# OpenVPN Monitor API v3 Documentation

This API provides access to OpenVPN monitoring data, including real-time client status and historical data stored in a Time Series Database (TSDB). It features optimized aggregation for fast visualization.

**Base URL:** `http://<your-server-ip>:5001/api/v1`

---

## 1. Global Analytics (Dashboard)

Provides aggregated trend data for the entire server. optimized for visualization with exactly **96 data points** regardless of the time range.

### `GET /analytics`

#### Query Parameters
| Parameter | Type | Default | Description |
| :--- | :--- | :--- | :--- |
| `range` | string | `24h` | Time range. Supported: `24h`, `7d`, `30d`. |

#### Behavior
*   **24h**: Returns 15-minute intervals.
*   **7d**: Returns 105-minute intervals (1h 45m).
*   **30d**: Returns 450-minute intervals (7h 30m).
*   **Zero-Filling**: Missing data periods are automatically filled with zeros to ensure graph continuity.

#### Example Response
```json
{
  "success": true,
  "timestamp": "2026-01-09 12:00:00",
  "range": "24h",
  "data": {
    "global_history_24h": [
      {
        "timestamp": "2026-01-09 11:45:00",
        "total_rx": 102400,
        "total_tx": 51200,
        "active_count": 5
      },
      ...
    ],
    "max_concurrent_24h": 12,
    "top_clients_24h": [ ... ],
    "traffic_distribution": { "rx": 1000, "tx": 500 }
  }
}
```

---

## 2. Client Statistics (Detail + History)

Main endpoint for individual client reports. Supports **Dynamic Aggregation** to optimize payload size (~98% reduction for 24h view).

### `GET /stats/<common_name>`

#### Query Parameters
| Parameter | Type | Default | Description |
| :--- | :--- | :--- | :--- |
| `range` | string | `24h` | Time range. Formats: `1h`, `3h`, `6h`, `12h`, `24h`, `7d`, `30d`. |
| `resolution` | string | `auto` | Force resolution (optional): `raw`, `5min`, `hourly`, `auto`. |

#### Dynamic Aggregation Logic (`resolution=auto`)
The API automatically selects the aggregation interval based on the requested range to balance detail and performance:

| Range | Resolution | Points | Source Table |
| :--- | :--- | :--- | :--- |
| **1h** | **30 sec** | 120 | `usage_history` (Raw) |
| **3h** | **1 min** | 180 | `usage_history` (Raw) |
| **6h** | **2 min** | 180 | `usage_history` (Raw) |
| **12h** | **5 min** | 144 | `usage_history` (Raw) |
| **24h** | **15 min** | 96 | `usage_history` (Raw) |
| **7d** | **1 Hour** | 168 | `stats_hourly` |
| **30d** | **6 Hours** | 120 | `stats_6h` |

*All short-term ranges (≤24h) include automatic **Zero-Filling**.*

#### Examples: Long-Term Aggregated Data

To explicitly request data from long-term storage tables (skipping raw data), use the `resolution` parameter or specific ranges.

**1. Last 7 Days (Hourly Resolution)**
Uses `stats_hourly` table. Reduced precision for weekly trends.
```http
GET /api/v1/stats/user-alice?range=7d
```
*or explicit resolution:*
```http
GET /api/v1/stats/user-alice?range=7d&resolution=hourly
```

**2. Last 30 Days (6-Hour Resolution)**
Uses `stats_6h` table. Ideal for monthly volume analysis.
```http
GET /api/v1/stats/user-alice?range=30d
```

**3. Last 1 Year (Daily Resolution)**
Uses `stats_daily` table. Extremely lightweight for annual reporting.
```http
GET /api/v1/stats/user-alice?range=1y&resolution=daily
```

#### Example Response
```json
{
  "success": true,
  "data": {
    "common_name": "user-alice",
    "status": "Active",
    "current_rates": { "recv_mbps": 1.5, "sent_mbps": 0.2 },
    "totals": { "received_mb": 500.25, "sent_mb": 120.10 },
    "history": [
      {
        "timestamp": "2026-01-09 11:30:00",
        "bytes_received": 5000,
        "bytes_sent": 2000,
        "bytes_received_rate_mbps": 0.5,
        "bytes_sent_rate_mbps": 0.1
      },
      ...
    ],
    "meta": {
      "resolution_used": "usage_history_hires",
      "record_count": 120
    }
  }
}
```

---

## 3. Current Statistics (All Clients)

Returns a snapshot of all known clients.

### `GET /stats`

#### Example Response
```json
{
  "success": true,
  "count": 2,
  "data": [
    {
      "common_name": "user-alice",
      "status": "Active",
      "current_recv_rate_mbps": 1.5,
      "total_received_mb": 500.2
    },
    ...
  ]
}
```

---

## 4. System Statistics

Aggregated metrics for the Server.

### `GET /stats/system`

#### Example Response
```json
{
  "success": true,
  "data": {
    "total_clients": 15,
    "active_clients": 3,
    "total_received_gb": 10.0,
    "total_sent_gb": 5.0
  }
}
```

---

## 5. Certificates

SSL Certificate expiration tracking.

### `GET /certificates`

#### Example Response
```json
{
  "success": true,
  "data": [
    {
      "file": "user-alice.crt",
      "days_remaining": "360 days",
      "is_expired": false
    }
  ]
}
```

---

## 6. Utility Methods

### `GET /clients`
Simple list of clients (Common Name + Status) for UI dropdowns.

### `GET /health`
Database connectivity check. Returns `{"status": "healthy"}`.