# Email Templates

The Email Templates feature provides a complete email template management system with variable substitution, versioning, and rich text editing. Create reusable email templates for campaigns, notifications, and communications.

## Overview

The Email Templates system consists of four integrated components:

1. **[Template System](template-system.md)** - Template CRUD and management
2. **[Editor](editor.md)** - Rich text editor with variable insertion
3. **[Variables](variables.md)** - Dynamic content placeholders
4. **[Versioning](versioning.md)** - Template version history

## Features

### Template Management

- Create/edit/delete templates
- Category organization
- Template types (campaign, notification, system)
- Published/draft status
- Search and filtering
- Clone templates

### Rich Text Editor

- WYSIWYG HTML editor
- Variable insertion menu
- Preview mode
- HTML source view
- Image upload (future)
- Link management

### Variable System

Dynamic placeholders:

- **User variables** - `{{user.name}}`, `{{user.email}}`
- **Campaign variables** - `{{campaign.name}}`, `{{campaign.description}}`
- **Representative variables** - `{{rep.name}}`, `{{rep.title}}`, `{{rep.email}}`
- **Custom variables** - Template-specific placeholders
- **System variables** - `{{site.name}}`, `{{current.date}}`

### Version History

- Auto-save on changes
- Version diff viewer
- Restore previous versions
- Change log

## User Flow

### Admin Experience

1. **Create Template** (`/app/email-templates`)
   - Click "New Template"
   - Enter name and category
   - Set template type
   - Save draft

2. **Edit Template** (`/app/email-templates/:id/edit`)
   - Full-screen rich text editor
   - Insert variables from dropdown
   - Preview with sample data
   - Save changes

3. **Use Template**
   - Select template in campaign form
   - Variables auto-populated from context
   - Send email with processed template

4. **Manage Versions** (`/app/email-templates/:id/versions`)
   - View version history
   - Compare versions
   - Restore previous version

## Architecture

### Backend Components

**Module:**
- `api/src/modules/email-templates/email-templates.routes.ts` - Template CRUD
- `api/src/modules/email-templates/email-templates.service.ts` - Business logic
- `api/src/modules/email-templates/email-templates.schemas.ts` - Zod validation

**Database Models:**
- `EmailTemplate` - Template definitions (name, content, variables)
- `EmailTemplateVersion` - Version history (future)

**Email Processing:**
- Variable substitution in `email.service.ts`
- Mustache-style templating: `{{variable}}`
- HTML escaping for security

### Frontend Components

**Admin Pages:**
- `admin/src/pages/EmailTemplatesPage.tsx` - Template management table
- `admin/src/pages/EmailTemplateEditorPage.tsx` - Full-screen editor

**Editor Components:**
- `admin/src/components/email-templates/TemplateEditor.tsx` - Rich text editor
- `admin/src/components/email-templates/VariableInserter.tsx` - Variable dropdown

## Configuration

### Template Types

- **campaign** - Campaign email templates
- **notification** - User notifications
- **system** - System emails (verification, password reset)
- **custom** - Custom templates

### Template Categories

- **Influence** - Campaign-related templates
- **Map** - Shift/canvass notifications
- **User** - User account emails
- **System** - Automated system emails

## Variable System

### Available Variables

**User Context:**
```
{{user.id}}           # User ID
{{user.email}}        # Email address
{{user.name}}         # Full name
{{user.role}}         # User role
```

**Campaign Context:**
```
{{campaign.id}}       # Campaign ID
{{campaign.name}}     # Campaign name
{{campaign.description}} # Description
{{campaign.emailTemplate}} # Email body
```

**Representative Context:**
```
{{rep.name}}          # Representative name
{{rep.title}}         # Title (MP, MLA, etc.)
{{rep.email}}         # Email address
{{rep.phone}}         # Phone number
{{rep.district}}      # District name
```

**System Context:**
```
{{site.name}}         # Site name
{{site.url}}          # Site URL
{{current.date}}      # Current date
{{current.year}}      # Current year
```

