       # Main modal container
└── feature-modal/            # Modal sub-components (kebab-case folder)
    ├── modals/               # Nested modals
    │   └── PickerModal.svelte
    └── tabs/                 # Tab content components
        ├── BasicInfoTab.svelte
        ├── SettingsTab.svelte
        └── AdvancedTab.svelte
```

### Example: Test Form Modal

**Location**: `src/routes/(app)/master-data/tests/test-modal/`

```svelte
<!-- TestFormModal.svelte -->
<script>
  import Modal from '$lib/components/Modal.svelte';
  import BasicInfoTab from './test-modal/tabs/BasicInfoTab.svelte';
  import TechDetailsTab from './test-modal/tabs/TechDetailsTab.svelte';
  import CalcDetailsTab from './test-modal/tabs/CalcDetailsTab.svelte';
  
  let { open = $bindable(false), test = null } = $props();
  let activeTab = $state('basic');
  let formData = $state({});
</script>

<Modal bind:open title={test ? 'Edit Test' : 'New Test'} size="xl">
  {#snippet children()}
    <div class="tabs tabs-boxed mb-4">
      <button class="tab" class:tab-active={activeTab === 'basic'} onclick={() => activeTab = 'basic'}>Basic</button>
      <button class="tab" class:tab-active={activeTab === 'technical'} onclick={() => activeTab = 'technical'}>Technical</button>
      <button class="tab" class:tab-active={activeTab === 'calculation'} onclick={() => activeTab = 'calculation'}>Calculation</button>
    </div>
    
    {#if activeTab === 'basic'}
      <BasicInfoTab bind:formData />
    {:else if activeTab === 'technical'}
      <TechDetailsTab bind:formData />
    {:else if activeTab === 'calculation'}
      <CalcDetailsTab bind:formData />
    {/if}
  {/snippet}
</Modal>
```

```svelte
<!-- test-modal/tabs/BasicInfoTab.svelte -->
<script>
  let { formData = $bindable({}) } = $props();
</script>

<div class="space-y-4">
  <div class="form-control">
    <label class="label">Test Name</label>
    <input class="input input-bordered" bind:value={formData.name} />
  </div>
  <div class="form-control">
    <label class="label">Description</label>
    <textarea class="textarea textarea-bordered" bind:value={formData.description}></textarea>
  </div>
</div>
```

## Data Flow

### Parent to Child
- Pass data via props (`bind:formData`)
- Use `$bindable()` for two-way binding
- Keep state in parent when shared across tabs

### Child to Parent
- Use callbacks for actions (`onSave`, `onClose`)
- Modify bound data directly (with `$bindable`)
- Emit events for complex interactions

## Props Interface Pattern

```javascript
// Define props with JSDoc
/** @type {{ formData: Object, onValidate: Function, readonly: boolean }} */
let { 
  formData = $bindable({}), 
  onValidate = () => true,
  readonly = false 
} = $props();
```

## Naming Conventions

- **Main modal**: `{Feature}Modal.svelte` (e.g., `TestFormModal.svelte`)
- **Tab components**: `{TabName}Tab.svelte` (e.g., `BasicInfoTab.svelte`)
- **Nested modals**: `{Action}Modal.svelte` (e.g., `ConfirmDeleteModal.svelte`)
- **Folder names**: kebab-case matching the modal name (e.g., `test-modal/`)

## Shared State Management

For complex modals with shared state across tabs:

```javascript
// In main modal
let sharedState = $state({
  dirty: false,
  errors: {},
  selectedItems: []
});

// Pass to tabs
<TabName formData={formData} sharedState={sharedState} />
```

## Import Order in Sub-components

Same as main components:
1. Svelte imports
2. `$lib/*` imports
3. External libraries
4. Relative imports (other tabs/modals)

## Testing Split Components

```bash
# Test individual tab component
vitest run src/routes/feature/modal-tabs/BasicInfoTab.test.js

# Test main modal integration
vitest run src/routes/feature/FeatureModal.test.js
```

## Benefits

- **Maintainability**: Each file has single responsibility
- **Collaboration**: Multiple developers can work on different tabs
- **Testing**: Test individual sections in isolation
- **Performance**: Only render visible tab content
- **Reusability**: Tabs can be used in different modals