# Partner DLQ API Endpoints

## Overview

RESTful API endpoints for monitoring and managing the Partner Dead Letter Queue (DLQ). These endpoints allow administrators to view statistics, process failed messages, retry tasks, and perform maintenance operations.

## Authentication

All DLQ endpoints require admin authentication. Include authentication token in request headers:

```
Authorization: Bearer <token>
```

## Endpoints

### 1. Get DLQ Statistics

Get comprehensive statistics about the DLQ and partner log processing status.

**Endpoint:** `GET /api/dlq/partner_tasks/stats`

**Authentication:** Required (Admin)

**Response:**
```json
{
  "dlq": {
    "messageCount": 5,
    "consumerCount": 0,
    "queueName": "partner_tasks_failed"
  },
  "trackers": {
    "failed": 12,
    "processing": 3,
    "downloaded": 8,
    "processed": 245,
    "archived": 7
  },
  "recentFailures": [
    {
      "id": "507f1f77bcf86cd799439011",
      "logFileName": "application_20250101_120000.log",
      "partner": {
        "id": "507f1f77bcf86cd799439012",
        "name": "SatLoc Systems",
        "code": "SATLOC"
      },
      "customer": {
        "id": "507f1f77bcf86cd799439013",
        "name": "John Doe",
        "username": "john@example.com"
      },
      "errorMessage": "Connection timeout",
      "retryCount": 3,
      "failedAt": "2025-10-02T10:30:00.000Z"
    }
  ]
}
```

**Example:**
```bash
curl -X GET http://localhost:3000/api/dlq/partner_tasks/stats \
  -H "Authorization: Bearer <token>"
```

---

### 2. Get DLQ Messages

Retrieve messages from the Dead Letter Queue without consuming them (peek mode).

**Endpoint:** `GET /api/dlq/partner_tasks/messages`

**Authentication:** Required (Admin)

**Query Parameters:**
- `limit` (optional): Maximum number of messages to retrieve (default: 50)

**Response:**
```json
{
  "messages": [
    {
      "taskInfo": {
        "logFileName": "application_20250101_120000.log",
        "partnerId": "507f1f77bcf86cd799439012",
        "customerId": "507f1f77bcf86cd799439013"
      },
      "errorMessage": "Connection timeout",
      "retryCount": 3,
      "enqueuedAt": "2025-10-02T10:00:00.000Z",
      "headers": {
        "x-death": [...]
      }
    }
  ]
}
```

**Example:**
```bash
curl -X GET "http://localhost:3000/api/dlq/partner_tasks/messages?limit=20" \
  -H "Authorization: Bearer <token>"
```

---

### 3. Process DLQ

Process messages in the Dead Letter Queue - categorizes errors and automatically retries or archives based on error type and age.

**Endpoint:** `POST /api/dlq/:queueName/process`

**Authentication:** Required (Admin)

**Request Body:**
```json
{
  "maxMessages": 100,
  "dryRun": false
}
```

**Parameters:**
- `maxMessages` (optional): Maximum number of messages to process (default: 100)
- `dryRun` (optional): If true, analyze without taking action (default: false)

**Response:**
```json
{
  "processed": 15,
  "retried": 8,
  "archived": 5,
  "categorization": {
    "transient": 8,
    "validation": 3,
    "processing": 2,
    "infrastructure": 1,
    "partner_api": 1,
    "unknown": 0
  },
  "dryRun": false,
  "timestamp": "2025-10-02T11:00:00.000Z"
}
```

**Error Categories:**
- **transient**: Network timeouts, temporary connection issues (auto-retried within 2h window)
- **validation**: Invalid data, missing fields (archived immediately)
- **processing**: Calculation errors, parsing errors (kept for review)
- **infrastructure**: Database errors, filesystem errors (retried with backoff)
- **partner_api**: API authentication failures, rate limiting (retried with delay)
- **unknown**: Unclassified errors (kept for review)

**Example:**
```bash
# Process DLQ
curl -X POST http://localhost:3000/api/dlq/partner_tasks/process \
  -H "Authorization: Bearer <token>" \
  -H "Content-Type: application/json" \
  -d '{"maxMessages": 50, "dryRun": false}'

# Dry run (analyze only)
curl -X POST http://localhost:3000/api/dlq/partner_tasks/process \
  -H "Authorization: Bearer <token>" \
  -H "Content-Type: application/json" \
  -d '{"dryRun": true}'
```

---

### 4. Retry Failed Task

Retry all messages currently in the DLQ back to the main queue.

**Endpoint:** `POST /api/dlq/:queueName/retryAll`

**Authentication:** Required (Admin)

**URL Parameters:**
- `queueName`: Queue name (e.g., "partner_tasks")

**Response:**
```json
{
  "success": true,
  "message": "Retried 15 messages from DLQ",
  "retriedCount": 15,
  "queueName": "partner_tasks"
}
```

**Example:**
```bash
curl -X POST http://localhost:3000/api/dlq/partner_tasks/retryAll \
  -H "Authorization: Bearer <token>"
```

---

### 5. Retry Messages by Position

Retry messages from specific positions in the DLQ.

**Endpoint:** `POST /api/dlq/:queueName/retryByPosition`

**Authentication:** Required (Admin)

**URL Parameters:**
- `queueName`: Queue name

**Request Body:**
```json
{
  "startPosition": 1,
  "endPosition": 10
}
```

**Response:**
```json
{
  "success": true,
  "message": "Retried 10 messages from positions 1-10",
  "retriedCount": 10
}
```

---

### 6. Retry Messages by Header

Retry messages matching specific header values (e.g., partner code).

