# Email Template Models

## Overview

The Email Template module provides a reusable template system with Handlebars-style variable interpolation, version history, and test email functionality.

**Models (4):**
- EmailTemplate — Template master with categories
- EmailTemplateVariable — Variable definitions
- EmailTemplateVersion — Version history
- EmailTemplateTestLog — Test email audit

**Key Features:**
- Handlebars-style {{VAR}} interpolation
- 3 categories: INFLUENCE, MAP, SYSTEM
- System template protection (isSystem flag prevents deletion)
- Version history with auto-increment version numbers
- Conditional variables for {{#if}} blocks
- Test email sending with sample data
- HTML + plain text content

See [Schema Reference](../schema.md#email-templates) for complete field listings.

---

## Template Categories

```prisma
enum EmailTemplateCategory {
  INFLUENCE  // Campaign emails, response verification
  MAP        // Shift confirmations, reminders
  SYSTEM     // Password resets, welcome emails
}
```

---

## Variable Interpolation

**Syntax:** Handlebars-style `{{VARIABLE_NAME}}`

**Example Template:**
```html
<p>Hello {{USER_NAME}},</p>
<p>Thank you for signing up for the shift:</p>
<ul>
  <li>Title: {{SHIFT_TITLE}}</li>
  <li>Date: {{SHIFT_DATE}}</li>
  <li>Time: {{SHIFT_TIME}}</li>
</ul>
{{#if IS_NEW_USER}}
<p>Your temporary password is: {{TEMP_PASSWORD}}</p>
{{/if}}
```

**Variable Record:**
```typescript
{
  key: 'USER_NAME',
  label: 'User Name',
  description: 'Name of the volunteer',
  isRequired: true,
  isConditional: false,
  sampleValue: 'Jane Doe',
  sortOrder: 0,
}
```

---

## Version History

**Auto-Increment Version Numbers:**
```typescript
const latestVersion = await prisma.emailTemplateVersion.findFirst({
  where: { templateId },
  orderBy: { versionNumber: 'desc' },
});

const newVersion = await prisma.emailTemplateVersion.create({
  data: {
    templateId,
    versionNumber: (latestVersion?.versionNumber || 0) + 1,
    subjectLine,
    htmlContent,
    textContent,
    changeNotes: 'Updated call-to-action wording',
    createdByUserId: user.id,
  },
});
```

---

## System Templates (4 seeded)

**1. campaign-email** (INFLUENCE)
- Variables: CAMPAIGN_TITLE, MESSAGE, USER_NAME, USER_EMAIL, POSTAL_CODE, RECIPIENT_NAME, RECIPIENT_LEVEL, ORGANIZATION_NAME, TIMESTAMP
- Used by: Campaign email sending

**2. response-verification** (INFLUENCE)
- Variables: CAMPAIGN_TITLE, RESPONSE_TYPE, RESPONSE_TEXT, SUBMITTER_NAME, SUBMITTED_DATE, VERIFICATION_URL, REPORT_URL, ORGANIZATION_NAME, TIMESTAMP
- Used by: Response wall submission verification

**3. shift-signup-confirmation** (MAP)
- Variables: ORGANIZATION_NAME, USER_NAME, USER_EMAIL, SHIFT_TITLE, SHIFT_DATE, SHIFT_TIME, SHIFT_LOCATION, IS_NEW_USER, TEMP_PASSWORD, LOGIN_URL
- Used by: Public shift signup

**4. shift-details** (MAP)
- Variables: ORGANIZATION_NAME, USER_NAME, SHIFT_TITLE, SHIFT_DATE, SHIFT_START_TIME, SHIFT_END_TIME, SHIFT_LOCATION, SHIFT_DESCRIPTION, CURRENT_VOLUNTEERS, MAX_VOLUNTEERS, SHIFT_STATUS
- Used by: Shift reminder emails

---

## Related Documentation

- [Schema Reference](../schema.md#email-templates) — Complete field listings
- [Seeding](../seeding.md) — Default templates
- [API Email Template Routes](../../api/email-templates.md) — REST endpoints