# HVAC Template System API Documentation

**Version**: 2.0
**Date**: September 25, 2025
**Status**: Production Ready

---

## 📋 Overview

The HVAC Template System API provides comprehensive template management functionality for the HVAC Event Form Builder, including template creation, retrieval, preview, and application capabilities.

## 🏗️ Architecture

### Core Components

1. **HVAC_Event_Form_Builder** - Form builder with template integration
2. **HVAC_Event_Template_Manager** - Template CRUD operations
3. **HVAC_Shortcodes** - AJAX handlers for template operations
4. **JavaScript Frontend** - Template UI interactions

---

## 🔧 PHP API Reference

### HVAC_Event_Form_Builder Methods

#### `add_template_selector(array $categories = []): self`
Adds an enhanced template selector dropdown to the form.

**Parameters:**
- `$categories` (array) - Optional array of template categories to filter

**Returns:** `self` for method chaining

**Example:**
```php
$form_builder->add_template_selector(['training', 'workshop', 'certification']);
```

#### `add_template_actions(): self`
Adds template action buttons including "Save as Template".

**Returns:** `self` for method chaining

#### `add_progressive_disclosure(): self`
Adds the progressive disclosure toggle for advanced options.

**Returns:** `self` for method chaining

#### `mark_field_as_advanced(string $field_name): self`
Marks a specific field as advanced for progressive disclosure.

**Parameters:**
- `$field_name` (string) - Name of the field to mark as advanced

**Returns:** `self` for method chaining

**Example:**
```php
$form_builder->mark_field_as_advanced('event_capacity')
             ->mark_field_as_advanced('event_cost');
```

#### `load_template(string $template_id): bool`
Loads template data into the form builder.

**Parameters:**
- `$template_id` (string) - Template ID to load

**Returns:** `bool` - Success status

### HVAC_Shortcodes AJAX Handlers

#### `ajax_get_template_preview()`
**Action:** `hvac_get_template_preview`
**Method:** POST
**Authentication:** Required (trainer role)

**Request Parameters:**
- `template_id` (string) - Template ID to preview
- `nonce` (string) - WordPress nonce for security

**Response:**
```json
{
  "success": true,
  "data": {
    "id": "template_123",
    "name": "Basic Training Template",
    "description": "Standard template for training events",
    "category": "training",
    "field_data": {
      "event_title": "Sample Training Event",
      "event_description": "...",
      "event_capacity": "50"
    },
    "created_by": 1,
    "created_at": "2025-09-25 12:00:00"
  }
}
```

#### `ajax_load_template_data()`
**Action:** `hvac_load_template_data`
**Method:** POST
**Authentication:** Required (trainer role)

**Request Parameters:**
- `template_id` (string) - Template ID to load
- `nonce` (string) - WordPress nonce for security

**Response:**
```json
{
  "success": true,
  "data": {
    "event_title": "Sample Training Event",
    "event_description": "Comprehensive training session",
    "event_capacity": "50",
    "event_cost": "299.00"
  }
}
```

#### `ajax_save_template()`
**Action:** `hvac_save_template`
**Method:** POST
**Authentication:** Required (trainer role)

**Request Parameters:**
- `template_name` (string) - Template name
- `template_description` (string) - Template description
- `template_category` (string) - Template category
- `is_public` (bool) - Whether template is public
- `field_data` (object) - Form field data to save
- `nonce` (string) - WordPress nonce for security

**Response:**
```json
{
  "success": true,
  "data": {
    "message": "Template saved successfully",
    "template_id": "template_456"
  }
}
```

---

## 🎨 JavaScript API Reference

### Template Preview Functions

#### `hvacShowTemplatePreview(templateId)`
Shows the template preview modal for the specified template.

**Parameters:**
- `templateId` (string) - Template ID to preview

**Example:**
```javascript
hvacShowTemplatePreview('template_123');
```

#### `hvacCloseTemplatePreview()`
Closes the template preview modal.

#### `hvacApplyTemplate()`
Applies the currently previewed template to the form.

### Save Template Functions

#### `hvacShowSaveTemplateDialog(event)`
Shows the save template dialog.

**Parameters:**
- `event` (Event) - Click event to prevent default

#### `hvacCloseSaveDialog()`
Closes the save template dialog.

#### `hvacSaveAsTemplate()`
Saves the current form as a new template.

### Progressive Disclosure Functions

#### `hvacToggleAdvancedOptions()`
Toggles the visibility of advanced form options with animations.

### Auto-save Functions

#### `performAutoSave()`
Performs an auto-save of the current form state.

#### `attemptDraftRecovery()`
Attempts to recover draft data on page load.

#### `updateAutoSaveStatus(status, message)`
Updates the auto-save status indicator.

**Parameters:**
- `status` (string) - Status type: 'saving', 'saved', 'error', 'draft-loaded'
- `message` (string) - Optional custom message