**Endpoint:** `POST /api/dlq/:queueName/retryByHeader`

**Authentication:** Required (Admin)

**URL Parameters:**
- `queueName`: Queue name

**Request Body:**
```json
{
  "headerName": "partnerCode",
  "headerValue": "SATLOC"
}
```

**Response:**
```json
{
  "success": true,
  "message": "Retried 8 messages matching header partnerCode=SATLOC",
  "retriedCount": 8
}
}
```

**Parameters:**
- `reason` (optional): Reason for archiving

**Response:**
```json
{
  "success": true,
  "message": "Task has been archived"
}
```

**Example:**
```bash
curl -X POST http://localhost:3000/api/dlq/partner_tasks/archive/507f1f77bcf86cd799439011 \
  -H "Authorization: Bearer <token>" \
  -H "Content-Type: application/json" \
  -d '{"reason": "Invalid file format"}'
```

---

### 6. Purge DLQ

⚠️ **DANGEROUS OPERATION** - Permanently delete all messages from the Dead Letter Queue.

**Endpoint:** `DELETE /api/dlq/:queueName/purge`

**Authentication:** Required (Admin)

**Request Body:**
```json
{
  "confirm": true
}
```

**Parameters:**
- `confirm` (required): Must be `true` to confirm the purge operation

**Response:**
```json
{
  "success": true,
  "purgedCount": 25,
  "message": "Purged 25 messages from DLQ"
}
```

**Example:**
```bash
curl -X DELETE http://localhost:3000/api/dlq/partner_tasks/purge \
  -H "Authorization: Bearer <token>" \
  -H "Content-Type: application/json" \
  -d '{"confirm": true}'
```

---

## Web Dashboard

A web-based monitoring dashboard is available at:

```
http://localhost:3000/dlq-monitor.html
```

**Features:**
- Real-time statistics display
- Recent failures with error categorization
- One-click retry/archive operations
- Bulk DLQ processing
- Auto-refresh every 30 seconds

---

## Error Handling

All endpoints return consistent error responses:

**400 Bad Request:**
```json
{
  "error": "Invalid ID format"
}
```

**404 Not Found:**
```json
{
  "error": "Partner log tracker not found"
}
```

**500 Internal Server Error:**
```json
{
  "error": "Failed to get DLQ statistics"
}
```

---

## Usage Examples

### Monitor DLQ Health

```bash
#!/bin/bash
# Check if DLQ has too many messages

STATS=$(curl -s -H "Authorization: Bearer $TOKEN" \
  http://localhost:3000/api/dlq/partner_tasks/stats)

DLQ_COUNT=$(echo $STATS | jq -r '.dlq.messageCount')

if [ "$DLQ_COUNT" -gt 50 ]; then
  echo "WARNING: DLQ has $DLQ_COUNT messages!"
  # Send alert to admin
fi
```

### Automated DLQ Processing

```bash
#!/bin/bash
# Process DLQ every hour via cron

curl -X POST http://localhost:3000/api/dlq/partner_tasks/process \
  -H "Authorization: Bearer $TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"maxMessages": 100}' \
  >> /var/log/dlq-processing.log 2>&1
```

### Retry All Failed Messages (Queue-Native)

```javascript
// Retry all failed messages in a queue (up to max limit)
async function retryAllDLQMessages(queueName = 'partner_tasks', maxMessages = 100) {
  const response = await fetch(`/api/partners/dlq/${queueName}/retryAll`, {
    method: 'POST',
    headers: {
      'Authorization': `Bearer ${token}`,
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({ maxMessages })
  });
  
  const result = await response.json();
  console.log(`Retried ${result.retriedCount} messages from ${queueName} DLQ`);
  return result;
}

// Retry by position range (0-based indexing)
async function retryByPosition(queueName, startPosition, endPosition) {
  const response = await fetch(`/api/partners/dlq/${queueName}/retryByPosition`, {
    method: 'POST',
    headers: {
      'Authorization': `Bearer ${token}`,
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({ startPosition, endPosition })
  });
  
  return await response.json();
}
```

---

## Integration with Monitoring

### Prometheus Metrics (Future Enhancement)

```
# HELP agm_dlq_messages_total Total messages in DLQ
# TYPE agm_dlq_messages_total gauge
agm_dlq_messages_total 5

# HELP agm_failed_tasks_total Total failed tasks
# TYPE agm_failed_tasks_total gauge
agm_failed_tasks_total 12

# HELP agm_processed_tasks_total Total successfully processed tasks
# TYPE agm_processed_tasks_total counter
agm_processed_tasks_total 245
```

### Grafana Dashboard Query Examples

```sql
-- Failed tasks by partner
SELECT p.name, COUNT(*) as failed_count
FROM partnerlogtrackers plt
JOIN partners p ON plt.partnerId = p._id
WHERE plt.status = 'failed'
GROUP BY p.name

-- Error categories over time
SELECT DATE(updatedAt) as date, 
       COUNT(*) as count,
       errorMessage
FROM partnerlogtrackers
WHERE status = 'failed'
GROUP BY DATE(updatedAt), errorMessage
```

---

## Best Practices

1. **Regular Monitoring**: Check DLQ stats daily
2. **Automated Processing**: Run DLQ processing every 4-6 hours
3. **Manual Review**: Review archived tasks weekly
4. **Alert Thresholds**: 
   - Warning: DLQ > 20 messages
   - Critical: DLQ > 50 messages
5. **Cleanup**: Archive tasks older than 7 days
6. **Documentation**: Document recurring error patterns

---

## Related Documentation

- [Partner DLQ Handling Guide](./PARTNER_DLQ_HANDLING.md)
- [Partner Integration Architecture](./PARTNER_INTEGRATION_ARCHITECTURE.md)
- [SatLoc Implementation Summary](./SATLOC_IMPLEMENTATION_SUMMARY.md)