### Variable Insertion

```typescript
// Insert variable at cursor position
editor.insertContent('{{user.name}}');

// Variable dropdown menu
<Select>
  <Option value="{{user.name}}">User Name</Option>
  <Option value="{{user.email}}">User Email</Option>
  <Option value="{{rep.name}}">Representative Name</Option>
</Select>
```

### Variable Processing

Server-side processing in `email.service.ts`:

```typescript
function processTemplate(
  template: string,
  variables: Record<string, any>
): string {
  let processed = template;

  for (const [key, value] of Object.entries(variables)) {
    const placeholder = `{{${key}}}`;
    processed = processed.replace(
      new RegExp(placeholder, 'g'),
      escapeHtml(String(value))
    );
  }

  return processed;
}
```

## Database Schema

### EmailTemplate Model

```prisma
model EmailTemplate {
  id          Int      @id @default(autoincrement())
  name        String
  subject     String
  body        String   @db.Text
  category    String?
  type        String   @default("custom")
  variables   Json?    # Available variables
  published   Boolean  @default(false)
  createdAt   DateTime @default(now())
  updatedAt   DateTime @updatedAt
}
```

## API Endpoints

### Admin Endpoints

```
GET    /api/email-templates            # List templates
POST   /api/email-templates            # Create template
GET    /api/email-templates/:id        # Get template
PATCH  /api/email-templates/:id        # Update template
DELETE /api/email-templates/:id        # Delete template
POST   /api/email-templates/:id/clone  # Clone template
GET    /api/email-templates/:id/preview # Preview with sample data
```

## Security

### HTML Escaping

All variable values are HTML-escaped to prevent XSS:

```typescript
import { escapeHtml } from '../utils/sanitize';

const safe = escapeHtml(userInput);
// Converts: < > & " ' to HTML entities
```

### Template Validation

- Subject line: 1-200 characters
- Body: Required, max 50,000 characters
- Variables: Valid JSON object
- Category: Predefined list

## Best Practices

### Template Design

- Clear subject lines (50-60 chars)
- Personalize with variables
- Mobile-responsive HTML
- Plain text alternative
- Unsubscribe link
- Branding consistency

### Variable Usage

- Document available variables
- Provide defaults for missing values
- Test with sample data
- Validate variable names

### Version Management

- Meaningful version names
- Document changes
- Test before publishing
- Keep version history

## Desktop-Only Editor

Email template editor requires desktop browser:

```typescript
const screens = Grid.useBreakpoint();
const isMobile = !screens.md;

if (isMobile) {
  return (
    <Alert
      message="Desktop Required"
      description="Email editor requires desktop browser"
      type="warning"
    />
  );
}
```

## Integration Points

### Campaign Emails

Campaign emails use templates:

```typescript
// Select template in campaign form
<Select>
  {templates.map(t => (
    <Option value={t.id}>{t.name}</Option>
  ))}
</Select>

// Process template with campaign data
const emailBody = processTemplate(template.body, {
  'user.name': user.name,
  'campaign.name': campaign.name,
  'rep.name': representative.name,
});
```

### System Emails

System emails (verification, password reset):

```typescript
// Load system template
const template = await getTemplateByType('email-verification');

// Process with user data
const emailBody = processTemplate(template.body, {
  'user.name': user.name,
  'verify.link': verificationUrl,
});

// Send email
await emailService.sendEmail({
  to: user.email,
  subject: template.subject,
  html: emailBody,
});
```

## Related Documentation

- [Template System](template-system.md)
- [Editor](editor.md)
- [Variables](variables.md)
- [Versioning](versioning.md)
- [Email Templates Page](../../frontend/pages/admin/email-templates-page.md)
- [Email Template Editor Page](../../frontend/pages/admin/email-template-editor-page.md)
- [Email Service](../../backend/services/index.md)
- [Campaign Manager Guide](../../user-guides/campaign-manager-guide.md)