---

## 🗄️ Data Structures

### Template Object Structure
```javascript
{
  id: "template_123",
  name: "Training Template",
  description: "Standard training event template",
  category: "training",
  is_public: true,
  field_data: {
    event_title: "Sample Title",
    event_description: "Sample Description",
    event_capacity: "50",
    event_cost: "299.00"
  },
  meta_data: {
    source: "event_form",
    created_at: "2025-09-25T12:00:00Z",
    user_ip: "192.168.1.1"
  },
  created_by: 1,
  created_at: "2025-09-25 12:00:00"
}
```

### Auto-save Data Structure
```javascript
{
  formData: {
    event_title: "Event Title",
    event_description: "Event Description",
    // ... other form fields
  },
  timestamp: "2025-09-25T12:00:00.000Z",
  url: "https://example.com/trainer/events/create/",
  version: "2.0"
}
```

---

## 🔒 Security Implementation

### Authentication & Authorization
- **Required Role:** `hvac_trainer` or `hvac_master_trainer`
- **Nonce Verification:** All AJAX requests require valid WordPress nonce
- **Permission Checks:** Role validation on all template operations

### Input Sanitization
```php
// Template data sanitization
$template_name = sanitize_text_field($_POST['template_name']);
$template_description = sanitize_textarea_field($_POST['template_description']);
$template_category = sanitize_text_field($_POST['template_category']);

// Field data sanitization
foreach ($field_data as $key => $value) {
    $sanitized_key = sanitize_key($key);
    if (is_array($value)) {
        $sanitized_field_data[$sanitized_key] = array_map('sanitize_text_field', $value);
    } else {
        $sanitized_field_data[$sanitized_key] = sanitize_text_field($value);
    }
}
```

### Error Handling
- **Template Not Found:** Returns appropriate error messages
- **Permission Denied:** Blocks unauthorized access attempts
- **Validation Failures:** Provides specific validation error messages
- **Storage Limits:** Handles localStorage quota exceeded gracefully

---

## 🎯 Usage Examples

### Creating a Form with Template Support
```php
// Initialize form builder with template support
$form_builder = new HVAC_Event_Form_Builder('hvac_event_form', true);

// Create form with all template features
$form_builder->create_event_form([
    'include_template_selector' => true,
    'include_venue_fields' => true,
    'include_organizer_fields' => true,
    'include_cost_fields' => true,
    'include_capacity_fields' => true,
    'include_datetime_fields' => true,
    'template_categories' => ['general', 'training', 'workshop', 'certification']
]);

// Render the form
echo $form_builder->render();
```

### JavaScript Template Integration
```javascript
jQuery(document).ready(function($) {
    // Initialize template selector functionality
    $(document).on('change', '[name="event_template"]', function() {
        const templateId = $(this).val();
        if (templateId && templateId !== '0') {
            hvacShowTemplatePreview(templateId);
        }
    });

    // Initialize auto-save
    createAutoSaveIndicator();
    setTimeout(attemptDraftRecovery, 500);

    // Initialize progressive disclosure
    if ($('.advanced-field').length > 0) {
        setupAdvancedFieldGroups();
    }
});
```

### Custom Template Categories
```php
// Define custom template categories
$custom_categories = [
    'certification' => 'Certification Events',
    'webinar' => 'Online Webinars',
    'conference' => 'Conference Sessions',
    'workshop' => 'Hands-on Workshops'
];

// Add template selector with custom categories
$form_builder->add_template_selector(array_keys($custom_categories));
```

---

## 📊 Performance Considerations

### Auto-save Optimization
- **Debounce Timing:** 1-3 seconds based on field type
- **Selective Storage:** Only saves fields with meaningful content
- **Quota Management:** Falls back to essential fields if storage full
- **Background Operation:** Uses `visibilitychange` for tab switching

### Template Loading
- **Cached Results:** Template lists cached for performance
- **AJAX Optimization:** Minimal data transfer for preview/apply operations
- **Progressive Loading:** Templates loaded on demand

### Animation Performance
- **CSS Transitions:** Hardware-accelerated transforms
- **Staggered Reveals:** 50ms delays prevent janky animations
- **Efficient Selectors:** Optimized jQuery selectors

---

## 🧪 Testing Guidelines

### Unit Testing
```php
// Test template creation
$template_data = [
    'name' => 'Test Template',
    'category' => 'testing',
    'field_data' => ['event_title' => 'Test Event']
];

$result = $template_manager->create_template($template_data);
$this->assertTrue($result['success']);
```

### Integration Testing
```javascript
// Test template preview functionality
QUnit.test('Template Preview', function(assert) {
    const done = assert.async();

    hvacShowTemplatePreview('test_template_123');

    setTimeout(function() {
        assert.ok($('#hvac-template-preview').is(':visible'), 'Preview modal shown');
        done();
    }, 500);
});
```

### Auto-save Testing
```javascript
// Test auto-save functionality
QUnit.test('Auto-save Operation', function(assert) {
    $('#event-title').val('Test Event').trigger('input');

    setTimeout(function() {
        const draftData = localStorage.getItem('hvac_event_draft');
        assert.ok(draftData, 'Draft data saved');

        const parsed = JSON.parse(draftData);
        assert.equal(parsed.formData.event_title, 'Test Event', 'Title saved correctly');
    }, 3500);
});
```

---

## 🚀 Deployment Notes

### Dependencies
- WordPress 5.0+
- jQuery 3.0+
- HVAC Event Template Manager
- TEC Core (for event creation)

### File Structure
```
includes/
├── class-hvac-event-form-builder.php
├── class-hvac-shortcodes.php
└── class-hvac-event-template-manager.php

templates/
└── page-tec-create-event.php

assets/
├── css/ (inline styles in template)
└── js/  (inline scripts in template)
```

### Configuration
```php
// Enable template mode in form builder
$form_builder = new HVAC_Event_Form_Builder('form_id', true); // true enables templates

// Configure auto-save timing (optional)
define('HVAC_AUTOSAVE_DELAY_TEXT', 3000);    // 3 seconds for text fields
define('HVAC_AUTOSAVE_DELAY_SELECT', 1000);  // 1 second for dropdowns
```

---

## 📚 Related Documentation

- **[PHASE-2B-TEMPLATE-SYSTEM-FEATURES.md](PHASE-2B-TEMPLATE-SYSTEM-FEATURES.md)** - Complete feature documentation
- **[PHASE-2-TEC-INTEGRATION-ANALYSIS.md](PHASE-2-TEC-INTEGRATION-ANALYSIS.md)** - Integration analysis
- **[ARCHITECTURE.md](ARCHITECTURE.md)** - System architecture
- **[TROUBLESHOOTING.md](TROUBLESHOOTING.md)** - Common issues and solutions

---

## 🐛 Troubleshooting

### Common Issues

#### Template Preview Not Loading
```javascript
// Check AJAX URL and nonce
console.log('AJAX URL:', ajaxurl);
console.log('Nonce:', $('[name="hvac_event_form_nonce"]').val());

// Verify template ID is valid
console.log('Template ID:', templateId);
```

#### Auto-save Not Working
```javascript
// Check localStorage availability
if (typeof(Storage) !== "undefined") {
    console.log('localStorage available');
} else {
    console.log('localStorage not supported');
}

// Check for quota exceeded errors
try {
    localStorage.setItem('test', 'data');
    console.log('Storage working');
} catch(e) {
    console.log('Storage error:', e);
}
```

#### Progressive Disclosure Issues
```javascript
// Check advanced field detection
console.log('Advanced fields found:', $('.advanced-field').length);

// Verify localStorage state
console.log('Advanced options state:', localStorage.getItem('hvac_advanced_options_visible'));
```

---

*API Documentation generated for HVAC Template System v2.0*
*🤖 Generated with [Claude Code](https://claude.ai/code)*